Molecular analysis of HPV integration in cervical and vulvar neoplasias

Objective: Our aim was to determine the role of Human Papillomaviruses (HPVs) in cervical and vulvar neoplasias. Methods: The presence and type-specificity of HPV DNA integration was analyzed in 12 genital neoplasias and 9 apparently normal specimens by Southern and dot blot. As positive and negative controls, DNAs from the human continuous cell lines HeLa, KB, HT1080 and from normal human skin fibroblasts (HSF), were also included. Results: DNA sequences of the non-oncogenic HPV 6b and 11 were detected in 30% of the tumors and in 50% of the condylomata; conversely, 20% of the carcinomas and no condylomata were positive for the oncogenic HPV 16 DNA. HPV 18 DNA sequences were never detectable in our clinical specimens whereas a vulvar carcinoma was positive for both HPV 6b and 11. The 9 normal tissue specimens were all negative. The pattern of viral DNA in the tumors showed both single and multiple integration sites, without any preferential chromosomal location, although multiple bands were more frequently observed. Finally, the human fibrosarcoma HT1080 cells showed an unknown HPV band of 5.5 kb. Conclusions: There is a close association between certain HPV types and malignancies of the female lower genital tract, with a prevalence of HPV 16. Interestingly, a vulvar carcinoma which was positive for both HPV 6b and 11 suggests a possible cooperation of this two "non-oncogenic" HPVs to promote cellular tumorigenicity. Moreover the unkwown HPV band seen in HT1080 indicates a possible viral etiology in the immortalization process of this permanent cell line.