Gene promoter hypermethylation in tumors and lymph nodes of stage I lung cancer patients.
Promoter hypermethylation is an important pathway for repression of gene transcription in cancer cells and a promising marker for cancer detection. We tested five gene promoters [CDKN2A (p16), O(6)-methylguanine-DNA-methyltransferase, glutathione S-transferase P1 (GSTP1), adenomatous polyposis coli (APC), and death-associated protein kinase (DAPK)] by real-time methylation-specific PCR in primary tumors from 90 stage I lung cancer patients for aberrant DNA methylation. We then used the presence of tumor methylation as a marker to investigate the presence of occult metastasis in corresponding histologically negative lymph nodes. Of the primary tumors, 73 of 90 (81%) displayed promoter hypermethylation in at least one of the genes studied: 17% (15 of 90) at p16 (CDKN2A); 16% (14 of 90) at O(6)-methylguanine-DNA-methyltransferase; 8% (7 of 90) at GSTP1; 72% (65 of 90) at APC; and 17% (15 of 90) at DAPK. Squamous histology was predictive of worse overall survival (P = 0.074, log-rank test). APC methylation and GSTP1 methylation in the primary tumor were both correlated with nonsquamous histology (P = 0.02 and P = 0.01 likelihood ratio respectively). The presence of both APC methylation and DAPK methylation in the primary tumor predicted a worse outcome, with 7 of 13 (54%) deaths in this group compared with 21 of 77 (27%) deaths in cases without both genes methylated (P = 0.229, log-rank test). The same methylation pattern was detected in DNA from at least one of the corresponding lymph nodes in 11 of 73 (15%) cases. Five of 11 (45%) patients with occult metastasis detected by methylation analysis have died compared with 17 of 62 (27%) patients with negative lymph nodes, although survival analysis did not reach statistical significance (P = 0.632, log-rank test). Promoter hypermethylation is common in lung cancer and represents a promising marker for the molecular staging of lung cancer patients. Although this study showed important trends, a larger prospective study is required to better understand the value of methylation analysis in detecting occult metastasis.
Harden
Susan V
SV
Department of Otolaryngology-Head and Neck Surgery, Division of Head and Neck Cancer Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21206-2198, USA.
Tokumaru
Yutaka
Y
Westra
William H
WH
Goodman
Steven
S
Ahrendt
Steven A
SA
Yang
Stephen C
SC
Sidransky
David
D
D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics; D004247:DNA / Q000378:metabolism; D019175:DNA Methylation; D005260:Female; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase / Q000235:genetics; D006801:Humans; D007527:Isoenzymes / Q000235:genetics; D008175:Lung Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000235:genetics; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013447:Sulfites / Q000494:pharmacology; D013997:Time Factors; D014158:Transcription, Genetic
D025601:Adenomatous Polyposis Coli Protein; D019941:Cyclin-Dependent Kinase Inhibitor p16; D007527:Isoenzymes; D013447:Sulfites; D004247:DNA; D019853:O(6)-Methylguanine-DNA Methyltransferase; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase