Cytokeratin 17 and p63 are Markers of the HPV Target Cell, the Cervical Stem Cell

Background: Basic research on HPV has focused on identifying the genetic changes that lead to cervical carcinoma. However, while focusing on the molecular biology of the cancer, understanding of its cellular biology has lagged: the target cell of the HPV infection is unknown. Materials and Methods: In this study we identified the stem cell population of the cervical epithelium by monoclonal antibodies against p63, a homologue of the tumor suppressor gene p53 and cytokeratin 17 (CK17). Results: We noted p63 expression consistently in the nuclei of reserve cells, hyperplasia of the reserve cells and the basal layer of the ectocervical epithelium, while CK17 only stained endocervical reserve cells and reserve cell hyperplasia. Conclusion: We conclude that both p63 and CK 17 are suitable markers for cervical stem cell identification. Both markers, therefore, qualify for the identification of the HPV target cell. The relationship between the development of cervical cancer and infection with certain types of Human Papilloma Viruses (High risk HPV) is well established (1). Cell cycle is influenced by molecular interactions of human papillomavirus gene products, particularly from the E6 and E7 open reading frames. These gene products have the ability to bind host regulatory proteins and lead to degradation of the p53 tumor suppressor gene product E6 and functional inactivation of the (tumor suppressor) retinoblastoma gene protein (pRb) E7 (2,3). However, the target cell of these transforming mutations, caused by high risk HPV infection in the uterine cervical epithelium still remains unknown.