MiR-126-5p Promotes Tumor Cell Proliferation, Metastasis and Invasion by Targeting TDO2 in Hepatocellular Carcinoma

TDO2 is a key enzyme in the kynurenine metabolic pathway, which is the most important pathway of tryptophan metabolism. It has been shown that miRNAs are involved in cell metastasis through interaction with target mRNAs. In this study, we found 645 miRNAs that could be immunoprecipitated with TDO2 through the RNA-immunoprecipitation experiment. miR-126-5p was selected as the research target, which was also confirmed by dual-luciferase reporter assay. Through qRT-PCR analysis, it was verified that the overexpression of miR-126-5p promoted the expression of TDO2, PI3K/AKT and WNT1. Meanwhile, it was verified that overexpression of miR-126-5p can promote intracellular tryptophan metabolism by HPLC. We also verified the effects of miR-126-5p on cell proliferation, migration, and invasion by cck-8, cell colony formation and trans-well assay in both HCCLM3 cells and HepG2 cells. In vivo experiments were also conducted to verify that miR-126-5p promoted tumor formation and growth via immunohistochemical detection of cell infiltration and proliferation to generate markers Ki-67, BAX, and VEGF. In conclusion, our results suggest that miR-126-5p is a biomarker and a potential new treatment target in the progression of HCC via promoting the expression of TDO2.