Methylation status of p14ARF, p15INK4b, and p16INK4a genes in human hepatocellular carcinoma.
BACKGROUND
The INK4 locus consisting of three genes involved in the regulation of cell cycle, p16INK4a, p15INK4b, and p14ARF is often disrupted in human neoplasms.


METHODS
We analyzed the promoter methylation of each gene by methylation-specific PCR in hepatocellular carcinoma (HCC).


RESULTS
The methylation of p16INK4a, p15INK4b, and p14ARF was found to occur in 27 (69.2%), seven (17.9%), and none out of 39 HCC tumors, respectively. Regarding corresponding nontumorous liver tissues, the promoter regions of p16INK4a, p15INK4b, and p14ARF were methylated in three (17.6%), three (17.6%), and none out of 17 samples, respectively. Analysis of mRNA expression revealed that loss of p16INK4a expression was frequently observed in HCC. In contrast, transcripts of p14ARF and p15INK4b were detected in 16 (88.9%) and 16 (88.9%) of 18 tumors, respectively.


CONCLUSIONS
The frequent loss of transcription of p16INK4a with promoter methylation not only in the advanced but also in the early stages of HCC suggests that the epigenetic alteration of p16INK4a promoter is likely to be involved in hepatocarcinogenesis. Together with the result of RT-PCR analysis, the role of aberrant methylation of p14ARF or p15INK4a promoter in hepatocarcinogenesis is thought to be limited.
Fukai
Kenichi
K
Department of Medicine and Clinical Oncology, Graduate School of Medicine, Chiba University, Chiba, Japan.
Yokosuka
Osamu
O
Imazeki
Fumio
F
Tada
Motohisa
M
Mikata
Rintaro
R
Miyazaki
Masaru
M
Ochiai
Takenori
T
Saisho
Hiromitsu
H
D000328:Adult; D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000235:genetics*; D045744:Cell Line, Tumor; D050762:Cyclin-Dependent Kinase Inhibitor p15 / Q000235:genetics*; D019175:DNA Methylation; D005260:Female; D019942:Genes, p16; D006801:Humans; D008099:Liver; D008113:Liver Neoplasms / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D011401:Promoter Regions, Genetic / Q000235:genetics; D012313:RNA / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015533:Transcriptional Activation; D025803:Tumor Suppressor Protein p14ARF / Q000235:genetics*
D050762:Cyclin-Dependent Kinase Inhibitor p15; D025803:Tumor Suppressor Protein p14ARF; D012313:RNA