Viral Load, Integration and Methylation of E2BS3 and 4 in Human Papilloma Virus (HPV) 16-Positive Vaginal and Vulvar Carcinomas

• Objective: To investigate if viral load, integration and methylation of E2BS3 and 4 represent different ways of tumor transformation in vaginal and vulvar carcinoma and to elucidate its clinical impact.Methods: Fifty-seven samples, positive for HPV16, were selected for the study. Detection of viral load was made with realtime-PCR using copy numbers of E6 and integration was calculated from comparing E2 to E6-copies. Methylation of E2BS3 and 4 was analysed using bisulphite treatment of tumor DNA, followed by PCR and pyrosequencing.Results: Vaginal tumors were found to have a higher viral load (p=0.024) compared to vulvar tumors but a high copy number (> median value, 15 000) as well as high methylation (> 50%) was significantly (p=0.010 and p=0.045) associated with a worse cancer-specific survival rate in vulvar carcinoma, but not in vaginal carcinoma. Four groups could be defined for the complete series using a Cluster Two step analysis; (1) tumors holding episomal viral DNA, viral load below 150 000 copies not highly methylated (n=25, 46.3%); (2) tumors harboring episomal viral DNA and being highly methylated (>50%; n=6, 11.1%); (3) tumors with viral DNA fully integrated (n=11, 20.4%), and (4) tumors harboring episomal viral DNA and being medium-or unmethylated (< 50%) and having a high viral load (> total mean value 150 000; n=12, 22.2%). The completely integrated tumors were found to be distinct group, whilst some overlap between the groups with high methylation and high viral load was observed.Conclusion: HPV16-related integration, methylation in E2BS3 and 4 and viral load may represent different viral characteristics driving vaginal and vulvar carcinogenesis. HPV16-related parameters were found to be of clinical importance in the vulvar series only.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Cancer och onkologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cancer and Oncology (hsv//eng)

Publication and Content Type

ref (subject category)

art (subject category)