C/EBPbeta activity and HPV-16 E6/E7 mRNA expression are not altered by imiquimod (ALDARA) in human cervical cancer cells in vitro.
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.


CONCLUSIONS
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.
Belcastro
Marycharmain
M
Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, West Virginia University School of Medicine, Morgantown, WV 26506, USA. mbelcastro@hsc.wvu.edu
Miller
Michael R
MR
Flynn
Daniel C
DC
Soisson
Andrew P
AP
D000634:Aminoquinolines / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism*; D004279:DNA, Viral / Q000187:drug effects / Q000235:genetics; D005260:Female; D015967:Gene Expression Regulation, Viral / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D000077271:Imiquimod; D009856:Oncogene Proteins, Viral / Q000096:biosynthesis / Q000235:genetics*; D027383:Papillomaviridae / Q000235:genetics; D050725:Papillomavirus E7 Proteins; D030361:Papillomavirus Infections / Q000150:complications / Q000378:metabolism / Q000821:virology; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D012097:Repressor Proteins; D014412:Tumor Virus Infections / Q000150:complications / Q000378:metabolism / Q000821:virology; D002583:Uterine Cervical Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000821:virology
D000634:Aminoquinolines; D000970:Antineoplastic Agents; D022782:CCAAT-Enhancer-Binding Protein-beta; D004279:DNA, Viral; C068651:E6 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; C059731:oncogene protein E7, Human papillomavirus type 16; D000077271:Imiquimod