p16 methylation does not affect protein expression in cervical carcinogenesis.
Previous studies have reported a frequency range of 19-61% for p16 methylation in cervical cancers. However, p16 is strongly expressed in over 90% of cervical cancers and pre-cancers, due to interactions of HPV oncogenes with p53 and pRb. In order to clarify these controversial findings, we developed a new bisulphite sequencing protocol to determine the methylation status of p16. DNA extracted from 17 cell lines and 94 microdissected clinical samples was subjected to methylation analysis. p16 expression was confirmed in Western blot and immunohistochemistry. Complete methylation of p16 was found in none of the dysplastic lesions, but in 26% of the cervical carcinomas. However, immunohistochemistry showed strong p16 expression in all cancers. These findings indicate that p16 methylation does not implicate loss of p16 expression in HPV-induced tumours. In cervical cancer, methylation of p16 does not seem to be an underlying pathogenic mechanism, but may be a result of increasing genetic and epigenetic instability.
Nehls
Kristina
K
Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany.
Vinokurova
Svetlana
S
Schmidt
Dietmar
D
Kommoss
Friedrich
F
Reuschenbach
Miriam
M
Kisseljov
Fjodor
F
Einenkel
Jens
J
von Knebel Doeberitz
Magnus
M
Wentzensen
Nicolas
N
D015153:Blotting, Western; D002294:Carcinoma, Squamous Cell / Q000378:metabolism* / Q000821:virology; D045744:Cell Line, Tumor; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism*; D019175:DNA Methylation; D005091:Exons / Q000502:physiology; D005260:Female; D015894:Genome, Human; D005838:Genotype; D052162:Human papillomavirus 16; D006801:Humans; D030361:Papillomavirus Infections / Q000378:metabolism* / Q000821:virology; D016133:Polymerase Chain Reaction / Q000379:methods; D002583:Uterine Cervical Neoplasms / Q000378:metabolism* / Q000821:virology; D002578:Uterine Cervical Dysplasia / Q000378:metabolism* / Q000821:virology
D019941:Cyclin-Dependent Kinase Inhibitor p16