bims-tucedo Biomed News
on Tumor cell dormancy
Issue of 2020‒09‒13
27 papers selected by
Isabel Puig Borreil
Vall d’Hebron Institute of Oncology

  1. Mol Cancer. 2020 09 09. 19(1): 139
    Yeh CH, Bellon M, Wang F, Zhang H, Fu L, Nicot C.
      BACKGROUND: Human T cell leukemia virus type 1 (HTLV-1)-associated adult T cell leukemia (ATL) has a very poor prognosis with a median survival of 8 months and a 4-year overall survival of 11% for acute ATL. Present treatment options are limited and there is no curative therapy for ATL. Ubiquitin ligase FBXW7 is commonly mutated or functionally inactivated in human cancers. Consistent with the notion that FBXW7 controls the degradation of many oncoproteins, loss of FBXW7 has been linked to increased drug resistance or sensitivity in cancer cells.METHOD: In this study, we have characterized FBXW7 mutants previously identified in HTLV-I-infected ATL patient samples. TET-inducible ATL cells carrying wild type or mutated FBXW7 were analyzed for target degradation and for drug sensitivity.
    RESULTS: Our results demonstrate that mutations in FBXW7 can selectively disrupt ubiquitination and proteasome degradation of target proteins: c-MYC, cyclin E and MCL1. Both c-MYC and MYCN were highly expressed in uncultured ATL patient's samples and ATL-derived cell lines; and ATL cells demonstrated sensitivity to BET inhibitors in vitro and in vivo. High-throughput reverse phase protein array revealed BRAF as a novel target of FBXW7 and further experiments showed that mutations in FBXW7 preventing degradation of BRAF provided resistance to BET inhibitors. In contrast to R465, hot spot FBXW7 mutations at R505C retained degradation of BRAF but not NOTCH1, c-MYC, cyclin E, or MCL1. Finally, a combination therapy using BET inhibitors along with a BRAF or an ERK inhibitor prevented tumor cell resistance and growth.
    CONCLUSION: Our results suggest that FBXW7 status may play an important role in drug therapy resistance of cancer cells. Genetic characterization of FBXW7 may be one factor included in future personalized cancer treatment identification.
  2. iScience. 2020 Aug 20. pii: S2589-0042(20)30672-6. [Epub ahead of print]23(9): 101480
    Hirata E, Ishibashi K, Kohsaka S, Shinjo K, Kojima S, Kondo Y, Mano H, Yano S, Kiyokawa E, Sahai E.
      Brain metastasis is an ineffective process, and many cancer cells enter into an indolent state following extravasation in the brain. Single cell RNA sequencing of melanoma brain metastases reveals that non-proliferating brain metastatic melanoma cells exhibit a pattern of gene expression associated with inhibition of DNA methyltransferase 1 (DNMT1). The brain microenvironment, specifically the combination of reactive astrocytes and mechanically soft surroundings, suppressed DNMT1 expression in various cancer types and caused cell cycle delay. Somewhat unexpectedly, we find that DNMT1 suppression not only induces cell cycle delay but also activates pro-survival signals in brain metastatic cancer cells, including L1CAM and CRYAB. Our results demonstrate that transcriptional changes triggered by DNMT1 suppression is a key step for cancer cells to survive in the brain microenvironment and that they also restrict cancer cell proliferation. The dual consequences of DNMT1 suppression can explain the persistence of indolent cancer cells in the brain microenvironment.
    Keywords:  Biological Sciences; Cancer; Cell Biology; Transcriptomics
  3. Nat Commun. 2020 Sep 09. 11(1): 4520
    Peng DH, Rodriguez BL, Diao L, Chen L, Wang J, Byers LA, Wei Y, Chapman HA, Yamauchi M, Behrens C, Raso G, Soto LMS, Cuentes ERP, Wistuba II, Kurie JM, Gibbons DL.
      Tumor extracellular matrix has been associated with drug resistance and immune suppression. Here, proteomic and RNA profiling reveal increased collagen levels in lung tumors resistant to PD-1/PD-L1 blockade. Additionally, elevated collagen correlates with decreased total CD8+ T cells and increased exhausted CD8+ T cell subpopulations in murine and human lung tumors. Collagen-induced T cell exhaustion occurs through the receptor LAIR1, which is upregulated following CD18 interaction with collagen, and induces T cell exhaustion through SHP-1. Reduction in tumor collagen deposition through LOXL2 suppression increases T cell infiltration, diminishes exhausted T cells, and abrogates resistance to anti-PD-L1. Abrogating LAIR1 immunosuppression through LAIR2 overexpression or SHP-1 inhibition sensitizes resistant lung tumors to anti-PD-1. Clinically, increased collagen, LAIR1, and TIM-3 expression in melanoma patients treated with PD-1 blockade predict poorer survival and response. Our study identifies collagen and LAIR1 as potential markers for immunotherapy resistance and validates multiple promising therapeutic combinations.
  4. Oncogene. 2020 Sep 11.
    Wen S, He Y, Wang L, Zhang J, Quan C, Niu Y, Huang H.
      Next generation antiandrogens such as enzalutamide (Enz) are effective initially for the treatment of castration-resistant prostate cancer (CRPC). However, the disease often relapses and the underlying mechanisms remain elusive. By performing H3-lysine-27 acetylation (H3K27ac) ChIP-seq in Enz-resistant CRPC cells, we identified a group of super enhancers (SEs) that are abnormally activated in Enz-resistant CRPC cells and associated with enhanced transcription of a subset of tumor promoting genes such as CHPT1, which catalyzes phosphatidylcholine (PtdCho) synthesis and regulates choline metabolism. Increased CHPT1 conferred CRPC resistance to Enz in vitro and in mice. While androgen receptor (AR) primarily binds to a putative CHPT1 enhancer and mediates androgen-dependent expression of CHPT1 gene in Enz-sensitive prostate cancer cells, AR binds to a different enhancer within the CHPT1 SE locus and facilities androgen-independent expression of CHPT1 in Enz-resistant cells. We further identified a long-non coding RNA transcribed at CHPT1 enhancer (also known as enhancer RNA) that binds to the H3K27ac reader BRD4 and participates in regulating CHPT1 SE activity and CHPT1 gene expression. Our findings demonstrate that aberrantly activated SE upregulates CHPT1 expression and confers Enz resistance in CRPC, suggesting that SE-mediated expression of downstream effectors such as CHPT1 can be viable targets to overcome Enz resistance in PCa.
  5. Cell Death Differ. 2020 Sep 07.
    Li Z, Wang D, Lu J, Huang B, Wang Y, Dong M, Fan D, Li H, Gao Y, Hou P, Li M, Liu H, Pan ZQ, Zheng J, Bai J.
      Enhancer of zeste homolog 2 (EZH2), a key histone methyltransferase and EMT inducer, is overexpressed in diverse carcinomas, including breast cancer. However, the molecular mechanisms of EZH2 dysregulation in cancers are still largely unknown. Here, we discover that EZH2 is asymmetrically dimethylated at R342 (meR342-EZH2) by PRMT1. meR342-EZH2 was found to inhibit the CDK1-mediated phosphorylation of EZH2 at T345 and T487, thereby attenuating EZH2 ubiquitylation mediated by the E3 ligase TRAF6. We also demonstrate that meR342-EZH2 resulted in a decrease in EZH2 target gene expression, but an increase in breast cancer cell EMT, invasion and metastasis. Moreover, we confirm the positive correlations among PRMT1, meR342-EZH2 and EZH2 expression in the breast cancer tissues. Finally, we report that high expression levels of meR342-EZH2 predict a poor clinical outcome in breast cancer patients. Our findings may provide a novel diagnostic target and promising therapeutic target for breast cancer metastasis.
  6. Cancer Immunol Res. 2020 Sep 11. pii: canimm.0005.2019. [Epub ahead of print]
    Jaiswal AR, Liu AJ, Pudakalakatti S, Dutta P, Jayaprakash P, Bartkowiak T, Ager CR, Wang ZQ, Reuben A, Cooper ZA, Ivan C, Ju Z, Nwajei F, Wang J, Davies MA, Davis RE, Wargo JA, Bhattacharya PK, Hong DS, Curran MA.
      Despite the clinical success of T cell checkpoint blockade, most cancer patients still fail to have durable responses to immunotherapy. The molecular mechanisms driving checkpoint blockade resistance, whether pre-existing or evolved, remain unclear. To address this critical knowledge gap, we treated B16 melanoma with the combination of CTLA-4, PD-1, and PD-L1 blockade and a Flt3 ligand vaccine (≥75% curative), isolated tumors resistant to therapy, and serially passaged them in vivo with the same treatment regimen until they developed complete resistance. Using gene expression analysis and immunogenomics, we determined the adaptations associated with this resistance phenotype. Checkpoint resistance coincided with acquisition of a "hypermetabolic" phenotype characterized by coordinated upregulation of the glycolytic, oxidoreductase, and mitochondrial oxidative phosphorylation pathways. These resistant tumors flourished under hypoxic conditions whereas metabolically starved T cells lost glycolytic potential, effector function, and the ability to expand in response to immunotherapy. Further, we found that checkpoint resistant versus sensitive tumors could be separated by non-invasive MRI imaging based solely on their metabolic state. In a cohort of melanoma patients resistant to both CTLA-4 and PD-1 blockade, we observed upregulation of pathways indicative of a similar hypermetabolic state. Together these data indicated that melanoma can evade T cell checkpoint blockade immunotherapy by adapting a hypermetabolic phenotype.
  7. Cancer Cell. 2020 Sep 02. pii: S1535-6108(20)30422-0. [Epub ahead of print]
    Lund AW, Soengas MS.
      Lymph nodes are typically the first clinically detectable site of metastasis in melanoma, but the mechanisms that determine this preference are not well understood. An article in Nature reports that the unique composition of lymph may protect melanoma cells from ferroptosis-a form of iron-dependent cell death, thereby increasing metastatic efficiency.
  8. Nat Commun. 2020 Sep 11. 11(1): 4545
    de Streel G, Bertrand C, Chalon N, Liénart S, Bricard O, Lecomte S, Devreux J, Gaignage M, De Boeck G, Mariën L, Van De Walle I, van der Woning B, Saunders M, de Haard H, Vermeersch E, Maes W, Deckmyn H, Coulie PG, van Baren N, Lucas S.
      TGF-β1, β2 and β3 bind a common receptor to exert vastly diverse effects in cancer, supporting either tumor progression by favoring metastases and inhibiting anti-tumor immunity, or tumor suppression by inhibiting malignant cell proliferation. Global TGF-β inhibition thus bears the risk of undesired tumor-promoting effects. We show that selective blockade of TGF-β1 production by Tregs with antibodies against GARP:TGF-β1 complexes induces regressions of mouse tumors otherwise resistant to anti-PD-1 immunotherapy. Effects of combined GARP:TGF-β1/PD-1 blockade are immune-mediated, do not require FcγR-dependent functions and increase effector functions of anti-tumor CD8+ T cells without augmenting immune cell infiltration or depleting Tregs within tumors. We find GARP-expressing Tregs and evidence that they produce TGF-β1 in one third of human melanoma metastases. Our results suggest that anti-GARP:TGF-β1 mAbs, by selectively blocking a single TGF-β isoform emanating from a restricted cellular source exerting tumor-promoting activity, may overcome resistance to PD-1/PD-L1 blockade in patients with cancer.
  9. Mol Cancer. 2020 Sep 11. 19(1): 141
    Horvath L, Thienpont B, Zhao L, Wolf D, Pircher A.
      Immunotherapy (IO) has revolutionized the therapy landscape of non-small cell lung cancer (NSCLC), significantly prolonging the overall survival (OS) of advanced stage patients. Over the recent years IO therapy has been broadly integrated into the first-line setting of non-oncogene driven NSCLC, either in combination with chemotherapy, or in selected patients with PD-L1high expression as monotherapy. Still, a significant proportion of patients suffer from disease progression. A better understanding of resistance mechanisms depicts a central goal to avoid or overcome IO resistance and to improve patient outcome.We here review major cellular and molecular pathways within the tumor microenvironment (TME) that may impact the evolution of IO resistance. We summarize upcoming treatment options after IO resistance including novel IO targets (e.g. RIG-I, STING) as well as interesting combinational approaches such as IO combined with anti-angiogenic agents or metabolic targets (e.g. IDO-1, adenosine signaling, arginase). By discussing the fundamental mode of action of IO within the TME, we aim to understand and manage IO resistance and to seed new ideas for effective therapeutic IO concepts.
    Keywords:  Immunotherapy resistance; NSCLC; Targeted therapy; Tumor microenvironment heterogeneity
  10. Drug Resist Updat. 2020 Aug 20. pii: S1368-7646(20)30049-2. [Epub ahead of print]53 100720
    Li B, Jiang J, Assaraf YG, Xiao H, Chen ZS, Huang C.
      Despite the development of targeted therapy, drug resistance remains a primary hindrance to curative treatment of various cancers. Among several novel approaches to overcome drug resistance, modulating N6-methyladenosine (m6A) RNA modification was found to be an important strategy in various types of cancer cells. Considered as one of the most common epigenetic RNA modifications, m6A regulates multiple biological processes including cellular proliferation, metabolism, and metastasis through modulation of RNA splicing, degradation, and translation, leading to anticancer drug resistance. This regulatory network is orchestrated mainly by several m6A regulators, including "writers", "readers", and "erasers". It is encouraging that several small molecules targeting m6A regulators have shown great potential in overcoming drug resistance in different cancer cell types, two of which entacapone and meclofenamate, are currently undergoing evaluation. However, the m6A modification participates in complex biological processes and its functions are context-dependent, which has challenged the clinical application of targeting the m6A modification in cancer therapy. In this review, we discuss the molecular mechanisms underlying the m6A modification in regulating anticancer drug resistance through modulation of drug-target interaction and drug-mediated cell death signaling. Alteration of the m6A modification interferes with drug efficacy through modulation of the expression of multidrug efflux transporters (e.g., ABCG2, ABCC9, ABCC10), drug metabolizing enzymes (e.g., CYP2C8), and drug targets (e.g., p53 R273 H). Furthermore, alterations of the m6A modification may protect cells from drug-mediated cell death by regulating DNA damage repair (e.g., p53, BRCA1, Pol κ, UBE2B, and ERCC1), downstream adaptive response (e.g., critical regulators of apoptosis, autophagy, pro-survival signaling, and oncogenic bypass signaling), cell stemness, and tumor microenvironment (e.g., ITGA6, ITGB3, and PD-1). We particularly highlight recent advances in therapeutic strategies targeting the m6A modification with the aim to surmount chemoresistance. The comprehensive understanding of the role of the m6A modification integrated with combined therapeutic strategies, should facilitate the development of future therapeutic strategies to circumvent or surmount drug resistance, thus enhancing therapeutic efficacy.
    Keywords:  Cancer; Chemotherapy; Drug resistance; RNA modification; Surmounting chemoresistance; m(6)A RNA modification
  11. Elife. 2020 Sep 11. pii: e59686. [Epub ahead of print]9
    Pathak T, Gueguinou M, Walter V, Delierneux C, Johnson MT, Zhang X, Xin P, Yoast RE, Emrich SM, Yochum GR, Sekler I, Koltun WA, Gill DL, Hempel N, Trebak M.
      Despite the established role of mitochondria in cancer, the mechanisms by which mitochondrial Ca2+ (mtCa2+) regulates tumorigenesis remain incompletely understood. The crucial role of mtCa2+ in tumorigenesis is highlighted by altered expression of proteins mediating mtCa2+ uptake and extrusion in cancer. Here, we demonstrate decreased expression of the mitochondrial Na+/Ca2+/Li+ exchanger NCLX (SLC8B1) in human colorectal tumors and its association with advanced-stage disease in patients. Downregulation of NCLX causes mtCa2+ overload, mitochondrial depolarization, decreased expression of cell-cycle genes and reduced tumor size in xenograft and spontaneous colorectal cancer mouse models. Concomitantly, NCLX downregulation drives metastatic spread, chemoresistance, and expression of epithelial-to-mesenchymal, hypoxia, and stem cell pathways. Mechanistically, mtCa2+ overload leads to increased mitochondrial reactive oxygen species, which activate HIF1α signaling supporting metastasis of NCLX-null tumor cells. Thus, loss of NCLX is a novel driver of metastasis, indicating that regulation of mtCa2+ is a novel therapeutic approach in metastatic colorectal cancer.
    Keywords:  human; molecular biophysics; mouse; structural biology
  12. Stem Cell Rev Rep. 2020 Sep 07.
    Lee SH, Reed-Newman T, Anant S, Ramasamy TS.
      Quiescence in cancer cells is considered a therapeutic challenge as it confers dormancy in tumour, hence circumventing inherent anti-neoplastic surveillance system and standard-of-care cancer therapeutics including chemotherapy and radiotherapy. Since majority of the therapeutics target actively proliferating cancer cells, cancer cells eventually develop quiescent nature as mechanism of survival and cancer progression under both niche and therapeutic pressures. Quiescence state in cancer cells, eventually, confers resistant and aggressive nature to conventional cancer therapies, resulting in disease progression and relapse. Therefore, targeting quiescent cancer cells or cancer stem cells is a promising therapeutic approach, however an extensive review of the relevant information is needed in order to device an effective therapy. While the evidence of quiescence regulation in CSCs is rather a complex molecular and cellular network, herein, we aim to provide a comprehensive understanding of both intrinsic and extrinsic regulation in association with the function of CSCs. Findings on induction of quiescent state in CSCs population, its regulation at both cellular and molecular level, key molecular regulators, cellular events and processes including potential targets to develop therapeutics are extensively reviewed. This review also highlights the impact of CSC plasticity on quiescence which capturing the key challenge of targeting the cells in this state. Beyond understanding the mechanisms underlying quiescence nature of cancer cells, this review provides insightful perspective and future direction on insight in targeting these populations, hence collapse the tumour dormancy programme in order to eradicate tumour mass as a whole. Capability of CSCs to establish quiescent state as a mechanism of survival during unfavorable conditions, as well as its impact in cancer progression and subsequent relapse, including the potential therapeutic strategy to eradicate this CSCs sub-population in the tumor mass as an effective cancer therapy.
    Keywords:  Cancer progression; Cancer stem cells (CSCs); Cellular plasticity; Quiescence; Survival; Tumour dormancy; Tumour relapse
  13. Proc Natl Acad Sci U S A. 2020 Sep 10. pii: 202002520. [Epub ahead of print]
    Esteban-Burgos L, Wang H, Nieto P, Zheng J, Blanco-Aparicio C, Varela C, Gómez-López G, Fernández-García F, Sanclemente M, Guerra C, Drosten M, Galán J, Caleiras E, Martínez-Torrecuadrada J, Fajas L, Peng SB, Santamaría D, Musteanu M, Barbacid M.
      KRAS mutant lung adenocarcinomas remain intractable for targeted therapies. Genetic interrogation of KRAS downstream effectors, including the MAPK pathway and the interphase CDKs, identified CDK4 and RAF1 as the only targets whose genetic inactivation induces therapeutic responses without causing unacceptable toxicities. Concomitant CDK4 inactivation and RAF1 ablation prevented tumor progression and induced complete regression in 25% of KRAS/p53-driven advanced lung tumors, yet a significant percentage of those tumors that underwent partial regression retained a population of CDK4/RAF1-resistant cells. Characterization of these cells revealed two independent resistance mechanisms implicating hypermethylation of several tumor suppressors and increased PI3K activity. Importantly, these CDK4/RAF1-resistant cells can be pharmacologically controlled. These studies open the door to new therapeutic strategies to treat KRAS mutant lung cancer, including resistant tumors.
    Keywords:  CDK4/RAF1 inhibition; KRAS; Lung Cancer; Resistance Mechanisms; Tumor Regression
  14. Elife. 2020 Sep 10. pii: e58374. [Epub ahead of print]9
    Oliemuller E, Newman R, Tsang SM, Foo S, Muirhead G, Noor F, Haider S, Aurrekoetxea-Rodríguez I, Vivanco MD, Howard BA.
      SOX11 is an embryonic mammary epithelial marker that is normally silenced prior to birth. High SOX11 levels in breast tumours are significantly associated with distant metastasis and poor outcome in breast cancer patients. Here, we show that SOX11 confers distinct features to ER-negative breast cancer cells, leading to populations enriched with highly plastic hybrid epithelial/mesenchymal cells, which display invasive features and alterations in metastatic tropism when xenografted into mice. We found that SOX11+DCIS tumour cells metastasize to brain and bone at greater frequency and to lungs at lower frequency compared to cells with lower SOX11 levels. High levels of SOX11 leads to the expression of markers associated with mesenchymal state and embryonic cellular phenotypes. Our results suggest that SOX11 may be a potential biomarker for breast tumours with elevated risk of developing metastases and may require more aggressive therapies.
    Keywords:  cancer biology; developmental biology; human
  15. EMBO Rep. 2020 Sep 10. e50078
    Melchionna R, Spada S, Di Modugno F, D'Andrea D, Di Carlo A, Panetta M, Mileo AM, Sperduti I, Antoniani B, Gallo E, Lawlor RT, Piemonti L, Visca P, Milella M, Grazi GL, Facciolo F, Chen E, Scarpa A, Nisticò P.
      The dynamic interplay between cancer cells and cancer-associated fibroblasts (CAFs) is regulated by multiple signaling pathways, which can lead to cancer progression and therapy resistance. We have previously demonstrated that hMENA, a member of the actin regulatory protein of Ena/VASP family, and its tissue-specific isoforms influence a number of intracellular signaling pathways related to cancer progression. Here, we report a novel function of hMENA/hMENAΔv6 isoforms in tumor-promoting CAFs and in the modulation of pro-tumoral cancer cell/CAF crosstalk via GAS6/AXL axis regulation. LC-MS/MS proteomic analysis reveals that CAFs that overexpress hMENAΔv6 secrete the AXL ligand GAS6, favoring the invasiveness of AXL-expressing pancreatic ductal adenocarcinoma (PDAC) and non-small cell lung cancer (NSCLC) cells. Reciprocally, hMENA/hMENAΔv6 regulates AXL expression in tumor cells, thus sustaining GAS6-AXL axis, reported as crucial in EMT, immune evasion, and drug resistance. Clinically, we found that a high hMENA/GAS6/AXL gene expression signature is associated with a poor prognosis in PDAC and NSCLC. We propose that hMENA contributes to cancer progression through paracrine tumor-stroma crosstalk, with far-reaching prognostic and therapeutic implications for NSCLC and PDAC.
    Keywords:   AXL ; GAS6; actin cytoskeleton; cancer-associated fibroblasts; lung cancer
  16. Cell Death Differ. 2020 Sep 08.
    Huang Y, Yang X, Lu Y, Zhao Y, Meng R, Zhang S, Dong X, Xu S, Wu G.
      UBE2O, an E2/E3 hybrid ubiquitin-protein ligase, has been implicated in the regulation of adipogenesis, erythroid differentiation, and tumor proliferation. However, its role in cancer radioresistance remains completely unknown. Here, we uncover that UBE2O interacts and targets Mxi1 for ubiquitination and degradation at the K46 residue. Furthermore, we show that genetical or pharmacological blockade of UBE2O impairs tumor progression and radioresistance in lung cancer in vitro and in vivo, and these effects can be restored by Mxi1 inhibition. Moreover, we demonstrate that UBE2O is overexpressed and negatively correlated with Mxi1 protein levels in lung cancer tissues. Collectively, our work reveals that UBE2O facilitates tumorigenesis and radioresistance by promoting Mxi1 ubiquitination and degradation, suggesting that UBE2O is an attractive radiosensitization target for the treatment of lung cancer.
  17. Cancer Res. 2020 Sep 08. pii: canres.0025.2020. [Epub ahead of print]
    Shim J, Lee JY, Jonus HC, Arnold A, Schnepp RW, Janssen KM, Maximov V, Goldsmith KC.
      Following chemotherapy and relapse, high-risk neuroblastoma tumors harbor more genomic alterations than at diagnosis, including increased transcriptional activity of the Yes-Associated Protein (YAP), a key downstream component of the Hippo signaling network. Although YAP has been implicated in many cancer types, its functional role in the aggressive pediatric cancer neuroblastoma (NB) is not well characterized. In this study, we performed genetic manipulation of YAP in human-derived NB cell lines to investigate YAP function in key aspects of the malignant phenotype, including mesenchymal properties, tumor growth, chemotherapy response, and MEK inhibitor response. Standard cytotoxic therapy induced YAP expression and transcriptional activity in patient-derived xenografts treated in vivo, which may contribute to neuroblastoma recurrence. Moreover, YAP promoted a mesenchymal phenotype in high-risk neuroblastoma that modulated tumor growth and therapy resistance in vivo. Finally, the BH3-only protein Harakiri (HRK) was identified as a novel target inhibited by YAP which, when suppressed, prevented apoptosis in response to nutrient deprivation in vitro and promoted tumor aggression, chemotherapy resistance, and MEK inhibitor resistance in vivo. Collectively, these findings suggest that YAP inhibition may improve chemotherapy response in neuroblastoma patients via its regulation of HRK, thus providing a critical strategic complement to MEK inhibitor therapy.
  18. Cancer Res. 2020 Sep 11. pii: canres.3044.2019. [Epub ahead of print]
    Azar WJ, Christie EL, Mitchell C, Liu DS, Au-Yeung G, Bowtell DDL.
      Ovarian clear cell adenocarcinoma (OCCA) is characterized by a particularly poor response to conventional chemotherapy and a short overall survival time in women with established disease. The development of targeted treatments for OCCA relies on a better understanding of its molecular characteristics. IL-6 is strongly expressed in OCCA and may therefore provide a novel therapeutic target. Here we use CRISPR/Cas9 and conditional short-hairpin interfering RNA to perform loss-of-function studies in human OCCA cell lines to explore the requirement for IL-6 in vitro and in vivo. While reduction of IL-6 expression exerted limited effects in vitro, its attenuation significantly impaired tumor growth and neovascularization in vivo. In contrast to typical signaling via STAT3, IL-6 in OCCA signaled via a non-canonical pathway involving gp130, Src, and the Hippo pathway protein YAP. A high-throughput combination drug screen identified agents that enhanced cell killing following reduction of IL-6 signaling. Intersection of screen hits obtained from two cell lines and orthogonal approaches to attenuation of IL-6 yielded AKT and EGFR inhibitors as enhancers of the inhibitory monoclonal IL-6 receptor antibody Tocilizumab. This study defines for the first time the requirements for, and mechanisms of, signaling by IL-6 in human OCCA cell lines and identifies potential combinatory therapeutic approaches. Given the molecular diversity of OCCA, further in vitro and in vivo studies are warranted to determine whether such approaches will overcome the limited efficacy of Tocilizumab observed in ovarian cancer to date.
  19. Nat Commun. 2020 Sep 09. 11(1): 4498
    Cioni B, Zaalberg A, van Beijnum JR, Melis MHM, van Burgsteden J, Muraro MJ, Hooijberg E, Peters D, Hofland I, Lubeck Y, de Jong J, Sanders J, Vivié J, van der Poel HG, de Boer JP, Griffioen AW, Zwart W, Bergman AM.
      The androgen receptor (AR) is the master regulator of prostate cancer (PCa) development, and inhibition of AR signalling is the most effective PCa treatment. AR is expressed in PCa cells and also in the PCa-associated stroma, including infiltrating macrophages. Macrophages have a decisive function in PCa initiation and progression, but the role of AR in macrophages remains largely unexplored. Here, we show that AR signalling in the macrophage-like THP-1 cell line supports PCa cell line migration and invasion in culture via increased Triggering Receptor Expressed on Myeloid cells-1 (TREM-1) signalling and expression of its downstream cytokines. Moreover, AR signalling in THP-1 and monocyte-derived macrophages upregulates IL-10 and markers of tissue residency. In conclusion, our data suggest that AR signalling in macrophages may support PCa invasiveness, and blocking this process may constitute one mechanism of anti-androgen therapy.
  20. Cells. 2020 Sep 05. pii: E2035. [Epub ahead of print]9(9):
    Benzarti M, Delbrouck C, Neises L, Kiweler N, Meiser J.
      The metastatic cascade is a highly plastic and dynamic process dominated by cellular heterogeneity and varying metabolic requirements. During this cascade, the three major metabolic pillars, namely biosynthesis, RedOx balance, and bioenergetics, have variable importance. Biosynthesis has superior significance during the proliferation-dominated steps of primary tumour growth and secondary macrometastasis formation and only minor relevance during the growth-independent processes of invasion and dissemination. Consequently, RedOx homeostasis and bioenergetics emerge as conceivable metabolic key determinants in cancer cells that disseminate from the primary tumour. Within this review, we summarise our current understanding on how cancer cells adjust their metabolism in the context of different microenvironments along the metastatic cascade. With the example of one-carbon metabolism, we establish a conceptual view on how the same metabolic pathway can be exploited in different ways depending on the current cellular needs during metastatic progression.
    Keywords:  ROS; RedOx balance; bioenergetics; biosynthesis; cancer metabolism; hypoxia; metabolic plasticity; metastasis; one-carbon metabolism; tumour microenvironment
  21. Cell Rep. 2020 Sep 08. pii: S2211-1247(20)31094-9. [Epub ahead of print]32(10): 108105
    Donato C, Kunz L, Castro-Giner F, Paasinen-Sohns A, Strittmatter K, Szczerba BM, Scherrer R, Di Maggio N, Heusermann W, Biehlmaier O, Beisel C, Vetter M, Rochlitz C, Weber WP, Banfi A, Schroeder T, Aceto N.
      Circulating tumor cells (CTCs) are shed from solid cancers in the form of single or clustered cells, and the latter display an extraordinary ability to initiate metastasis. Yet, the biological phenomena that trigger the shedding of CTC clusters from a primary cancerous lesion are poorly understood. Here, when dynamically labeling breast cancer cells along cancer progression, we observe that the majority of CTC clusters are undergoing hypoxia, while single CTCs are largely normoxic. Strikingly, we find that vascular endothelial growth factor (VEGF) targeting leads to primary tumor shrinkage, but it increases intra-tumor hypoxia, resulting in a higher CTC cluster shedding rate and metastasis formation. Conversely, pro-angiogenic treatment increases primary tumor size, yet it dramatically suppresses the formation of CTC clusters and metastasis. Thus, intra-tumor hypoxia leads to the formation of clustered CTCs with high metastatic ability, and a pro-angiogenic therapy suppresses metastasis formation through prevention of CTC cluster generation.
  22. Cell Rep. 2020 Sep 08. pii: S2211-1247(20)31091-3. [Epub ahead of print]32(10): 108102
    Zhang S, Shen Y, Li H, Bi C, Sun Y, Xiong X, Wei W, Sun Y.
      Anaphase-promoting complex/cyclosome (APC/C) is a well-characterized E3 ligase that couples with UBE2C and UBE2S E2s for substrate ubiquitylation by the K11 linkage. Our recent data show that SAG/RBX2/ROC2, a RING component of Cullin-RING E3 ligase, also complexes with these E2s for K11-linked substrate polyubiquitylation. Whether these two E3s cross-talk with each other was previously unknown. Here, we report that SAG competes with APC2 for UBE2C/UBE2S binding to act as a potential endogenous inhibitor of APC/C, thereby regulating the G2-to-M progression. As such, SAG knockdown triggers premature activation of APC/C, leading to mitotic slippage and resistance to anti-microtubule drugs. On the other hand, SAG itself is a substrate of APC/CCDH1 for targeted degradation at the G1 phase. The degradation-resistant mutant of SAG-R98A/L101A accelerates the G1-to-S progression. Our study reveals that the negative cross-talk between SAG and APC/C is likely a mechanism to ensure the fidelity of cell cycle progression.
    Keywords:  APC/C; APC2; SAG; UBE2C; UBE2S; cell cycle; mitotic slippage; ubiquitylation
  23. Cancers (Basel). 2020 Sep 07. pii: E2534. [Epub ahead of print]12(9):
    Balachandran AA, Larcher LM, Chen S, Veedu RN.
      Brain cancer is one among the rare cancers with high mortality rate that affects both children and adults. The most aggressive form of primary brain tumor is glioblastoma. Secondary brain tumors most commonly metastasize from primary cancers of lung, breast, or melanoma. The five-year survival of primary and secondary brain tumors is 34% and 2.4%, respectively. Owing to poor prognosis, tumor heterogeneity, increased tumor relapse, and resistance to therapies, brain cancers have high mortality and poor survival rates compared to other cancers. Early diagnosis, effective targeted treatments, and improved prognosis have the potential to increase the survival rate of patients with primary and secondary brain malignancies. MicroRNAs (miRNAs) are short noncoding RNAs of approximately 18-22 nucleotides that play a significant role in the regulation of multiple genes. With growing interest in the development of miRNA-based therapeutics, it is crucial to understand the differential role of these miRNAs in the given cancer scenario. This review focuses on the differential expression of ten miRNAs (miR-145, miR-31, miR-451, miR-19a, miR-143, miR-125b, miR-328, miR-210, miR-146a, and miR-126) in glioblastoma and brain metastasis. These miRNAs are highly dysregulated in both primary and metastatic brain tumors, which necessitates a better understanding of their role in these cancers. In the context of the tumor microenvironment and the expression of different genes, these miRNAs possess both oncogenic and/or tumor-suppressive roles within the same cancer.
    Keywords:  brain cancer; cancer metastasis; glioblastoma; glioma; miRNA
  24. Clin Cancer Res. 2020 Sep 08. pii: clincanres.2077.2020. [Epub ahead of print]
    Adachi Y, Ito K, Hayashi Y, Kimura R, Tan TZ, Yamaguchi R, Ebi H.
      PURPOSE: KRAS is among the most commonly mutated oncogene in cancer including non-small cell lung cancer (NSCLC). In early clinical trials, inhibitors targeting G12C mutant KRAS have achieved responses in some patients with NSCLC. Possible intrinsic and acquired resistance mechanisms to KRAS G12C inhibitors are not fully elucidated and will likely become important to identify.EXPERIMENTAL DESIGN: To identify potential resistance mechanisms, we defined the sensitivity of a panel of KRAS G12C mutant lung cancer cell lines to a KRAS G12C inhibitor, AMG510. Gene set enrichment analyses were performed to identify pathways related to the sensitivity, which was further confirmed biochemically. Additionally, we created two cell lines that acquired resistance to AMG510 and the underlying resistance mechanisms were analyzed.
    RESULTS: KRAS expression and activation were associated with sensitivity to KRAS G12C inhibitor. Induction of epithelial to mesenchymal transition (EMT) led to both intrinsic and acquired resistance to KRAS G12C inhibition. In these EMT-induced cells, PI3K remained activated in the presence of KRAS G12C inhibitor and was dominantly regulated by the IGFR-IRS1 pathway. We found SHP2 plays a minimal role in the activation of the PI3K pathway in contrast to its critical role in the activation of the MAPK pathway. The combination of KRAS G12C inhibitor, PI3K inhibitor and SHP2 inhibitor resulted in tumor regressions in mouse models of acquired resistance to AMG510.
    CONCLUSIONS: Our findings suggest that EMT is a cause of both intrinsic and acquired resistance by activating the PI3K pathway in the presence of KRAS G12C inhibitor.
  25. Mol Cancer Res. 2020 Sep 10. pii: molcanres.0359.2020. [Epub ahead of print]
    Bao B, Teslow EA, Mitrea C, Boerner JL, Dyson G, Bollig-Fischer A.
      Triple negative breast cancer (TNBC) is a subtype of breast cancer that lacks expression of estrogen receptor, progesterone receptor and the epidermal growth factor receptor 2 (HER2) but is enriched with cancer stem cell-like cells (CSCs). CSCs are the fraction of cancer cells recognized as the source of primary malignant tumors that also give rise to metastatic recurrence. 5-hydroxymethylcytosine (5hmC) is a DNA epigenetic feature derived from 5-methylcytosine (5mC) by action of tet methylcytosine dioxygenase enzymes (e.g., TET1); and while TET1 and 5hmC are required to maintain embryonic stem cells, the mechanism and role in CSCs remain unknown. Data presented in this report support the conclusion that TET1 and TET1-dependent 5hmC mediate hydrogen peroxide (H2O2)-dependent activation of a novel gene expression cascade driving self-renewal and expansion of CSCs in TNBC. Evidence presented also supports that the H2O2 impacting this pathway arises due to endogenous mechanisms - including down-regulation of antioxidant enzyme catalase in TNBC cells - and by exogenous routes, such as systemic inflammation and oxidative stress coupled with obesity, a known risk factor for TNBC incidence and recurrence. Implications: This study elucidates a pathway dependent on H2O2 and linked to obesity-driven TNBC tumor-initiating CSCs; thus, it provides new understanding that may advance TNBC prevention and treatment strategies.
  26. Cancer Res. 2020 Sep 09. pii: canres.3883.2019. [Epub ahead of print]
    McClatchy DM, Willers H, Hata AN, Piotrowska Z, Sequist LV, Paganetti H, Grassberger C.
      Optimal integration of molecularly targeted therapies such as tyrosine kinase inhibitors (TKI) with concurrent chemotherapy and radiation (CRT) to improve outcomes in genotype-defined cancers remains a current challenge in clinical settings. Important questions regarding optimal scheduling and length of induction period for neoadjuvant use of targeted agents remain unsolved and vary among clinical trial protocols. Here we develop and validate a bio-mathematical framework encompassing drug resistance and radiobiology to simulate patterns of local versus distant recurrences in a non-small cell lung cancer (NSCLC) population with mutated epidermal growth factor receptor (EGFR) receiving TKI and CRT. Our model predicted that targeted induction before CRT, an approach currently being tested in clinical trials, may render adjuvant targeted therapy less effective due to proliferation of drug-resistant cancer cells when using very long induction periods. Furthermore, simulations not only demonstrated the competing effects of drug-resistant cell expansion versus overall tumor regression as a function of induction length, but also directly estimated the probability of observing an improvement in progression-free survival at a given cohort size. We thus demonstrate that such stochastic biological simulations have the potential to quantitatively inform the design of multimodality clinical trials in genotype-defined cancers.
  27. Cancers (Basel). 2020 Sep 08. pii: E2553. [Epub ahead of print]12(9):
    Jun BH, Guo T, Libring S, Chanda MK, Paez JS, Shinde A, Wendt MK, Vlachos PP, Solorio L.
      Tumor metastasis is connected to epithelial-mesenchymal heterogeneity (EMH) and the extracellular matrix (ECM) within the tumor microenvironment. Mesenchymal-like fibronectin (FN) expressing tumor cells enhance metastasis within tumors that have EMH. However, the secondary tumors are primarily composed of the FN null population. Interestingly, during tumor cell dissemination, the invasive front has more mesenchymal-like characteristics, although the outgrowths of metastatic colonies consist of a more epithelial-like population of cells. We hypothesize that soluble FN provided by mesenchymal-like tumor cells plays a role in supporting the survival of the more epithelial-like tumor cells within the metastatic niche in a paracrine manner. Furthermore, due to a lower rate of proliferation, the mesenchymal-like tumor cells become a minority population within the metastatic niche. In this study, we utilized a multi-parametric cell-tracking algorithm and immunoblotting to evaluate the effect of EMH on the growth and invasion of an isogenic cell series within a 3D collagen network using a microfluidic platform. Using the MCF10A progression series, we demonstrated that co-culture with FN-expressing MCF10CA1h cells significantly enhanced the survival of the more epithelial MCF10CA1a cells, with a two-fold increase in the population after 5 days in co-culture, whereas the population of the MCF10CA1a cells began to decrease after 2.5 days when cultured alone (p < 0.001). However, co-culture did not significantly alter the rate of proliferation for the more mesenchymal MCF10CA1h cells. Epithelial tumor cells not only showed prolonged survival, but migrated significantly longer distances (350 µm compared with 150 µm, respectively, p < 0.01) and with greater velocity magnitude (4.5 µm/h compared with 2.1 µm/h, respectively, p < 0.001) under co-culture conditions and in response to exogenously administered FN. Genetic depletion of FN from the MCF10CA1h cells resulted in a loss of survival and migration capacity of the epithelial and mesenchymal populations. These data suggest that mesenchymal tumor cells may function to support the survival and outgrowth of more epithelial tumor cells within the metastatic niche and that inhibition of FN production may provide a valuable target for treating metastatic disease.
    Keywords:  breast cancer; cell migration tracking; epithelial mesenchymal transition; extracellular matrix; fibronectin; metastasis; microfluidics; plasticity; premetastatic niche