ABSTRACT
AIM:To investigate the effects of p62 on drug resistance of human laryngocarcinoma cell line Hep-2.METHODS:The abundance of p62 in Hep-2/5-FU and Hep-2 cells was measured by RT-qPCR and Western blot.After silencing of p62 with p62 siRNA in the Hep-2/5-FU cells, the cell viability and cell apoptosis were determined by CCK-8 assay and flow cytometry.The levels of malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were measured to reflect the status of oxidative stress in the cells.The protein levels of apoptosis-related molecules Bcl-2, Bax, caspase-8/cleaved caspase-8 and caspase-3/cleaved caspase-3,and the activity of anti-oxidative stress pathway-related proteins Keap1/Nrf2 were measured by Western blot.RESULTS:The expression of p62 at both mRNA and protein levels was significantly up-regulated in the Hep-2/5-FU cells.The expression of p62 and Nrf2 increased in a dose-dependent manner in the Hep-2 cells.Knockdown of p62 inhibited the viability and promoted the apoptosis of the Hep-2/5-FU cells.Increased content of MDA, and suppressed activity of SOD and GSH-Px were also observed.Furthermore, knockdown of p62 up-regulated the protein levels of Bax, cleaved caspase-8, cleaved caspase-3 and Keap1, but down-regulated the protein levels of Bcl-2, Nrf2 and HO-1.CONCLUSION:Knockdown of p62 increases the sensitivity of Hep-2/5-FU cells to 5-FU exposure.The mechanism may be related to the inhibition of Keap1/Nrf2 pathway and the modulation of oxidative stress and cell apoptosis.