miR-302c-3p regulates TRAF4 expression by directly binding to its 3'-UTR in HCC cells. (A) The complementary sequences of miR-302c-3p were discovered in 3'-UTR of TRAF4 mRNA using TargetScan (http://www.targetscan.org) and miRanda (microRNA.org). The mutagenesis was performed in the complementary sites for the seed region of miR-302c-3p. (B) miR-302c-3p overexpression reduced while miR-302c-3p knockdown increased the expression of TRAF4 in HepG2 cells. n= three repeats with similar results, *P<0.05 by Student's t-test. (C) miR-302c-3p inversely modulated the luciferase activity of plasmids that carried wt rather than mt 3'-UTR of TRAF4 (wt, wild type; mt, mutant type). n= three repeats with similar results, *P<0.05 by Student's t-test. (D) The expression of TRAF4 mRNA in HCC tissues was significantly higher than that in matched tumor-adjacent tissues. n= 80, *P<0.05 by Student's t-test. (E) A negative correlation between TRAF4 mRNA expression and miR-302c-3p level was found in HCC tissues. n= 80, *P<0.05 by Pearson correlation test. (F) Western blotting analysis indicated that the expression of TRAF protein in HCC tissues with high miR-302c level was remarkably lower than that in cases with low miR-302c level. n= 6, *P<0.05 by Student's t-test.