CD40/CD40 LIGAND INTERACTIONS AND TNFα TREATMENT REDUCE ACTIVITY OF P105 PROMOTER OF THE HUMAN PAPILLOMA VIRUS-18 IN VITRO

Abstract

Cervical carcinoma cells including those infected with the oncogenic human papilloma virus (HPV) and several cervical carcinoma cell lines show a strong expression of the CD40 receptor, unlike benign cervical epithelial cells infected with HPV. The functional relevance of this up-regulated expression in the tumor is not fully understood. Nevertheless, it might offer a unique possibility to target those malignant cells due to the antiviral and antitumoral effects of the CD40/CD40 ligand (CD40L) interactions. In vitro assessment of the effect of CD40L on HPV 18-P105 promoter activity and the subsequent release of IL-6 by the promoter transfected HeLa(CD40) cells, which express CD40 constitutively. Transfection of HeLa(CD40) cells was achieved by electroporation after optimizing the parameters by the pCMV-β-Gal vector and β-Gal stain. Transfected HeLa(CD40) cells were challenged with BHK(CD40L) and TNFα, in addition to BHK(wt) and medium alone as controls. HPV18-P105 promoter activity was demonstrated by luciferase reporter gene assay while IL-6 was assessed by ELISA. CD40/CD40L interactions and TNFα treatment significantly reduced HPV18-P105 promoter activity (56.0 ± 10.2% and 64.1 ± 9.1% vs. control, respectively; p < 0.001). Likewise, IL-6, which is a sensitive cytokine of CD40 activation, was significantly increased in HeLa(CD40) cells in the same experiments (2.7 fold after stimulation with BHK(CD40L) and 5.2 fold after stimulation with TNFα vs. control; p < 0.01 and p < 0.001, respectively). It is likely that the CD40/CD40L interactions and TNFα are effective against cervical carcinomas by repressing transcriptional activity of HPV promoter. This can result in new adjuvant treatments.