Aberrant gene methylation in the lymph nodes provides a possible marker for diagnosing micrometastasis in gastric cancer.
BACKGROUND
This study was designed to determine whether gene methylation is a novel diagnostic marker for micrometastasis to the lymph nodes (LNs) in gastric cancer.


METHODS
The gene methylation of CHFR, p16, RUNX3, E-cadherin, MGMT, hMLH1, and ABCG2 genes were analyzed in 49 primary gastric cancer tissues, corresponding to noncancerous tissues and matched LNs by quantitative methylation-specific PCR (q-MSP).


RESULTS
CHFR, RUNX3, MGMT, and hMLH1 were more frequently methylated in primary cancer compared with the noncancerous mucosa. Further analyses investigated whether the methylation of the four cancer-specific genes was preserved in LN tissues using the 29 control cases, in which LN metastasis had been histologically confirmed. The methylation of both lesions (M/M pattern) in at least one gene, which was judged to be positive for cancer cells in LNs, was observed in 25 of 29 cases (86%). Quantitative RT-PCR (qRT-PCR) of CEA, CK19, and CK20 mRNA was conducted using the same samples. The mRNA expression of at least one of the three genes was observed in 100% of the specimens. The results of the control analysis were used to attempt to predict micrometastasis by q-MSP and qRT-PCR in the 20 test cases without histological LN metastasis. Six cases (30%) showed the M/M pattern in at least one of the four genes. Three of 20 cases (15%) exhibited both the M/M pattern and positive mRNA.


CONCLUSIONS
The methylation analysis revealed the clinical feasibility of detecting occult neoplastic cells in the regional LNs.
Hiraki
Masatsugu
M
Department of Surgery, Saga University Faculty of Medicine, 5-1-1 Nabeshima, Saga, 849-8501, Japan.
Kitajima
Yoshihiko
Y
Sato
Seiji
S
Mitsuno
Mayumi
M
Koga
Yasuo
Y
Nakamura
Jun
J
Hashiguchi
Kazuyoshi
K
Noshiro
Hirokazu
H
Miyazaki
Kohji
K
D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000235:genetics*; D015820:Cadherins / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics; D050677:Core Binding Factor Alpha 3 Subunit / Q000235:genetics; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000235:genetics; D045643:DNA Repair Enzymes / Q000235:genetics; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D009363:Neoplasm Proteins / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics; D000075223:Poly-ADP-Ribose Binding Proteins; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000235:genetics* / Q000473:pathology; D025521:Tumor Suppressor Proteins / Q000235:genetics; D044767:Ubiquitin-Protein Ligases
C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D048868:Adaptor Proteins, Signal Transducing; D014408:Biomarkers, Tumor; D015820:Cadherins; D018797:Cell Cycle Proteins; D050677:Core Binding Factor Alpha 3 Subunit; D019941:Cyclin-Dependent Kinase Inhibitor p16; C501486:MLH1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; C493729:Runx3 protein, human; D025521:Tumor Suppressor Proteins; D015254:DNA Modification Methylases; C515491:MGMT protein, human; C412002:CHFR protein, human; D044767:Ubiquitin-Protein Ligases; D000070957:MutL Protein Homolog 1; D045643:DNA Repair Enzymes