p62/SQSTM1 involved in cisplatin resistance in human ovarian cancer cells by clearing ubiquitinated proteins.

Mechanisms of cisplatin resistance in cancer cells are not fully understood. Here, we show a critical role for the ubiquitin-binding protein p62/SQSTM1 in cisplatin resistance in human ovarian cancer cells (HOCCs). Specifically, we found that cisplatin-resistant SKOV3/DDP cells express much higher levels of p62 than do cisplatin-sensitive SKOV3 cells. The protein p62 binds ubiquitinated proteins for transport to autophagic degradation, reducing apoptosis induced by endoplasmic reticulum (ER) stress in SKOV3/DDP cells. Knockdown of p62 or inhibition of autophagy using 3-methyladenine resensitises SKOV3/DDP cells to cisplatin. Collectively, our data indicate that p62 acts as a receptor or adaptor for autophagic degradation of ubiquitinated proteins, and plays an important role in preventing ER stress-induced apoptosis, leading to cisplatin resistance in HOCCs.