miR-193a-3p Enhanced the Chemosensitivity to Trametinib in Gallbladder Carcinoma by Targeting KRAS and Downregulating ERK Signaling

Objective: In this study, the authors identified miR-193a-3p as a tumor-suppressing microRNA, and its effects on the chemosensitivity to trametinib in gallbladder carcinoma (GBC) were evaluated. Materials and Methods: The levels of miR-193a-3p in clinical GBC tissues and GBC cells were determined by quantitative real-time polymerase chain reaction. The protein levels of KRAS, ERK, and phosphorylated ERK (p-ERK) were examined by Western blot. Dual-luciferase reporter assays were performed to confirm the interaction between miR-193a-3p and KRAS. The effect of miR-193a-3p knockdown or overexpression on the malignant behaviors and chemosensitivity of GBC was determined by 3-(4,5-dimethlthiazol-2-yl)-2,5-diphenyl-tetrazoliumbromide and flow cytometry assays in vitro and further examined in a xenograft model. Results: The levels of miR-193a-3p were significantly decreased in GBC cell lines, especially with KRAS mutations. In addition, miR-193a-3p overexpression retarded cell proliferation of GBC, but induced cell apoptosis. Moreover, miR-193a-3p overexpression significantly improved the chemosensitivity of GBC to trametinib both in in vitro assays and in vivo xenograft mouse model. Further mechanisms disclosed that KRAS was a target of miR-193a-3p and levels of p-ERK were increased by treatment with miR-193a-3p inhibitor in GBC. Conclusions: These data suggested that miR-193a-3p enhanced the chemosensitivity to trametinib in GBC with wild-type KRAS or KRAS mutations by directly targeting KRAS and finally downregulated ERK signaling.