Inhibition of ErbB2 by Herceptin reduces viability and survival, induces apoptosis and oxidative stress in Calu-3 cell line

Human epidermal growth factor receptor 2 (ErbB2) amplification and overexpression has been seen in many cancer types including non-small cell lung cancer (NSCLC). Thus, ErbB2 is an important target for cancer therapies. Increased ErbB2 expression has been associated with drug resistance in cancer cells. Herceptin is a humanized monoclonal antibody that targets the extracellular domain of ErbB2. In this study, we aimed to block ErbB2 signaling with Herceptin and assess cytotoxicity and effects on apoptosis, oxidative stress, nuclear factor kappa-B (NF-kB), and Survivin expression in Calu-3 cell line. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay were used to assess cell viability as a marker of proliferation. Acridine orange/ethidium bromide (AO/EB) staining and caspase 3/7 activity were measured as the markers of apoptosis. The relative expressions of NF-kB-p50 and Survivin mRNAs were evaluated. Activities of antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT), and the levels of glutathione (GSH) and reactive oxygen species (ROS) were determined in a time- and dose-dependent manner. Our results show that Herceptin treatment inhibits cell proliferation and activates apoptosis but without effects on Survivin and NF-kB expression in Calu-3 cell line. Intracellular glutathione levels and SOD and CAT activities were decreased in a time- and dose-dependent manner associated with oxidative stress. Also, ROS were increased at 24 h. These results provide evidence that Herceptin can be used as a cytotoxic and apoptotic agent in NSCLC.