胰腺癌细胞株Puta8988对培美曲塞产生获得性耐药的分子生物学机制初步研究

目的探索胰腺癌细胞株Puta8988对培美曲塞（pemetrexed，Alimate）产生获得性耐药的机制，分析这种耐药与培美曲塞调控通路上相关基因的关系。方法对胰腺癌细胞株Puta8988进行耐药诱导，使其对培美曲塞产生获得性耐药。然后检测正常Puta8988细胞和耐药Puta8988细胞中胸苷酸合酶（thymidylate synthase，TS），叶酰聚谷氨酸合酶（folylpolyglutamate synthetase，VPGS），还原型叶酸盐载体（reduced folate carrier，RFC）的mRNA表达水平变化。结果胰腺癌细胞株Pum8988对培美曲塞产生了耐药作用，培美曲塞长期作用后，Puta8988的50％抑制浓度（IC50）上升2．2倍（P〈0．05）。mRNA分析结果提示耐药细胞株偈的mRNA表达上调，FPGS变化不明显，RFC表达下调。结论化疗药物长期作用后，TS、FPGS、RFC的基因表达失衡，胰腺癌细胞产生了获得性耐药。对这些基因进行干预有可能提高胰腺癌细胞对培美曲塞的敏感性，从而提高疗效。

The molecular biological mechanism of acquired resistance of pancreatic cancer cells to pemetrexed

Objective To investigate the mechanism of acquired resistance of pancreatic cancer cell Puta8988 to pemetrexed and to analyze its correlation with the expression of TS, FPGS and RFC. Methods After more than two months inducing of pemetrexed, the cytotoxicity of drugs to the parental and resistant lines was assessed by MTT assay. When the IC5 of the resistant lines raise to a level which our experiment need, it is considered acquiring the character to resistance pemetrexed. Then the mRNA expression levels of TS, FPGS and RFC were detected using RT - PCR. Results Pancreatic cancer cells acquired drug - resistance to pemetrexed. After recurrem treatment with pemetrexed, the IC50 values in Puta8988 cells were increased by 2.2 fold as compared to their parental cells. （ P 〈 0.05）. RT - PCR showed a correlation between TS, FPGS and RFC mRNA expression levels and the sensitivity to pemetrexed after pemetrexed treatment. Conclusion These findings reveal that the levels of TS, FPGS and RFC following recurrent exposure to pemetrexed are associated with resistance to these drugs. These findings suggest that the activation of TS, FPGS and RFC genes after recurrent drug exposure contributes to the chemoresistance of pancreatic cancer cells and that their intervention might enhance chemosensitivity in pancreatic cancer.