食管癌中MICA的表达及其意义

  目的  观察食管癌细胞株组织膜MHCⅠ链相关分子A(MHC class Ⅰ chain-related gene A, MICA)及血清中可溶性MICA表达, 探讨食管癌中MICA的表达及其临床意义。  方法  流式细胞术检测膜型MICA(mMICA)及NK细胞表面NKG2D表达, ELISA方法检测乳腺肿瘤患者外周血可溶性MICA(sMICA)的分泌。分组实验分析可溶性MICA(sMICA)对NKG2D表达的影响。  结果  食管细胞膜型MICA在食管癌旁组织无表达, 在31.7%食管癌组织有表达, 表达量为(42.2±3.6)%。可溶性MICA含量在健康成年者为阴性, 食管癌患者中74.67%阳性, 含量为(1977.30±292.67)ng/L。食管癌患者中血清sMICA含量高低与TNM分期呈正相关, 远处转移组比无远处转移组高(P < 0.05), 但和病理类型表达无差异。含可溶性M!CA的血清可明显下调NK细胞NKG2D的表达, 从而降低NK细胞对食管癌细胞株ECA-109的杀伤活性。  结论  食管癌细胞膜表达MICA, 可作为食管肿瘤相关性抗原。而可溶性MICA含量高低与TNM分期呈正相关, 可通过下调NK细胞NKG2D表达介导肿瘤免疫逃逸。 

Expression and significance of MIC A in esophageal cancer

  Objective  This work aims to evaluate MHC class Ⅰ chain-related gene A (MICA) expression on the cell membrane of esophageal cancer cells, and soluble MICA expression in the serum of patients with esophageal cancer. The work also aims to investigate the function of MICA in esophageal cancer.  Methods  Flow cytometry was performed to detect the expressions of membranous MICA (mMICA) in esophageal cancer tissues and cell lines and natural-killer group 2, member D (NKG 2D) in natural killer (NK) cells. En zyme-linked immunosorbent assay was performed to examine the secretion of soluble MICA (sMICA) in the peripheral blood. The effect of sMICA on NKG 2D expression was observed in the group experiments.  Results  mMICA was not detected in normal esophageal tissues, but the mMICA expression level was 31.7% in esophageal cancer tissues. The maximum expression level was (42.2 ± 3.6)%. sMICA was not detected in the serum of healthy subjects, but the sMICA expression level was74.67 % in esophageal cancer tissues with a concentration of (1 977.30 ± 292.67)ng/L. A positive correlation was observed between sMICA levels and esophageal cancer stage. sMICA content was higher in cancer patients with distant metastasis compared with those without metastasis. However, the content had no relationship with nodal metastasis and pathologic types. NKG2D expression was down-regulated, and the NK cell cytotoxicity to the esophageal cancer cell line ECA-109 decreased after the NK cells were cultured in sMICA serum.  Conclusion  MICA is expressed on the membrane of some esophageal cells. sMICA level is positively correlated with the Tumor-Node-metastasis stages of esophageal cancer. sMICA can reduce the expression of NKG2D and can result in immunity to esophageal cancer.