The 50 most-cited articles in Cancer Research, 2020

Ras is frequently mutated in cancer, however, there is a lack of consensus in the literature regarding the cancer mutation frequency of Ras, with quoted values varying from 10%-30%. This variability is at least in part due to the selective aggregation of data from different databases and the dominant influence of particular cancer types and particular Ras isoforms within these datasets. To provide a more definitive figure for Ras mutation frequency in cancer, we cross-referenced the data in all major publicly accessible cancer mutation databases to determine reliable mutation frequency values for each Ras isoform in all major cancer types. These percentages were then applied to current U.S. cancer incidence statistics to estimate the number of new patients each year that have Ras-mutant cancers. We find that approximately 19% of patients with cancer harbor Ras mutations, equivalent to approximately 3.4 million new cases per year worldwide. We discuss the Ras isoform and mutation-specific trends evident within the datasets that are relevant to current Ras-targeted therapies.

Abstract Adoptive cell therapy with genetically modified T cells has generated exciting outcomes in hematologic malignancies, but its application to solid tumors has proven challenging. This gap has spurred the investigation of alternative immune cells as therapeutics. Macrophages are potent immune effector cells whose functional plasticity leads to antitumor as well as protumor function in different settings, and this plasticity has led to notable efforts to deplete or repolarize tumor-associated macrophages. Alternatively, macrophages could be adoptively transferred after ex vivo genetic modification. In this review, we highlight the role of macrophages in solid tumors, the progress made with macrophage-focused immunotherapeutic modalities, and the emergence of chimeric antigen receptor macrophage cell therapy.

Abstract Tumor-associated macrophages (TAM) are important tumor-promoting cells. However, the mechanisms underlying how the tumor and its microenvironment reprogram these cells remain elusive. Here we report that lipids play a crucial role in generating TAMs in the tumor microenvironment (TME). Macrophages from both human and murine tumor tissues were enriched with lipids due to increased lipid uptake by macrophages. TAMs expressed elevated levels of the scavenger receptor CD36, accumulated lipids, and used fatty acid oxidation (FAO) instead of glycolysis for energy. High levels of FAO promoted mitochondrial oxidative phosphorylation, production of reactive oxygen species, phosphorylation of JAK1, and dephosphorylation of SHP1, leading to STAT6 activation and transcription of genes that regulate TAM generation and function. These processes were critical for TAM polarization and activity, both in vitro and in vivo. In summary, we highlight the importance of lipid metabolism in the differentiation and function of protumor TAMs in the TME. Significance: This study highlights the role…

Abstract Therapeutic checkpoint antibodies blocking programmed death receptor 1/programmed death ligand 1 (PD-L1) signaling have radically improved clinical outcomes in cancer. However, the regulation of PD-L1 expression on tumor cells is still poorly understood. Here we show that intratumoral copper levels influence PD-L1 expression in cancer cells. Deep analysis of the The Cancer Genome Atlas database and tissue microarrays showed strong correlation between the major copper influx transporter copper transporter 1 (CTR-1) and PD-L1 expression across many cancers but not in corresponding normal tissues. Copper supplementation enhanced PD-L1 expression at mRNA and protein levels in cancer cells and RNA sequencing revealed that copper regulates key signaling pathways mediating PD-L1–driven cancer immune evasion. Conversely, copper chelators inhibited phosphorylation of STAT3 and EGFR and promoted ubiquitin-mediated degradation of PD-L1. Copper-chelating drugs also significantly increased the number of tumor-infiltrating CD8+ T and natural killer cells, slowed tumor growth, and…

Abstract Determining mechanisms of resistance to αPD-1/PD-L1 immune-checkpoint immunotherapy is key to developing new treatment strategies. Cancer-associated fibroblasts (CAF) have many tumor-promoting functions and promote immune evasion through multiple mechanisms, but as yet, no CAF-specific inhibitors are clinically available. Here we generated CAF-rich murine tumor models (TC1, MC38, and 4T1) to investigate how CAFs influence the immune microenvironment and affect response to different immunotherapy modalities [anticancer vaccination, TC1 (HPV E7 DNA vaccine), αPD-1, and MC38] and found that CAFs broadly suppressed response by specifically excluding CD8+ T cells from tumors (not CD4+ T cells or macrophages); CD8+ T-cell exclusion was similarly present in CAF-rich human tumors. RNA sequencing of CD8+ T cells from CAF-rich murine tumors and immunochemistry analysis of human tumors identified significant upregulation of CTLA-4 in the absence of other exhaustion markers; inhibiting CTLA-4 with a nondepleting antibody overcame the CD8+ T-cell exclusion effect without affecting…

Abstract Pancreatic ductal adenocarcinoma (PDA) is an aggressive malignancy typified by a highly stromal and weakly immunogenic tumor microenvironment that promotes tumor evolution and contributes to therapeutic resistance. Here, we demonstrate that PDA tumor cell–derived proinflammatory cytokine IL1β is essential for the establishment of the protumorigenic PDA microenvironment. Tumor cell–derived IL1β promoted the activation and secretory phenotype of quiescent pancreatic stellate cells and established an immunosuppressive milieu mediated by M2 macrophages, myeloid-derived suppressor cells, CD1dhiCD5+ regulatory B cells, and Th17 cells. Loss of tumor cell–derived IL1 signaling in tumor stroma enabled intratumoral infiltration and activation of CD8+ cytotoxic T cells, attenuated growth of pancreatic neoplasia, and conferred survival advantage to PDA-bearing mice. Accordingly, antibody-mediated neutralization of IL1β significantly enhanced the antitumor activity of α-PD-1 and was accompanied by increased tumor infiltration of CD8+ T cells. Tumor cell expression of IL1β in vivo was…

Abstract Adipocytes are critical for ovarian cancer cells to home to the omentum, but the metabolic changes initiated by this interaction are unknown. To this end, we carried out unbiased mass spectrometry–based metabolomic and proteomic profiling of cancer cells cocultured with primary human omental adipocytes. Cancer cells underwent significant proteo-metabolomic alteration(s), typified by changes in the lipidome with corresponding upregulation of lipid metabolism proteins. FABP4, a lipid chaperone protein, was identified as the critical regulator of lipid responses in ovarian cancer cells cocultured with adipocytes. Subsequently, knockdown of FABP4 resulted in increased 5-hydroxymethylcytosine levels in the DNA, downregulation of gene signatures associated with ovarian cancer metastasis, and reduced clonogenic cancer cell survival. In addition, clustered regularly interspaced short palindromic repeats (CRISPR)-mediated knockout of FABP4 in high-grade serous ovarian cancer cells reduced metastatic tumor burden in mice. Consequently, a small-molecule inhibitor of FABP4 (BMS309403)…

In this review, we highlight recent discoveries regarding mechanisms contributing to nerve-cancer cross-talk and the effects of nerve-cancer cross-talk on tumor progression and dissemination. High intratumoral nerve density correlates with poor prognosis and high recurrence across multiple solid tumor types. Recent research has shown that cancer cells express neurotrophic markers such as nerve growth factor, brain-derived neurotrophic factor, and glial cell-derived neurotrophic factor and release axon-guidance molecules such as ephrin B1 to promote axonogenesis. Tumor cells recruit new neural progenitors to the tumor milieu and facilitate their maturation into adrenergic infiltrating nerves. Tumors also rewire established nerves to adrenergic phenotypes via exosome-induced neural reprogramming by p53-deficient tumors. In turn, infiltrating sympathetic nerves facilitate cancer progression. Intratumoral adrenergic nerves release noradrenaline to stimulate angiogenesis via VEGF signaling and enhance the rate of tumor growth. Intratumoral parasympathetic nerves may have a dichotomous…

Pancreatic cancer is a disease with limited therapeutic options. Resistance to chemotherapies poses a significant clinical challenge for patients with pancreatic cancer and contributes to a high rate of recurrence. Oncogenic KRAS, a critical driver of pancreatic cancer, promotes metabolic reprogramming and upregulates NRF2, a master regulator of the antioxidant network. Here, we show that NRF2 contributed to chemoresistance and was associated with a poor prognosis in patients with pancreatic cancer. NRF2 activation metabolically rewired and elevated pathways involved in glutamine metabolism. This curbed chemoresistance in KRAS-mutant pancreatic cancers. In addition, manipulating glutamine metabolism restrained the assembly of stress granules, an indicator of chemoresistance. Glutaminase inhibitors sensitized chemoresistant pancreatic cancer cells to gemcitabine, thereby improving the effectiveness of chemotherapy. This therapeutic approach holds promise as a novel therapy for patients with pancreatic cancer harboring KRAS mutation. SIGNIFICANCE: These findings illuminate the…

Genome-wide association studies (GWAS) have identified thousands of germline susceptibility loci associated with risk for cancer as well as a wide range of other traits and diseases. An interest of many investigators is identifying traits or diseases that share common susceptibility loci. We developed LDtrait (https://ldlink.nci.nih.gov/?tab=ldtrait) as an open access web tool for finding germline variation associated with multiple traits. LDtrait searches the NHGRI-EBI GWAS Catalog to identify susceptibility loci in linkage disequilibrium (LD) with a user-provided list of query variants. Options allow for modifying LD thresholds, calculating LD from a diverse set of reference populations, and downloading annotated variant lists. Results from example query searches highlight the utility of LDtrait in uncovering cross-trait associations for cancer risk and other traits. LDtrait accelerates etiologic understanding of cancer genetics by rapidly identifying genetic similarities with other traits or diseases. SIGNIFICANCE: The new GWAS search tool LDtrait will expedite discovery of…

Abstract Next-generation genomic sequencing has identified multiple novel molecular alterations in cancer. Since the identification of DNA methylation and histone modification, it has become evident that genes encoding epigenetic modifiers that locally and globally regulate gene expression play a crucial role in normal development and cancer progression. The histone methyltransferase enhancer of zeste homolog 2 (EZH2) is the enzymatic catalytic subunit of the polycomb-repressive complex 2 (PRC2) that can alter gene expression by trimethylating lysine 27 on histone 3 (H3K27). EZH2 is involved in global transcriptional repression, mainly targeting tumor-suppressor genes. EZH2 is commonly overexpressed in cancer and shows activating mutations in subtypes of lymphoma. Extensive studies have uncovered an important role for EZH2 in cancer progression and have suggested that it may be a useful therapeutic target. In addition, tumors harboring mutations in other epigenetic genes such as ARID1A, KDM6, and BAP1 are highly sensitive to EZH2 inhibition, thus increasing its potential as a…

Abstract Defining traits of platinum-tolerant cancer cells could expose new treatment vulnerabilities. Here, new markers associated with platinum-tolerant cells and tumors were identified using in vitro and in vivo ovarian cancer models treated repetitively with carboplatin and validated in human specimens. Platinum-tolerant cells and tumors were enriched in ALDH+ cells, formed more spheroids, and expressed increased levels of stemness-related transcription factors compared with parental cells. Additionally, platinum-tolerant cells and tumors exhibited expression of the Wnt receptor Frizzled-7 (FZD7). Knockdown of FZD7 improved sensitivity to platinum, decreased spheroid formation, and delayed tumor initiation. The molecular signature distinguishing FZD7+ from FZD7− cells included epithelial-to-mesenchymal (EMT), stemness, and oxidative phosphorylation-enriched gene sets. Overexpression of FZD7 activated the oncogenic factor Tp63, driving upregulation of glutathione metabolism pathways, including glutathione peroxidase 4 (GPX4), which protected cells from chemotherapy-induced…

Abstract N6-methyladenosine (m6A) is the most prevalent internal RNA modification in mammals that regulates homeostasis and function of modified RNA transcripts. Here, we aimed to investigate the role of YTH m6A RNA-binding protein 1 (YTHDF1), a key regulator of m6A methylation in gastric cancer tumorigenesis. Multiple bioinformatic analyses of different human cancer databases identified key m6A-associated genetic mutations that regulated gastric tumorigenesis. YTHDF1 was mutated in about 7% of patients with gastric cancer, and high expression of YTHDF1 was associated with more aggressive tumor progression and poor overall survival. Inhibition of YTHDF1 attenuated gastric cancer cell proliferation and tumorigenesis in vitro and in vivo. Mechanistically, YTHDF1 promoted the translation of a key Wnt receptor frizzled7 (FZD7) in an m6A-dependent manner, and mutated YTHDF1 enhanced expression of FZD7, leading to hyperactivation of the Wnt/β-catenin pathway and promotion of gastric carcinogenesis. Our results demonstrate the oncogenic role of YTHDF1 and its m6A-mediated regulation of…

Abstract The progression and metastatic capacity of solid tumors are strongly influenced by immune cells in the tumor microenvironment. In non–small cell lung cancer (NSCLC), accumulation of anti-inflammatory tumor-associated macrophages (TAM) is associated with worse clinical outcome and resistance to therapy. Here we investigated the immune landscape of NSCLC in the presence of protumoral TAMs expressing the macrophage receptor with collagenous structure (MARCO). MARCO-expressing TAM numbers correlated with increased occurrence of regulatory T cells and effector T cells and decreased natural killer (NK) cells in these tumors. Furthermore, transcriptomic data from the tumors uncovered a correlation between MARCO expression and the anti-inflammatory cytokine IL37. In vitro studies subsequently showed that lung cancer cells polarized macrophages to express MARCO and gain an immune-suppressive phenotype through the release of IL37. MARCO-expressing TAMs blocked cytotoxic T-cell and NK-cell activation, inhibiting their proliferation, cytokine production, and tumor killing capacity.…

Therapeutic interventions to harness the immune system against tumor cells have provided mixed results in the past for several solid tumors and hematologic malignancies. However, immunotherapy has advanced considerably over the last decade and is becoming an integral combination for treating patients with advanced solid tumors. In particular, prostate cancer immunotherapy has shown modest efficacy for patients in the past. With several key discoveries on immune mechanisms and advanced molecular diagnostic platforms recently, immunotherapy is re-emerging as a viable option for prostate cancer, especially castration-resistant prostate cancer (CRPC), to stimulate antitumor immunity. Combination of patient-tailored immunotherapy and immune checkpoint blockers with conventional cytotoxic agents and androgen receptor-targeted therapies should move the field forward. With a recent adaptation that the application of immune checkpoint inhibitors has been successful in the treatment of more than a dozen solid tumors, including melanoma, lymphoma, liver, cervical, gastrointestinal, and breast…

A new ecologically inspired paradigm in cancer treatment known as "adaptive therapy" capitalizes on competitive interactions between drug-sensitive and drug-resistant subclones. The goal of adaptive therapy is to maintain a controllable stable tumor burden by allowing a significant population of treatment-sensitive cells to survive. These, in turn, suppress proliferation of the less-fit resistant populations. However, there remain several open challenges in designing adaptive therapies, particularly in extending these therapeutic concepts to multiple treatments. We present a cancer treatment case study (metastatic castrate-resistant prostate cancer) as a point of departure to illustrate three novel concepts to aid the design of multidrug adaptive therapies. First, frequency-dependent "cycles" of tumor evolution can trap tumor evolution in a periodic, controllable loop. Second, the availability and selection of treatments may limit the evolutionary "absorbing region" reachable by the tumor. Third, the velocity of evolution significantly influences the optimal timing of drug…

N6-Methyladenosine (m6A) is the most abundant modification of mammalian mRNAs. RNA methylation fine tunes RNA stability and translation, altering cell fate. The fat mass- and obesity-associated protein (FTO) is an m6A demethylase with oncogenic properties in leukemia. Here, we show that FTO expression is suppressed in ovarian tumors and cancer stem cells (CSC). FTO inhibited the self-renewal of ovarian CSC and suppressed tumorigenesis in vivo, both of which required FTO demethylase activity. Integrative RNA sequencing and m6A mapping analysis revealed significant transcriptomic changes associated with FTO overexpression and m6A loss involving stem cell signaling, RNA transcription, and mRNA splicing pathways. By reducing m6A levels at the 3′UTR and the mRNA stability of two phosphodiesterase genes (PDE1C and PDE4B), FTO augmented second messenger 3′, 5′-cyclic adenosine monophosphate (cAMP) signaling and suppressed stemness features of ovarian cancer cells. Our results reveal a previously unappreciated tumor suppressor function of FTO in ovarian CSC mediated through inhibition of…

Abstract Cancers that are deficient in BRCA1 or BRCA2 are hypersensitive to genotoxic agents, including platinums and other first-line chemotherapeutics. The established models propose that these cancers are hypersensitive because the chemotherapies block or degrade DNA replication forks and thereby create DNA double strand breaks, both of which require functional BRCA proteins to prevent or resolve by mechanisms termed fork protection (FP) or homologous recombination (HR). However, recent findings challenge this dogma because genotoxic agents do not initially cause DNA double strand breaks or stall replication forks. Here, we propose a new model for genotoxic chemotherapy in which ssDNA replication gaps underlie the hypersensitivity of BRCA deficient cancer, and we propose that defects in HR or FP do not. Specifically, we observed that ssDNA gaps develop in BRCA deficient cells because DNA replication is not effectively restrained in response to genotoxic stress. Moreover, we observe gap suppression (GS) by either restored fork restraint or by gap filling, both of which conferred…

The respective antitumoral and protumoral roles of M1 and M2 tumor-associated macrophages (TAM) typify the complexity of macrophage function in cancer. In lung cancer, density and topology of distinct TAM phenotypes at the tumor center (TC) versus the invasive margin (IM) are largely unknown. Here, we investigated TAM subtype density and distribution between TC and IM in human lung cancer and TAM associations with overall survival. Macrophages isolated from adjacent nontumor tissue (NM), the TC (TC-TAM), and the IM (IM-TAM) were analyzed with RNA-sequencing (RNA-seq). Lung tumor tissue microarrays from 104 patient samples were constructed. M1 and M2 TAMs were identified using multiplex immunofluorescence staining and a tumor cell-TAM proximity analysis was performed. RNA-seq identified marked differences among NM, TC-TAM, and IM-TAM. On the basis of a panel of five selected markers (CD68, IL12, CCR7, CD163, and ALOX15), M2 predominance over M1 and M2 proximity to tumor cells was observed, especially at IM. Tumor cell proximity to TAM was linked with tumor cell survival and hypoxia…

Abstract FGFR signaling is deregulated in many human cancers, and FGFR is considered a valid target in FGFR-deregulated tumors. Here, we examine the preclinical profile of futibatinib (TAS-120; 1-[(3S)-[4-amino-3-[(3,5-dimethoxyphenyl)ethynyl]-1H-pyrazolo[3, 4-d] pyrimidin-1-yl]-1-pyrrolidinyl]-2-propen-1-one), a structurally novel, irreversible FGFR1–4 inhibitor. Among a panel of 296 human kinases, futibatinib selectively inhibited FGFR1–4 with IC50 values of 1.4 to 3.7 nmol/L. Futibatinib covalently bound the FGFR kinase domain, inhibiting FGFR phosphorylation and, in turn, downstream signaling in FGFR-deregulated tumor cell lines. Futibatinib exhibited potent, selective growth inhibition of several tumor cell lines (gastric, lung, multiple myeloma, bladder, endometrial, and breast) harboring various FGFR genomic aberrations. Oral administration of futibatinib led to significant dose-dependent tumor reduction in various FGFR-driven human tumor xenograft models, and tumor reduction was associated with sustained FGFR inhibition, which was proportional to the administered dose. The…

Abstract Perineural invasion is a common feature of pancreatic ductal adenocarcinoma (PDAC). Here, we investigated the effect of perineural invasion on the microenvironment and how this affects PDAC progression. Transcriptome expression profiles of PDAC tissues with different perineural invasion status were compared, and the intratumoral T-cell density and levels of neurotransmitters in these tissues were assessed. Perineural invasion was associated with impaired immune responses characterized by decreased CD8+ T and Th1 cells, and increased Th2 cells. Acetylcholine levels were elevated in severe perineural invasion. Acetylcholine impaired the ability of PDAC cells to recruit CD8+ T cells via HDAC1-mediated suppression of CCL5. Moreover, acetylcholine directly inhibited IFNγ production by CD8+ T cells in a dose-dependent manner and favored Th2 over Th1 differentiation. Furthermore, hyperactivation of cholinergic signaling enhanced tumor growth by suppressing the intratumoral T-cell response in an orthotopic PDAC model. Conversely, blocking perineural invasion with bilateral…

Abstract Yes-associated protein (YAP) and its paralog, transcriptional coactivator with PDZ-binding motif (TAZ), play pivotal roles in promoting the progression of hepatocellular carcinoma. However, the regulatory mechanism underpinning aberrant activation of YAP/TAZ in hepatocellular carcinoma remains unclear. In this study, we globally profiled the contribution of deubiquitinating enzymes (DUB) to both transcriptional activity and protein abundance of YAP/TAZ in hepatocellular carcinoma models and identified ubiquitin-specific peptidase 10 (USP10) as a potent YAP/TAZ-activating DUB. Mechanistically, USP10 directly interacted with and stabilized YAP/TAZ by reverting their proteolytic ubiquitination. Depletion of USP10 enhanced polyubiquitination of YAP/TAZ, promoted their proteasomal degradation, and ultimately arrested the proliferation of hepatocellular carcinoma in vitro and in vivo. Expression levels of USP10 positively correlated with the abundance of YAP/TAZ in hepatocellular carcinoma patient samples as well as in N-nitrosodiethylamine (DEN)-induced liver cancer mice models.…

Abstract Immune therapies have had limited efficacy in high-grade serous ovarian cancer (HGSC), as the cellular targets and mechanism(s) of action of these agents in HGSC are unknown. Here we performed immune functional and single-cell RNA sequencing transcriptional profiling on novel HGSC organoid/immune cell co-cultures treated with a unique bispecific anti-programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) antibody compared with monospecific anti-PD-1 or anti-PD-L1 controls. Comparing the functions of these agents across all immune cell types in real time identified key immune checkpoint blockade (ICB) targets that have eluded currently available monospecific therapies. The bispecific antibody induced superior cellular state changes in both T and natural killer (NK) cells. It uniquely induced NK cells to transition from inert to more active and cytotoxic phenotypes, implicating NK cells as a key missing component of the current ICB-induced immune response in HGSC. It also induced a subset of CD8 T cells to transition from naïve to more active and cytotoxic…

The detailed biological functions of circular RNA (circRNA) are largely unexplored. Using circRNA sequencing, we identified 169 differentially expressed circRNA in pancreatic ductal adenocarcinoma (PDAC) cells compared with nontumor human pancreatic ductal epithelial cells. Among them, circFOXK2 was validated with significant upregulation in PDAC cells and 63% of primary tumors (53 of 84). circFOXK2 promoted cell growth, migration, and invasion and was involved in cell-cycle progression and apoptosis. circFOXK2 contained multiple miRNA binding sites, functioning as a sponge for miR-942, which in turn promoted expression of ANK1, GDNF, and PAX6. A novel and highly specific circRNA-pulldown followed by mass spectrometry analysis identified 94 circFOXK2-interacting proteins, which were involved in cell adhesion, mRNA splicing, and structural molecule activity. Of these, circFOKX2 interactions with YBX1 and hnRNPK enhanced expression of oncogenes NUF2 and PDXK. Knockdown of circFOXK2 reduced binding of YBX1 and hnRNPK to NUF2 and PDXK, in turn decreasing their expression. Collectively,…

Abstract Long noncoding RNAs (lncRNA) have been shown to play critical roles in many diseases, including esophageal squamous cell carcinoma (ESCC). Recent studies have reported that some lncRNA encode functional micropeptides. However, the association between ESCC and micropeptides encoded by lncRNA remains largely unknown. In this study, we characterized a Y-linked lncRNA, LINC00278, which was downregulated in male ESCC. LINC00278 encoded a Yin Yang 1 (YY1)-binding micropeptide, designated YY1BM. YY1BM was involved in the ESCC progression and inhibited the interaction between YY1 and androgen receptor (AR), which in turn decreased expression of eEF2K through the AR signaling pathway. Downregulation of YY1BM significantly upregulated eEF2K expression and inhibited apoptosis, thus conferring ESCC cells more adaptive to nutrient deprivation. Cigarette smoking decreased m6A modification of LINC00278 and YY1BM translation. In conclusion, these results provide a novel mechanistic link between cigarette smoking and AR signaling in male ESCC progression. Significance: Posttranscriptional…

Abstract The prognosis for pancreatic ductal adenocarcinoma (PDAC) remains poor despite decades of effort. The abundant extracellular matrix (ECM) in PDAC comprises a major fraction of the tumor mass and plays various roles in promoting resistance to therapies. However, nonselective depletion of ECM has led to poor patient outcomes. Consistent with that observation, we previously showed that individual matrisome proteins derived from stromal cells correlate with either long or short patient survival. In marked contrast, those derived from cancer cells correlate strongly with poor survival. Here, we studied three cancer cell–derived matrisome proteins that are significantly overrepresented during PDAC progression, AGRN (agrin), SERPINB5 (serine protease inhibitor B5), and CSTB (cystatin B). Using both overexpression and knockdown experiments, we demonstrate that all three are promoters of PDAC metastasis. Furthermore, these proteins operate at different metastatic steps. AGRN promoted epithelial-to-mesenchymal transition in primary tumors, whereas SERPINB5 and CSTB enhanced late…

Abstract Hypoxia induces a vast array of long noncoding RNAs (lncRNA) in breast cancer cells, but their biological functions remain largely unknown. Here, we identified a hitherto uncharacterized hypoxia-induced lncRNA RAB11B-AS1 in breast cancer cells. RAB11B-AS1 is a natural lncRNA upregulated in human breast cancer and its expression is induced by hypoxia-inducible factor 2 (HIF2), but not HIF1, in response to hypoxia. RAB11B-AS1 enhanced the expression of angiogenic factors including VEGFA and ANGPTL4 in hypoxic breast cancer cells by increasing recruitment of RNA polymerase II. In line with increased angiogenic factors, conditioned media from RAB11B-AS1-overexpressing breast cancer cells promoted tube formation of human umbilical vein endothelial cells in vitro. Gain- and loss-of-function studies revealed that RAB11B-AS1 increased breast cancer cell migration and invasion in vitro and promoted tumor angiogenesis and breast cancer distant metastasis without affecting primary tumor growth in mice. Taken together, these findings uncover a fundamental mechanism of hypoxia-induced…

Abstract Targeting epigenetics in cancer has emerged as a promising anticancer strategy. p300/CBP is a central regulator of epigenetics and plays an important role in hepatocellular carcinoma (HCC) progression. Tumor-associated metabolic alterations contribute to the establishment and maintenance of the tumorigenic state. In this study, we used a novel p300 inhibitor, B029-2, to investigate the effect of targeting p300/CBP in HCC and tumor metabolism. p300/CBP–mediated acetylation of H3K18 and H3K27 increased in HCC tissues compared with surrounding noncancerous tissues. Conversely, treatment with B029-2 specifically decreased H3K18Ac and H3K27Ac and displayed significant antitumor effects in HCC cells in vitro and in vivo. Importantly, ATAC-seq and RNA-seq integrated analysis revealed that B029-2 disturbed metabolic reprogramming in HCC cells. Moreover, B029-2 decreased glycolytic function and nucleotide synthesis in Huh7 cells by reducing H3K18Ac and H3K27Ac levels at the promoter regions of amino acid metabolism and nucleotide synthesis enzyme genes, including PSPH, PSAT1,…

New and provocative insights into the relationships between iron and cancer have been uncovered in recent years. These include delineation of connections that link cellular iron to DNA repair, genomic integrity, and oncogenic signaling as well as the discovery of ferroptosis, a novel iron-dependent form of cell death. In parallel, new molecules and pathways that regulate iron influx, intracellular iron trafficking, and egress in normal cells, and their perturbations in cancer have been discovered. In addition, insights into the unique properties of iron handling in tumor-initiating cells (cancer stem cells), novel contributions of the tumor microenvironment to the uptake and regulation of iron in cancer cells, and new therapeutic modalities that leverage the iron dependence of cancer have emerged.

Pathologic complete response (pCR) following neoadjuvant therapy has been associated with improved event-free survival (EFS) and overall survival (OS) in early-stage breast cancer. The magnitude of this association varies by breast cancer subtype, yet further research focusing on subtype-specific populations is limited. Here we provide an updated and comprehensive evaluation of the association between pCR and survival outcomes in triple-negative breast cancer (TNBC). A literature review identified neoadjuvant studies, including clinical trials, real-world cohort studies, and studies that pooled multiple trials or cohorts, which reported EFS/OS results by pCR in patients with early-stage TNBC. Meta-analyses were performed to evaluate the association between pCR and EFS/OS and to predict long-term survival outcomes based on pCR status. Sensitivity analyses were conducted to assess the impact of cross-study variations. Twenty-five studies with over 4,000 patients with TNBC were identified. A synthesis of evidence from these studies suggested substantial improvement in EFS and OS for…

Abstract Tumor-associated macrophages (TAM) in the tumor microenvironment (TME) cooperate with cancer stem cells (CSC) to maintain stemness. We recently identified cluster of differentiation 44 (CD44) as a surface marker defining head and neck squamous cell carcinoma (HNSCC) CSC. PI3K–4EBP1–SOX2 activation and signaling regulate CSC properties, yet the upstream molecular control of this pathway and the mechanisms underlying cross-talk between TAM and CSC in HNSCC remain largely unknown. Because CD44 is a molecular mediator in the TME, we propose here that TAM-influenced CD44 signaling could mediate stemness via the PI3K–4EBP1–SOX2 pathway, possibly by modulating availability of hyaluronic acid (HA), the main CD44 ligand. HNSCC IHC was used to identify TAM/CSC relationships, and in vitro coculture spheroid models and in vivo mouse models were used to identify the influence of TAMs on CSC function via CD44. Patient HNSCC–derived TAMs were positively and negatively associated with CSC marker expression at noninvasive and invasive edge regions, respectively. TAMs increased availability…

Abstract Aberrant N6-methyladenosine (m6A) modification has emerged as a driver of tumor initiation and progression, yet how long noncoding RNAs (lncRNA) are involved in the regulation of m6A remains unknown. Here we utilize data from 12 cancer types from The Cancer Genome Atlas to comprehensively map lncRNAs that are potentially deregulated by DNA methylation. A novel DNA methylation–deregulated and RNA m6A reader–cooperating lncRNA (DMDRMR) facilitated tumor growth and metastasis in clear cell renal cell carcinoma (ccRCC). Mechanistically, DMDRMR bound insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3) to stabilize target genes, including the cell-cycle kinase CDK4 and three extracellular matrix components (COL6A1, LAMA5, and FN1), by specifically enhancing IGF2BP3 activity on them in an m6A-dependent manner. Consequently, DMDRMR and IGF2BP3 enhanced the G1–S transition, thus promoting cell proliferation in ccRCC. In patients with ccRCC, high coexpression of DMDRMR and IGF2BP3 was associated with poor outcomes. Our findings reveal that DMDRMR cooperates with IGF2BP3 to…

Abstract Oncogene-induced metabolic reprogramming is a hallmark of pancreatic cancer (PDAC), yet the metabolic drivers of metastasis are unclear. In PDAC, obesity and excess fatty acids accelerate tumor growth and increase metastasis. Here, we report that excess lipids, stored in organelles called lipid droplets (LD), are a key resource to fuel the energy-intensive process of metastasis. The oncogene KRAS controlled the storage and utilization of LD through regulation of hormone-sensitive lipase (HSL), which was downregulated in human PDAC. Disruption of the KRAS–HSL axis reduced lipid storage, reprogrammed tumor cell metabolism, and inhibited invasive migration in vitro and metastasis in vivo. Finally, microscopy-based metabolic analysis revealed that migratory cells selectively utilize oxidative metabolism during the process of migration to metabolize stored lipids and fuel invasive migration. Taken together, these results reveal a mechanism that can be targeted to attenuate PDAC metastasis. Significance: KRAS-dependent regulation of HSL biases cells towards lipid storage for…

Immunotherapies targeting programmed cell death protein 1 (PD-1) and programmed cell death 1 ligand 1 (PD-L1) immune checkpoints represent a major breakthrough in cancer treatment. PD-1 is an inhibitory receptor expressed on the surface of activated T cells that dampens T-cell receptor (TCR)/CD28 signaling by engaging with its ligand PD-L1 expressed on cancer cells. Despite the clinical success of PD-1 blockade using mAbs, most patients do not respond to the treatment, and the underlying regulatory mechanisms of PD-1 remain incompletely defined. Here we show that PD-1 is extensively N-glycosylated in T cells and the intensities of its specific glycoforms are altered upon TCR activation. Glycosylation was critical for maintaining PD-1 protein stability and cell surface localization. Glycosylation of PD-1, especially at the N58 site, was essential for mediating its interaction with PD-L1. The mAb STM418 specifically targeted glycosylated PD-1, exhibiting higher binding affinity to PD-1 than FDA-approved PD-1 antibodies, potently inhibiting PD-L1/PD-1 binding, and enhancing antitumor…

Abstract Extracellular vesicles (EV) from cancer-associated fibroblasts (CAF) are composed of diverse payloads. Although CAFs impact the aggressive characteristics of gastric cancer cells, the contribution of CAF-EV to gastric cancer progression has not been elucidated. Here, we investigated the molecular mechanism of the changes in gastric cancer characteristics induced by CAF-EV. CAF abundance in gastric cancer tissues was associated with poor prognosis of patients with gastric cancer receiving chemotherapy. Moreover, CAF-EV induced tubular network formation and drug resistance of gastric cancer cells in the extracellular matrix (ECM). Comprehensive proteomic analysis of CAF-EV identified that Annexin A6 plays a pivotal role in network formation and drug resistance of gastric cancer cells in the ECM via activation of β1 integrin-focal adhesion kinase (FAK)-YAP. A peritoneal metastasis mouse model revealed that CAF-EV induced drug resistance in peritoneal tumors, and inhibition of FAK or YAP efficiently attenuated gastric cancer drug resistance in vitro and in vivo. These findings…

Abstract Lungs are one of the main sites of breast cancer metastasis. The metastatic microenvironment is essential to facilitate growth of disseminated tumor cells. Cancer-associated fibroblasts (CAF) are prominent players in the microenvironment of breast cancer. However, their role in the formation of a permissive metastatic niche is unresolved. Here we show that IL33 is upregulated in metastases-associated fibroblasts in mouse models of spontaneous breast cancer metastasis and in patients with breast cancer with lung metastasis. Upregulation of IL33 instigated type 2 inflammation in the metastatic microenvironment and mediated recruitment of eosinophils, neutrophils, and inflammatory monocytes to lung metastases. Importantly, targeting of IL33 in vivo resulted in inhibition of lung metastasis and significant attenuation of immune cell recruitment and type 2 immunity. These findings demonstrate a key function of IL33 in facilitating lung metastatic relapse by modulating the immune microenvironment. Our study shows a novel interaction axis between CAF and immune cells and reveals…

Abstract p27 binds and inhibits cyclin-CDK to arrest the cell cycle. p27 also regulates other processes including cell migration and development independent of its cyclin-dependent kinase (CDK) inhibitory action. p27 is an atypical tumor suppressor–deletion or mutational inactivation of the gene encoding p27, CDKN1B, is rare in human cancers. p27 is rarely fully lost in cancers because it can play both tumor suppressive and oncogenic roles. Until recently, the paradigm was that oncogenic deregulation results from either loss of growth restraint due to excess p27 proteolysis or from an oncogenic gain of function through PI3K-mediated C-terminal p27 phosphorylation, which disrupts the cytoskeleton to increase cell motility and metastasis. In cancers, C-terminal phosphorylation alters p27 protein–protein interactions and shifts p27 from CDK inhibitor to oncogene. Recent data indicate p27 regulates transcription and acts as a transcriptional coregulator of cJun. C-terminal p27 phosphorylation increases p27-cJun recruitment to and action on target genes to drive oncogenic pathways and…

Lipid rafts are tightly packed, cholesterol- and sphingolipid-enriched microdomains within the plasma membrane that play important roles in many pathophysiologic processes. Rafts have been strongly implicated as master regulators of signal transduction in cancer, where raft compartmentalization can promote transmembrane receptor oligomerization, shield proteins from enzymatic degradation, and act as scaffolds to enhance intracellular signaling cascades. Cancer cells have been found to exploit these mechanisms to initiate oncogenic signaling and promote tumor progression. This review highlights the roles of lipid rafts within the metastatic cascade, specifically within tumor angiogenesis, cell adhesion, migration, epithelial-to-mesenchymal transition, and transendothelial migration. In addition, the interplay between lipid rafts and different modes of cancer cell death, including necrosis, apoptosis, and anoikis, will be described. The clinical role of lipid raft-specific proteins, caveolin and flotillin, in assessing patient prognosis and evaluating metastatic potential of various…

ABSTRACT The spatial organization of different types of cells in tumor tissues reveals important information about the tumor microenvironment (TME). In order to facilitate the study of cellular spatial organization and interactions, we developed a comprehensive nuclei segmentation and classification tool to characterize the TME from standard Hematoxylin and Eosin (H&E)-stained pathology images. This tool can computationally “stain” different types of cell nuclei in H&E pathology images to facilitate pathologists in analyzing the TME. A Mask Regional-Convolutional Neural Network (Mask-RCNN) model was developed to segment the nuclei of tumor, stromal, lymphocyte, macrophage, karyorrhexis and red blood cells in lung adenocarcinoma (ADC). Using this tool, we identified and classified cell nuclei and extracted 48 cell spatial organization-related features that characterize the TME. Using these features, we developed a prognostic model from the National Lung Screening Trial dataset, and independently validated the model in The Cancer Genome Atlas (TCGA) lung ADC dataset, in which the…

Glioma stem cells (GSC) are a subpopulation of tumor cells with special abilities to proliferate and differentiate in gliomas. They are one of the main causes of tumor recurrence, especially under hypoxic conditions. Although long noncoding RNAs (lncRNA) are known to be involved in numerous biological processes and are implied in the occurrence of certain diseases, their role in tumor development and progression remains poorly understood. Here we explored the mechanisms by which lncRNA derived from hypoxic GSCs (H-GSC) cause glioma progression. Isolation and identification of the Linc01060 gene, the exosomes containing them, and the proteins from tumor cells regulating the gene allowed for studying the effects of Linc01060 on proliferation and glycometabolism. H-GSC exerted their effects by transferring exosomes to glioma cells, resulting in a significant increase in Linc01060 levels. Mechanistically, Linc01060 directly interacted with the transcription factor myeloid zinc finger 1 (MZF1) and enhanced its stability. Linc01060 facilitated nuclear translocation of MZF1 and promoted…

Abstract Adaptive therapy seeks to exploit intratumoral competition to avoid, or at least delay, the emergence of therapy resistance in cancer. Motivated by promising results in prostate cancer, there is growing interest in extending this approach to other neoplasms. As such, it is urgent to understand the characteristics of a cancer that determine whether or not it will respond well to adaptive therapy. A plausible candidate for such a selection criterion is the fitness cost of resistance. In this article, we study a general, but simple, mathematical model to investigate whether the presence of a cost is necessary for adaptive therapy to extend the time to progression beyond that of a standard-of-care continuous therapy. Tumor cells were divided into sensitive and resistant populations and we model their competition using a system of two ordinary differential equations based on the Lotka–Volterra model. For tumors close to their environmental carrying capacity, a cost was not required. However, for tumors growing far from carrying capacity, a cost may be required to see meaningful…

Abstract Malignant glioma constitutes one of the fatal primary brain tumors in adults. Such poor prognosis calls for a better understanding of cancer-related signaling pathways of this disease. Here we elucidate a MYC-miRNA-MXI1 feedback loop that regulates proliferation and tumorigenesis in glioma. MYC suppressed MXI1 expression via microRNA-155 (miR-155) and the microRNA-23a∼27a∼24-2 cluster (miR-23a cluster), whereas MXI1, in turn, inhibited MYC expression by binding to its promoter. Overexpression of miR-155 and the miR-23a cluster promoted tumorigenesis in U87 glioma cells. Furthermore, fat mass and obesity-associated protein (FTO), an N6-methyladenosine (m6A) RNA demethylase, regulated the loop by targeting MYC. The ethyl ester form of meclofenamic acid (MA2) inhibited FTO and enhanced the effect of the chemotherapy drug temozolomide on suppressing proliferation of glioma cells and negatively regulated the loop. These data collectively highlight a key regulatory circuit in glioma and provide potential targets for clinical treatment. Significance: These findings elucidate a…

Tumor progression is recognized as a result of an evolving cross-talk between tumor cells and their surrounding nontransformed stroma. Although Wnt signaling has been intensively studied in colorectal cancer, it remains unclear whether activity in the tumor-associated stroma contributes to malignancy. To specifically interfere with stromal signals, we generated Wnt-independent tumor organoids that secrete the Wnt antagonist Sfrp1. Subcutaneous transplantation into immunocompetent as well as immunodeficient mice resulted in a strong reduction of tumor growth. Histologic and transcriptomic analyses revealed that Sfrp1 induced an epithelial-mesenchymal transition (EMT) phenotype in tumor cells without affecting tumor-intrinsic Wnt signaling, suggesting involvement of nonimmune stromal cells. Blockage of canonical signaling using Sfrp1, Dkk1, or fibroblast-specific genetic ablation of β-catenin strongly decreased the number of cancer-associated myofibroblasts (myCAF). Wnt activity in CAFs was linked with distinct subtypes, where low and high levels induced an inflammatory-like CAF…

Abstract PIK3CA encodes the p110α catalytic subunit of PI3K and is frequently mutated in human cancers, including ∼30% of colorectal cancer. Oncogenic mutations in PIK3CA render colorectal cancers more dependent on glutamine. Here we report that the glutaminase inhibitor CB-839 preferentially inhibits xenograft growth of PIK3CA-mutant, but not wild-type (WT), colorectal cancers. Moreover, the combination of CB-839 and 5-fluorouracil (5-FU) induces PIK3CA-mutant tumor regression in xenograft models. CB-839 treatment increased reactive oxygen species and caused nuclear translocation of Nrf2, which in turn upregulated mRNA expression of uridine phosphorylase 1 (UPP1). UPP1 facilitated the conversion of 5-FU to its active compound, thereby enhancing the inhibition of thymidylate synthase. Consistently, knockout of UPP1 abrogated the tumor inhibitory effect of combined CB-839 and 5-FU administration. A phase I clinical trial showed that the combination of CB-839 and capecitabine, a prodrug of 5-FU, was well tolerated at biologically-active doses. Although not designed to test efficacy,…

Abstract Myeloid-derived suppressor cells (MDSC) include immature monocytic (M-MDSC) and granulocytic (PMN-MDSC) cells that share the ability to suppress adaptive immunity and to hinder the effectiveness of anticancer treatments. Of note, in response to IFNγ, M-MDSCs release the tumor-promoting and immunosuppressive molecule nitric oxide (NO), whereas macrophages largely express antitumor properties. Investigating these opposing activities, we found that tumor-derived prostaglandin E2 (PGE2) induces nuclear accumulation of p50 NF-κB in M-MDSCs, diverting their response to IFNγ toward NO-mediated immunosuppression and reducing TNFα expression. At the genome level, p50 NF-κB promoted binding of STAT1 to regulatory regions of selected IFNγ-dependent genes, including inducible nitric oxide synthase (Nos2). In agreement, ablation of p50 as well as pharmacologic inhibition of either the PGE2 receptor EP2 or NO production reprogrammed M-MDSCs toward a NOS2low/TNFαhigh phenotype, restoring the in vivo antitumor activity of IFNγ. Our results indicate that inhibition of the PGE2/p50/NO axis…

Abstract The ubiquitous second messenger Ca2+ has long been recognized as a key regulator in cell migration. Locally confined Ca2+, in particular, is essential for building front-to-rear Ca2+ gradient, which serves to maintain the morphologic polarity required in directionally migrating cells. However, little is known about the source of the Ca2+ and the mechanism by which they crosstalk between different signaling pathways in cancer cells. Here, we report that calcium release–activated calcium modulator 2 (ORAI2), a poorly characterized store-operated calcium (SOC) channel subunit, predominantly upregulated in the lymph node metastasis of gastric cancer, supports cell proliferation and migration. Clinical data reveal that a high frequency of ORAI2-positive cells in gastric cancer tissues significantly correlated with poor differentiation, invasion, lymph node metastasis, and worse prognosis. Gain- and loss-of-function showed that ORAI2 promotes cell motility, tumor formation, and metastasis in both gastric cancer cell lines and mice. Mechanistically, ORAI2 mediated SOC activity and…

Abstract Cellular senescence entails an irreversible growth arrest that evolved in part to prevent cancer. Paradoxically, senescent cells secrete proinflammatory and growth-stimulatory molecules, termed the senescence-associated secretory phenotype (SASP), which is correlated with cancer cell proliferation in culture and xenograft models. However, at what tumor stage and how senescence and the SASP act on endogenous tumor growth in vivo is unknown. To understand the role of senescence in cancer etiology, we subjected p16-3MR transgenic mice, which permit the identification and selective elimination of senescent cells in vivo, to the well-established two-step protocol of squamous cell skin carcinoma, in which tumorigenesis is initiated by a carcinogen 7,12-dimethylbenz[α]anthracene, and then promoted by 12-O-tetradecanoyl-phorbol-13-acetate (TPA). We show that TPA promotes skin carcinogenesis by inducing senescence and a SASP. Systemic induction of senescence in nontumor-bearing p16-3MR mice using a chemotherapy followed by the two-step carcinogenesis protocol potentiated the…

Abstract Targeted delivery of chemotherapeutics aims to increase efficacy and lower toxicity by concentrating drugs at the site-of-action, a method embodied by the seven current FDA-approved antibody–drug conjugates (ADC). However, a variety of pharmacokinetic challenges result in relatively narrow therapeutic windows for these agents, hampering the development of new drugs. Here, we use a series of prostate-specific membrane antigen–binding single-domain (Humabody) ADC constructs to demonstrate that tissue penetration of protein–drug conjugates plays a major role in therapeutic efficacy. Counterintuitively, a construct with lower in vitro potency resulted in higher in vivo efficacy than other protein–drug conjugates. Biodistribution data, tumor histology images, spheroid experiments, in vivo single-cell measurements, and computational results demonstrate that a smaller size and slower internalization rate enabled higher tissue penetration and more cell killing. The results also illustrate the benefits of linking an albumin-binding domain to the single-domain ADCs. A construct…

Chemotherapy is important for cancer treatment, however, toxicities limit its use. While great strides have been made to ameliorate the acute toxicities induced by chemotherapy, long-term comorbidities including bone loss remain a significant problem. Chemotherapy-driven estrogen loss is postulated to drive bone loss, but significant data suggests the existence of an estrogen-independent mechanism of bone loss. Using clinically relevant mouse models, we showed that senescence and its senescence-associated secretory phenotype (SASP) contribute to chemotherapy-induced bone loss that can be rescued by depleting senescent cells. Chemotherapy-induced SASP could be limited by targeting the p38MAPK-MK2 pathway, which resulted in preservation of bone integrity in chemotherapy-treated mice. These results transform our understanding of chemotherapy-induced bone loss by identifying senescent cells as major drivers of bone loss and the p38MAPK-MK2 axis as a putative therapeutic target that can preserve bone and improve a cancer survivor's quality of life. SIGNIFICANCE: Senescence drives…

Abstract Frontier evidence suggests that dysregulation of long noncoding RNAs (lncRNA) is ubiquitous in all human tumors, indicating that lncRNAs might have essential roles in tumorigenesis. Therefore, an in-depth study of the roles of lncRNA in nasopharyngeal carcinoma (NPC) carcinogenesis might be helpful to provide novel therapeutic targets. Here we report that lncRNA TINCR was significantly upregulated in NPC and was associated positively with poor survival. Silencing TINCR inhibited NPC progression and cisplatin resistance. Mechanistically, TINCR bound ACLY and protected it from ubiquitin degradation to maintain total cellular acetyl-CoA levels. Accumulation of cellular acetyl-CoA promoted de novo lipid biosynthesis and histone H3K27 acetylation, which ultimately regulated the peptidyl arginine deiminase 1 (PADI1)–MAPK–MMP2/9 pathway. In addition, insulin-like growth factor 2 mRNA-binding protein 3 interacted with TINCR and slowed its decay, which partially accounted for TINCR upregulation in NPC. These findings demonstrate that TINCR acts as a crucial driver of NPC progression…