目的：探讨MHC-Ⅰ类链相关分子A（MHC class I chain-related molecule A，MICA）多态性与乳腺癌细胞对NK细胞杀伤敏感性的关系。方法：测序分析乳腺癌细胞系MCF-7、MDA-MB-231、MDA-MB-435S和SK-BR-3 的MICA等位基因，用Western blotting 和流式细胞术检测MICA 重组表达载体转染293T 细胞（分别命名为pMCFA5.1、pMCFA4、p231A5R、p231A9 和p435A5P）MICA蛋白的表达水平，用LDH法检测NK细胞对转染MICA的293T细胞的杀伤活性，酶联免疫斑点法检测NK细胞穿孔素、颗粒酶B分泌水平。结果：MCF-7 细胞表达MICA*008/A5.1 和MICA*001/A4，MDA-MB-231 和SK-BR-3 细胞均表达MICA*019/A5 和MICA*002/A9，MDA-MB-435S 细胞表达MICA*010/A5。转染MICA 后，pMCFA5.1 组293T 细胞MICA蛋白的表达水平最低（P<0.05），p435A5P组次之（P<0.05），pMCFA4 组、p231A5R组和p231A9 组表达水平较高（均P<0.05）。NK细胞对转染MICA的293T细胞杀伤活性及穿孔素、颗粒酶B分泌：p435A5P组对NK细胞杀伤的敏感性最低（P<0.05），穿孔素、颗粒酶B分泌水平最低（均P<0.05）；pMCFA5.1、pMCFA4、p231A5R和p231A9 各组之间比较差异无统计学意义（P>0.05）。结论：MICA基因多态性与乳腺癌细胞对NK细胞杀伤的敏感性密切相关。

Objective: To investigate the associations of MHC class I chain-related molecule A（MICA）gene polymorphism with susceptibility of breast cancer cells to NK cell-mediated cytotoxicity. Methods: MICA alleles of breast cancer cell lines（MCF-7, MDAMB-231, MDA-MB-435S and SK-BR-3）were analyzed by DNA sequencing. MICA protein expression in 293T cells transfected with MICA recombinant expression vectors (namely pMCFA5.1 ，pMCFA4 ，p231A5R ，p231A9 and p435A5P) was detected by Western blotting and Flow cytometry; the cytotoxicity of NK cells against the above 293T cells were measured by lactate dehydrogenase （LDH）assay and the release of perforin（PFN）and granzymes B（Gzm B）were measured by ELISPOT assay. Results: DNA sequencing result showed that MICA*008/A5.1 and MICA*001/A4 were expressed in MCF-7 cells, MICA*019/A5 and MICA*002/A9 were expressed in both MDA-MB-231 and SK-BR-3 cells while MICA*010/A5 was expressed in MDA-MB-435S cells. After the MICA recombinant expression vectors were transfected into 293T cells, the level of MICA were the lowest in pMCFA5.1 group (P<0.05), following after p435A5P group (P<0.05), and highly expressed in the pMCFA4, p231AR and p231A9 groups (P<0.05). NK cell-mediated cytotoxicity and the release of PFN and Gzm B: NK cell-mediated cytotoxicity were the lowest in p435A5P group (P<0.05), and the ability of inducing NK cells to release PFN and Gzm B was also the lowest in p435A5P group (P<0.05), but there were no statistical difference among the other transfected groups (P>0.05). Conclusion: MICA gene polymorphism is closely associated with susceptibility of breast cancer cells to NK cell-mediated cytotoxicity.

国家临床重点专科建设项目资助（国卫办医函[2013]544 号）；福建省自然科学基金资助项目（No. 2015J01433）