MiR-494-3p mediates oxaliplatin resistance of colorectal cancer cells via PTEN/AKT pathway

Purpose: To unravel the influence of miR-494-3p on the insensitivity of colorectal cancer (CRC) cells to oxaliplatin. Methods: The mRNA level of miR-494-3p in oxaliplatin-resistant HT-29 cells was evaluated with reverse transcript-polymerase chain reaction (RT-PCR). The cells were treated with miR-494-3p suppressor or mimic, and then apoptotic changes were determined flow cytometrically. Resistancerelated gene expressions were measured using RT-PCR and western blotting. In addition, in vivo mouse experiments were conducted. Results: MiR-494-3p expression in oxaliplatin-resistant HT-29 cells was much higher than that in parental HT-29 cells, accompanied by increased levels of MRP, P-gp, and AKT phosphorylation (pAKT), and decreased phosphatase and tensin homolog (PTEN) (p < 0.001). The miR-494-3p mimic suppressed oxaliplatin-induced parental HT-29 cell apoptosis, while miR-494-3p inhibitor promoted oxaliplatin-resistant HT-29 cell apoptosis and decreased the levels of p-AKT, MRP and P-gp, while upregulating PTEN (p < 0.001). Furthermore, AKT inhibitor had similar effects as miR-494-3p inhibitor (p < 0.001). Experiments using nude mice demonstrated that inhibition of miR-494-3p accentuated the sensitivity of oxaliplatin-resistant HT-29 cells to oxaliplatin (p < 0.05). Conclusion: Suppression of miR-494-3p attenuates oxaliplatin insensitivity to CRC cells via a mechanism which may involve PTEN/AKT pathway. Therefore, miR-494-3p may be an effective target for overcoming drug resistance of CRC.