Androgen Receptor-Activated Enhancers Simultaneously Regulate Oncogene TMPRSS2 and lncRNA PRCAT38 in Prostate Cancer.

Prostate cancer is a common carcinoma in males, the development of which involves the androgen receptor (AR) as a key regulator. AR transactivation induces the high expression of androgen-regulated genes, including transmembrane protease serine 2 (TMPRSS2) and long noncoding RNA prostate cancer-associated transcript 38 (PRCAT38). PRCAT38 and TMPRSS2 are both located on chromosome 21, separated by a series of enhancers. PRCAT38 is a prostate-specific long noncoding RNA that is highly expressed in cancer tissue as compared to normal tissue. Here, we show chromatin looping by enhancers E1 and E2 with the promoters for PRCAT38 and TMPRSS2, indicating the co-regulation of PRCAT38 and TMPRSS2 by the same enhancers. The knockout of enhancer E1 or E2 simultaneously impaired the transcription of PRCAT38 and TMPRSS2 and inhibited cell growth and migration. Moreover, the loop formation and enhancer activity were mediated by AR/FOXA1 binding and the activity of acetyltransferase p300. Our findings demonstrate the utilization of shared enhancers in the joint regulation of two oncogenes in prostate cancer cells.

Aberrant activation of CYR61 enhancers in colorectal cancer development.

BACKGROUND: High expression of secreted matricellular protein cysteine-rich 61 (CYR61) correlates with poor prognosis in colorectal cancer (CRC). Aberrant enhancer activation has been shown to correlate with expression of key genes involved in cancer progression. However, such mechanisms in CYR61 transcription regulation remain unexplored. METHODS: Expression of CYR61 was determined by immunohistochemistry (IHC), quantitative real-time PCR (qRT-PCR) and western blotting (WB) in CRC patients paraffin specimens and colon cell lines. ChIP-seq data of enhancer-characteristic histone modifications, in CRC tissues from the Gene Expression Omnibus (GEO) database, were reanalyzed to search for putative enhancers of CYR61. Dual-luciferase reporter assay was used to detected enhancer activity. Physical interactions between putative enhancers and CYR61 promoter were detected by chromosome conformation capture (3C) assay. Histone modification and transcription factors (TFs) enrichment were detected by ChIP-qPCR. Additionally, biological function of enhancers was investigated by transwell migration assays. RESULTS: CRC tissues and cell lines expressed higher level of CYR61 than normal colon mucosa. Three putative enhancers located downstream of CYR61 were found in CRC tissues by ChIP-seq data reanalysis. Consistent with the ChIP-seq analysis results in the GEO database, the normal colon mucosal epithelial cell line NCM460 possessed no active CYR61 enhancers, whereas colon cancer cells exhibited different patterns of active CYR61 enhancers. HCT116 cells had an active Enhancer3, whereas RKO cells had both Enhancer1 and Enhancer3 active. Pioneer factor FOXA1 promoted CYR61 expression by recruiting CBP histone acetyltransferase binding and increasing promoter-enhancer looping frequencies and enhancer activity. CBP knockdown attenuated H3K27ac enrichment, promoter-enhancer looping frequencies, and enhancer activity. Small molecule compound 12-O-tetradecanoyl phorbol-13-acetate (TPA) treatment, which stimulated CYR61 expression, and verteporfin (VP) treatment, which inhibited CYR61 expression, confirmed that the enhancers regulated CYR61 expression. Knockdown and ectopic expression of CYR61 rescued cell migration changes induced by over-expressing and knockdown of FOXA1, respectively. CONCLUSIONS: CYR61 enhancer activation, mediated by FOXA1 and CBP, occurs during CRC progression to up-regulate CYR61 expression and promote cell migration in CRC, suggesting inhibition of recruitment of FOXA1 and/or CBP to CYR61 enhancers may have therapeutic implications.

Vimentin acetylation is involved in SIRT5-mediated hepatocellular carcinoma migration.

Sirtuin 5 (SIRT5) belongs to the sirtuin family of protein deacetylases and contributes to tumorigenesis and migration. However, the underlying molecular mechanism of SIRT5 in hepatocellular carcinoma (HCC) migration is not fully understood. Here we report that SIRT5 was significantly downregulated in HCC, based on analysis of RNA-seq data from the liver HCC dataset of The Cancer Genome Atlas (TCGA). In addition, as compared to adjacent non-tumor tissues, SIRT5 was also significantly downregulated in HCC tissues. In vitro, gain and loss-of-function studies were performed to evaluate the role of SIRT5 in epithelial-mesenchymal transition (EMT). Knockdown of SIRT5 promoted EMT, as indicated by the upregulation of Snail and downregulation of E-cadherin, whereas overexpression of SIRT5 decreased Snail and upregulated E-cadherin. Mechanistically, SIRT5 was found to bind to and deacetylate vimentin at lysine 120. Cell migration was enhanced by overexpression of either wild-type vimentin or acetylation mimetic vimentin (K120Q), whereas cell migration was inhibited by overexpression of the non-acetylation vimentin (K120R). Taken together, these findings indicated that downregulated SIRT5-mediated vimentin acetylation may be involved in the EMT in HCC. Better understanding of SIRT5 may lead to its clinical application as a biomarker for prognosis of prediction of prognosis, as well as a novel therapeutic target.