Study On The Function Of P31-comet / MAD2 In Glioma And The Function Of MiR-146a In Hepatocellular Carcinoma

MAD2 (mitotic arrest deficient 2 protein 1, MAD2L1) is an important function protein of protein spindle assembly checkpoint and is closely related to chromosome stability.P31-comet is a MAD2 binding protein that can inhibit the function of MAD2 and relate to silencing the mitotic checkpoint and mitotic exit. In the process of mitosis, the abnormal function of mitotic checkpoint can result in chromosomal instability, which may eventually lead to cell malignant transformation.In glioma, the expression of MAD2 was abnormal and significantly higher than that in normal brain tissue.But its function in glioma is still unknown. In this study, we used lentivirus mediated knockdown of MAD2 or overexpression p31-comet to study the function of endogenous Mad2 and p31-comet in glioma.The results showed that knockdown of MAD2 or overexpression p31-comet could effectively inhibit glioma cell line U87 and U251 cell proliferation, survival and migration.Further research found that knockdown MAD2 or overexpression of p31-comet could affect the cell cycle distribution and the expression of mitosis-associated proteins, and promote cellular senescence. In addition, we also studied the effect of MAD2 and p31-comet on the drug resistance of glioma cells. Using two different microtubule inhibitors, PTX and VBL, we found that knockdown of MAD2 or overexpression of p31-comet could enhance the tolerance of U87 and U251 cells to PTX and VBL.Taken together, our findingsdemonstrated that endogenous p31-comet/MAD2 played an important role in glioma cell proliferation, migration, and drug resistance, which indicated that p31-comet/MAD2 may be molecular a potential target for the treatment of glioma.MicroRNAs is a relatively conserved non-coding RNA, which has been proved to play an important role in many physiological processes. Studies have shown that miR-146a (microRNA-146a) as a potential tumor suppressor can inhibit the proliferation and migration of breast cancer, prostate cancer and other tumor cells. However, the expression and function of miR-146a in hepatocellular carcinoma is still unknown. In the present study, we found that the relative expression level of miR-146a in HCC tissues was lower than that in adjacent tissues. Using lentiviral vector mediated overexpression of miR-146a could inhibit the proliferation and invasion of hepatocellular carcinoma cell line SMCC-7721 and HepG2. Further studyfound that TRAF6 (tumor necrosis factor receptor associated protein 6) was a direct target of miR-146a. The relative expression level of TRAF6 in HCC tissues was significantly higher than that in adjacent tissues. Overexpression of TRAF6 in overexpressed miR-146a HCC cells can partlyrescuethe proliferation and invasion of HCC cells. In addition, we also established the subcutaneous tumor model in nude mice. These results showed that overexpression of miR-14a inhibited HepG2 cell growth in nude mice. Correspondingly, overexpression of TRAF6 promoted the subcutaneous tumor formation of HepG2 cells in nude mice and resused the inhibitory effect of overexpressed miR-146a on the subcutaneous tumor formation.In summary, our studies demonstrated that miR-146a was involved in the occurrence and development ofHCC through the negative regulation of TRAF6, suggesting that miR-146a may be a potential molecular target for the treatment ofHCC.