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Objective: Our aims were to examine the ability of the human papillomaviruse (HPV) 16 E2 protein to induce apoptosis in a murine HPV-transformed cell line, and to evaluate its antitumor properties on HPV-associated tumors in vivo in immunocompetent mice. Methods: HPV-transformed murine BMK-16/myc cells and human SiHa cells were transfected with the HPV 16 E2 gene to examine the effects of the E2 protein on cell growth and on the E6 and E7 oncogenes as well as DNA fragmentation and activation of the extrinsic pathway of apoptosis. Finally, to test the antitumor effect of the E2 protein on an experimental mouse tumor model, we generated a recombinant adenovirus expressing the E2 protein. Results: The E2 protein inhibited the growth of SiHa and BMK-16/myc cell lines, and repressed the E6 and E7 oncogenes. Moreover, the E2 protein induced DNA fragmentation and apoptosis through activation of caspases 8 and 3 in BMK-16/myc cells. On the other hand, E2 also showed antitumor effects in vivo. Conclusions: Our findings indicate that E2 exerts pro-apoptotic activity in a murine HPV-transformed cell line as well as an antitumor effect in vivo.

Oscar Peralta-Zaragoza,1 Víctor Hugo Bermúdez-Morales,1 Carlos Pérez-Plasencia,2,3 Jonathan Salazar-León,1 Claudia Gómez-Cerón,1 Vicente Madrid-Marina11Direction of Chronic Infections and Cancer, Research Center in Infection Diseases, National Institute of Public Health, Cuernavaca, Morelos, México; 2Oncogenomics Laboratory, National Cancer Institute of Mexico, Tlalpan, México; 3Biomedicine Unit, FES-Iztacala UNAM, México City, MéxicoAbstract: Cervical cancer is the second most common cause of cancer death in women worldwide and the development of new diagnosis, prognostic, and treatment strategies merits special attention. Although surgery and chemoradiotherapy can cure 80%–95% of women with early stage cancer, the recurrent and metastatic disease remains a major cause of cancer death. Many efforts have been made to design new drugs and develop gene therapies to treat cervical cancer. In recent decades, research on treatment strategies has proposed several options, including the role of HPV E6 and E7 oncogenes, which are retained and expressed in most cervical cancers and whose respective oncoproteins are critical to the induction and maintenance of the malignant phenotype. Other efforts have been focused on antitumor immunotherapy strategies. It is known that during the development of cervical cancer, a cascade of abnormal events is induced, including disruption of cellular cycle control, perturbation of antitumor immune response, alteration of gene expression, and deregulation of microRNA expression. Thus, in this review article we discuss potential targets for the treatment of cervical cancer associated with HPV infection, with special attention to immunotherapy approaches, clinical trials, siRNA molecules, and their implications as gene therapy strategies against cervical cancer development.Keywords: Cervical cancer, clinical trials, gene therapy, HPV E6 and E7 oncogenes, siRNAs

Persistent infection with high-risk HPV is the etiologic agent associated with the development of cervical cancer (CC) development. However, environmental, social, epidemiological, genetic, and host factors may have a joint influence on the risk of disease progression. Cervical lesions caused by HPV infection can be removed naturally by the host immune response and only a small percentage may progress to cancer; thus, the immune response is essential for the control of precursor lesions and CC. We present a review of recent research on the molecular mechanisms that allow HPV-infected cells to evade immune surveillance and potential targets of molecular therapy to inhibit tumor immune escape.