Zehbe I, Wilander E, Delius H, Tommasino M
Deutsches Krebsforschungszentrum, Angewandte Tumorvirologie, Heidelberg, Germany.
Cancer Res. 1998 Feb 15;58(4):829-33.
High-risk human papillomavirus (HPV) is a known risk factor in the etiology of cervical intraepithelial neoplasia (CIN) I-III and invasive cervical carcinoma (ICC). The most severe preinvasive lesion is CIN III, and it is still not entirely understood why some cases progress to invasion, whereas others do not. Our hypothesis that this could be predicted by intratype variation of the immortalizing and transforming early proteins E6 and E7 was tested. Because HPV16 is frequently detected in cervical neoplastic lesions, 25 CIN III and 17 ICC cases from Swedish women, all positive for this genotype, were selected to investigate the E6 and E7 genes for mutations. PCR-amplified products were sequenced by the fluorescent dideoxy termination method. ICC harbored almost exclusively HPV16 E6 variants (94%) and rarely harbored the prototype (6%), whereas CIN III demonstrated a more uniform distribution of variants (56%) and prototype (44%; P = 0.013). All variants contained variations that were identified in areas likely to be important for protein-protein interaction with p53 or in areas of immunological significance. The most frequent E6 variation was seen at residue 83. This polymorphism was detected alone or in combination with others in 88% of ICC and 44% of CIN III cases. E7 variations were extremely rare and were only detected together with E6 variations in 4% of CIN III and in 6% of ICC cases, suggesting that the HPV16 E7 but not the HPV16 E6 oncoprotein is highly conserved in vivo. This indicates that HPV16 E6 variants, specifically those containing the substitution at residue 83, may be more oncogenic than the prototype and thus carry a higher risk for the development of invasive cervical disease. This may be due to subtle differences in the type of transformation produced or to evasion of host immune defenses. These results might have implications for future in vitro studies, diagnostics, treatment, and vaccine design.
高危型人乳头瘤病毒（HPV）是宫颈上皮内瘤变（CIN）I - III级及浸润性宫颈癌（ICC）病因学中已知的危险因素。最严重的癌前病变是CIN III级，目前仍不完全清楚为何有些病例会进展为浸润癌，而有些则不会。我们对如下假说进行了验证：这种情况可通过永生化和转化早期蛋白E6和E7的型内变异来预测。由于HPV16在宫颈肿瘤性病变中经常被检测到，因此选取了25例CIN III级和17例ICC病例，这些病例均来自瑞典女性且该基因型均呈阳性，以研究E6和E7基因的突变情况。采用荧光双脱氧末端终止法对PCR扩增产物进行测序。ICC几乎只含有HPV16 E6变异体（94%），很少含有原型（6%），而CIN III级则显示变异体（56%）和原型（44%；P = 0.013）的分布更为均匀。所有变异体都包含在可能对与p53的蛋白质 - 蛋白质相互作用很重要的区域或具有免疫学意义的区域中鉴定出的变异。最常见的E6变异出现在第83位残基处。在88%的ICC病例和44%的CIN III级病例中单独或与其他变异一起检测到这种多态性。E7变异极其罕见，仅在4%的CIN III级病例和6%的ICC病例中与E6变异一起被检测到，这表明HPV16 E7而非HPV16 E6癌蛋白在体内高度保守。这表明HPV16 E6变异体，特别是那些在第83位残基处含有替代的变异体，可能比原型更具致癌性，因此发生浸润性宫颈疾病的风险更高。这可能是由于所产生的转化类型存在细微差异或逃避宿主免疫防御所致。这些结果可能对未来的体外研究、诊断、治疗和疫苗设计具有启示意义。
