目的：研究miRNA-200c对人胃癌耐药SGC7901/DDP细胞顺铂敏感性的影响及其机制。方法：Western blotting检测SGC7901/DDP及其亲代SGC7901细胞E-cadherin、PTEN、p-Akt及总Akt蛋白的表达；瞬时转染miRNA-200c前体（miRNA-200c precursor，Pre-200c）提高SGC7901/DDP细胞miRNA-200c的表达，MTT法检测转染后SGC7901/DDP细胞对顺铂的敏感性，并分析p-Akt表达的改变；应用Akt通路抑制剂LY94002 处理SGC7901/DDP细胞抑制Akt磷酸化，检测处理后细胞对顺铂的敏感性。结果：与SGC7901细胞相比，SGC7901/DDP细胞中p-Akt蛋白的表达量显著增高（1.02±0.09 vs 0.17±002，P<0.05），E-cadherin、PTEN蛋白的表达量显著降低（0.10±0.03 vs 0.47±0.06，0.18±0.06 vs 0.87±0.06；均P<005）。转染Pre-200c后，顺铂对SGC7901/DDP细胞的IC50显著低于对照组\[（7.52±0.19） vs (12.18±0.29) mg/L，P<005\]，细胞中p-Akt蛋白的表达量也显著低于对照组（0.22±0.04 vs 0.69±0.09，P<0.05）；LY94002处理后，SGC7901/DDP细胞p-Akt蛋白的表达显著抑制（0.18±0.06 vs 0.66±0.10，P<0.05），顺铂对细胞的IC50显著低于对照组\[（6.80±0.28) vs (11.94±1.73) mg/L，P<0.05\]。结论：SGC7901/DDP细胞的耐药可能与E-cadherin和PTEN蛋白的表达缺失及Akt通路的异常激活有关，而miRNA-200c提高该细胞对顺铂的敏感性可能是通过抑制Akt通路而发挥作用。

Objective:To explore the effect of miRNA-200c on chemosensitivity of drug-resistant human gastric cancer SGC7901/DDP cells to cisplatin (DDP) and its mechanism. Methods: The expressions of E-cadherin, PTEN, p-Akt and total Akt proteins in SGC7901/DDP cells and its parental SGC7901 cells were detected by Western blotting. miRNA-200c precursor (Pre-200c) was transiently transfected into SGC7901/DDP cells to increase the expression of miRNA-200c. The drug sensitivity of cells to cisplatin and the expression level of p-Akt were detected by MTT assay and Western blotting, respectively. Finally, SGC7901/DDP cells were treated with LY94002 to inactivate the phosphorylation of Akt, and the sensitivity of SGC7901/DDP cells to DDP was detected. Results: Compared with SGC7901 cells, the expression of p-Akt protein in SGC7901/DDP cells was significantly increased (\[1.02±0.09\] vs \[0.17±0.02\], P<0.05), while the expressions of E-cadherin and PTEN protein were significantly decreased (\[0.10±0.03\] vs \[0.47±0.06\]; \[0.18±006\] vs \[0.87±0.06\] respectively, P<0.05). The IC50 of cisplatin in the Pre-200c tansfected group was significantly lower than that in the negative control group (\[7.52±0.19\] mg/L vs \[12.18±0.29\] mg/L, P<0.05). Furthermore, the expression of p-Akt protein in the Pre-200c transfected group was significantly lower than that in the control group (\[0.22±0.04\] vs \[0.69±0.09\], P<0.05); the level of p-Akt protein was significantly inhibited (\[0.18±0.06\] vs \[0.66±0.10\], P<0.05) in SGC7901/DDP cells treated with LY94002. Moreover, the IC50 of DDP in the LY94002 treated group was significantly lower than that in the control group (\[6.80±0.28\] mg/L vs \[11.94±1.73\] mg/L, P<0.05). Conclusion: Drug resistance phenotype of SGC7901/DDP cells may be associated with the loss of E-cadherin and PTEN proteins and abnormally activation of Akt signaling pathway, and the chemotherapeutic sensitization of miRNA-200c may be through the inactivation of Akt signal pathway.

国家自然科学基金资助项目（No.81172333）