胃癌细胞系MKN中HLA-Ⅰ类分子表达降低的机制研究-东南大学学报医学版

胃癌细胞系MKN中HLA-Ⅰ类分子表达降低的机制研究

单位：东南大学医学院,发育与疾病相关基因教育部重点实验室、江苏省"基因诊断与治疗"医学重点实验室,江苏,南京,210009

分类号：R735.2, R392.11

出版年·卷·期（页码）：2006·25·第四期（236-239）

摘要：

目的:探讨胃癌细胞系MKN中HLA-Ⅰ类抗原表达水平异常的分子机制.方法:以胃癌细胞系BGC823、MGC803和SGC7901为对照,利用流式细胞仪检测细胞表面HLA-Ⅰ类复合物的表达情况,Western blot检测HLA-Ⅰ类分子重链及轻链表达情况,半定量RT-PCR检测HLA-Ⅰ类分子重链、轻链和抗原加工分子mRNA水平的表达情况,并利用HLA基因区域的微卫星序列检测MKN细胞HLA基因在DNA水平的完整性.结果:胃癌细胞系MKN表面HLA-Ⅰ类复合物表达降低,重链A及B/C位点蛋白无表达而轻链表达无异常.在mRNA水平,胃癌细胞系MKN存在重链A、B、C各位点和抗原加工分子TAP1、LMP2、Tapasin、PA28β的表达缺失.微卫星DNA扩增结果初步显示,MKN细胞无HLA基因区域DNA的大片段丢失.结论:胃癌细胞系MKN HLA-Ⅰ类分子复合物表达降低可能是由HLA-Ⅰ类分子重链及其加工分子在转录水平改变而引起的.

Objective To investigate the mechanism of HLA class Ⅰ downregulation in a gastric cell line MKN.Methods The expression of HLA class Ⅰ complex was determined by flow cytometry.Then the expression of HLA class Ⅰ heavy chain and light chain were detected by Western blot assay using a panel of antibodies.To characterize the downregulation of HLA class Ⅰ complex,the analysis was extended to RNA level by RT-PCR using specific primers.Results It was found that the expression of HLA class Ⅰ complex in MKN cell was reduced in comparison with other gastric cell lines BGC823,MGC803 and SGC7901.HLA class Ⅰ heavy chain expression(A and B/C locus) was lost in MKN while the expression of the light chain was normal.RT-PCR showed that the expression of HLA class Ⅰ heavy chain,TAP1,LMP2,Tapasin and PA28β mRNA were lost in MKN cells,while DNA of those genes might be intact by detecting microsatellite marker in HLA region.Conclusion The abnormal expression of HLA class I complex in gastric cell line MKN might be due to low efficiency of HLA gene transcription.

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