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  • 1
    Publication Date: 2018-02-16
    Description: Purpose: Intratumoral androgen synthesis (IAS) is a key mechanism promoting androgen receptor (AR) reactivation and antiandrogen resistance in castration-resistant prostate cancer (CRPC). However, signaling pathways driving aberrant IAS remain poorly understood. Experimental Design: The effect of components of the AKT-RUNX2-osteocalcin (OCN)–GPRC6A–CREB signaling axis on expression of steroidogenesis genes CYP11A1 and CYP17A1 and testosterone level were examined in PTEN-null human prostate cancer cell lines. Pten knockout mice were used to examine the effect of Runx2 heterozygous deletion or abiraterone acetate (ABA), a prodrug of the CYP17A1 inhibitor abiraterone on Cyp11a1 and Cyp17a1 expression, testosterone level and tumor microenvironment (TME) remodeling in vivo . Results: We uncovered that activation of the AKT–RUNX2–OCN–GPRC6A–CREB signaling axis induced expression of CYP11A1 and CYP17A1 and testosterone production in PTEN-null prostate cancer cell lines in culture. Deletion of Runx2 in Pten homozygous knockout prostate tumors decreased Cyp11a1 and Cyp17a1 expression, testosterone level, and tumor growth in castrated mice. ABA treatment also inhibited testosterone synthesis and alleviated Pten loss-induced tumorigenesis in vivo . Pten deletion induced TME remodeling, but Runx2 heterozygous deletion or ABA treatment reversed the effect of Pten loss by decreasing expression of the collagenase Mmp9. Conclusions: Abnormal RUNX2 activation plays a pivotal role in PTEN loss-induced IAS and TME remodeling, suggesting that the identified signaling cascade represents a viable target for effective treatment of PTEN-null prostate cancer, including CRPC. Clin Cancer Res; 24(4); 834–46. ©2017 AACR .
    Print ISSN: 1078-0432
    Electronic ISSN: 1557-3265
    Topics: Medicine
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  • 2
    Publication Date: 2018-09-15
    Description: Purpose: Deletions or mutations in PTEN and TP53 tumor suppressor genes have been linked to lineage plasticity in therapy-resistant prostate cancer. Fusion-driven overexpression of the oncogenic transcription factor ERG is observed in approximately 50% of all prostate cancers, many of which also harbor PTEN and TP53 alterations. However, the role of ERG in lineage plasticity of PTEN / TP53 –altered tumors is unclear. Understanding the collective effect of multiple mutations within one tumor is essential to combat plasticity-driven therapy resistance. Experimental Design: We generated a Pten -negative/ Trp53 -mutated/ ERG -overexpressing mouse model of prostate cancer and integrated RNA-sequencing with ERG chromatin immunoprecipitation-sequencing (ChIP-seq) to identify pathways regulated by ERG in the context of Pten / Trp53 alteration. We investigated ERG-dependent sensitivity to the antiandrogen enzalutamide and cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor palbociclib in human prostate cancer cell lines, xenografts, and allografted mouse tumors. Trends were evaluated in TCGA, SU2C, and Beltran 2016 published patient cohorts and a human tissue microarray. Results: Transgenic ERG expression in mice blocked Pten / Trp53 alteration–induced decrease of AR expression and downstream luminal epithelial genes. ERG directly suppressed expression of cell cycle–related genes, which induced RB hypophosphorylation and repressed E2F1-mediated expression of mesenchymal lineage regulators, thereby restricting adenocarcinoma plasticity and maintaining antiandrogen sensitivity. In ERG-negative tumors, CDK4/6 inhibition delayed tumor growth. Conclusions: Our studies identify a previously undefined function of ERG to restrict lineage plasticity and maintain antiandrogen sensitivity in PTEN / TP53 –altered prostate cancer. Our findings suggest ERG fusion as a biomarker to guide treatment of PTEN / TP53 -altered, RB1 -intact prostate cancer. Clin Cancer Res; 24(18); 4551–65. ©2018 AACR .
    Print ISSN: 1078-0432
    Electronic ISSN: 1557-3265
    Topics: Medicine
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  • 3
    Publication Date: 2018-12-04
    Description: Metastatic melanoma is responsible for approximately 80% of deaths from skin cancer. Microphthalmia-associated transcription factor (MITF) is a melanocyte-specific transcription factor that plays an important role in the differentiation, proliferation, and survival of melanocytes as well as in melanoma oncogenesis. MITF is amplified in approximately 15% of patients with metastatic melanoma. However, no small-molecule inhibitors of MITF currently exist. MITF was shown to associate with p300/CBP, members of the KAT3 family of histone acetyltransferase. p300 and CREB-binding protein (p300/CBP) regulate a wide range of cellular events such as senescence, apoptosis, cell cycle, DNA damage response, and cellular differentiation. p300/CBP act as transcriptional coactivators for multiple proteins in cancers, including oncogenic transcription factors such as MITF. In this study, we showed that our novel p300/CBP catalytic inhibitor, A-485, induces senescence in multiple melanoma cell lines, similar to silencing expression of EP300 (encodes p300) or MITF . We did not observe apoptosis and increase invasiveness upon A-485 treatment. A-485 regulates the expression of MITF and its downstream signature genes in melanoma cell lines undergoing senescence. In addition, expression and copy number of MITF is significantly higher in melanoma cell lines that undergo A-485–induced senescence than resistant cell lines. Finally, we showed that A-485 inhibits histone-H3 acetylation but did not displace p300 at promoters of MITF and its putative downstream genes. Taken together, we provide evidence that p300/CBP inhibition suppressed the melanoma-driven transcription factor, MITF, and could be further exploited as a potential therapy for treating melanoma.
    Print ISSN: 1535-7163
    Electronic ISSN: 1538-8514
    Topics: Medicine
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  • 4
    Publication Date: 2018-11-16
    Description: Purpose: Inflammatory infiltration plays important roles in both carcinogenesis and metastasis. We are interested in understanding the inhibitory mechanism of metformin on tumor-associated inflammation in prostate cancer. Experimental Design: By using a transgenic adenocarcinoma of the mouse prostate (TRAMP) mouse model, in vitro macrophage migration assays, and patient samples, we examined the effect of metformin on tumor-associated inflammation during the initiation and after androgen deprivation therapy of prostate cancer. Results: Treating TRAMP mice with metformin delays prostate cancer progression from low-grade prostatic intraepithelial neoplasia to high-grade PIN, undifferentiated to well-differentiated, and PIN to adenocarcinoma with concurrent inhibition of inflammatory infiltration evidenced by reduced recruitment of macrophages. Furthermore, metformin is capable of inhibiting the following processes: inflammatory infiltration after androgen deprivation therapy (ADT) induced by surgically castration in mice, bicalutamide treatment in patients, and hormone deprivation in LNCaP cells. Mechanistically, metformin represses inflammatory infiltration by downregulating both COX2 and PGE2 in tumor cells. Conclusions: Metformin is capable of repressing prostate cancer progression by inhibiting infiltration of tumor-associated macrophages, especially those induced by ADT, by inhibiting the COX2/PGE2 axis, suggesting that a combination of ADT with metformin could be a more efficient therapeutic strategy for prostate cancer treatment. Clin Cancer Res; 24(22); 5622–34. ©2018 AACR .
    Print ISSN: 1078-0432
    Electronic ISSN: 1557-3265
    Topics: Medicine
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  • 5
    Publication Date: 2018-04-03
    Description: Integrin αV gene expression is often dysregulated in cancers especially in hepatocellular carcinoma (HCC); however, the mechanism of regulation is poorly understood. Here, it is demonstrated that sulfatide activated integrin αV gene transcription, through histone H3K9/14 acetylation at the promoter, and high integrin αV expression are closely associated with poor prognosis. To elucidate the mechanism of regulation of acetylation, sulfatide-bound proteins were screened by mass spectrometry (MS), and bromodomain containing protein 1 (BRD1) was identified as an interacting protein that also colocalized with sulfatide in HCC cells. BRD1 was also formed a complex with Sp1, which was recruited to the integrin αV gene promoter. Sulfatide was also found to induce BRD1, monocytic leukemia zinc finger (MOZ) and histone acetyltransferase binding to ORC1 (HBO1) acetyltransferase multiprotein complex recruitment to the integrin αV promoter, which is responsible for histone H3K9/14 acetylation. Finally, knockdown of BRD1 limited sulfatide-induced H3K9/14 acetylation and occupancy of MOZ or HBO1 on integrin αV gene promoter. Implications: This study demonstrates that sulfatide interaction with BRD1 mediates acetylation and is important for regulation of integrin αV gene expression. Mol Cancer Res; 16(4); 610–22. ©2018 AACR .
    Print ISSN: 1541-7786
    Electronic ISSN: 1557-3125
    Topics: Medicine
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  • 6
    Publication Date: 2018-12-15
    Description: Purpose: Epigenetic alterations play important roles in metastasis and drug resistance through gene regulation. However, the functional features and molecular mechanisms of epigenetic changes remain largely unclear in nasopharyngeal carcinoma (NPC) metastasis. Experimental Design: Gene regulatory network analysis was used to identify metastatic-specific dysregulated genes between normal and NPC tissues and the expression was validated in published Gene-Expression Omnibus data set. The regulatory and functional role of RAB37 downregulation was examined in NPC and was validated in vitro and in vivo , and downstream target of RAB37 was explored. The clinical value of RAB37 methylation was evaluated in NPC metastasis and chemosensitivity. Results: We identified RAB37 as a specific hypermethylated gene that is most commonly downregulated in NPC. Moreover, RAB37 downregulation was attributed to hypermethylation of its promoter and was significantly associated with metastasis- and docetaxel chemoresistance-related features in NPC. Ectopic RAB37 overexpression suppressed NPC cell metastasis and enhanced chemosensitivity to docetaxel. Mechanistically, RAB37 colocalized with TIMP2, regulated TIMP2 secretion, inhibited downstream MMP2 activity, and consequently altered NPC cell metastasis. Furthermore, RAB37 hypermethylation was correlated with poor clinical outcomes in patients with NPC. We developed a prognostic model based on RAB37 methylation and N stage that effectively predicted an increased risk of distant metastasis and a favorable response to docetaxel-containing induction chemotherapy (IC) in NPC patients. Conclusions: This study shows that RAB37 hypermethylation is involved in NPC metastasis and chemoresistance, and that our prognostic model can identify patients who are at a high risk of distant metastasis and might benefit from for docetaxel IC.
    Print ISSN: 1078-0432
    Electronic ISSN: 1557-3265
    Topics: Medicine
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