中文摘要：

目的：探讨人乳腺癌亲本细胞株（MCF-7）及耐多柔比星乳腺癌细胞株（MCF-7/ADR）中叶酸受体（FOLR）的表达及亚甲基四氢叶酸还原酶（MTHFR）基因多态性与乳腺癌细胞多药耐药的相关性。方法：流式细胞仪检测不同浓度叶酸对MCF-7细胞及MCF-7/ADR细胞周期的影响;RT-PCR检测MCF-7细胞及MCF-7/ADR细胞中FOLR和mdr-1 mRNA的表达水平;PCR-RFLP方法检测MCF-7细胞及MCF-7/ADR细胞中MTHFR基因C677T及A1298C基因多态性。结果：当叶酸≥270nmol/L时,MCF-7和MCF-7/ADR细胞处于G0/G1期细胞数增加。在MCF-7细胞中S期细胞数在叶酸≥270 nmol/L时显著减少（P〈0.001）;在MCF-7/ADR细胞中S期细胞数在叶酸≥30nmol/L时开始显著减少,且随着叶酸浓度升高,S期细胞数减少更显著（P〈0.001）。在两株细胞中,FOLR和mdr-1基因mRNA表达水平呈负相关,MTHFR的C677T基因多态性及A1298C转录水平无差异;但经限制性核酸内切酶反应后,MCF-7细胞的MTHFR基因有A1298C及C677T两种基因多态性;而MCF-7/ADR细胞MTHFR基因只存在C677T基因多态性。结论：叶酸对MCF-7和MCF-7/ADR细胞的DNA合成均有抑制作用,该抑制作用在MCF-7/ADR细胞中更显著,可能通过阻断细胞从G0/G1期进入S期实现。在MCF-7/ADR细胞MTHFR A1298C基因多态性消失,可能与MCF-7细胞耐药相关。

英文摘要：

Objective：To evaluate the relationship between expression of FOLR and gene polymorphism of MTH- FR and drug resistance of breast cancer cells. Methods： FAC test cell cycle under treatment of folic acid of different concentration, mRNA level of FOLR and mdr - 1 were tested by RT - PCR. Gene polymorphism of C677T and A1298C sites in MTHFR were tested by PCR - RFLP. Results：Treating MCF -7 cells and MCF -7/ADR cells with folie acid,when folio acid at or above 270nmol/L,the ratio of MCF -7 and MCF -7/ADR cells in phase G0/G1 was increased. The ratio of MCF -7 cells in phase S was significantly decreased when the concentration of folio acid was more than 270nmol/L （P 〈0. 001 ）. In the MCF -7/ADR cell line,the ratio of cells in phase S decreases when the concentration of folio acid was more than 30nmol/L, and cells inphase S reduces more significantly with increasing fo- lic acid concentration （P 〈 0. 001 ）. In MCF -7 cells and MCF -7/ADR cells, there was negative correlation between the transcription level of FOLR gene and mdr - 1 gene. No differences were found between MCF - 7 and MCF - 7/ ADR cell MTHFR gene polymorphism of C677T and A1298C transcription level. By restriction endonuclease reaction, MTHFR gene of MCF -7 cells had two gene polymorphism： A1298C and C677T, and MCF -7/ADR cell MTHFR gene only had gene polymorphism of C677T. Conclusion ： The DNA synthesis of MCF - 7/ADR and MCF - 7 cells can both be inhibited by folic acid, and the inhibition is more significant in MCF -7/ADR cells, by blocking cellsent- er phase S from phase G0/G1. The drug resistance of MCF -7 maybe related to the loss of MTHFR A1298C polymor- phism.