Objective: The purpose of this study was to determine the potential relationship between imiquimod and C/EBPbeta by investigating the extent to which imiquimod could alter C/EBPbeta binding activity to known sequences of the HPV-16 NCR, which could lead to the repression of HPV-16 E6/E7 oncogene expression, possibly impacting a major mechanism by which HPV causes cellular transformation.
Methods: The effect of imiquimod treatment on C/EBPbeta binding activity to its consensus sequence as well as to two specific regions of the HPV-16 NCR was determined by electromobility shift assay (EMSA) in CaSki cervical cancer cells. HPV-16 E6/E7 gene expression was evaluated by RNase protection assay (RPA) in CaSki and in W12-E cells treated with imiquimod. In addition, C/EBPbeta mRNA expression and protein production in response to imiquimod were evaluated by reverse transcription polymerase chain reaction (RT-PCR) and Western blotting, respectively, in the cervical cancer cell lines, CaSki, HeLa, and C33A.
Results: C/EBPbeta binding activity, mRNA expression, and protein production remained unchanged with imiquimod treatment. Initially, HPV-16 E6/E7 expression appeared to be increased with imiquimod treatment in CaSki cells, but this effect was not reproducible. HPV-16 E6/E7 expression was not reproducibly altered with imiquimod treatment in W12-E cells.
Conclusion: While these results indicate that imiquimod does not alter C/EBPbeta binding activity, nor does it appear to decrease HPV-16 E6/E7 oncogene expression in vitro, it remains possible that imiquimod may have utility in treating cervical dysplasia or cervical cancer via another mechanism.