Accumulated evidence indicates that CCAT1 functions as an oncogene in the progression of a variety of tumors. However, little is known as to how CCAT1 impacts tumorigenesis in human prostate cancer. In this study, we found from The Cancer Genome Atlas and Memorial Sloan Kettering Cancer Center database that CCAT1 is highly upregulated in castration-resistant prostate cancer (CRPC) compared with androgen-dependent prostate cancer (ADPC). Higher level of CCAT1 leads to increased mortality in patients with CRPC. In vitro and in vivo studies show that CCAT1 promotes prostate cancer cell proliferation as well as the tumor growth of prostate cancer xenografts. Mechanistically, in cytoplasm, CCAT1 sponges MIR-28-5P to prevent the anticancer effect. In nucleus, CCAT1 acts as a scaffold for DDX5 (P68) and AR transcriptional complex to facilitate the expression of AR-regulated genes, thus stimulating CRPC progression. Our findings suggest that CCAT1 is an oncogenic factor in the progression of CRPC with different regulatory mechanisms in the nucleus and cytoplasm of cells.

Accumulated evidence indicate that miR-744 functions as either tumor suppressor or oncogene in the progression of a variety of tumors, with a tumor type-specific way. However, little is known about how miR-744 impacts on the tumorigenesis of human prostate cancer. In this study, employing the analyses of microarray, qRT-PCR and re-analysis of MSKCC data, we found that CRPC tissues expressed much more miR-744 than ADPC tissues did, and the expression level of miR-744 was inversely associated with survival of CRPC patients. In vitro studies revealed that miR-744 promotes PCa cells proliferation, enhances migration, invasion; in vivo results demonstrated that silencing of miR-744 mediated by shRNA dramatically reduces PCa xenograft tumor growth. Importantly, through human gene expression array, pathway enrichment analysis and Western blot, we identified that miR-744 dramatically activated Wnt/β-catenin pathway by targeting multiple negative regulators of Wnt/β-catenin signaling, including SFRP1, GSK3β, TLE3 and NKD1. At molecular level, we further defined that NKD1 is a major functional target of miR-744. Our findings indicate that miR-744 acts as one of oncogenic factor in the progression of CRPC by recruiting a mechanism of aberrant activation of Wnt/β-catenin signaling.

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BackgroundProstate cancer (PCa) is one of the most common malignant diseases among male patients. Although androgen deprivation therapy remains the main treatment for PCa, most patients would inevitably progress to castration-resistant PCa, which is the main cause of cancer-related deaths. Thus, novel antitumor agents are urgently needed. Recent studies demonstrated that aloperine (ALO) as a natural alkaloid showed antitumor effects in other cancer types. However, the biological function and underlying mechanisms of ALO in PCa have not been investigated.MethodsPCa cell lines including LNCaP, PC3 and DU145 were cultured and treated with ALO. Cell Counting Kit-8 assay, colony formation assay, apoptosis assay and cell cycle assay were conducted to assess the biological role of ALO. In addition, a PCa subcutaneous xenograft mouse model was established to evaluate the role of ALO in terms of proliferation and apoptosis in vivo. We further measured the protein expression levels of p-Akt/Akt, p-ERK/ERK, c-Myc, cleaved caspase 3, p21, p53, Bcl-2 and Bax using the Western blot 48 h after ALO treatment of PCa cells.ResultsALO effectively inhibited the cell viability of PCa by inducing cell cycle arrest via the activation of the p53/p21 pathway and triggering apoptosis in vitro and in vivo. ALO also inhibited phosphorylation of Akt and ERK protein kinases and activated cleaved caspase 3 while exerting antiproliferation function through inducing apoptosis and cell cycle arrest in PCa cells.ConclusionBased on our findings, we conclude that ALO could suppress the tumor growth and promote cell apoptosis and cell cycle arrest in PCa cells, which indicated that ALO could act as a novel therapeutic agent in treatment of human PCa.

Prostate cancer (PCa) is a leading cause of death among men. The dysregulation of metabolism and autophagy contributes to the progression of PCa. The transcription factor specificity protein 1 (Sp1) is implicated in the regulation of metabolism and autophagy. We confirmed that Sp1 is overexpressed in castration-resistant prostate cancer (CRPC) cells. However, the roles of Sp1 in PCa metabolism and autophagy remain unclear. Thus, in the present study, we retrieved the GSE35988 dataset from Gene Expression Omnibus (GEO) database to reinvestigate Sp1 expression and its role in PCa.We found that in PCa, Sp1 knockdown significantly inhibited cell growth, aerobic glycolysis, and hypoxia-induced autophagy, which were accompanied by an increased G1 cell cycle arrest. Pearson correlation indicated that pyruvate kinase isoenzyme type M2 (PKM2) is positively correlated with Sp1 expression. Western blot analysis demonstrated that Sp1 directly regulates PKM2; therefore, Sp1 modulates metabolism and autophagy in CRPC. Western blot analysis and luciferase reporter assay also indicated that the tumor suppressor miR-361-5p inversely regulates Sp1 by directly targeting the binding site in the 3'UTR of Sp1. miR-361-5p overexpression presented effects that are similar to Sp1 depletion in PCa. In summary, this study is the first to demonstrate that miR-361-5p suppresses the Sp1/PKM2 axis, consequently affecting the progression of PCa and the metabolism and autophagy of PCa cells. Therefore, targeting the miR-361-5p/Sp1/PKM2 pathway has considerable clinical significance in preventing the malignant progression of PCa.