Epithelial-to-mesenchymal transition, circulating tumor cells and cancer metastasis: Mechanisms and clinical applications Epithelial-to-mesenchymal transition, circulating tumor cells and cancer metastasis: Mechanisms and clinical applications

MicroRNAs (miRNAs) are important regulators of gene expression during tumorigenesis. The downregulation of microRNA-9 (miR-9) has been reported in ovarian serous carcinoma (OSC), indicating a role for miR-9 in this type of cancer. In this study, we investigated the biological significance of miR-9 in OSC in vitro. Using 3 OSC cell lines, SKOV3, CAOV3 and OVCAR3, which underexpresss miR-9, we demonstrate that the exogenous miR-9 transfection inhibits OSC cell proliferation, migration and invasion. In addition, we demonstrate that the focal adhesion protein, talin 1 (TLN1), whose expression has been associated with OSC development and progression to metastasis, is a direct target of miR-9. TLN1 knockdown mimicked the effects of miR-9 overexpression. Moreover, the activation of the TLN1-modulated FAK/AKT pathway was inhibited by the increased miR-9 levels. These results suggest that miR-9 plays a role as a tumor suppressor in OSC by suppressing TLN1 expression.

Protein arginine methyltransferase 6 (PRMT6) is a type I PRMT that is involved in epigenetic regulation of gene expression through methylating histone or non-histone proteins, and other processes such as alternative splicing, DNA repair, cell proliferation and senescence, and cell signaling. In addition, PRMT6 also plays different roles in various cancers via influencing cell growth, migration, invasion, apoptosis, and drug resistant, which make PRMT6 an anti-tumor therapeutic target for a variety of cancers. As a result, many PRMT6 inhibitors are being utilized to explore their efficacy as potential drugs for various cancers. In this review, we summarize the current knowledge on the function and structure of PRMT6. At the same time, we highlight the role of PRMT6 in different cancers, including the differentiation of its promotive or inhibitory effects and the underlying mechanisms. Apart from the above, current research progress and the potential mechanisms of PRMT6 behind them were also summarized.