Periostin过表达诱导人胃癌细胞化疗耐药性的机制研究

Mechanism of Periostin Overexpression Inducing Chemoresistance in Human Gastric Cancer Cells

前期研究发现periostin过表达可增强人胃癌细胞株SGC-7901对顺铂和5-氟尿嘧啶(5-Fu)诱导的细胞凋亡的抵抗能力。目的:探讨periostin过表达诱导人胃癌细胞化疗耐药性的可能机制。方法:Periostin稳转组和空载体稳转组SGC-7901细胞分别以5μmol/L顺铂或10μmol/L 5-Fu处理24 h或不予化疗药物处理,其中periostin稳转组在化疗药物处理前可接受或不接受Akt特异性抑制剂MK-2206(1μmol/L)预处理30 min。以蛋白质印迹法检测各组细胞的总Akt、磷酸化Akt(p-Akt)、p53蛋白表达,流式细胞术检测细胞凋亡。结果:periostin稳转组SGC-7901细胞Akt磷酸化水平明显高于空载体稳转组,两组间总Akt无明显差异。在经顺铂或5-Fu处理的各组SGC-7901细胞中,periostin稳转组p53蛋白表达和细胞凋亡率明显低于空载体稳转组,而MK-2206预处理可在一定程度上逆转periostin对p53表达的抑制作用及其诱导的凋亡保护效应。结论:通过激活Akt通路抑制p53表达可能是periostin过表达诱导人胃癌细胞化疗耐药性的机制之一,有望作为胃癌治疗的潜在靶点。

Background： Previous study revealed that overexpression of periostin conferred a resistance to cisplatin- and 5- fluorouracil （5-Fu）-induced apoptosis in human gastric cancer cell line SGC-7901. Aims： To investigate the possible mechanism of periostin overexpression inducing chemoresistance in human gastric cancer cells. Methods： SGC-7901 ceils stably transfected with recombinant plasmid expressing full-length human periostin gene and with empty plasmid were established, respectively, and were exposed to 5 ~mol/L cisplatin or 10 p^mol/L 5-Fu for 24 hours, or without any chemotherapeutics. In a subgroup of periostin-transfected SGC-7901 cells, Akt-specific inhibitor MK-2206 （ 1 tLmol/L） was added 30 minutes prior to treating with chemotherapeutics. Expressions of total Akt, phosphorylated-Akt （p-Akt） and p53 proteins in SGC-79~）1 cells were determined by Western blotting, and cell apoptosis was assessed by flow cytometry. Results： An enhancement of Akt phosphorylation was observed in periostin-transfected SGC-7901 cells than in mock- transfected cells, while no significant difference in total Akt was found between the two groups. In SGC-7901 cells exposure to cisplatin or 5-Fu, expression of p53 protein and the apoptosis rate were significantly lower in periostin-transfected cells than in mock-transfected cells, and the effect of periostin could be reversed to some extent by pretreatment with MK-2206. Conclusions： Overexpression of periostin might confer chemoresistance to human gastric cancer cells, at least partially, through activating Akt pathway and subsequently inhibiting p53 expression. The periostin-mediated Akt activation might be a potential target for treatment of gastric cancer.