5-氟尿嘧啶增强HeLa细胞对自然杀伤细胞敏感性研究

Enhancement of Susceptibility of HeLa Cells to NK Lysitic Activity through Upregulation of NKG2D Ligand MICA by 5-FU Treatment

目的用5-氟尿嘧啶（5-fluorouracil，5-FU）处理HeLa细胞，检测其NKG2D配体MICA的表达及其对NK92细胞杀伤敏感性的变化。方法不同浓度的5-Fu处理HeLa细胞，在不同时间点用半定量PCR及流式细胞术检测HeLa细胞表面的NKG2D配体MICA在RNA及蛋白水平的表达变化情况，用MTT法检测NKG2D抗体封闭NK92细胞的NKG2D受体前后，NK92细胞对HeLa细胞的杀伤作用。结果不同浓度的5．Fu作用于HeLa细胞后，半定量RT—PCR结果显示MICA表达随5-Fu作用浓度增加逐渐增高。而且40μg／ml5．Fu作用于HeLa细胞后随着作用时间的延长（0、8、16、24h）MICA表达增加，流式细胞术检测结果表明，MICA表达的增加主要依赖于未凋亡细胞的MICA表达。在40μg／ml5-FU作用24h，效靶比为2．5：1，5：1，10：1，20：1时都检测到NK92细胞对HeLa细胞的杀伤增强，杀伤作用可部分被NKG2D抗体抑制。结论5-FU能够上调HeLa细胞表面NKG2D配体MICA的表达，增强HeLa细胞对NK92细胞的敏感性，提示化疗联合NK细胞免疫治疗宫颈癌可产生协同作用，提高治疗效果。

Objective To investigate the expression of NKG2D ligand MICA in HeLa cells treated by 5 - fluorouracil （5-FU） and the susceptibility of treated HeLa cells to NK92 cell-mediated killing. Methods HeLa cells were treated with different concentrations of 5-FU. Expression of MI- CA in RNA and protein level was detected by semi-quantitative PCR and flow cytometry： NK cell- mediated killing of HeLa cells was determined by MTI＇ assay. The cytolytic activity of NK92 cells was compared in the presence or absence of NKG2D antibody. Results The results of semi-quanti- tative RT-PCR showed that MICA was expressed with the increase of 5-FU dose range and upregulat- ed along with the exposure time course （Oh, 8h, 16h, 24h） of HeLa cells to 5-FU. Flow cytometry data demonstrated that the upregulation of MICA expression mainly result from the non-apoptotic cells. The cytolytic effect of NK92 cells on HeLa cells was enhanced by 5-FU treatment for 24h at different effect/target ratio. NK-cell mediated killing of HeLa cells was partially inhibited by NKG2D antibody. Conclusion 5-FU increases cell surface expression of NKG2D ligand MICA on HeLa cells, thus enhancing the sensitivity of Hela cells to lysitic effect of NK92 cells, suggesting that combination of chemotherapy and immunotherapy with NK cells might improve the treatment of cervical cancer patients.