Figure 5

Comparison of proportion of methylated- Alu in primary gastric carcinomas and the corresponding normal samples by the Cac 8I COBRA-DHPLC assay. Bisulfite modified Alu elements in 48 pairs of gastric carcinomas (GC) and the corresponding normal tissues (GC-Nor) with or without lymph node metastasis (M+/M-) were amplified with the primer set-2. The 156-bp PCR-2 products of Alu elements were digested with Cac8I at 37°C for 6 hours. The methylated-Alu was cut and the unmethylated-Alu was not cut by Cac8I. The digested PCR-2 products were separated by DHPLC at the undenatured temperature 48°C. The proportion of methylated-Alu was calculated according to ratio of the adjusted peak height for the methylated-Alu to that for the unmethylated-Alu. Hypomethylation was observed in 33 of 48 of GCs and marked with the colour blue.