Absolute quantification of gene E7 in cervical samples of women infected by HPV using real time PCR

ABSTRACT

Objective: High grade oncogenic types of human papillomavirus (HPV), especially HPV16 and HPV18, possess a gene called E7, which acts on genes that regulate cell growth, promoting development of pre-neoplastic lesions that can lead to invasive carcinomas. The absolute quantification of this gene in cervical samples of HPV-infected women may contribute for better understanding the evolution of these lesions induced by the virus. Methods: We collected 60 cervicovaginal smears of women infected by HPV with or without uterine cervical squamous intraepithelial lesion, SIL) and 10 samples of women with no HPV infection or SIL. The absolute quantification of gene E7 was performed by Realtime PCR using specific primers and probes. Results: Samples infected by HPV16 have a higher number of gene E7 copies when compared to samples infected by HPV18. In the HPV18 group it was observed that those obtained from patients with low or high grade squamous intraepithelial lesions (HSIL) or invasive cervical cancer presented significantly higher concentrations of gene E7 when compared to patients with no cervical lesions. The number of gene E7 copies was higher in the group infected by HPV16 than by HPV18. In spite of that, there was no difference in the number of gene E7 copies in samples infected by HPV16 with or without SIL. Conclusions: Among the samples with HPV18, the number of copies of gene E7 was higher in the group with cervical lesions, and no differences were found for SIL, HSIL or invasive cancer patients.