Recent epidemiological studies continue to provide evidence that tobacco smoking is an independent risk factor for cervical cancer. Literature data also identifies human papillomaviruses (HPV) as an important etiological factor in the development of this disease. However, only a small population of HPV-infected individuals will develop cervical cancer. In addition, the transfection of human cervical cells with HPV immortalizes those cells but does not make them carcinogenic. It has, therefore, been suggested that other genetic changes are needed for the development of malignancy. These changes may result from oxidative damage or alkylation caused by tobacco derived carcinogens. We have demonstrated that these tobacco carcinogens are present in human cervical mucus and can be metabolically activated to genotoxic intermediates that can damage cervical DNA. It is our hypothesis that genetic damage induced by tobacco-derived carcinogens can lead to mutations of proto-oncogenes (e.g. c-myc, H- and K-ras, and c-erbB). Thus, genetic damaged induced by B[a]P and/or NNK combined with HPV-induced deactivation of tumor suppresser genes and inhibition of apoptosis can be expected to lead to the development of cervical cancer. Test our hypotheses we propose the following specific aims: (1) Develop an appropriate animal model to determine the role of carcinogenic activity of TSNA, PAH and HPV individually and in combination; and HPV transgenic mouse available in the laboratory of our collaborator is prerequisite to achieve the goals of this aim. (2) Examine the metabolism of NNK, NNAL and B[a]P in normal and HPV 16-immortalized human cervical cells and characterize enzymes responsible for their metabolic activation. (3) Evaluate the capacity of NNK, NNAL and B[a]P to induce malignant transformation to human cervical cells immortalized with HPV-16 as compared to controls. (4) Carry out a pilot study to establish the feasibility and conditions for a case-control study of the association between exposure to tobacco carcinogens (using representative biomarkers derived from the animal studies) and risk of cervical dysplasia/cancers, and risk modification by HPV infections. The studies proposed in this Project will provide important knowledge that is requisite to our understanding of the association of HPV infection and tobacco usage as it relates to the mechanism of induction of cervical neoplasias in humans. These studies will also provide a foundation to later test the chemopreventive efficacy of various chemopreventive agents.
Showing the most recent 10 out of 46 publications
