We used antisense transfection, over-expression, or knock-down of IL-32 to assess the effects of the HPV-16 E7 oncogene on IL-32 expression in
cervical cancer cells. Cyclo-oxygenase 2 (COX-2) inhibitor treatment PS-341 clinical trial was conducted, and the expression levels, as well as the promoter activities, of IL-32 and COX-2 were evaluated in human HPV-positive cervical cancer cell lines. E7 antisense treatment reduced the expression levels and promoter activities of COX-2, which is constitutively expressed in HPV-infected cells. Constitutively expressed IL-32 was also inhibited by E7 antisense treatment. Moreover, IL-32 expression was blocked by the application of the selective COX-2 inhibitor, NS398, whereas COX-2 over-expression resulted in increased IL-32 levels. These results show that the high-risk variant of HPV induces IL-32 expression via E7-mediated COX-2 stimulation. However, E7 and COX-2 were down-regulated in the IL-32γ over-expressing cells and recovered by IL-32 small interfering RNA, indicating that E7 and COX-2 were feedback-inhibited by IL-32γ selleck chemicals in cervical cancer cells. Cervical cancer is the second most frequent cause of cancer death in women worldwide, and molecular epidemiological studies
have demonstrated clearly that human papillomavirus (HPV) is a prerequisite for the development of cervical carcinoma.1,2 Approximately 200 different HPV types have been characterized, Carnitine palmitoyltransferase II and the two most frequent high-risk HPV genotypes, HPV-16 and HPV-18, account for at least 50% of cervical cancers worldwide.3,4 Several HPV-16 type oncoproteins expressed during the early stage of infection have been associated with oncogenicity; specifically, E5, E6 and E7 have been demonstrated to contribute to the maintenance
of malignant cervical cancer phenotypes.5 The function of the E5 oncoprotein-activating epidermal growth factor receptor remains to be clearly elucidated, and E6 promotes the degradation of p53 via its interaction with E6AP.6 The E7 oncoprotein binds to the pRb retinoblastoma protein, and disrupts its formation of a complex with the E2F transcription factor in the G1 phase of the cell cycle. E7 also binds to and activates cyclin complexes such as cyclin-dependent kinase cdk2 and cyclin A, which control cell cycle progression.7 The viral genes E6 and E7 found in a specific subset of HPVs are invariably expressed in HPV-positive cervical cancer cells.8 It has also been previously reported that the E7 gene of HPV-16 triggers a cellular immunosuppression and profoundly enhances the release of angiogenic cytokines by macrophages or dendritic cells.9 The E6 and E7 oncogenes also inhibit the IL-18-mediated immune response, which carries out crucial functions in host defence mechanisms against infection and cancer.