bims-tucedo Biomed News
on Tumor cell dormancy
Issue of 2020‒05‒24
twenty-five papers selected by
Isabel Puig Borreil
Vall d’Hebron Institute of Oncology


  1. Proc Natl Acad Sci U S A. 2020 May 19. pii: 202005156. [Epub ahead of print]
    Gupta R, Malvi P, Parajuli KR, Janostiak R, Bugide S, Cai G, Zhu LJ, Green MR, Wajapeyee N.
      Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with a dismal prognosis. Currently, there is no effective therapy for PDAC, and a detailed molecular and functional evaluation of PDACs is needed to identify and develop better therapeutic strategies. Here we show that the transcription factor Krüppel-like factor 7 (KLF7) is overexpressed in PDACs, and that inhibition of KLF7 blocks PDAC tumor growth and metastasis in cell culture and in mice. KLF7 expression in PDACs can be up-regulated due to activation of a MAP kinase pathway or inactivation of the tumor suppressor p53, two alterations that occur in a large majority of PDACs. ShRNA-mediated knockdown of KLF7 inhibits the expression of IFN-stimulated genes (ISGs), which are necessary for KLF7-mediated PDAC tumor growth and metastasis. KLF7 knockdown also results in the down-regulation of Discs Large MAGUK Scaffold Protein 3 (DLG3), resulting in Golgi complex fragmentation, and reduced protein glycosylation, leading to reduced secretion of cancer-promoting growth factors, such as chemokines. Genetic or pharmacologic activation of Golgi complex fragmentation blocks PDAC growth and metastasis similar to KLF7 inhibition. Our results demonstrate a therapeutically amenable, KLF7-driven pathway that promotes PDAC growth and metastasis by activating ISGs and maintaining Golgi complex integrity.
    Keywords:  Golgi complex; IFN-stimulated genes; KLF7; metastasis; pancreatic cancer
    DOI:  https://doi.org/10.1073/pnas.2005156117
  2. Nat Commun. 2020 May 19. 11(1): 2498
    Jewer M, Lee L, Leibovitch M, Zhang G, Liu J, Findlay SD, Vincent KM, Tandoc K, Dieters-Castator D, Quail DF, Dutta I, Coatham M, Xu Z, Puri A, Guan BJ, Hatzoglou M, Brumwell A, Uniacke J, Patsis C, Koromilas A, Schueler J, Siegers GM, Topisirovic I, Postovit LM.
      Plasticity of neoplasia, whereby cancer cells attain stem-cell-like properties, is required for disease progression and represents a major therapeutic challenge. We report that in breast cancer cells NANOG, SNAIL and NODAL transcripts manifest multiple isoforms characterized by different 5' Untranslated Regions (5'UTRs), whereby translation of a subset of these isoforms is stimulated under hypoxia. The accumulation of the corresponding proteins induces plasticity and "fate-switching" toward stem cell-like phenotypes. Mechanistically, we observe that mTOR inhibitors and chemotherapeutics induce translational activation of a subset of NANOG, SNAIL and NODAL mRNA isoforms akin to hypoxia, engendering stem-cell-like phenotypes. These effects are overcome with drugs that antagonize translational reprogramming caused by eIF2α phosphorylation (e.g. ISRIB), suggesting that the Integrated Stress Response drives breast cancer plasticity. Collectively, our findings reveal a mechanism of induction of plasticity of breast cancer cells and provide a molecular basis for therapeutic strategies aimed at overcoming drug resistance and abrogating metastasis.
    DOI:  https://doi.org/10.1038/s41467-020-16352-z
  3. Cancer Cell. 2020 May 13. pii: S1535-6108(20)30213-0. [Epub ahead of print]
    Wang Z, Hausmann S, Lyu R, Li TM, Lofgren SM, Flores NM, Fuentes ME, Caporicci M, Yang Z, Meiners MJ, Cheek MA, Howard SA, Zhang L, Elias JE, Kim MP, Maitra A, Wang H, Bassik MC, Keogh MC, Sage J, Gozani O, Mazur PK.
      Molecular mechanisms underlying adaptive targeted therapy resistance in pancreatic ductal adenocarcinoma (PDAC) are poorly understood. Here, we identify SETD5 as a major driver of PDAC resistance to MEK1/2 inhibition (MEKi). SETD5 is induced by MEKi resistance and its deletion restores refractory PDAC vulnerability to MEKi therapy in mouse models and patient-derived xenografts. SETD5 lacks histone methyltransferase activity but scaffolds a co-repressor complex, including HDAC3 and G9a. Gene silencing by the SETD5 complex regulates known drug resistance pathways to reprogram cellular responses to MEKi. Pharmacological co-targeting of MEK1/2, HDAC3, and G9a sustains PDAC tumor growth inhibition in vivo. Our work uncovers SETD5 as a key mediator of acquired MEKi therapy resistance in PDAC and suggests a context for advancing MEKi use in the clinic.
    Keywords:  KRAS; MEK inhibition; RAS signaling; SETD5; lysine methylation; pancreatic cancer; protein methylation
    DOI:  https://doi.org/10.1016/j.ccell.2020.04.014
  4. Nat Commun. 2020 May 19. 11(1): 2487
    Zhang P, Liu Y, Lian C, Cao X, Wang Y, Li X, Cong M, Tian P, Zhang X, Wei G, Liu T, Hu G.
      Cancer stem-like cells (CSCs) are the tumorigenic cell subpopulation and contribute to cancer recurrence and metastasis. However, the understanding of CSC regulatory mechanisms remains incomplete. By transcriptomic analysis, we identify a scaffold protein SH3RF3 (also named POSH2) that is upregulated in CSCs of breast cancer clinical tumors and cancer cell lines, and enhances the CSC properties of breast cancer cells. Mechanically, SH3RF3 interacts with the c-Jun N-terminal kinase (JNK) in a JNK-interacting protein (JIP)-dependent manner, leading to enhanced phosphorylation of JNK and activation of the JNK-JUN pathway. Further the JNK-JUN signaling expands CSC subpopulation by transcriptionally activating the expression of Pentraxin 3 (PTX3). The functional role of SH3RF3 in CSCs is validated with patient-derived organoid culture, and supported by clinical cohort analyses. In conclusion, our work elucidates the role and molecular mechanism of SH3RF3 in CSCs of breast cancer, and might provide opportunities for CSC-targeting therapy.
    DOI:  https://doi.org/10.1038/s41467-020-16051-9
  5. Nat Genet. 2020 May 18.
    Hu Z, Li Z, Ma Z, Curtis C.
      Metastasis is the primary cause of cancer-related deaths, but the natural history, clonal evolution and impact of treatment are poorly understood. We analyzed whole-exome sequencing (WES) data from 457 paired primary tumor and metastatic samples from 136 patients with breast, colorectal and lung cancer, including untreated (n = 99) and treated (n = 100) metastases. Treated metastases often harbored private 'driver' mutations, whereas untreated metastases did not, suggesting that treatment promotes clonal evolution. Polyclonal seeding was common in untreated lymph node metastases (n = 17 out of 29, 59%) and distant metastases (n = 20 out of 70, 29%), but less frequent in treated distant metastases (n = 9 out of 94, 10%). The low number of metastasis-private clonal mutations is consistent with early metastatic seeding, which we estimated occurred 2-4 years before diagnosis across these cancers. Furthermore, these data suggest that the natural course of metastasis is selectively relaxed relative to early tumorigenesis and that metastasis-private mutations are not drivers of cancer spread but instead associated with drug resistance.
    DOI:  https://doi.org/10.1038/s41588-020-0628-z
  6. Mol Cell. 2020 May 07. pii: S1097-2765(20)30269-0. [Epub ahead of print]
    Shu S, Wu HJ, Ge JY, Zeid R, Harris IS, Jovanović B, Murphy K, Wang B, Qiu X, Endress JE, Reyes J, Lim K, Font-Tello A, Syamala S, Xiao T, Reddy Chilamakuri CS, Papachristou EK, D'Santos C, Anand J, Hinohara K, Li W, McDonald TO, Luoma A, Modiste RJ, Nguyen QD, Michel B, Cejas P, Kadoch C, Jaffe JD, Wucherpfennig KW, Qi J, Liu XS, Long H, Brown M, Carroll JS, Brugge JS, Bradner J, Michor F, Polyak K.
      BET bromodomain inhibitors (BBDIs) are candidate therapeutic agents for triple-negative breast cancer (TNBC) and other cancer types, but inherent and acquired resistance to BBDIs limits their potential clinical use. Using CRISPR and small-molecule inhibitor screens combined with comprehensive molecular profiling of BBDI response and resistance, we identified synthetic lethal interactions with BBDIs and genes that, when deleted, confer resistance. We observed synergy with regulators of cell cycle progression, YAP, AXL, and SRC signaling, and chemotherapeutic agents. We also uncovered functional similarities and differences among BRD2, BRD4, and BRD7. Although deletion of BRD2 enhances sensitivity to BBDIs, BRD7 loss leads to gain of TEAD-YAP chromatin binding and luminal features associated with BBDI resistance. Single-cell RNA-seq, ATAC-seq, and cellular barcoding analysis of BBDI responses in sensitive and resistant cell lines highlight significant heterogeneity among samples and demonstrate that BBDI resistance can be pre-existing or acquired.
    Keywords:  ATAC-seq; BET bromodomain inhibitors; CRISPR screen; ChIP-seq; cellular barcoding; single cell ATAC-seq; single cell RNA-seq; small molecule inhibitor screen; therapeutic resistance; triple-negative breast cancer
    DOI:  https://doi.org/10.1016/j.molcel.2020.04.027
  7. Clin Cancer Res. 2020 May 22. pii: clincanres.4121.2019. [Epub ahead of print]
    Lheureux S, Oaknin A, Garg S, Bruce JP, Madariaga A, Dhani NC, Bowering V, White J, Accardi S, Tan Q, Braunstein M, Karakasis K, Cirlan I, Pedersen S, Li T, Fariñas-Madrid L, Lee YC, Liu ZA, Pugh TJ, Oza AM.
      BACKGROUND: PARP inhibitors (PARPis) are standard-of-care therapy for high-grade serous ovarian cancer (HGSOC). We investigated combining cediranib (antiangiogenic) with olaparib (PARPi) at emergence of PARPi resistance.METHODS: The proof-of-concept EVOLVE study (NCT02681237) assessed cediranib-olaparib combination therapy after progression on a PARPi. Women with HGSOC and radiographic evidence of disease progression were enrolled into one of three cohorts: platinum sensitive after PARPi; platinum resistant after PARPi; or progression on standard chemotherapy after progression on PARPi (exploratory cohort). Patients received olaparib tablets 300 mg twice daily with cediranib 20 mg once daily until progression or unacceptable toxicity. The co-primary endpoints were objective response rate (RECIST v1.1) and progression-free survival (PFS) at 16 weeks. Archival tissue (PARPi-naïve) and baseline biopsy (post-PARPi) samples were mandatory. Genomic mechanisms of resistance were assessed by whole-exome and RNA sequencing.
    RESULTS: Among 34 heavily pretreated patients, objective responses were observed in 0/11 (0%) platinum-sensitive patients, 2/10 (20%) platinum-resistant patients, and 1/13 (8%) in the exploratory cohort. 16-week PFS rates were 55%, 50%, and 39%, respectively. The most common grade 3 toxicities were diarrhea (12%) and anemia (9%). Acquired genomic alterations at PARPi progression were reversion mutations in BRCA1, BRCA2, or RAD51B (19%), CCNE1 amplification (16%), ABCB1 upregulation (15%), and SLFN11 downregulation (7%). Patients with reversion mutations in homologous recombination genes and/or ABCB1 upregulation had poor outcomes.
    CONCLUSION: This is currently the largest post-PARPi study identifying genomic mechanisms of resistance to PARPis. In this setting, the activity of cediranib-olaparib varied according to the PARPi resistance mechanism.
    DOI:  https://doi.org/10.1158/1078-0432.CCR-19-4121
  8. Nat Commun. 2020 May 19. 11(1): 2508
    Blomme A, Ford CA, Mui E, Patel R, Ntala C, Jamieson LE, Planque M, McGregor GH, Peixoto P, Hervouet E, Nixon C, Salji M, Gaughan L, Markert E, Repiscak P, Sumpton D, Blanco GR, Lilla S, Kamphorst JJ, Graham D, Faulds K, MacKay GM, Fendt SM, Zanivan S, Leung HY.
      Despite the clinical success of Androgen Receptor (AR)-targeted therapies, reactivation of AR signalling remains the main driver of castration-resistant prostate cancer (CRPC) progression. In this study, we perform a comprehensive unbiased characterisation of LNCaP cells chronically exposed to multiple AR inhibitors (ARI). Combined proteomics and metabolomics analyses implicate an acquired metabolic phenotype common in ARI-resistant cells and associated with perturbed glucose and lipid metabolism. To exploit this phenotype, we delineate a subset of proteins consistently associated with ARI resistance and highlight mitochondrial 2,4-dienoyl-CoA reductase (DECR1), an auxiliary enzyme of beta-oxidation, as a clinically relevant biomarker for CRPC. Mechanistically, DECR1 participates in redox homeostasis by controlling the balance between saturated and unsaturated phospholipids. DECR1 knockout induces ER stress and sensitises CRPC cells to ferroptosis. In vivo, DECR1 deletion impairs lipid metabolism and reduces CRPC tumour growth, emphasizing the importance of DECR1 in the development of treatment resistance.
    DOI:  https://doi.org/10.1038/s41467-020-16126-7
  9. Trends Cancer. 2020 May 13. pii: S2405-8033(20)30137-0. [Epub ahead of print]
    Fares J, Kanojia D, Rashidi A, Ulasov I, Lesniak MS.
      Brain metastasis is an important cause of mortality in patients with cancer and represents the majority of all intracranial tumors. A key step during the metastatic journey of the cancer cell to the brain is the invasion through the blood-brain barrier (BBB). Nevertheless, the molecular mechanisms that govern this process remain unknown. The BBB has been blamed for limiting the access of therapeutic drugs to the brain, which provides a safe haven for cancer cells in the brain and confers poor prognosis for the patient. Here, we explore the genes that control the transmigration of metastatic cancer cells across the BBB, offering new targets for the development of gene and cell therapies against brain metastases.
    Keywords:  blood–tumor barrier; brain metastases; cancer; paracellular migration; tight junctions; transcellular migration
    DOI:  https://doi.org/10.1016/j.trecan.2020.04.007
  10. Nat Cell Biol. 2020 May 18.
    Bi M, Zhang Z, Jiang YZ, Xue P, Wang H, Lai Z, Fu X, De Angelis C, Gong Y, Gao Z, Ruan J, Jin VX, Marangoni E, Montaudon E, Glass CK, Li W, Huang TH, Shao ZM, Schiff R, Chen L, Liu Z.
      Acquired therapy resistance is a major problem for anticancer treatment, yet the underlying molecular mechanisms remain unclear. Using an established breast cancer cellular model, we show that endocrine resistance is associated with enhanced phenotypic plasticity, indicated by a general downregulation of luminal/epithelial differentiation markers and upregulation of basal/mesenchymal invasive markers. Consistently, similar gene expression changes are found in clinical breast tumours and patient-derived xenograft samples that are resistant to endocrine therapies. Mechanistically, the differential interactions between oestrogen receptor α and other oncogenic transcription factors, exemplified by GATA3 and AP1, drive global enhancer gain/loss reprogramming, profoundly altering breast cancer transcriptional programs. Our functional studies in multiple culture and xenograft models reveal a coordinated role of GATA3 and AP1 in re-organizing enhancer landscapes and regulating cancer phenotypes. Collectively, our study suggests that differential high-order assemblies of transcription factors on enhancers trigger genome-wide enhancer reprogramming, resulting in transcriptional transitions that promote tumour phenotypic plasticity and therapy resistance.
    DOI:  https://doi.org/10.1038/s41556-020-0514-z
  11. Leukemia. 2020 May 21.
    Kumar R, Pereira RS, Zanetti C, Minciacchi VR, Merten M, Meister M, Niemann J, Dietz MS, Rüssel N, Schnütgen F, Tamai M, Akahane K, Inukai T, Oellerich T, Kvasnicka HM, Pfeifer H, Nicolini FE, Heilemann M, Van Etten RA, Krause DS.
      Therapy resistance in leukemia may be due to cancer cell-intrinsic and/or -extrinsic mechanisms. Mutations within BCR-ABL1, the oncogene giving rise to chronic myeloid leukemia (CML), lead to resistance to tyrosine kinase inhibitors (TKI), and some are associated with clinically more aggressive disease and worse outcome. Using the retroviral transduction/transplantation model of CML and human cell lines we faithfully recapitulate accelerated disease course in TKI resistance. We show in various models, that murine and human imatinib-resistant leukemia cells positive for the oncogene BCR-ABL1T315I differ from BCR-ABL1 native (BCR-ABL1) cells with regards to niche location and specific niche interactions. We implicate a pathway via integrin β3, integrin-linked kinase (ILK) and its role in deposition of the extracellular matrix (ECM) protein fibronectin as causative of these differences. We demonstrate a trend towards a reduced BCR-ABL1T315I+ tumor burden and significantly prolonged survival of mice with BCR-ABL1T315I+ CML treated with fibronectin or an ILK inhibitor in xenogeneic and syngeneic murine transplantation models, respectively. These data suggest that interactions with ECM proteins via the integrin β3/ILK-mediated signaling pathway in BCR-ABL1T315I+ cells differentially and specifically influence leukemia progression. Niche targeting via modulation of the ECM may be a feasible therapeutic approach to consider in this setting.
    DOI:  https://doi.org/10.1038/s41375-020-0866-1
  12. Proc Natl Acad Sci U S A. 2020 May 18. pii: 201922207. [Epub ahead of print]
    Alumkal JJ, Sun D, Lu E, Beer TM, Thomas GV, Latour E, Aggarwal R, Cetnar J, Ryan CJ, Tabatabaei S, Bailey S, Turina CB, Quigley DA, Guan X, Foye A, Youngren JF, Urrutia J, Huang J, Weinstein AS, Friedl V, Rettig M, Reiter RE, Spratt DE, Gleave M, Evans CP, Stuart JM, Chen Y, Feng FY, Small EJ, Witte ON, Xia Z.
      The androgen receptor (AR) antagonist enzalutamide is one of the principal treatments for men with castration-resistant prostate cancer (CRPC). However, not all patients respond, and resistance mechanisms are largely unknown. We hypothesized that genomic and transcriptional features from metastatic CRPC biopsies prior to treatment would be predictive of de novo treatment resistance. To this end, we conducted a phase II trial of enzalutamide treatment (160 mg/d) in 36 men with metastatic CRPC. Thirty-four patients were evaluable for the primary end point of a prostate-specific antigen (PSA)50 response (PSA decline ≥50% at 12 wk vs. baseline). Nine patients were classified as nonresponders (PSA decline <50%), and 25 patients were classified as responders (PSA decline ≥50%). Failure to achieve a PSA50 was associated with shorter progression-free survival, time on treatment, and overall survival, demonstrating PSA50's utility. Targeted DNA-sequencing was performed on 26 of 36 biopsies, and RNA-sequencing was performed on 25 of 36 biopsies that contained sufficient material. Using computational methods, we measured AR transcriptional function and performed gene set enrichment analysis (GSEA) to identify pathways whose activity state correlated with de novo resistance. TP53 gene alterations were more common in nonresponders, although this did not reach statistical significance (P = 0.055). AR gene alterations and AR expression were similar between groups. Importantly, however, transcriptional measurements demonstrated that specific gene sets-including those linked to low AR transcriptional activity and a stemness program-were activated in nonresponders. Our results suggest that patients whose tumors harbor this program should be considered for clinical trials testing rational agents to overcome de novo enzalutamide resistance.
    Keywords:  androgen receptor; enzalutamide; resistance; stemness
    DOI:  https://doi.org/10.1073/pnas.1922207117
  13. Cancers (Basel). 2020 May 14. pii: E1231. [Epub ahead of print]12(5):
    Kannathasan T, Kuo WW, Chen MC, Viswanadha VP, Shen CY, Tu CC, Yeh YL, Bharath M, Shibu MA, Huang CY.
      Guanine nucleotide-binding protein-like-3-like (GNL3L) is a crucial regulator of NF-κB signaling that is aberrantly activated during diverse chemoresistance-associated cellular processes. However, the molecular mechanisms of GNL3L tumor initiation and resistant state are largely unknown. Moreover, the identification of predictive biomarkers is necessary to effectively generate therapeutic strategies for metastatic human colorectal cancer (CRC). This study aims to identify how cells acquire resistance to anticancer drugs and whether the downregulation of miR-4454 is associated with the progression of CRC. Here, we have shown that the overexpression of miR-4454 in resistant tumors is a crucial precursor for the posttranscriptional repression of GNL3L in human chemoresistant CRC progression, and we used doxycycline induced miR-4454 overexpression that significantly reduced tumor volume in a subcutaneous injection nude mice model. Together, these observations highlight that the downregulation of miR-4454 in resistant clones is prominently responsible for maintaining their resistance against anticancer drug therapy. Our study indicates that the development of miR-4454 as a microRNA-based therapeutic approach to silence GNL3L may remarkably reduce oncogenic cell survival that depends on GNL3L/NF-κB signaling, making miR-4454 a candidate for treating metastatic human CRC.
    Keywords:  GNL3L (guanine nucleotide-binding protein-like-3-like); colorectal cancer (CRC); irinotecan (CPT-11); miR-4454
    DOI:  https://doi.org/10.3390/cancers12051231
  14. J Clin Invest. 2020 May 19. pii: 138577. [Epub ahead of print]
    Lu H, Xie Y, Tran L, Lan J, Yang Y, Murugan NL, Wang R, Wang YJ, Semenza GL.
      Breast cancer stem cells (BCSCs) play a critical role in cancer recurrence and metastasis. Chemotherapy induces BCSC specification through increased expression of pluripotency factors, but how their expression is regulated is not fully understood. Here, we delineate a hypoxia-inducible factor 1 (HIF-1)-controlled pathway that epigenetically activates pluripotency factor gene transcription in response to chemotherapy. Paclitaxel induces HIF-1-dependent expression of S100A10, which forms a complex with ANXA2 that interacts with histone chaperone SPT6 and histone demethylase KDM6A. S100A10, ANXA2, SPT6, and KDM6A are recruited to OCT4 binding sites and KDM6A erases H3K27me3 chromatin marks, facilitating transcription of genes encoding the pluripotency factors NANOG, SOX2, and KLF4, which along with OCT4 are responsible for BCSC specification. Silencing of S100A10, ANXA2, SPT6, or KDM6A expression blocks chemotherapy-induced enrichment of BCSCs, impairs tumor initiation, and increases time to tumor recurrence after chemotherapy is discontinued. Pharmacological inhibition of KDM6A also impairs chemotherapy-induced BCSC enrichment. These results suggest that targeting HIF-1/S100A10-dependent and KDM6A-mediated epigenetic activation of pluripotency factor gene expression in combination with chemotherapy may block BCSC enrichment and improve clinical outcome.
    Keywords:  Breast cancer; Oncology; Transcription; hypoxia
    DOI:  https://doi.org/10.1172/JCI138577
  15. J Clin Invest. 2020 May 19. pii: 131572. [Epub ahead of print]
    Such L, Zhao F, Liu D, Thier B, Le-Trilling VTK, Sucker A, Coch C, Pieper N, Howe S, Bhat H, Kalkavan H, Ritter C, Brinkhaus R, Ugurel S, Köster J, Seifert U, Dittmer U, Schuler M, Lang KS, Kufer TA, Hartmann G, Becker JC, Horn S, Ferrone S, Liu D, Van Allen EM, Schadendorf D, Griewank K, Trilling M, Paschen A.
      Understanding tumor resistance to T cell immunotherapies is critical to improve patient outcomes. Our study revealed a role for transcriptional suppression of the tumor-intrinsic HLA class I (HLA-I) antigen processing and presentation machinery (APM) in therapy resistance. Low HLA-I APM mRNA levels in melanoma metastases prior to immune checkpoint blockade (ICB) correlated with non-responsiveness to therapy and poor clinical outcome. Patient-derived melanoma cells with silenced HLA-I APM escaped recognition by autologous CD8+ T cells. However, targeted activation of the innate immunoreceptor RIG-I initiated de novo HLA-I APM transcription thereby overcoming T cell resistance. Antigen presentation was restored in interferon (IFN)-sensitive but also immunoedited IFN-resistant melanoma models through RIG-I-dependent stimulation of an IFN-independent salvage pathway involving IRF1 and IRF3. Likewise, enhanced HLA-I APM expression was detected in RIG-I (DDX58)-high melanoma biopsies, correlating with improved patient survival. Induction of HLA-I APM by RIG-I synergized with antibodies blocking PD-1 and TIGIT inhibitory checkpoints in boosting the anti-tumor T cell activity of ICB non-responders. Overall, the herein identified IFN-independent effect of RIG-I on tumor antigen presentation and T cell recognition proposes innate immunoreceptor targeting as a strategy to overcome intrinsic T cell resistance of IFN-sensitive and IFN-resistant melanomas and improve clinical outcomes in immunotherapy.
    Keywords:  Antigen presentation; Immunology; Melanoma; Oncology
    DOI:  https://doi.org/10.1172/JCI131572
  16. Cancer Discov. 2020 May 19. pii: CD-20-0187. [Epub ahead of print]
    Amodio V, Yaeger R, Arcella P, Cancelliere C, Lamba S, Lorenzato A, Arena S, Montone M, Mussolin B, Bian Y, Whaley A, Pinnelli M, Murciano-Goroff YR, Vakiani E, Valeri N, Liao WL, Bhalkikar A, Thyparambil S, Zhao HY, de Stanchina E, Marsoni S, Siena S, Bertotti A, Trusolino L, Li BT, Rosen N, Di Nicolantonio F, Bardelli A, Misale S.
      Most KRAS G12C mutant non-small cell lung cancer (NSCLC) patients experience clinical benefit from selective KRAS G12C inhibition, while patients with colorectal cancer (CRC) bearing the same mutation rarely respond. To investigate the cause of the limited efficacy of KRAS G12C inhibitors in CRC, we examined the effects of AMG510 in KRAS G12C CRC cell lines. Unlike NSCLC cell lines, KRAS G12C CRC models have high basal receptor tyrosine kinase (RTK) activation and are responsive to growth factor stimulation. In CRC lines, KRAS G12C inhibition induces higher phospho-ERK rebound than in NSCLC cells. Although upstream activation of several RTKs interferes with KRAS G12C blockade, we identify EGFR signaling as the dominant mechanism of CRC resistance to KRAS G12C inhibitors. The combinatorial targeting of EGFR and KRAS G12C is highly effective in CRC cells, patient-derived organoids and xenografts, suggesting a novel therapeutic strategy to treat KRAS G12C CRC patients.
    DOI:  https://doi.org/10.1158/2159-8290.CD-20-0187
  17. Proc Natl Acad Sci U S A. 2020 May 22. pii: 201918845. [Epub ahead of print]
    Xie J, Xia L, Xiang W, He W, Yin H, Wang F, Gao T, Qi W, Yang Z, Yang X, Zhou T, Gao G.
      Metastatic colorectal cancer (mCRC) patients have poor overall survival despite using irinotecan- or oxaliplatin-based chemotherapy combined with anti-EGFR (epidermal growth factor receptor) drugs, especially those with the oncogene mutation of KRAS Metformin has been reported as a potentially novel antitumor agent in many experiments, but its therapeutic activity is discrepant and controversial so far. Inspiringly, the median survival time for KRAS-mutation mCRC patients with diabetes on metformin is 37.8 mo longer than those treated with other hypoglycemic drugs in combination with standard systemic therapy. In contrast, metformin could not improve the survival of mCRC patients with wild-type KRAS Interestingly, metformin is preferentially accumulated in KRAS-mutation mCRC cells, but not wild-type ones, in both primary cell cultures and patient-derived xenografts, which is in agreement with its tremendous effect in KRAS-mutation mCRC. Mechanistically, the mutated KRAS oncoprotein hypermethylates and silences the expression of multidrug and toxic compound extrusion 1 (MATE1), a specific pump that expels metformin from the tumor cells by up-regulating DNA methyltransferase 1 (DNMT1). Our findings provide evidence that KRAS-mutation mCRC patients benefit from metformin treatment and targeting MATE1 may provide a strategy to improve the anticancer response of metformin.
    Keywords:  DNA methyltransferase 1 (DNMT1); KRAS mutation; metastatic colorectal cancer; metformin; multidrug and toxic compound extrusion 1 (MATE1)
    DOI:  https://doi.org/10.1073/pnas.1918845117
  18. Leukemia. 2020 May 18.
    Du T, Song Y, Ray A, Chauhan D, Anderson KC.
      Our prior study showed that inhibition of 19S proteasome-associated ubiquitin receptor Rpn13 can overcome bortezomib resistance in MM cells. Here, we performed proteomic analysis of Rpn13 inhibitor (RA190)-treated MM cells and identified an antioxidant enzyme superoxide dismutase (SOD1) as a mediator of Rpn13 signaling. SOD1 levels are higher in MM patient cells versus normal PBMCs; and importantly, SOD1 expression correlates with the progression of disease and shorter survival. Functional validation studies show that RA190-induced cytotoxicity in bortezomib-sensitive and -resistant MM cells is associated with decrease in SOD1 levels; conversely, forced expression of SOD1 inhibits RA190-induced cell death. Genetic knockdown and biochemical blockade of SOD1 with LCS-1 sensitizes bortezomib-resistant MM cells to bortezomib. SOD1 inhibitor LCS-1 decreases viability in MM cell lines and patient cells. LCS-1-induced cell death is associated with: (1) increase in superoxide and ROS levels; (2) activation of caspases, and p53/p21 signaling; (3) decrease in MCL-1, BCLxL, CDC2, cyclin-B1, and c-Myc; (4) ER stress response; and (5) inhibition of proteasome function. In animal model studies, LCS-1 inhibits xenografted bortezomib-resistant human MM cell growth and prolongs host survival. Our studies therefore show that targeting Rpn13 overcomes bortezomib resistance by decreasing cellular SOD1 levels, and provide the rationale for novel therapeutics targeting SOD1 to improve patient outcome in MM.
    DOI:  https://doi.org/10.1038/s41375-020-0865-2
  19. Cancers (Basel). 2020 May 15. pii: E1243. [Epub ahead of print]12(5):
    Manna D, Sarkar D.
      Hepatocellular carcinoma (HCC), the primary liver cancer arising from hepatocytes, is a universal health problem and one of the most common malignant tumors. Surgery followed by chemotherapy as well as tyrosine kinase inhibitors (TKIs), such as sorafenib, are primary treatment procedures for HCC, but recurrence of disease because of therapy resistance results in high mortality. It is necessary to identify novel regulators of HCC for developing effective targeted therapies that can significantly interfere with progression of the disease process. Non-coding RNAs (ncRNAs) are an abundant group of versatile RNA transcripts that do not translate into proteins, rather serve as potentially functional RNAs. The role of ncRNAs in regulating diverse aspects of the carcinogenesis process are gradually being elucidated. Recent advances in RNA sequencing technology have identified a plethora of ncRNAs regulating all aspects of hepatocarcinogenesis process and serving as potential prognostic or diagnostic biomarkers. The present review provides a comprehensive description of the biological roles of ncRNAs in disease process and therapy resistance, and potential clinical application of these ncRNAs in HCC.
    Keywords:  hepatocellular carcinoma; non-coding RNA; therapy resistance
    DOI:  https://doi.org/10.3390/cancers12051243
  20. Clin Cancer Res. 2020 May 21. pii: clincanres.3142.2019. [Epub ahead of print]
    McDaniel NK, Iida M, Nickel KP, Longhurst CA, Fischbach SR, Rodems TS, Kranjac CA, Bo AY, Luo Q, Gallagher MM, Welke NB, Mitchell KR, Schulz AE, Eckers JC, Hu R, Salgia R, Hong S, Bruce JY, Kimple RJ, Wheeler DL.
      PURPOSE: Radiation and cetuximab are therapeutics used in management of head and neck squamous cell carcinoma (HNSCC). Despite clinical success with these modalities, development of both intrinsic and acquired resistance is an emerging problem in the management of this disease. The purpose of this study was to investigate signaling of the receptor tyrosine kinase AXL in resistance to radiation and cetuximab treatment.EXPERIMENTAL DESIGN: To study AXL signaling in the context of treatment-resistant HNSCC, we used patient-derived xenografts (PDXs) implanted into mice and evaluated the tumor response to AXL inhibition in combination with cetuximab or radiation treatment. To identify molecular mechanisms of how AXL signaling leads to resistance, three tyrosine residues of AXL (Y779, Y821, Y866) were mutated and examined for their sensitivity to cetuximab and/or radiation. Furthermore, reverse phase protein array (RPPA) was employed to analyze the proteomic architecture of signaling pathways in these genetically altered cell lines.
    RESULTS: Treatment of cetuximab- and radiation-resistant PDXs with AXL inhibitor R428 was sufficient to overcome resistance. RPPA analysis revealed that such resistance emanates from signaling of tyrosine 821 of AXL via the tyrosine kinase c-ABL. In addition, inhibition of c-ABL signaling resensitized cells and tumors to cetuximab or radiation therapy even leading to complete tumor regression without recurrence in head and neck cancer models.
    CONCLUSIONS: Collectively, the studies presented herein suggest that tyrosine 821 of AXL mediates resistance to cetuximab by activation of c-ABL kinase in HNSCC and that targeting of both EGFR and c-ABL leads to a robust anti-tumor response.
    DOI:  https://doi.org/10.1158/1078-0432.CCR-19-3142
  21. Cell Death Differ. 2020 May 20.
    Stöhr D, Schmid JO, Beigl TB, Mack A, Maichl DS, Cao K, Budai B, Fullstone G, Kontermann RE, Mürdter TE, Tait SWG, Hagenlocher C, Pollak N, Scheurich P, Rehm M.
      The influence of 3D microenvironments on apoptosis susceptibility remains poorly understood. Here, we studied the susceptibility of cancer cell spheroids, grown to the size of micrometastases, to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Interestingly, pronounced, spatially coordinated response heterogeneities manifest within spheroidal microenvironments: In spheroids grown from genetically identical cells, TRAIL-resistant subpopulations enclose, and protect TRAIL-hypersensitive cells, thereby increasing overall treatment resistance. TRAIL-resistant layers form at the interface of proliferating and quiescent cells and lack both TRAILR1 and TRAILR2 protein expression. In contrast, oxygen, and nutrient deprivation promote high amounts of TRAILR2 expression in TRAIL-hypersensitive cells in inner spheroid layers. COX-II inhibitor celecoxib further enhanced TRAILR2 expression in spheroids, likely resulting from increased ER stress, and thereby re-sensitized TRAIL-resistant cell layers to treatment. Our analyses explain how TRAIL response heterogeneities manifest within well-defined multicellular environments, and how spatial barriers of TRAIL resistance can be minimized and eliminated.
    DOI:  https://doi.org/10.1038/s41418-020-0559-3
  22. Cancer Discov. 2020 May 20.
      Unlike melanomas and colorectal cancers with a high tumor mutation burden, hypermutated gliomas generally do not respond to checkpoint blockade, a study concludes. Hypermutation shortens patient survival, and the results suggest that it occurs because of selective pressure from the chemotherapeutic temozolomide.
    DOI:  https://doi.org/10.1158/2159-8290.CD-NB2020-045
  23. Cancer Discov. 2020 May 20. pii: CD-19-1384. [Epub ahead of print]
    Kieffer Y, Hocine HR, Gentric G, Pelon F, Bernard C, Bourachot B, Lameiras S, Albergante L, Bonneau C, Guyard A, Tarte K, Zinovyev A, Baulande S, Zalcman G, Vincent-Salomon A, Mechta-Grigoriou F.
      A subset of Cancer-Associated Fibroblasts (FAP+/CAF-S1) mediates immunosuppression in breast cancers (BC), but its heterogeneity and its impact on immunotherapy response remain unknown. Here, we identify 8 CAF-S1 clusters by analyzing more than 19000 single CAF-S1 fibroblasts from BC. We validate the 5 most abundant clusters by flow cytometry and in silico analyses in other cancer types, highlighting their relevance. Myofibroblasts from clusters 0 and 3, characterized by extra-cellular matrix proteins and TGFB signaling respectively, are indicative of primary resistance to immunotherapies. Cluster 0/ecm-myCAF up-regulates PD-1 and CTLA-4 protein levels in regulatory T lymphocytes (Tregs), which in turn increases CAF-S1 cluster 3/TGFB-myCAF cellular content. Thus, our study highlights a positive feedback loop between specific CAF-S1 clusters and Tregs and uncovers their role in immunotherapy resistance.
    DOI:  https://doi.org/10.1158/2159-8290.CD-19-1384
  24. Cancers (Basel). 2020 May 14. pii: E1239. [Epub ahead of print]12(5):
    Vikram R, Chou WC, Hung SC, Shen CY.
      Cells with high CD44 but low CD24 expression (CD44high/CD24-/low) and high aldehyde dehydrogenase activity (ALDHbr) are widely considered to be drivers of metastasis, therapy resistance and tumor recurrence in breast cancer. However, the role of the CD44high/CD24-/low and ALDHbr phenotypes in identifying tumorigenic cells in breast cancer remains controversial due to the discrepancy in their distribution and tumorigenic potential in intrinsic breast cancer subtypes. In this study, we analyzed the cells expressing these markers in six different breast cancer cell lines representing major breast cancer subtypes (T47D, MCF-7, BT-474, AU-565, Hs578T and MDA-MB-231). CD44high/CD24-/low, ALDHbr and CD44-/low/CD24-/low cell populations were isolated by flow cytometry and analyzed for hallmark stem cell characteristics of differentiation, migration, invasiveness and metastasis using in vitro and in vivo techniques. Our results demonstrate that the CD44-/low/CD24-/low cell population, which is enriched in luminal cell lines (T47D, MCF-7 and BT-474), possesses metastatic and tumorigenic properties. We also show that, contrary to previous claims, the expression of the ALDH1 isoform ALDH1A1 does not affect the tumorigenic potential of cell lines with high ALDH activity (BT-474 and AU-565). Further transcriptomic and clinical studies are needed to determine the potential of these markers as early diagnostic tools and treatment targets.
    Keywords:  ALDH1A1; CD24; CD44; breast cancer; metastasis, ALDH
    DOI:  https://doi.org/10.3390/cancers12051239
  25. J Natl Cancer Inst. 2020 May 16. pii: djaa072. [Epub ahead of print]
    Zaanan A, Henriques J, Cohen R, Sefrioui D, Evrard C, de la Fouchardiere C, Lecomte T, Aparicio T, Svrcek M, Taieb J, André T, Vernerey D, Tougeron D, .
      Anti-EGFR efficacy in patients with microsatellite instability (MSI) metastatic colorectal cancer (mCRC) according to sporadic versus familial origin is unknown. We retrospectively analyzed 128 patients with MSI mCRC treated with first-line chemotherapy ± anti-EGFR. Among them, 61 and 67 patients were respectively categorized as familial and sporadic based on mismatch repair protein immunostaining, BRAF mutational status and MLH1 promoter methylation status. We observed that addition of anti-EGFR to chemotherapy was associated with a statistically significant improvement of progression-free survival (PFS) for familial (median: 5.0 versus 10.2 months; HR = 0.47; 95% CI, 0.23-0.94; P=.03) but not for sporadic (median: 4.4 versus 5.4 months; HR = 0.80; 95% CI, 0.39-1.60; P=.52) MSI mCRC patients. In multivariate analysis, the survival benefit of adding anti-EGFR to chemotherapy remained statistically significant for familial MSI cases (P=.04). These findings deserve to be confirmed in a prospective study and could help decision-making in MSI mCRC without access or resistant to immunotherapy.
    Keywords:  Colorectal Cancer; Familial MSI; Mismatch Repair; Sporadic MSI; anti-EGFR
    DOI:  https://doi.org/10.1093/jnci/djaa072