No evidence for promoter region methylation of the succinate dehydrogenase and fumarate hydratase tumour suppressor genes in breast cancer

BACKGROUND: Succinate dehydrogenase (SDH) and fumarate hydratase (FH) are tricarboxylic acid (TCA) cycle enzymes that are also known to act as tumour suppressor genes. Increased succinate or fumarate levels as a consequence of SDH and FH deficiency inhibit hypoxia inducible factor-1α (HIF-1α) prolyl hydroxylases leading to sustained HIF-1α expression in tumours. Since HIF-1α is frequently expressed in breast carcinomas, DNA methylation at the promoter regions of the SDHA, SDHB, SDHC and SDHD and FH genes was evaluated as a possible mechanism in silencing of SDH and FH expression in breast carcinomas. FINDINGS: No DNA methylation was identified in the promoter regions of the SDHA, SDHB, SDHC, SDHD and FH genes in 72 breast carcinomas and 10 breast cancer cell lines using methylation-sensitive high resolution melting which detects both homogeneous and heterogeneous methylation. CONCLUSION: These results show that inactivation via DNA methylation of the promoter CpG islands of SDH and FH is unlikely to play a major role in sporadic breast carcinomas.