Effects and mechanisms of glutamic-pyruvic transaminase 2 on cisplatin resistance in gastric cancer / 上海交通大学学报（医学版）

ABSTRACT

Objective: To investigate the role and mechanism of glutamic-pyruvic transaminase 2 (GPT2) on cisplatin resistance in gastric cancer. Methods:The Kaplan Meier-Plotter database was used to analyze the relationship between GPT2 expression and poor prognosis of gastric cancer. The expressions of GPT2 in gastric cancer cells and tissues were detected by quantitative real-time PCR (qPCR), Western blotting and immunohistochemistry (IHC). The cytotoxicity of cisplatin at different concentrations to human gastric cancer cells and normal gastric epithelial cells was detected by CCK-8 assay. GPT2 overexpression and knockdown cell lines were constructed in cisplatin sensitive MKN28 cells and insensitive MKN45 cells, respectively. CCK-8 assay, colony formation assay and Western blotting were performed to evaluate the cellular cytotoxicity, stemness of cancer cells and the changes of key proteins in stemness-related signaling pathways in GPT2 overexpression and knockdown cell lines, respectively. Results:The high expression of GPT2 was negatively correlated with the survival of gastric cancer patients. Gastric cancer cells with high expression of GPT2 were resistant to cisplatin, while cells with low expression of GPT2 were sensitive to cisplatin. Overexpression of GPT2 could decrease the cell sensitivity to cisplatin, nevertheless knockdown of GPT2 could increase the cell sensitivity to cisplatin. Meanwhile, the further study revealed that overexpression of GPT2 could activate the extracellular regulated protein kinases (ERK) signaling pathway, up-regulate the expression of SRY-box 2 (SOX2) and Nanog homeobox (NANOG), and enhance the ability of colony formation, while knockdown of GPT2 could inhibit ERK signaling pathway, reduce the expression of SOX2 and NANOG, and suppress the ability of colony formation. Conclusion:GPT2 expression are related to the sensitivity of cisplatin treatment. Overexpression of GPT2 can increase the resistance of gastric cancer to cisplatin treatment by activating ERK signaling pathway and up-regulating the expression of SOX2 and NANOG.