The methylation status and protein expression of CDH1, p16(INK4A), and fragile histidine triad in nonsmall cell lung carcinoma: epigenetic silencing, clinical features, and prognostic significance.
BACKGROUND
Aberrant methylation of the promoter CpG island (methylation) is known as a major inactivation mechanism of tumor suppressor and tumor-related genes. In this study, the authors studied the presence of methylation by investigated the inactivation of genes and prognostic factors in patients with nonsmall cell lung carcinoma (NSCLC) by examining resection samples for the presence of methylation.


METHODS
Samples were obtained from 224 patients who underwent pulmonary resection for NSCLC. The authors used those samples to study methylation status with methylation-specific polymerase chain reaction analysis and to study protein expression with immunohistochemistry for 3 different genes: CDH1, p16INK4A, and fragile histidine triad (FHIT).


RESULTS
The frequency of methylation in NSCLC was determined as 58.0% for CDH1, 21.9% for p16INK4A, and 52.2% for FHIT. The methylation of p16INK4A was observed significantly in heavy smokers compared either with nonsmokers or with patients who had smoked for <20 pack-years (P = .0420); it also was more significant in squamous cell carcinomas than in adenocarcinomas (P = .0343). FHIT methylation also was correlated significantly with lymph node metastasis (P = .0361). Patients who had tumors with both methylation and reduced expression of CDH1 had a significantly poorer prognosis compared with patients who had tumors both without methylation and with positive expression of CDH1 (P = .0259 and P = .0369, respectively; multivariate Cox analysis). For p16INK4A methylation, 63.3% of tumors showed reduced expression; whereas, in p16INK4A-unmethylated tumors, 33.7% showed reduced expression (P = .0002). However, for CDH1 and FHIT, no significant correlation was found for either methylation or reduced expression.


CONCLUSIONS
Although protein expression was not inactivated by methylation alone, p16 expression was inactivated strongly by methylation. In addition, the analysis of methylation and expression of CDH1 played a clinically important role in treatment strategies for patients with NSCLC.
Nakata
Shoji
S
Second Department of Surgery, University of Occupational and Environmental Health, Iseigaoka, Kitakyushu, Japan.
Sugio
Kenji
K
Uramoto
Hidetaka
H
Oyama
Tsunehiro
T
Hanagiri
Takeshi
T
Morita
Masaru
M
Yasumoto
Kosei
K
D017766:Acid Anhydride Hydrolases / Q000235:genetics*; D000328:Adult; D000368:Aged; D001483:Base Sequence; D014408:Biomarkers, Tumor / Q000032:analysis; D015820:Cadherins / Q000235:genetics*; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D015331:Cohort Studies; D019175:DNA Methylation; D018450:Disease Progression; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D019942:Genes, p16; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D015999:Multivariate Analysis; D009361:Neoplasm Invasiveness / Q000235:genetics / Q000473:pathology; D009363:Neoplasm Proteins / Q000235:genetics*; D009367:Neoplasm Staging; D016133:Polymerase Chain Reaction; D011336:Probability; D011379:Prognosis; D016016:Proportional Hazards Models; D012494:Sampling Studies; D016019:Survival Analysis; D000099170:Bis(5'-adenosyl)triphosphatase
D017766:Acid Anhydride Hydrolases; D014408:Biomarkers, Tumor; D015820:Cadherins; D009363:Neoplasm Proteins; D000099170:Bis(5'-adenosyl)triphosphatase