Promoter methylation profile in gallbladder cancer.
BACKGROUND
Methylation in the promoter region of genes is an important mechanism of inactivation of tumor suppressor genes. Our objective was to analyze the methylation pattern of some of the genes involved in carcinogenesis of the gallbladder, examining the immunohistochemical expression of proteins, clinical features, and patient survival time.


METHODS
Twenty cases of gallbladder cancer were selected from the frozen tumor bank. The DNA extracted was analyzed by means of a methylation-specific polymerase chain reaction test for the CDKN2A (p16), MLH1, APC, FHIT, and CDH1 (E-cadherin) genes. Morphological and clinical data and follow-up information were obtained.


RESULTS
All cases were in an advanced stage: histologically moderate or poorly differentiated tumors (95%). Methylation of the promoter area of genes was observed in 5%, 20%, 30%, 40%, and 65% of cases, and an altered immunohistochemical pattern (AIP) in 5%, 35%, 21%, 25%, and 66% for the MLH1, CDKN2A, FHIT, APC, and CDH1 genes, respectively. The Kappa concordance index between methylation of the promoter area and AIP for the MLH1 and CDH1 genes was very high (K > 0.75) and substantial for APC (K > 0.45). No correlation was found between survival time and the methylation of the genes studied.


CONCLUSIONS
The high frequency of gene methylation (with the exception of MLH1) and the high agreement between AIP and methylation of the gene promoter area for the MLH1, APC, and CDH1 genes suggest that the inactivation of tumor suppressor genes and of the genes related to the control of cellular proliferation through this mechanism is involved in gallbladder carcinogenesis.
Roa
Juan Carlos
JC
Department of Pathology, Faculty of Medicine, Universidad de La Frontera, Manuel Montt 112, Temuco, 478-1176, Chile.
Anabalón
Leonardo
L
Roa
Iván
I
Melo
Angélica
A
Araya
Juan Carlos
JC
Tapia
Oscar
O
de Aretxabala
Xavier
X
Muñoz
Sergio
S
Schneider
Barbara
B
D017766:Acid Anhydride Hydrolases / Q000235:genetics / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing; D000230:Adenocarcinoma / Q000235:genetics* / Q000378:metabolism; D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015703:Antigens, CD; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002677:Chile; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D005706:Gallbladder Neoplasms / Q000235:genetics* / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D020022:Genetic Predisposition to Disease; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D016019:Survival Analysis; D000099170:Bis(5'-adenosyl)triphosphatase
D017766:Acid Anhydride Hydrolases; D048868:Adaptor Proteins, Signal Transducing; D025601:Adenomatous Polyposis Coli Protein; D015703:Antigens, CD; D015820:Cadherins; D002352:Carrier Proteins; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004273:DNA, Neoplasm; D000070957:MutL Protein Homolog 1; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D000099170:Bis(5'-adenosyl)triphosphatase; C513384:CDH1 protein, human; C501486:MLH1 protein, human