Epigenetic mechanisms in virus-induced tumorigenesis

About 15–20% of human cancers worldwide have viral etiology. Emerging data clearly indicate that several human DNA and RNA viruses, such as human papillomavirus, Epstein–Barr virus, Kaposi’s sarcoma-associated herpesvirus, hepatitis B virus, hepatitis C virus, and human T-cell lymphotropic virus, contribute to cancer development. Human tumor-associated viruses have evolved multiple molecular mechanisms to disrupt specific cellular pathways to facilitate aberrant replication. Although oncogenic viruses belong to different families, their strategies in human cancer development show many similarities and involve viral-encoded oncoproteins targeting the key cellular proteins that regulate cell growth. Recent studies show that virus and host interactions also occur at the epigenetic level. In this review, we summarize the published information related to the interactions between viral proteins and epigenetic machinery which lead to alterations in the epigenetic landscape of the cell contributing to carcinogenesis

Prevalence of Chlamydia trachomatis and Oncogenic Human Papillomavirus Types in Cytologic Atypia of the Uterine Cervix

A history of having substantial Chlamydia trachomatis exposure as detected by serum antibodies is a cofactor of human papillomavirus (HPV) mediated cervical carcinogenesis. In this study, we examined the concurrent C. trachomatis infections in cytologic atypia of the uterine cervix in order to evaluate the impact of C. trachomatis infection in patients with high risk for cervical intraepithelial neoplasia. Cervical scrapes form 707 patients were subjected to PCR amplification with primer sets for HPV and C. trachomatis . Based on negative beta-globin results, 10 specimens were not eligible for further analysis. Oncogenic HPV types were detected in 278 specimens (39.8%). C. trachomatis was found only in six specimens (0.9%). In conclusion, concurrent C. trachomatis infection was uncommon and hence it was an improbable risk factor in cytologic atypia