Department of Clinical Laboratory, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital, Shandong University, Jinan, China.
Int J Gynecol Cancer. 2010 Feb;20(2):227-32. doi: 10.1111/IGC.0b013e3181cceec5.
High-risk human papillomaviruses (HPVs) are the major causative agents of cervical cancer, and the E6 and E7 genes encode the major HPV oncoproteins. The E7 protein of high-risk HPV types disturbs cell cycle control and down-regulates components of the antigen presentation pathway, suggesting a role for E7 in tumor immune evasion. We previously reported that HPV-16 E7 expression and down-regulation of HLA class I was highly correlated in cervical lesions. This study was aimed to determine whether HPV-16 E7 oncoprotein could down-regulate surface HLA class I antigen in HPV-16 E7-transfected cells, and whether it had correlation with the expression of the transporter associated with antigen processing (TAP).
The HPV-16 E7 open reading frame was transfected into HaCaT cells. After G418 selection, resistant colonies were individually picked and expanded into clonal cell lines. Using the fluoresence-activated cell sorting analysis, the levels of cell surface HLA class I antigen and intracellular TAP-1 and TAP-2 expressions were detected.
Compared with the empty vector control, a statistical significant decrease of approximately 50% in cell surface HLA class I expression was observed in HPV-16 E7 expressing HaCaT cells (P < 0.001). Moreover, the expression of HPV-16 E7 in HaCaT cells resulted in decreased expression of TAP-1 that was essential for HLA class I expression at the cell surface, a statistical significant decrease of approximately 40% compared with that with the empty vector control (P < 0.001).
Our finding demonstrates that HPV-16 E7 down-regulates surface HLA class I antigen, which in part correlates with the decrease of TAP-1.
高危型人乳头瘤病毒（HPV）是宫颈癌的主要致病因子，E6 和 E7 基因编码 HPV 的主要致癌蛋白。高危型 HPV 的 E7 蛋白扰乱细胞周期控制，并下调抗原呈递途径的成分，提示 E7 在肿瘤免疫逃逸中起作用。我们之前的研究报告称，HPV-16 E7 表达与 HLA Ⅰ类下调在宫颈病变中高度相关。本研究旨在确定 HPV-16 E7 致癌蛋白是否能下调 HPV-16 E7 转染细胞表面 HLA Ⅰ类抗原，以及其是否与抗原加工相关转运体（TAP）的表达相关。
将 HPV-16 E7 开放阅读框转染至 HaCaT 细胞中。经 G418 选择后，挑取抗性克隆并扩增为克隆细胞系。采用荧光激活细胞分选分析检测细胞表面 HLA Ⅰ类抗原和细胞内 TAP-1、TAP-2 的表达水平。
与空载体对照相比，HPV-16 E7 表达的 HaCaT 细胞表面 HLA Ⅰ类表达下降约 50%（P<0.001）。此外，HPV-16 E7 在 HaCaT 细胞中的表达导致 TAP-1 表达减少，而 TAP-1 对细胞表面 HLA Ⅰ类的表达至关重要，与空载体对照相比，TAP-1 的表达减少约 40%（P<0.001）。
我们的研究结果表明，HPV-16 E7 下调表面 HLA Ⅰ类抗原，这与 TAP-1 的减少部分相关。
