The effect of the human papillomavirus type 16 (HPV 16) E6 and E7 proteins was studied on the transcriptional activity of the human transforming growth factor β2 (TGF-β2) promoter in different cell lines. Luciferase tests were performed after co-transfection of cells with TGF-β2 reporter constructs and HPV 16 E6 or E7 expression vectors. HPV 16 E7, but not E6 significantly repressed TGF-β2 promoter activity in NIH/3T3 cells, which have wild-type p53 and pRb proteins. The repressive effect of HPV 16 E7 on the transcriptional activity of the TGF-β2 promoter could be localized to the promoter region -528 to -251 relative to the transcriptional start site. Ability of E7 to bind pRb was necessary to inhibit the TGF-β2 promoter. Over-expression of the transcription factor E2F-1 had an effect on the TGF-β2 promoter similar to that of E7, which may indicate that HPV 16 E7 represses the TGF-β2 promoter by releasing E2F from pRb.
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