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Background/Aims: MIAT is a long noncoding RNA (lncRNA) involved in cell proliferation and the development of tumor. However, the exact effects and molecular mechanisms of MIAT in clear cell renal cell carcinoma (ccRCC) progression are still unknown. Methods: We screened the lncRNAs’ profile of ccRCC in The Cancer Genome Atlas database, and then examined the expression levels of lncRNA MIAT in 45 paired ccRCC tissue specimens and in cell lines by q-RT-PCR. MTS, colony formation, EdU, and Transwell assays were performed to examine the effect of MIAT on proliferation and metastasis of ccRCC. Western blot and luciferase assays were performed to determine whether MIAT can regulate Loxl2 expression by competitively binding miR-29c in ccRCC. Results: MIAT was up-regulated in ccRCC tissues and cell lines. High MIAT expression correlated with worse clinicopathological features and shorter survival rate. Functional assays showed that knockdown of MIAT inhibited renal cancer cell proliferation and metastasis in vitro and in vivo. Luciferase and western blot assays further confirmed that miR-29c binds with MIAT. Additionally, the correlation of miR-29c with MIAT and Loxl2 was further verified in patients' samples. Conclusion: Our data indicated that MIAT might be an oncogenic lncRNA that promoted proliferation and metastasis of ccRCC, and could be a potential therapeutic target in human ccRCC.

Background/Aims: We previously performed microRNA (miRNA) microarray to identify effective indicators of clear cell renal cell carcinoma (ccRCC) tissue samples and preoperative/postoperative plasma in which we identified miR-144-3p as an oncomiRNA. However, the molecular mechanism of miR-144-3p remains unclear. This study aims to explore the roles of miR-144-3p in the invasion, migration and Sunitinib-resistance in ccRCC and to elucidate the underlying mechanisms. Methods: Gain and loss of function approaches were used to investigate the cell proliferation, cycle distribution, clonogenicity, migration, invasion, chemosensitivity of miR-144-3p in vitro. The xenograft model was used to assess the effects of miR-144-3p overexpression on tumorigenesis. Bioinformatics analysis and dual-luciferase reporter assay were used to indentify AT-rich interactive domain 1A (ARID1A) as a direct target gene of miR-144-3p. Quantitative RT-PCR, Western blotting, and immunohistochemical (IHC) staining were used to explore ARID1A expression level of the mRNA and protein. Results: We found that miR-144-3p overexpression enhanced cell proliferation, clonogenicity, migration, invasion, and chemoresistance in ccRCC cells. Notably, the oncotumor activities of miR-144-3p were mediated by repressing the expression of ARID1A. The downregulation of ARIDIA could promote the function of miR-144-3p in cell proliferation, metastasis and chemoresistance. Consistently, ARID1A mRNA and protein levels were decreased in ccRCC and in nude mice, and they negatively correlated with miR-144-3p. Conclusion: Higher miR-144-3p may enhance malignancy and resistance to Sunitinib in ccRCC by targeting ARID1A, the observations may uncover novel strategies of ccRCC treatment.

Background Growing evidence suggests that hepatitis C virus (HCV) contributes to hepatocellular carcinoma (HCC) by directly modulating oncogenic signaling pathways. Protein phosphatase magnesium-dependent 1A (PPM1A) has recently emerged as an important tumor suppressor as it can block a range of tumor-centric signaling pathways through protein dephosphorylation. However, the role and regulatory mechanisms of PPM1A in HCV-infected cells have not been reported. Methods Total, cytoplasmic, and nuclear PPM1A protein after HCV infection or overexpression of HCV nonstructural protein 3 (NS3) were detected by western blotting. The expression of PPM1A in normal liver and HCV-related HCC tissues was quantified by immunohistochemistry. The effects of HCV infection and NS3 expression on the PPM1A protein level were systematically analyzed, and the ubiquitination level of PPM1A was determined by precipitation with anti-PPM1A and immunoblotting with either anti-ubiquitin or anti-PPM1A antibody. Finally, the roles of NS3 and PPM1A in hepatoma cell migration and invasion were assessed by wound healing and transwell assays, respectively. Results HCV infection and replication decreased PPM1A abundance, mediated by NS3, in hepatoma cells. Compared to normal liver tissues, the expression of PPM1A was significantly decreased in the HCC tumor tissues and adjacent non-tumor tissues. NS3 directly interacted with PPM1A to promote PPM1A ubiquitination and degradation, which was dependent on its protease domain. Blockade of PPM1A through small interfering RNA significantly promoted HCC cell migration, invasion, and epithelial mesenchymal transition (EMT), which were further intensified by TGF-β1 stimulation, in vitro. Furthermore, restoration of PPM1A abrogated the NS3-mediated promotion of HCC migration and invasion to a great extent, which was dependent on its protein phosphatase function. Conclusions Our findings demonstrate that the HCV protein NS3 can downregulate PPM1A by promoting its ubiquitination and proteasomal degradation, which might contribute to the migration and invasion of hepatoma cells and may represent a new strategy of HCV in carcinogenesis. Electronic supplementary material The online version of this article (doi:10.1186/s13046-017-0510-8) contains supplementary material, which is available to authorized users.