DNA content and methylation of p16, DAPK and RASSF1A gene in tumour and distant, normal mucosal tissue of head and neck squamous cell carcinoma patients.
Long-term survival of head and neck squamous cell carcinoma (HNSCC) patients has not improved significantly during the last 20 years and recurrent disease is frequently observed. In this study, the potential presence of pre-malignant cells or rare malignant cells at the time of diagnosis in HNSCC was investigated.


METHODS
Fifty-nine biopsies obtained from 41 HNSCC patients were analysed. Eighteen of these biopsies were normal mucosal tissue, located at least 5 cm from the tumour margin. DNA content and DNA methylation of p16, DAPK and RASSF1A was examined.


RESULTS
Thirty-nine out of 41 (95%) tumour biopsies showed p16 methylation and 21 (51%) of them displayed aneuploidy. Of 18 distant normal mucosal biopsies, 6 (33%) of these showed evidence of aneuploidy and 15(83%) of them showed methylated p16 genes. Among paired samples, the highest frequencies of DNA methylation were found in tumours with aneuploidy. Regardless of DNA content, methylation at DAPK, RASSF1A or p16 were found in the corresponding distant mucosal biopsies.


CONCLUSIONS
The cells with abnormal DNA content or DNA methylation in mucosal tissue were not detected clinically or by pathological macroscopic and microscopic examination. Thus, distant mucosal tissue DNA content and DNA methylation analyses in combination with histopathology will provide a better prognostic base for the evaluation and treatment of HNSCC patients.
Department of Oncology, Rudbeck Laboratory, Uppsala University Hospital, SE-75185 Uppsala, Sweden. nongnit.laytragoon-lewin@onkologi.uu.se.
Nongnit
N
Laytragoon-Lewin
Fu
F
Chen
Juan
J
Castro
Göran
G
Elmberger
Lars Erik
LE
Rutqvist
Freddi
F
Lewin
Ingela
I
Turesson
Jan
J
Lundgren
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000782:Aneuploidy; D051017:Apoptosis Regulatory Proteins / Q000235:genetics*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics*; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000473:pathology; D018899:CpG Islands; D019941:Cyclin-Dependent Kinase Inhibitor p16; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000235:genetics*; D064550:Death-Associated Protein Kinases; D005260:Female; D006258:Head and Neck Neoplasms / Q000235:genetics* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009092:Mucous Membrane / Q000378:metabolism / Q000473:pathology; D009363:Neoplasm Proteins / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics; D015996:Survival Rate; D025521:Tumor Suppressor Proteins / Q000235:genetics*
D051017:Apoptosis Regulatory Proteins; C000614131:CDKN2A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; C411762:RASSF1 protein, human; D025521:Tumor Suppressor Proteins; D064550:Death-Associated Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases