GOLPH3 inhibition reverses oxaliplatin resistance of colon cancer cells via suppression of PI3K/AKT/mTOR pathway

Objective: To explore whether GOLPH3 regulated oxaliplatin (L-OHP) resistance of colon cancer cells via PI3K/AKT/mTOR pathway. Methods: HCT116/L-OHP cells were divided into Blank, Control/GOLPH3 shRNA, BEZ235 (a PI3K/AKT/mTOR inhibitor), and GOLPH3 + BEZ235 groups followed by the detection with MIT, soft agar colony formation, flow cytometry and TUNEL assays. Mice bearing HCT116/L-OHP xenografts were randomized into Control, L-OHP, NC/GOLPH3 shRNA, L-OHP + NC/GOLPH3 shRNA groups. The expressions of Ki67, Caspase-3, and PI3K/AKT/mTOR pathway proteins were examined by immunohistochemistry. Results: HCT116/L-OHP cells had increased GOLPH3 expression compared to HCT116 cells, which positively regulated PI3K/AKT/mTOR pathway in HCT116/L-OHP cells. BEZ235 declined IC50 of HCT116/L-OHP cells to L-OHP, decreased the expressions of ABCB1, ABCC1, ABCG2, ATP7A, ATP7B, MATE1, p-gp, MRP1 and BCRP, induced cell apoptosis, reduced cell proliferation, and arrested cells at GO/G1, which was reversed by GOLPH3 overexpression. L-OHP and GOLPH3 shRNA decreased tumor volume and reduced expression of Ki67 in tumor tissues with the increased Caspase-3. Meanwhile, the combined treatment had the better treatment effect. Conclusion: GOLPH3 inhibition reduced proliferation and promoted apoptosis of HCT116/L-OHP cells, and also reversed the L-OHP resistance of HCT116/L-OHP, which may be associated with the suppression of PI3K/AKT/mTOR pathway.