Synergistic anticancer activity of cisplatin combined with tannic acid enhances apoptosis in lung cancer through the PERK-ATF4 pathway

BACKGROUND: Cisplatin (CDDP) is a common anticancer drug whose side effects limit its clinical applications. Tannins (TA) are plant-derived polyphenols that inhibit tumor growth in different types of cancer. Here, we evaluated the anticancer effect of TA combined with CDDP on lung cancer cell lines (GLC-82 and H1299) and investigated the underlying molecular mechanism of endoplasmic reticulum (ER) stress-induced apoptosis. METHODS: Cell lines were treated with CDDP, TA, and CDDP + TA, and the effect of the combination was assessed using MTT assay and observed under light and fluorescence microscopes. Cell apoptosis was detected by flow cytometry, and the levels of ERS apoptosis pathway related genes were valuated by qRT-PCR and western blotting. The effects of the drug combination on the tumors of nude mice injected with H1299 cells were investigated, and the expression of key factors in the ER stress apoptotic pathway was investigated. RESULTS: The combination of CDDP and TA significantly inhibited lung cancer cell viability indicating a synergistic antitumoral effect. The mRNA and protein expression levels of key ER stress factors in the CDDP + TA group were considerably higher than those in the CDDP and TA groups, the tumor volume in tumor-bearing mice was the smallest, and the number of apoptotic cells and the protein expression levels of the key ER stress in the combination group were considerably higher. CONCLUSIONS: The combination of TA and CDDP may produce synergistic antitumoral effects mediated by the PERK-ATF4-CHOP apoptotic axis, suggesting a novel adjuvant treatment for lung cancer.