Taxol-Resistant Gene 1 (Txr1) Mediates Oxaliplatin Resistance by Inducing Autophagy in Human Nasopharyngeal Carcinoma Cells.

BACKGROUND Oxaliplatin (L-OHP) is an important chemotherapy regimen for nasopharyngeal carcinoma (NPC), but can fail due to drug resistance. In this study, the role of Txr1 (taxol-resistant gene 1) in oxaliplatin resistance was investigated. MATERIAL AND METHODS Cell viability assay was carried out using the CellTiter-Glo Luminescent Cell Viability Assay Kit. CNE1 and CNE2 cells were cultured continuously with gradually increasing concentrations of L-OHP for 6 months to establish drug-resistant cell lines. Autophagy was detected by electron microscopy. Txr1 expression in NPC cells was detected via Western blotting and real-time quantitative PCR (qRT-PCR). RESULTS In L-OHP-resistant CNE1/L-OHP and CNE2/L-OHP cells, mRNA and protein expression of Txr1 increased compared to the parental cells, and downregulation of Txr1 re-sensitized drug-resistant cells to L-OHP. Moreover, we found that Txr1-mediated L-OHP resistance was associated with increased autophagy. Txr1-overexpression cells developed L-OHP resistance and a high level of autophagy. Inhibiting autophagy using 2 different methods - inhibition of autophagy-related gene expression and autophagy inhibitor - attenuated L-OHP resistance of NPC cells. CONCLUSIONS We conclude that the detection of Txr1 might become a good indicator to evaluate the treatment and prognosis of nasopharyngeal carcinoma. Our data suggest that further investigation of Txr1 in the setting of L-OHP resistance is warranted.