Effects of ALA-PDT on HPV16-immortalized cervical epithelial cell

Current treatments for high-grade cervical intraepithelial neoplasia (CIN) and persistent infection with high-risk human papillomavirus (HR-HPV) type are mainly surgical interventions. However, such treatments are associated with adverse side effects and pose risks for future pregnancies. In order to reduce the requirement for excisional procedures, an effective and noninvasive therapy is needed for women at reproductive age. ALA-PDT has proved to be effective in the treatment of HPV-associated disease in several clinical investigations. In this study, the anti-proliferative effect of ALA-PDT was investigated in HPV16-immortalized cervical epithelial H8 cells. CCK-8 assay was used to measure cytotoxicity in H8 cells. The IC50 of ALA-PDT on H8 cells was about 120.75 ± 1.18 µM. We have now evaluated the mechanism by which ALA-PDT induces cell death. Annexin V-FITC/PI staining showed a significant dose-dependent induction of apoptosis by ALA-PDT in H8 cells, associated with accumulation of the tumor suppressor protein p53 and the cyclin-dependent kinase inhibitor p21. Furthermore, ALA-PDT down-regulates expression of HPV E6/E7 oncogene as well as up-regulate tumor suppressor RbAp48 protein. Together, our data provides a basis for understanding and developing ALA-PDT as a cure for HPV infection-associated diseases and prevention of cervical cancer.