HPV-16 E2 gene disruption and sequence variation in CIN 3 lesions and invasive squamous cell carcinomas of the cervix: relation to numerical chromosome abnormalities

Aim-To test the hypothesis that, because the human papillomavirus (HPV) E2 protein represses viral early gene transcription, E2 gene sequence variatio n or disruption could play a part in the induction of the numerical chromos ome abnormalities that have been described in squamous cervical lesions. Methods-The integrity and sequence of the E2 gene from 11 cervical intraepi thelial neoplasia (CIN) grade 3 lesions and 14 invasive squamous cell carci nomas, all of which contained HPV-16, were analysed by the polymerase chain reaction (PCR). The E2 gene was amplified in three overlapping fragments a nd PCR products sequenced directly. Chromosome abnormalities were identifie d by interphase cytogenetics using chromosome specific probes for chromosom es 1, 3, 11, 17, 18, and X. Results-E2 gene disruption was present in significantly more invasive carci nomas (eight of 14) than CIN 3 lesions tone of 11) (p = 0.03). No associati on was found between E2 disruption and the presence of a numerical chromoso me abnormality. The E2 gene from the non-disrupted isolates was sequenced a nd wild-type (n = 5) and variant (n = 11) sequences identified. Variant seq uences belonged to European and African classes and contained from one to 1 5 amino acid substitutions. Although numerical chromosome abnormalities wer e significantly more frequent in invasive squamous cell carcinoma than CIN 3 (p = 0.04), there was no significant relation between the presence of seq uence variation and either histological diagnosis or chromosome abnormality . Conclusions-These data do not support the hypothesis that E2 gene disruptio n or variation is important in the induction of chromosome imbalance in the se lesions. However, there is a relation between E2 gene disruption and the presence of invasive disease.