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Background/Aims: Long non-coding RNAs (lncRNAs) play important roles in diverse biological processes, such as cell growth, apoptosis and migration. Although downregulation of lncRNA maternally expressed gene 3 (MEG3) has been identified in several cancers, little is known about its role in prostate cancer progression. The aim of this study was to detect MEG3 expression in clinical prostate cancer tissues, investigate its biological functions in the development of prostate cancer and the underlying mechanism. Methods: MEG3 expression levels were detected by qRT-PCR in both tumor tissues and adjacent non-tumor tissues from 21 prostate cancer patients. The effects of MEG3 on PC3 and DU145 cells were assessed by MTT assay, colony formation assay, western blot and flow cytometry. Transfected PC3 cells were transplanted into nude mice, and the tumor growth curves were determined. Results: MEG3 decreased significantly in prostate cancer tissues relative to adjacent normal tissues. MEG3 inhibited intrinsic cell survival pathway in vitro and in vivo by reducing the protein expression of Bcl-2, enhancing Bax and activating caspase 3. We further demonstrated that MEG3 inhibited the expression of cell cycle regulatory protein Cyclin D1 and induced cell cycle arrest in G0/G1 phase. Conclusions: Our study presents an important role of MEG3 in the molecular etiology of prostate cancer and implicates the potential application of MEG3 in prostate cancer therapy.

People who develop bladder cancer frequently succumb to the intractable disease. Current treatment strategies are limited presumably due to the underlying molecular complexity and insufficient comprehension. Therefore, exploration of new therapeutic targets in bladder cancer remains necessary. Here, we identify that bromodomain-4 protein (BRD4), an important epigenome reader of bromodomain and extraterminal domain (BET) family member, is a key upstream regulator of enhancer of zeste homologue 2 (EZH2), and represents a novel therapeutic target in bladder cancer. We found that BRD4 was significantly overexpressed in bladder cancer cells and tissues. Inhibition of BRD4 decreased bladder cancer cell proliferation concomitantly with the accumulation of cell apoptosis in vitro and suppressed tumor growth in vivo. We further found that suppression of BRD4 decreased the mRNA and protein levels of EZH2, which was reversed by ectopic expression of C-MYC. In particular, individual silencing of BRD4 using shRNA or the BET inhibitor JQ1 strikingly diminished the recruitment of C-MYC to EZH2 promoter in bladder cancer. Briefly, our research reveals that BRD4 positively regulates EZH2 transcription through upregulation of C-MYC, and is a novel promising target for pharmacologic treatment in transcriptional program intervention against this intractable disease.

Background/Aims: Renal cell carcinoma (RCC) remains an intractable genitourinary malignancy. Resistance to chemotherapy or targeted therapies in RCC is presumably due to the complicated underlying molecular mechanisms and insufficient understanding. The aim of this research was to assess the expression and role of bromodomain-4 protein (BRD4) in RCC and evaluate the effects of BRD4 inhibitor JQ1 for RCC treatment. Methods: BRD4 expressionlevels were assessed by qRT-PCR and western blot in RCC tissues and cells. The effects of BRD4 knockdown or JQ1 on RCC cells were assessed by MTT assay and flow cytometry. The effects of in vivo treatment were evaluated through xenograft experiments. Results: BRD4 is significantly overexpressed in RCC, and is related to tumor stage and lymph node metastasis. Inhibition of BRD4 suppressed RCC cell proliferation, induced cell apoptosis in vitro and repressed tumor growth in vivo. Inhibition of BRD4 decreased BCL2 and C-MYC expression while increased BAX and cleaved caspase3 expression, and strikingly diminished the recruitment of BRD4 to BCL2 promoter. Conclusions: Our research reveals that BRD4 probably play a critical role in RCC progression, and is a new promising target for pharmacological treatment directed against this intractable disease.

Inactivation of human SET domain containing protein 2 (SETD2) is a common event in clear cell renal cell carcinoma (ccRCC). However, the mechanism underlying loss of SETD2 function, particularly the post-transcriptional regulatory mechanism, still remains unclear. In the present study, we found that SETD2 was downregulated and inversely correlated with high expression of miR-106b-5p in ccRCC tissues and cell lines. Over-expression of miR-106b-5p resulted in the decreased mRNA and protein levels of SETD2 in ccRCC cells. In an SETD2 3′-UTR luciferase reporter system, miR-106b-5p downregulated the luciferase activity, and the effects were abolished by mutating the predicted miR-106b-5p binding site. Moreover, attenuation of miR-106b-5p induced cell cycle arrest at G0/G1 phase, suppressed cell proliferation, enhanced processing of caspase-3, and promoted cell apoptosis in ccRCC cells, whereas these effects were reversed upon knockdown of SETD2. In addition, transfection of miR-106b-5p antagomir resulted in the increased binding of H3K36me3 to the promoter of p53 and enhanced its activity, as well as upregulated the mRNA and protein levels of p53, and the effects were also abolished by cotransfection with si-SETD2. Collectively, our findings extend the knowledge about the regulation of SETD2 at the posttranscriptional level by miRNA and regulatory mechanism downstream of SETD2 in ccRCC.

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Pituitary tumor-transforming gene 1 (PTTG1) is identified as an oncogene, and overexpresses in many tumors. However, the role of PTTG1 in bladder cancer (BC) hasn't yet been characterized well. In this study, we showed the expression of PTTG1 mRNA and protein were both significantly increased in BC tissues and cells. The PTTG1 protein levels were positive correlated with increased tumor size, tumor–node–metastasis (TNM) stage, lymphatic invasion and distant metastasis of BC. PTTG1 knockdown dramatically suppressed the migration, invasion, metastasis and growth, and induced senescence and cell-cycle arrest at G0/G1 phase of BC cells. We further identified PTTG1 was the direct target of miR-146a-3p through using target prediction algorithms and luciferase reporter assay. miR-146a-3p was low expressed and negatively correlated with PTTG1 levels in BC tissues and cells. miR-146a-3p overexpression inhibited migration, invasion, metastasis and growth, and induced senescence of BC cells. Rescue experiment suggested ectopic expression of miR-146a-3p and PTTG1 suppressed migration, invasion and induced cell cycle arrest and senescence of BC cells compared to PTTG1 overexpression, confirming miR-146a-3p inhibited BC progression by targeting PTTG1. In summary, our study found miR-146a-3p/PTTG1 axis regulated BC migration, invasion, metastasis and growth, and might be a targets for BC therapy.

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