Prostate cancer is a leading cause of cancer-related mortality in men worldwide and there is a lack of effective treatment options for advanced (metastatic) prostate cancer. Currently, limited knowledge is available concerning the role of long non-coding RNAs in prostate cancer metastasis. In this study, we found that long non-coding RNA H19 (H19) and H19-derived microRNA-675 (miR-675) were significantly downregulated in the metastatic prostate cancer cell line M12 compared with the non-metastatic prostate epithelial cell line P69. Upregulation of H19 in P69 and PC3 cells significantly increased the level of miR-675 and repressed cell migration; however, ectopic expression of H19 in M12 cells could not increase the level of miR-675 and therefore had no effect on cell migration. Furthermore, we found that the expression level of either H19 or miR-675 in P69 cells was negatively associated with the expression of transforming growth factor b induced protein (TGFBI), an extracellular matrix protein involved in cancer metastasis. Dual luciferase reporter assays showed that miR-675 directly bound with 3 0 UTR of TGFBI mRNA to repress its translation. Taken together, we show for the first time that the H19-miR-675 axis acts as a suppressor of prostate cancer metastasis, which may have possible diagnostic and therapeutic potential for advanced prostate cancer. IntroductionProstate cancer is a leading cause of cancer-related mortality in men worldwide [1]. Bone metastases responsible for poor clinical outcomes are detectable in about 80% of advanced prostate cancer patients [2]. Since no effective treatment is available for advanced prostate cancer, it is urgent to understand the molecular mechanisms underlying prostate cancer metastasis, which may help identify novel diagnostic and therapeutic targets.Long non-coding RNAs (lncRNAs), with length > 200 nucleotides, have been considered as one type of gene expression regulator for decades. The first Abbreviations ECM, extracellular matrix; EGF, epidermal growth factor; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; H19, lncRNA H19; hTGF-b-1, human transforming growth factor b-1; lncRNA, long non-coding RNA; miR-675, microRNA-675; miRNA, microRNA; RTCA, real-time cell analysis; TGFBI, transforming growth factor b induced protein.

The membrane association of the tumour suppressor phosphatase and tensin homologue (PTEN) is required to oppose the phosphatidylinositol-3-kinase / AKT pathway by dephosphorylation of phosphatidylinositol-3,4,5-triphosphate (PIP3). How cytosolic PTEN interacts with its main substrate, PIP3, localized at the inner face of plasma membrane remains unclear. Here we show that PTEN is covalently modifi ed by SUMO1 at both K 266 and K 254 sites in the C2 domain of PTEN. SUMO1 modifi cation at K 266 located in the CBR3 loop, which has a central role in PTEN membrane association, mainly facilitates cooperative binding of PTEN to the plasma membrane by electrostatic interactions. This results in the downregulation of the phosphatidylinositol-3 kinase / AKT pathway and consequently, suppression of anchorageindependent cell proliferation and tumour growth in vivo . Our data demonstrate a molecular mechanism whereby SUMO1 modifi cation is required for PTEN tumour suppressor function by controlling PTEN membrane association and regulation of the phosphatidylinositol-3 kinase / AKT pathway.

NF-κB is constitutively activated in psoriatic epidermis. However, how activated NF-κB promotes keratinocyte hyperproliferation in psoriasis is largely unknown. Here we report that the NF-κB activation triggered by inflammatory cytokines induces the transcription of microRNA (miRNA) miR-31, one of the most dynamic miRNAs identified in the skin of psoriatic patients and mouse models. The genetic deficiency of miR-31 in keratinocytes inhibits their hyperproliferation, decreases acanthosis and reduces the disease severity in psoriasis mouse models. Furthermore, protein phosphatase 6 (ppp6c), a negative regulator that restricts the G1 to S phase progression, is diminished in human psoriatic epidermis and is directly targeted by miR-31. The inhibition of ppp6c is functionally important for miR-31-mediated biological effects. Moreover, NF-κB activation inhibits ppp6c expression directly through the induction of miR-31, and enhances keratinocyte proliferation. Thus, our data identify NF-κB-induced miR-31 and its target, ppp6c, as critical factors for the hyperproliferation of epidermis in psoriasis.

The methyltransferase like 3 (METTL3) is a key component of the large N6-adenosine-methyltransferase complex in mammalian responsible for N6-methyladenosine (m6A) modification in diverse RNAs including mRNA, tRNA, rRNA, small nuclear RNA, microRNA precursor and long non-coding RNA. However, the characteristics of METTL3 in activation and post-translational modification (PTM) is seldom understood. Here we find that METTL3 is modified by SUMO1 mainly at lysine residues K177, K211, K212 and K215, which can be reduced by an SUMO1-specific protease SENP1. SUMOylation of METTL3 does not alter its stability, localization and interaction with METTL14 and WTAP, but significantly represses its m6A methytransferase activity resulting in the decrease of m6A levels in mRNAs. Consistently with this, the abundance of m6A in mRNAs is increased with re-expression of the mutant METTL3-4KR compared to that of wild-type METTL3 in human non-small cell lung carcinoma (NSCLC) cell line H1299-shMETTL3, in which endogenous METTL3 was knockdown. The alternation of m6A in mRNAs and subsequently change of gene expression profiles, which are mediated by SUMOylation of METTL3, may directly influence the soft-agar colony formation and xenografted tumor growth of H1299 cells. Our results uncover an important mechanism for SUMOylation of METTL3 regulating its m6A RNA methyltransferase activity.