Human papillomaviruses and associated malignancies

The human papillomaviruses (HPVs) are small DNA tumor viruses that infect epithelial cells and induce proliferative lesions. Substantial epidemiologic data along with in vitro and in vive studies have led to the implication of particular HPVs with the development of epithelial malignancies. Greater than 90% of all cervical carcinomas are positive for HPV infection. Most of these lesions are caused by infection with mucosal- associated high-risk HPV subtypes. Much work has been undertaken in basic science laboratories to determine the molecular basis for HPV-associated malignancies. Although many significant advances have been made in understanding the biologic properties of these viruses using in vitro analyses, the field has been greatly hindered until recently by the inability to propagate the virus in culture. In this review, we discuss the basic biologic properties of HPVs and the current understanding of the mechanisms of cellular transformation by malignancy-associated viral subtypes. We place particular emphasis an discussion of the HPV oncogenes, E6 and E7. We also discuss premalignant and malignant disorders of squamous and mucosal epithelia, which have been associated with HPV infections, and the current understanding of the mechanism of HPV-associated carcinogenesis in these settings. We focus these discussions on cervical carcinogenesis and briefly review the particulars regarding HPV-associated malignancies in normal and immunocompromised hosts. We end with a discussion of potential targeted molecular therapies for HPV-associated malignancies that may result from the current knowledge of HPV-related cellular growth dysregulation and carcinogenesis.