Study of synthetic lethality in HPV-transformed cells

Abstract

Persistent infection with high-oncogenic risk human papillomavirus (types) is etiologically associated almost all cervical cancer cases and with more than 50% of other anogenital malignant tumors. Infection with these viruses has been associated with genomic instability, a hallmark of most human cancers. High-risk HPV types express two oncoproteins, E6 and E7 that act on specific cellular factors promoting cell proliferation. These proteins are capable of inducing numeric and structural chromosomal alterations. Furthermore, they can modulate the cell response to DNA damage. Synthetic lethality describes a cellular condition where two (or more) non-allelic non-essential mutations, which do not cause cell death when expressed individually, are lethal when expressed together in the same cell. Cells transformed with high-risk HPV types constitute an interesting model for the study of synthetic lethality since E6 and E7 oncoproteins affect several signal transduction pathways such as those regulated by p53 and pRb, respectively. In the present study we will analyze the viability of HPV16 and HPV18 transformed cell lines (SiHa, CasKi, HeLa) upon systematic inhibition of genes involved in DNA damage repair or tumor suppressor genes. For this purpose we will use lentiviral libraries expressing specific shRNAs. Besides, we will study the effect of drugs that inhibit the different DNA damage repair systems or that cause DNA damage on these cell lines. The results will be validated in epithelial organotypic cultures expressing different viral genes to determine the involvement of the different HPV oncoproteins. Our approach may contribute to the identification of genes that are essential for HPV-transformed cell survival and to the development of new therapeutic strategies for the treatment of HPV-associated lesions. (AU)