bims-tucedo Biomed News
on Tumor cell dormancy
Issue of 2020‒12‒20
seventeen papers selected by
Isabel Puig Borreil
Vall d’Hebron Institute of Oncology


  1. Methods Mol Biol. 2021 ;2258 221-239
    Clark AM.
      Cancer mortality predominantly results from distant metastases that are undetectable at diagnosis and escape initial therapies to lie as dormant micrometastases for years. To study the behavior of micrometastases-how they resist initial treatments and then awaken from a dormant state-we utilize the Legacy LiverChip®, an all-human ex vivo hepatic microphysiological system. The functional liver bioreactor, comprising hepatocytes and non-parenchymal cells in a 3D microperfused culture format, mimics the dormant-emergent metastatic progression observed in human patients: (a) a subpopulation of cancer cells spontaneously enter dormancy, (b) cycling cells are eliminated by standard chemotherapies, while quiescent dormant cells remain, and (c) chemoresistant dormant cells can be stimulated to emerge. The system effluent and tissue can be queried for proteomic and genomic data, immunofluorescent imaging as well as drug efficacy and metabolism. This microphysiological system continues to provide critical insights into the biology of dormant and re-emergent micrometastases and serves as an accessible tool to identify new therapeutic strategies targeting the various stages of metastasis, while concurrently evaluating antineoplastic agent efficacy for metastasis, metabolism, and dose-limiting toxicity.
    Keywords:  Cancer; Dormancy; Emergence; Microphysiological system; Model of metastasis; Organ-on-a-chip
    DOI:  https://doi.org/10.1007/978-1-0716-1174-6_15
  2. Proc Natl Acad Sci U S A. 2020 Dec 14. pii: 202007991. [Epub ahead of print]
    Hoj JP, Mayro B, Pendergast AM.
      Brain metastases are the most common intracranial tumors in adults and are associated with increased patient morbidity and mortality. Limited therapeutic options are currently available for the treatment of brain metastasis. Here, we report on the discovery of an actionable signaling pathway utilized by metastatic tumor cells whereby the transcriptional regulator Heat Shock Factor 1 (HSF1) drives a transcriptional program, divergent from its canonical role as the master regulator of the heat shock response, leading to enhanced expression of a subset of E2F transcription factor family gene targets. We find that HSF1 is required for survival and outgrowth by metastatic lung cancer cells in the brain parenchyma. Further, we identify the ABL2 tyrosine kinase as an upstream regulator of HSF1 protein expression and show that the Src-homology 3 (SH3) domain of ABL2 directly interacts with HSF1 protein at a noncanonical, proline-independent SH3 interaction motif. Pharmacologic inhibition of the ABL2 kinase using small molecule allosteric inhibitors, but not ATP-competitive inhibitors, disrupts this interaction. Importantly, knockdown as well as pharmacologic inhibition of ABL2 using allosteric inhibitors impairs expression of HSF1 protein and HSF1-E2F transcriptional gene targets. Collectively, these findings reveal a targetable ABL2-HSF1-E2F signaling pathway required for survival by brain-metastatic tumor cells.
    Keywords:  ABL kinases; ABL2; HSF1; brain metastasis; lung adenocarcinoma
    DOI:  https://doi.org/10.1073/pnas.2007991117
  3. Cancer Discov. 2020 Dec 16. pii: CD-20-0603. [Epub ahead of print]
    Dongre A, Rashidian M, Eaton EN, Reinhardt F, Thiru P, Zagorulya M, Nepal S, Banaz T, Martner A, Spranger S, Weinberg RA.
      The epithelial-to-mesenchymal transition (EMT), which conveys epithelial (E) carcinoma cells to quasi-mesenchymal (qM) states, enables them to metastasize and acquire resistance to certain treatments. Murine tumors composed of qM mammary carcinoma cells assemble an immunosuppressive tumor microenvironment (TME) and develop resistance to anti-CTLA4 immune checkpoint blockade therapy (ICB), unlike their E counterparts. Importantly, minority populations of qM cells within a tumor can cross-protect their more E neighbors from immune attack. The underlying mechanisms of immunosuppression and cross-protection have been unclear. We demonstrate that abrogation of qM carcinoma cell-derived factors (CD73, CSF1 or SPP1) prevents the assembly of an immunosuppressive TME and sensitizes otherwise refractory qM tumors partially or completely to anti-CTLA4 ICB. Most strikingly, mixed tumors in which minority populations of carcinoma cells no longer express CD73, are now sensitized to anti-CTLA4 ICB. Finally, loss of CD73 also enhances the efficacy of anti-CTLA4 ICB during the process of metastatic colonization.
    DOI:  https://doi.org/10.1158/2159-8290.CD-20-0603
  4. Cancers (Basel). 2020 Dec 15. pii: E3786. [Epub ahead of print]12(12):
    Karkampouna S, De Filippo MR, Ng CKY, Klima I, Zoni E, Spahn M, Stein F, Haberkant P, Thalmann GN, Kruithof de Julio M.
      Resistance acquisition to androgen deprivation treatment and metastasis progression are a major clinical issue associated with prostate cancer (PCa). The role of stroma during disease progression is insufficiently defined. Using transcriptomic and proteomic analyses on differentially aggressive patient-derived xenografts (PDXs), we investigated whether PCa tumors predispose their microenvironment (stroma) to a metastatic gene expression pattern. RNA sequencing was performed on the PCa PDXs BM18 (castration-sensitive) and LAPC9 (castration-resistant), representing different disease stages. Using organism-specific reference databases, the human-specific transcriptome (tumor) was identified and separated from the mouse-specific transcriptome (stroma). To identify proteomic changes in the tumor (human) versus the stroma (mouse), we performed human/mouse cell separation and subjected protein lysates to quantitative Tandem Mass Tag labeling and mass spectrometry. Tenascin C (TNC) was among the most abundant stromal genes, modulated by androgen levels in vivo and highly expressed in castration-resistant LAPC9 PDX. The tissue microarray of primary PCa samples (n = 210) showed that TNC is a negative prognostic marker of the clinical progression to recurrence or metastasis. Stroma markers of osteoblastic PCa bone metastases seven-up signature were induced in the stroma by the host organism in metastatic xenografts, indicating conserved mechanisms of tumor cells to induce a stromal premetastatic signature. A 50-gene list stroma signature was identified based on androgen-dependent responses, which shows a linear association with the Gleason score, metastasis progression and progression-free survival. Our data show that metastatic PCa PDXs, which differ in androgen sensitivity, trigger differential stroma responses, which show the metastasis risk stratification and prognostic biomarker potential.
    Keywords:  patient-derived xenografts; prostate cancer; stroma signature
    DOI:  https://doi.org/10.3390/cancers12123786
  5. Cancer Lett. 2020 Dec 09. pii: S0304-3835(20)30656-X. [Epub ahead of print]
    Chen Y, Su L, Huang C, Wu S, Qiu X, Zhao X, Meng Q, Meng YM, Kong X, Wang M, Liu C, Wong PP.
      Aberrant glycosylation in pancreatic cancer has been linked to cancer development, progression and chemoresistance. However, the role of glycogene, such as galactosyltransferase, in pancreatic cancer remains unknown. Herein, we establish beta-1.4-galactosyltransferase 1 (B4GALT1) as a clinical marker and regulator of chemoresistance. Clinically, high B4GALT1 expression correlates with poor survival, enhanced tumor size, increased lymph node metastasis, elevated cancer progression and enhanced incidence of relapse in PDAC patients. Expression of B4GALT1 is up-regulated in gemcitabine resistant patient derived organoids as well as chemoresistant cancer cell lines, while genetic perturbation of its expression in PDAC cell lines regulates cancer progression and chemoresistance. Mechanistically, we show that elevated p65 activity transcriptionally up-regulates B4GALT1 expression, which then interacts with and stabilizes cyclin dependent kinase 11 isomer CDK11p110 protein via N-linked glycosylation, in order to promote cancer progression and chemoresistance. Finally, depletion of B4GALT1 rescues the response of chemoresistant cells to gemcitabine in an orthotopic PDAC model. Overall, our data uncovers a mechanism by which p65-B4GALT1-CDK11p110 signalling axis determines cancer progression and chemoresistance, providing a new therapeutic target for an improved pancreatic cancer treatment.
    Keywords:  B4GALT1; CDK11(p110); Chemoresistance; N-linked glycosylation; Pancreatic ductal adenocarcinomas
    DOI:  https://doi.org/10.1016/j.canlet.2020.12.006
  6. Cancers (Basel). 2020 Dec 14. pii: E3761. [Epub ahead of print]12(12):
    Hüser L, Kokkaleniou MM, Granados K, Dworacek J, Federico A, Vierthaler M, Novak D, Arkhypov I, Hielscher T, Umansky V, Altevogt P, Utikal J.
      Melanoma is an aggressive form of skin cancer that is often characterized by activating mutations in the Mitogen-Activated Protein (MAP) kinase pathway, causing hyperproliferation of the cancer cells. Thus, inhibitors targeting this pathway were developed. These inhibitors are initially very effective, but the occurrence of resistance eventually leads to a failure of the therapy and is the major obstacle for clinical success. Therefore, investigating the mechanisms causing resistance and discovering ways to overcome them is essential for the success of therapy. Here, we observed that treatment of melanoma cells with the B-Raf Proto-Oncogene, Serine/Threonine Kinase (BRAF) inhibitor vemurafenib caused an increased cell surface expression and activation of human epidermal growth factor receptor 3 (HER3) by shed ligands. HER3 promoted the activation of signal transducer and activator of transcription 3 (STAT3) resulting in upregulation of the STAT3 target gene SRY-Box Transcription Factor 2 (SOX2) and survival of the cancer cells. Pharmacological blocking of HER led to a diminished STAT3 activation and increased sensitivity toward vemurafenib. Moreover, HER blocking sensitized vemurafenib-resistant cells to drug treatment. We conclude that the inhibition of the STAT3 upstream regulator HER might help to overcome melanoma therapy resistance toward targeted therapies.
    Keywords:  BRAF inhibitor; HER3; STAT3; adaptive resistance; melanoma
    DOI:  https://doi.org/10.3390/cancers12123761
  7. Clin Cancer Res. 2020 Dec 11. pii: clincanres.2853.2020. [Epub ahead of print]
    Tanimoto A, Matsumoto S, Takeuchi S, Arai S, Fukuda K, Nishiyama A, Yoh K, Ikeda T, Furuya N, Nishino K, Ohe Y, Goto K, Yano S.
      Purpose:In ALK-rearranged non-small cell lung cancer (NSCLC), impacts of concomitant genetic alterations on targeted therapies with ALK-tyrosine kinase inhibitors (ALK-TKIs) have not yet well understood. Here, we investigated genetic alterations related to ALK-TKI resistance using clinico-genomic data and explored effective therapies to overcome the resistance in preclinical models through the identification of underlying molecular mechanisms. Experimental Design:We used integrated clinical and next-generation sequencing data generated in a nationwide lung cancer genome screening project (LC-SCRUM-Japan). ALK-rearranged NSCLC cell lines expressing wild-type or mutant TP53 were used to evaluate cellular apoptosis induced by ALK-TKIs. Results:In 90 ALK-rearranged NSCLC patients who were treated with a selective ALK-TKI, alectinib, TP53 co-mutated patients showed significantly worse progression-free survival (PFS) than TP53 wild-type patients [median PFS, 11.7 months (95% CI, 6.3-not reached [NR]) vs. NR (23.6-NR); p=0.0008; hazard ratio, 0.33 (95% CI, 0.17-0.65)]. ALK-rearranged NSCLC cell lines which lost p53 function were resistant to alectinib-induced apoptosis, but a proteasome inhibitior, ixazommib markedly induced apoptosis in the alectinib-treated cells by increasing the expression of a pro-apoptotic protein, Noxa which bound to an anti-apoptotic protein, Mcl-1. In subcutaneous tumor models, combination of ixazomib and alectinib prominently induced tumor regression and apoptosis even though the tumors were generated from ALK-rearranged NSCLC cells with non-functional p53. Conclusions:These clinical and preclinical results indicate concomitant TP53 mutations reduce the efficacy of alectinib for ALK-rearranged NSCLC and the combined use of a proteasome inhibitor with alectinib is a promising therapy for ALK-rearranged/TP53-mutated NSCLC.
    DOI:  https://doi.org/10.1158/1078-0432.CCR-20-2853
  8. Cancer Discov. 2020 Dec 16. pii: CD-20-0652. [Epub ahead of print]
    Knight JRP, Alexandrou C, Skalka GL, Vlahov N, Pennel K, Officer L, Teodosio A, Kanellos G, Gay DM, May-Wilson S, Smith EM, Najumudeen AK, Gilroy K, Ridgway RA, Flanagan DJ, Smith RCL, McDonald L, MacKay C, Cheasty A, McArthur K, Stanway E, Leach JDG, Jackstadt R, Waldron JA, Campbell AD, Vlachogiannis G, Valeri N, Haigis KM, Sonenberg N, Proud CG, Jones NP, Swarbrick ME, McKinnon HJ, Faller WJ, Le Quesne J, Edwards J, Willis AE, Bushell M, Sansom OJ.
      KRAS-mutant colorectal cancers (CRC) are resistant to therapeutics, presenting a significant problem for ~40% of cases. Rapalogs, which inhibit mTORC1 and thus protein synthesis, are significantly less potent in KRAS-mutant CRC. Using Kras-mutant mouse models and mouse- and patient-derived organoids we demonstrate that KRAS with G12D mutation fundamentally rewires translation to increase both bulk and mRNA-specific translation initiation. This occurs via the MNK/eIF4E pathway culminating in sustained expression of c-MYC. By genetic and small molecule targeting of this pathway, we acutely sensitize KRASG12D models to rapamycin via suppression of c-MYC. We show that 45% of CRCs have high signaling through mTORC1 and the MNKs, with this signature correlating with a 3.5-year shorter cancer-specific survival in a subset of patients. This work provides a c-MYC-dependent co-targeting strategy with remarkable potency in multiple Kras-mutant mouse models and metastatic human organoids and identifies a patient population who may benefit from its clinical application.
    DOI:  https://doi.org/10.1158/2159-8290.CD-20-0652
  9. Mol Cancer. 2020 Dec 12. 19(1): 171
    Wen S, Wei Y, Zen C, Xiong W, Niu Y, Zhao Y.
      BACKGROUND: N6-methyladenosine (m6A) is the most prevalent messenger RNA modification in mammalian cells. However, the disease relevant function of m6A on specific oncogenic long non-coding RNAs (ncRNAs) is not well understood.METHODS: We analyzed the m6A status using patients samples and bone metastatic PDXs. Through m6A high-throughput sequencing, we identified the m6A sites on NEAT1-1 in prostate bone metastatic PDXs. Mass spec assay showed interaction among NEAT1-1, CYCLINL1 and CDK19. RNA EMSA, RNA pull-down, mutagenesis, CLIP, western blot, ChIP and ChIRP assays were used to investigate the molecular mechanisms underlying the functions of m6A on NEAT1-1. Loss-of function and rescued experiments were executed to detect the biological roles of m6A on NEAT1-1 in the PDX cell phenotypes in vivo.
    RESULTS: In this study, we identified 4 credible m6A sites on long ncRNA NEAT1-1. High m6A level of NEAT1-1 was related to bone metastasis of prostate cancer and m6A level of NEAT1-1 was a powerful predictor of eventual death. Transcribed NEAT1-1 served as a bridge to facility the binding between CYCLINL1 and CDK19 and promoted the Pol II ser2 phosphorylation. Importantly, depletion of NEAT1-1or decreased m6A of NEAT1-1 impaired Pol II Ser-2p level in the promoter of RUNX2. Overexpression of NEAT1-1 induced cancer cell metastasis to lung and bone; xenograft growth and shortened the survival of mice, but NEAT1-1 with m6A site mutation failed to do these.
    CONCLUSION: Collectively, the findings indicate that m6A on ncRNA NEAT1-1 takes critical role in regulating Pol II ser2 phosphorylation and may be novel specific target for bone metastasis cancer therapy and diagnosis. New complex CYCLINL1/CDK19/NEAT1-1 might provide new insight into the potential mechanism of the pathogenesis and development of bone metastatic prostate cancer.
    Keywords:  Bone metastatic prostate cancer; CDK19; CYCLINL1; NEAT1–1; m6A; ncRNA
    DOI:  https://doi.org/10.1186/s12943-020-01293-4
  10. Nature. 2020 Dec 16.
    Pastushenko I, Mauri F, Song Y, de Cock F, Meeusen B, Swedlund B, Impens F, Van Haver D, Opitz M, Thery M, Bareche Y, Lapouge G, Vermeersch M, Van Eycke YR, Balsat C, Decaestecker C, Sokolow Y, Hassid S, Perez-Bustillo A, Agreda-Moreno B, Rios-Buceta L, Jaen P, Redondo P, Sieira-Gil R, Millan-Cayetano JF, Sanmatrtin O, D'Haene N, Moers V, Rozzi M, Blondeau J, Lemaire S, Scozzaro S, Janssens V, De Troya M, Dubois C, Pérez-Morga D, Salmon I, Sotiriou C, Helmbacher F, Blanpain C.
      FAT1, which encodes a protocadherin, is one of the most frequently mutated genes in human cancers1-5. However, the role and the molecular mechanisms by which FAT1 mutations control tumour initiation and progression are poorly understood. Here, using mouse models of skin squamous cell carcinoma and lung tumours, we found that deletion of Fat1 accelerates tumour initiation and malignant progression and promotes a hybrid epithelial-to-mesenchymal transition (EMT) phenotype. We also found this hybrid EMT state in FAT1-mutated human squamous cell carcinomas. Skin squamous cell carcinomas in which Fat1 was deleted presented increased tumour stemness and spontaneous metastasis. We performed transcriptional and chromatin profiling combined with proteomic analyses and mechanistic studies, which revealed that loss of function of FAT1 activates a CAMK2-CD44-SRC axis that promotes YAP1 nuclear translocation and ZEB1 expression that stimulates the mesenchymal state. This loss of function also inactivates EZH2, promoting SOX2 expression, which sustains the epithelial state. Our comprehensive analysis identified drug resistance and vulnerabilities in FAT1-deficient tumours, which have important implications for cancer therapy. Our studies reveal that, in mouse and human squamous cell carcinoma, loss of function of FAT1 promotes tumour initiation, progression, invasiveness, stemness and metastasis through the induction of a hybrid EMT state.
    DOI:  https://doi.org/10.1038/s41586-020-03046-1
  11. Cancer Discov. 2020 Dec 14. pii: CD-20-0735. [Epub ahead of print]
    Saqcena M, Leandro-Garcia LJ, Maag JLV, Tchekmedyian V, Krishnamoorthy GP, Tamarapu PP, Tiedje V, Reuter V, Knauf JA, de Stanchina E, Xu B, Liao XH, Refetoff S, Ghossein R, Chi P, Ho AL, Koche RP, Fagin JA.
      Mutations of subunits of the SWI/SNF chromatin remodeling complexes occur commonly in cancers of different lineages, including advanced thyroid cancers. Here we show that thyroid-specific loss of Arid1a, Arid2 or Smarcb1 in mouse BrafV600E-mutant tumors promotes disease progression and decreased survival, associated with lesion-specific effects on chromatin accessibility and differentiation. As compared to normal thyrocytes, BrafV600E-mutant mouse PTCs have decreased lineage transcription factor expression and accessibility to their target DNA binding sites, leading to impairment of thyroid differentiated gene expression and radioiodine incorporation, which is rescued by MAPK inhibition. Loss of individual Swi/Snf subunits in Braf tumors leads to a repressive chromatin state that cannot be reversed by MAPK pathway blockade, rendering them insensitive to its redifferentiation effects. Our results show that SWI/SNF complexes are central to the maintenance of differentiated function in thyroid cancers, and their loss confers radioiodine refractoriness and resistance to MAPK inhibitor-based redifferentiation therapies.
    DOI:  https://doi.org/10.1158/2159-8290.CD-20-0735
  12. Nat Rev Urol. 2020 Dec 16.
    Haffner MC, Zwart W, Roudier MP, True LD, Nelson WG, Epstein JI, De Marzo AM, Nelson PS, Yegnasubramanian S.
      From a clinical, morphological and molecular perspective, prostate cancer is a heterogeneous disease. Primary prostate cancers are often multifocal, having topographically and morphologically distinct tumour foci. Sequencing studies have revealed that individual tumour foci can arise as clonally distinct lesions with no shared driver gene alterations. This finding demonstrates that multiple genomically and phenotypically distinct primary prostate cancers can be present in an individual patient. Lethal metastatic prostate cancer seems to arise from a single clone in the primary tumour but can exhibit subclonal heterogeneity at the genomic, epigenetic and phenotypic levels. Collectively, this complex heterogeneous constellation of molecular alterations poses obstacles for the diagnosis and treatment of prostate cancer. However, advances in our understanding of intra-tumoural heterogeneity and the development of novel technologies will allow us to navigate these challenges, refine approaches for translational research and ultimately improve patient care.
    DOI:  https://doi.org/10.1038/s41585-020-00400-w
  13. Cancer Discov. 2020 Dec 14. pii: CD-20-0873. [Epub ahead of print]
    Hong A, Piva M, Liu S, Hugo W, Lomeli SH, Zoete V, Randolph CE, Yang Z, Wang Y, Lee JJ, Lo SJ, Sun L, Vega-Crespo A, Garcia AJ, Shackelford DB, Dubinett SM, Scumpia PO, Byrum SD, Tackett AJ, Donahue TR, Michielin O, Holmen SL, Ribas A, Moriceau G, Lo RS.
      MAPK-targeting in cancer often fails due to MAPK-reactivation. MEK inhibitor (MEKi) monotherapy provides limited clinical benefits but may serve as a foundation for combination. Here, we showed that combining a type II RAFi with an allosteric MEKi durably prevents and overcomes acquired resistance among cancers with KRAS, NRAS, NF1, BRAFnon-V600 and BRAFV600 mutations. Tumor cell-intrinsically, type II RAFi plus MEKi sequester MEK in RAF complexes, reduce MEK/MEK dimerization, and uncouple MEK from ERK in acquired-resistant tumor subpopulations. Immunologically, this combination expands memory and activated/exhausted CD8+ T-cells, and durable tumor regression elicited by this combination requires CD8+ T-cells, which can be reinvigorated by anti-PD-L1 therapy. Whereas MEKi reduces dominant intra-tumoral T-cell clones, type II RAFi co-treatment reverses this effect and promotes T-cell clonotypic expansion. These findings rationalize the clinical development of type II RAFi plus MEKi and their further combination with PD-1/L1-targeted therapy.
    DOI:  https://doi.org/10.1158/2159-8290.CD-20-0873
  14. Sci Transl Med. 2020 Dec 16. pii: eabb5647. [Epub ahead of print]12(574):
    Dong B, Jaeger AM, Hughes PF, Loiselle DR, Hauck JS, Fu Y, Haystead TA, Huang J, Thiele DJ.
      Heat shock factor 1 (HSF1) is a cellular stress-protective transcription factor exploited by a wide range of cancers to drive proliferation, survival, invasion, and metastasis. Nuclear HSF1 abundance is a prognostic indicator for cancer severity, therapy resistance, and shortened patient survival. The HSF1 gene was amplified, and nuclear HSF1 abundance was markedly increased in prostate cancers and particularly in neuroendocrine prostate cancer (NEPC), for which there are no available treatment options. Despite genetic validation of HSF1 as a therapeutic target in a range of cancers, a direct and selective small-molecule HSF1 inhibitor has not been validated or developed for use in the clinic. We described the identification of a direct HSF1 inhibitor, Direct Targeted HSF1 InhiBitor (DTHIB), which physically engages HSF1 and selectively stimulates degradation of nuclear HSF1. DTHIB robustly inhibited the HSF1 cancer gene signature and prostate cancer cell proliferation. In addition, it potently attenuated tumor progression in four therapy-resistant prostate cancer animal models, including an NEPC model, where it caused profound tumor regression. This study reports the identification and validation of a direct HSF1 inhibitor and provides a path for the development of a small-molecule HSF1-targeted therapy for prostate cancers and other therapy-resistant cancers.
    DOI:  https://doi.org/10.1126/scitranslmed.abb5647
  15. J Clin Invest. 2020 Dec 17. pii: 141335. [Epub ahead of print]
    Lv S, Song Q, Chen G, Cheng E, Chen W, Cole R, Wu Z, Pascal LE, Wang K, Wipf P, Nelson JB, Wei Q, Huang W, Wang Z.
      Androgen receptor (AR) nuclear localization is necessary for its activation as a transcription factor. Defining the mechanisms regulating AR nuclear localization in androgen-sensitive cells, and how these mechanisms are dysregulated in castration-resistant prostate cancer (CRPC) cells are fundamentally important and clinically relevant. According to the classical model of AR intracellular trafficking, androgens induce AR nuclear import and androgen withdrawal causes AR nuclear export. The present study led to an updated model that AR could be imported in the absence of androgens, ubiquitinated, and degraded in the nucleus. Androgen withdrawal caused nuclear AR degradation but not export. In comparison to their parental androgen-sensitive LNCaP prostate cancer cells, castration-resistant C4-2 cells exhibited reduced nuclear AR polyubiquitination and increased nuclear AR level. We previously identified 3-(4-chlorophenyl)-6,7-dihydro-5H-pyrrolo[1,2-a]imidazole (CPPI) in a high throughput screen for its inhibition of androgen-independent AR nuclear localization in CRPC cells. The current study showed that CPPI was a novel competitive AR antagonist capable of enhancing AR interaction with its E3 ligase MDM2, and degradation of AR in the nuclei of CRPC cells. Also, CPPI blocked androgen-independent AR nuclear import. Overall, these findings suggest the feasibility of targeting androgen-independent AR nuclear import and stabilization, two necessary steps leading to AR nuclear localization and activation in CRPC cells, with small molecule inhibitors.
    Keywords:  Drug therapy; Oncology; Prostate cancer; Therapeutics
    DOI:  https://doi.org/10.1172/JCI141335
  16. Nat Protoc. 2020 Dec 14.
    Neufert C, Heichler C, Brabletz T, Scheibe K, Boonsanay V, Greten FR, Neurath MF.
      Despite advances in the detection and therapy of colorectal cancer (CRC) in recent years, CRC has remained a major challenge in clinical practice. Although alternative methods for modeling CRC have been developed, animal models of CRC remain helpful when analyzing molecular aspects of pathogenesis and are often used to perform preclinical in vivo studies of potential therapeutics. This protocol updates our protocol published in 2007, which provided an azoxymethane (AOM)-based setup for investigations into sporadic (Step 5A) and, when combined with dextran sodium sulfate (Step 5B), inflammation-associated tumor growth. This update also extends the applications beyond those of the original protocol by including an option in which AOM is serially applied to mice with p53 deficiency in the intestinal epithelium (Step 5C). In this model, the combination of p53 deficiency and AOM promotes tumor development, including growth of invasive cancers and lymph node metastasis. It also provides details on analysis of colorectal tumor growth and metastasis, including analysis of partial epithelial-to-mesenchymal transition, cell isolation and co-culture studies, high-resolution mini-endoscopy, light-sheet fluorescence microscopy and micro-CT imaging in mice. The target audience for our protocol is researchers who plan in vivo studies to address mechanisms influencing sporadic or inflammation-driven tumor development, including the analysis of local invasiveness and lymph node metastasis. It is suitable for preclinical in vivo testing of novel drugs and other interventional strategies for clinical translation, plus the evaluation of emerging imaging devices/modalities. It can be completed within 24 weeks (using Step 5A/C) or 10 weeks (using Step 5B).
    DOI:  https://doi.org/10.1038/s41596-020-00412-1
  17. Cancer Res. 2020 Dec 11. pii: canres.0049.2020. [Epub ahead of print]
    Wu S, Chen M, Huang J, Zhang F, Lv Z, Jia Y, Cui YZ, Sun LZ, Wang Y, Tang Y, Verhoeft KR, Li Y, Qin Y, Lin X, Guan XY, Lam KO.
      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 morphological 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, is predominantly upregulated in the lymph node (LN) metastasis of gastric cancer (GC), supporting cell proliferation and migration. Clinical data reveal that a high frequency of ORAI2-positive cells in GC tissues significantly correlated with poor differentiation, invasion, LN metastasis and worse prognosis. Gain- and loss-of-function showed that ORAI2 promotes cell motility, tumor formation and metastasis in both GC cell lines and mice. Mechanistically, ORAI2 mediated SOC activity and regulated tumorigenic properties through the activation of the PI3K/Akt signaling pathways. Moreover, ORAI2 enhanced the metastatic ability of GC cells by inducing FAK-mediated mitogen-activated protein kinase (MAPK)/ERK activation and promoted focal adhesion disassembly at rear-edge of the cell. Collectively, our results demonstrate that ORAI2 is a novel gene that plays an important role in the tumorigenicity and metastasis of GC.
    DOI:  https://doi.org/10.1158/0008-5472.CAN-20-0049