Promoter methylation of INK4a/ARF as detected in bile-significance for the differential diagnosis in biliary disease.
OBJECTIVE
There is a need to enhance endobiliary cytotechniques by molecular marker lesions. This is of special significance for patients with primary sclerosing cholangitis, a disease predisposing for the development of cholangiocarcinoma. The INK4a/ADP ribosylation factor (ARF) locus encodes two tumor suppressor genes: p16INK4a and p14ARF. p16INK4a has been shown to be of major significance in cholangiocarcinoma.


METHODS
In an effort to evaluate the potential diagnostic role of p16INK4a and p14ARF promoter methylation in biliary disease, endoscopical obtained bile specimens of 71 patients were analyzed (26 choledocholithiasis, 6 with normal results, 23 bile duct carcinoma, 5 gall bladder carcinoma). Eleven patients with primary sclerosing cholangitis were enrolled.


RESULTS
Merely 6% of specimens (2 of 32) obtained from patients without evidence for malignant biliary disease but 53.5% of malignancies (15 of 28) showed p16 promoter methylation (p14: 3 and 46.2%, respectively). The concordance of methylation rates detected in either bile or tissue specimens was high. In primary sclerosing cholangitis, a similar prevalence of methylation was detected as in malignant disease.


CONCLUSIONS
This study demonstrates: (a) a high frequency and specificity of INK4a/ARF methylation in malignant biliary disease compared with mere cholangitis; and (b) the capability to detect these alterations reliably in endoscopically obtained bile. Thus, INK4a/ARF's promoter methylation status represents a candidate marker for the endoscopic diagnosis of biliary disease.
Department of Internal Medicine I, University Hospital of Tübingen, Germany. bodo.klump@med.uni-tuebingen.de
Bodo
B
Klump
Chih-Jen
CJ
Hsieh
Stephan
S
Dette
Karlheinz
K
Holzmann
Ralf
R
Kiebetalich
Michael
M
Jung
Udo
U
Sinn
Marianne
M
Ortner
Rainer
R
Porschen
Michael
M
Gregor
D000328:Adult; D000368:Aged; D001650:Bile Duct Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism; D001653:Bile Ducts, Intrahepatic; D014408:Biomarkers, Tumor / Q000378:metabolism; D018281:Cholangiocarcinoma / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism; D042883:Choledocholithiasis / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics*; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000235:genetics; D003937:Diagnosis, Differential; D005705:Gallbladder Diseases / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism; D020868:Gene Silencing; D006801:Humans; D008875:Middle Aged; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015996:Survival Rate; D025803:Tumor Suppressor Protein p14ARF / Q000235:genetics*
D014408:Biomarkers, Tumor; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004273:DNA, Neoplasm; D025803:Tumor Suppressor Protein p14ARF