Nestin overexpression reduces the sensitivity of gastric cancer cells to trastuzumab

BACKGROUND: Trastuzumab (TRA) shows significant efficacy in patients with human epidermal growth factor receptor 2 (HER2)-positive gastric cancer (GC). While TRA can help treat HER2-positive breast cancer, TRA resistance is a key clinical challenge. Nestin reportedly regulates the cellular redox homeostasis in lung cancer. This study aimed at identifying the functions of Nestin on the TRA sensitivity of HER2-positive GC cells. METHODS: Real-time polymerase chain reaction (PCR) and Western blotting (WB) were performed to explore the association between the mRNA and protein expression profiles, respectively, of Nestin and the Keap1-Nrf2 pathway. The influence of Nestin overexpression on the in vitro sensitivity of GC cells to TRA was explored by Cell Counting Kit-8 (CCK-8) assay, colony formation assay, reactive oxygen species (ROS) detection, and flow cytometry. RESULTS: TRA treatment caused Nestin downregulation in two HER2-positive GC cell lines (MKN45 and NCI-N87). Nestin overexpression reduced the sensitivity of GC cells to TRA. The expression and activity of Nrf2 and relevant downstream antioxidant genes were increased by Nestin overexpression. Nestin overexpression also significantly suppressed TRA-induced apoptosis and ROS generation. In vivo tumor growth experiment with female BALB/c nude mice indicated that Nestin upregulation restored the tumor growth rate which was inhibited by TRA treatment. CONCLUSIONS: Collectively, the inhibitory effect of Nestin on the TRA sensitivity of cells to TRA was confirmed in this study. These results imply that the antioxidant Nestin-Nrf2 axis may play a role in the mechanism underlying the resistance of GC cells to TRA.