Epidemiologic research has shown that infection with the human papillomavirus (HPV) is a cause of most cases of cervical cancer and that specific HPV types (e.g., 16 and 18) are associated with high risk of progression to cervical cancer. However, HPV infection is an insufficient cause of cervical cancer and appears to require the presence of other factors for the infection to progress to a significant cervical lesion. One factor that may modify progression of HPV to cervical neoplasia is DNA methylation. In support of this hypothesis, in vitro work from zur Hausen's laboratory indicated that methylation in the Upstream Regulatory Region (URR) of oncogenic HPV exerts a powerful effect on transcriptional activity and hence carcinogenicity of the virus. HPV DNA methylation patterns may modify the virulence resulting in increased risk for progression of HPV infection to high grade SIL. However, the association between HPV methylation patterns specifically has only been tested in vitro. In this application, we propose to conduct the first epidemiological study of the association between HPV methylation status and cervical cancer risk. The overall goal of this application is to examine in vivo methylation patterns of oncogenic HPV and determine if these patterns are associated with SIL. The primary aims of this study are to determine: 1) the overall methylation status and site-specific methylation in the URR of oncogenic HPV among women previously identified with normal, ASCUS, LgSIL, and HgSIL cytology; 2) whether methylation patterns of HPV are related to viral load; 3) the factors (such as smoking, oral contraceptives, and co-infections) associated with HPV methylation status; 4) whether HPV DNA methylation status is independently associated with risk of SIL Study Design: Data and biological samples collected from the USA-Mexico Border HPV, Cervical Dysplasia and Chlamydia trachomatis study (1997-1998) will be used for this proposed study. A population of 2,246 women, 246 of whom are HPV positive for one of eight oncogenic HPV types, 15 years and older were recruited from family planning clinics in 3 pairs of contiguous communities at the Arizona (US) - Sonora (Mexico) border, and in Tucson, AZ and Hermosillo, Sonora, Mexico. HPV DNA methylation status will be assessed among 246 women positive for one of eight HPV types (HPV types 16, 18, 31, 39, 45, 51, 52, and 58) utilizing the Bisulfite Genomic Sequencing technique. Data available from the completed study include laboratory measures (HPV typing, HPV viral load, C. trachomatis status, and cytology), and risk factor data (reproductive, sexual and medical histories, and demographic data). Results from this study may provide a novel biomarker for women at risk of progression of HPV infection to SIL.
