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Human papillomavirus (HPV) infection has been identified as an etiologic factor of head and neck cancers (HNCs). We explored the potential use of antisense HPV RNA transcripts for gene therapy and its effect in combination with cisplatin (CDDP) for HPV-positive HNCs. We introduced the antisense RNA transcripts of the E6 and E7 genes of HPV type 16 into UM-SCC-47 cells harboring HPV 16 and YCU-T892 cells that were HPV-negative using a recombinant adenoviral vector, Ad-E6/E7-AS. We then analyzed the effects of the introduction of Ad-E7-AS on cell and tumor growth and the synergistic effect with CDDP in vitro and in vivo. After infection of Ad-E6/E7-AS, the cellular growth of UM-SCC-47 cells were suppressed, but not that of YCU-T892 cells. E7 protein expression was suppressed, and p53 and pRb protein expression increased after infection of Ad-E7-AS. Cell growth and tumorigenicity were greatly suppressed in combination with CDDP compared with Ad-E7-AS or CDDP treatment alone in vitro. Ad-E7-AS combined with CDDP treatment significantly reduced the volumes of established subcutaneous tumors. Transfection with HPV 16 E7 antisense RNA combined with CDDP treatment might be a potentially useful approach to the therapy of HPV 16-positive HNC.

Conclusion: Our results indicate that siRNA E6 and/or E7 may have potential as a gene-specific therapy for human papillomavirus (HPV) type 16 (HPV16)-related squamous cell carcinoma of the head and neck (HNSCC). Objectives: To evaluate the effectiveness of siRNA targeting E6 and/or E7 on the in vitro and in vivo growth suppression of HPV16-related HNSCC. Methods: HPV16-related HNSCC (UM-SCC47) cell lines were used for the present study. Expression of HPV viral oncogenes E6 and/or E7 and their cellular targets, p53 and pRb, was evaluated by real-time PCR, Western blotting, and immunofluorescence staining. To study the effect of siRNA on tumor growth in vivo, we developed animal models. Representative tumors harvested from each group were processed for apoptosis analyses (TUNEL assay) and immunofluorescence staining for p53 and pRb. Results: E6 and E7 oncogenes of HPV16 were down-regulated by E6 and/or E7 targeting siRNAs, respectively. The expression of p53 and pRb proteins in both the E6 siRNA group and E7 siRNA group was up-regulated compared with those of control groups. The cellular proliferation and apoptosis indexes of E6 and/or E7 siRNA groups were higher than those of controls. In vivo studies showed significant inhibitory effect of E6 and/or E7 siRNA compared with those of control groups, which was consistent with in vitro studies. [ABSTRACT FROM AUTHOR]