Differential DNA hypermethylation of critical genes mediates the stage-specific tobacco smoke-induced neoplastic progression of lung cancer.
Promoter DNA methylation status of six genes in samples derived from 27 bronchial epithelial cells and matching blood samples from 22 former/current smokers and five nonsmokers as well as 49 primary non-small cell lung cancer samples with corresponding blood controls was determined using methylation-specific PCR (MSP). Lung tumor tissues showed a significantly higher frequency of promoter DNA methylation in p16, MGMT, and DAPK (P < 0.05; Fisher's exact test). p16 promoter DNA methylation in tumors was observed at consistently higher levels when compared with all the other samples analyzed (P = 0.001; Fisher's exact test). ECAD and DAPK exhibited statistically insignificant differences in their levels of DNA methylation among the tumors and bronchial epithelial cells from the smokers. Interestingly, similar levels of methylation were observed in bronchial epithelial cells and corresponding blood from smokers for all four genes (ECAD, p16, MGMT, and DAPK) that showed smoking/lung cancer-associated methylation changes. In summary, our data suggest that targeted DNA methylation silencing of ECAD and DAPK occurs in the early stages and that of p16 and MGMT in the later stages of lung cancer progression. We also provide preliminary evidence that peripheral lymphocytes could potentially be used as a surrogate for bronchial epithelial cells to detect altered DNA methylation in smokers.
Russo
Andrea L
AL
Department of Medicine (Genetics Program and Cancer Research Center), Boston University School of Medicine, Boston, Massachusetts 02118, USA.
Thiagalingam
Arunthathi
A
Pan
Hongjie
H
Califano
Joseph
J
Cheng
Kuang-hung
KH
Ponte
Jose F
JF
Chinnappan
Dharmaraj
D
Nemani
Pratima
P
Sidransky
David
D
Thiagalingam
Sam
S
D051017:Apoptosis Regulatory Proteins; D014408:Biomarkers, Tumor / Q000235:genetics*; D001980:Bronchi / Q000378:metabolism / Q000473:pathology; D015820:Cadherins / Q000235:genetics; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics; D002289:Carcinoma, Non-Small-Cell Lung / Q000209:etiology / Q000235:genetics*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics; D064550:Death-Associated Protein Kinases; D018450:Disease Progression; D015972:Gene Expression Regulation, Neoplastic; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase / Q000235:genetics; D006801:Humans; D007527:Isoenzymes / Q000235:genetics; D008175:Lung Neoplasms / Q000097:blood / Q000209:etiology / Q000235:genetics*; D008954:Models, Biological; D009367:Neoplasm Staging; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000235:genetics; D016133:Polymerase Chain Reaction; D011230:Precancerous Conditions / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D020545:Respiratory Mucosa / Q000378:metabolism / Q000473:pathology; D051904:Smad8 Protein; D012907:Smoking / Q000009:adverse effects*; D015534:Trans-Activators / Q000235:genetics
D051017:Apoptosis Regulatory Proteins; D014408:Biomarkers, Tumor; D015820:Cadherins; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; D007527:Isoenzymes; C107514:SMAD9 protein, human; D051904:Smad8 Protein; D015534:Trans-Activators; D019853:O(6)-Methylguanine-DNA Methyltransferase; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase; D064550:Death-Associated Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases