Methylenetetrahydrofolate reductase C677T genotype affects promoter methylation of tumor-specific genes in sporadic colorectal cancer through an interaction with folate/vitamin B12 status

Figure 1 Representative example of MS-PCR assay for genotyping of codon 677 of MTHFR gene. For PCR-primers and reaction conditions see methods. In case of the MTHFR 677 C allele, a product with 168 base pairs (bp) in length was generated, whereas the MTHFR 677 T allele yielded a 148-bp product. The differently sized allele-specific PCR products were separated by agarose gel electrophoresis. In 42 patients genotyping was performed in both cancer tissue (T) and adjacent normal tissue (N). Lanes 2-5 in the lower panel show heterozygote (CT) samples. M: DNA size marker.

Figure 2 Representative examples of MSP reactions for promoter methylation analysis of p16, hMLH1, and hMSH2 genes in primary CLC tumors. The presence of a visible PCR product in those lanes marked U indicates the presence of unmethylated genes; the presence of a product in those lanes marked M indicates the presence of methylated genes. Lane 1 indicates the 50 bp DNA size marker.