Abstract
Objective: 1) Investigate whether siRNA selectively alters viral gene expression and cellular proliferation of HNSCC containing HPV16. 2) Compare the effectiveness of siRNA for E6 and that of E7 on the inhibition of cellular proliferation and induction of apoptosis in HNSCC.
Method: HNSCC (UM-SCC47) and Cervical Cancer (Caski) cell lines were used for this study and have been confirmed to contain HPV16. Expressions of HPV oncogene E6/E7 and their cellular targets p53 and pRb were evaluated by real-time PCR, western-blotting and immunofluorescence. The cellular-proliferation and apoptosis by in vitro cytotoxicity assay and flow-cytometry.
Results: HPV16 E6 and E7 oncogenes were down-regulated by either HPV16 E6 or E7 siRNAs, respectively. Furthermore, reduction of E6 and E7 oncogenes expression up-regulated the expression of P53 and pRb protein, and induced apoptosis in both UM-SCC47 and Caski Cells. In UM-SCC47 (E6/E7 siRNA groups), real-time PCR analysis showed that the levels of E6 (P = .005/P = .027) and E7 (P = .002/P = .011) mRNA were significantly down-regulated compared with those of control groups. The inhibition of cellular proliferation and induction of apoptosis in combination of E6 and E7 siRNA groups was higher than that of E6 or E7 siRNA group alone and control.
Conclusion: Introduction of HPV16 E6/E7 siRNA might be a potentially potent and specific approach to inhibit proliferation and induce apoptosis of HNSCC containing HPV16 cell lines. For clinical we are currently preparing to test the effects of HPV16 E6/E7 siRNA on xenograft of HNSCC containing HPV16 cell lines.
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