Methylation of HPV-16 and HPV-18 E6 promoter CpG sites in women with abnormal pap smears

Introduction: HPV-16 and HPV-18 account for around 70% of cases of invasive cervical cancer worldwide. These are highly pathogenic and high-risk genotypes. The most prevalent sexually transmitted disease is human high-risk papillomavirus (HR-HPV), which can infect anyone who engages in sexual activity at any time in their life. To evaluate the possibility that the virus causes malignant lesions in infected women with high-risk HPV types who have normal and abnormal Pap smears, the current study examined the methylation pattern of CpG islands in the oncogene promoter of high-risk HPV E6. Methods: Forty-eight Pap smears were collected from women referred to Shahid Sadoughi Hospital in Yazd for this case-control study. The Sinaclon kit was used for DNA extraction. PCR amplification with specific primers allowed the identification of HPV-16 and HPV-18 types. The bisulfite modification method, based on the EpiTect Bisulfite Conversion Kit, was then used to identify methylation in the E6 gene. Version 22 of the SPSS program was used to collect the data, and the corresponding statistical tests were used for analysis. Results: In this study, methylation at position 506 in the HPV-16 E6 gene was detected in 10.4% (n = 5/48) of cases; however, methylation in the 1985 region for the E6 promoter of HPV-18 was 20.8% (n = 10/48). Comparison of the methylation rate in the HPV-18 nucleotide 1985 in normal and abnormal Pap smear samples showed that the methylation rate in normal and abnormal samples was 55.8% and 44.2%, respectively. There was no significant difference between the frequency of HPV-18 and HPV-16 DNA methylation in all selected CpG nucleotide regions (P ≥ 0.05). Conclusion: Our results indicate that the methylation change in the E6 gene promoter was not involved in the development of infection with HPV-16 and HPV-18 types in the study population.