Am J Cancer Res 2012;2(3):309-321

Original Article
Knock down of p53 or its ubiquitin ligase E6AP does not affect the sensitivity of
human papillomavirus-positive cervical cancer cells to cisplatin

Michnov Olga, Solomayer Erich, Fehm Tanja, Stubenrauch Frank, Iftner Thomas

Institute for Medical Virology and Epidemiology of Viral Diseases, Division of Experimental Virology, University Hospital
Tuebingen, Elfriede-Aulhorn-Str. 6, 72076 Tuebingen, Germany; Department of Obstetrics and Gynecology, University of
Saarland, Kirrbergerstr. 100, 66424, Homburg, Saar, Germany; Department of Obstetrics & Gynecology, University  Hospital of
Tuebingen, Calwer Str. 7, 72076 Tuebingen, Germany

Received April 11, 2012; accepted April 20, 2012; Epub April 22, 2012; Published May 15, 2012

Abstract: The persistent infection with high risk human papillomaviruses (hrHPV) is a necessary risk factor for the development
of cervical cancer, which is the second most frequent cancer in women worldwide. Cisplatin-based radiotherapy represents the
current treatment regimen. However, the results for advanced and recurrent disease are far from optimal. Since almost all
cervical cancers contain wild type (wt) p53, which is degraded by the complex of hrHPV E6 and the ubiquitin ligase E6AP, we
addressed if the reconstitution of p53 via silencing of E6AP sensitizes cervical cancer cells towards cisplatin treatment. For this
we established and characterized two novel cervical cancer cell lines that contain integrated HPV16 genomes. Long-term
established HeLa and SiHa cells and the novel cervical cancer cell lines at low passage numbers were treated with different
concentrations of cisplatin. Cell viability was measured by the WST-1 assay. In addition, single cisplatin treatment was
combined with the silencing of E6AP or p53. The comparison to HeLa and SiHa cells revealed a higher sensitivity of the novel
cell lines to cisplatin treatment, which caused p53 accumulation and transcriptional induction of p21. Silencing of E6AP further
increased p53 protein levels, but had no effect on cell viability when combined with cisplatin treatment. Interestingly, silencing of
p53 had also no effect. We therefore conclude that reactivation of p53 via silencing of E6AP does not increase the sensitivity of
cervical cancer cells towards cisplatin treatment. (AJCR00000115).

Keywords: Cervical cancer, HPV, cisplatin, p53, E6AP, chemoresistance

Address all correspondence to:
Dr. Thomas Iftner
University Hospital Tuebingen
Institute for Medical Virology and Epidemiology of Viral Diseases
Division of Experimental Virology, Elfriede-Aulhorn-Str
6 D-72076 Tuebingen, Germany.
Tel: ++49 7071/29-80246; Fax: ++49 7071/29-5419
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American Journal of Cancer Research
ISSN: 2156-6976