Evaluating mitochondrial DNA in patients with breast cancer and benign breast disease.

PURPOSE: To evaluate the role of mtDNA in breast cancer. METHODS: We carried out an investigation into the mtDNA major control region or D-loop region and an essential and the largest mtDNA protein-coding gene, NADH dehydrogenase subunit 5 (ND5), together with a mitochondrial haplogroup analysis in 64 patients with breast cancer (BC) and 54 patients with benign breast disease (BBD) as controls. RESULTS: Mutations in D-loop region were found in 10/64 or 15.6% of patients with BC and 14/54 or 25.9% of patients with BBD, while mutations in ND5 were detected in 6/64 or 9.4% of patients with BC and 5/54 or 9.3% of patients with BBD. In addition, in patients with BBD, mtDNA mutations were more likely to rise in D-loop region and the mutations were more likely to be heteroplasmic. However, in patients with BC, those with metastatic feature were less likely to carry mutations in D-loop region. Finally, we found haplogroup M has an increased risk of breast cancer compared with haplogroup N. CONCLUSION: mtDNA mutation may play a role in early stage of tumorigenesis, and mitochondrial haplogroup can also modulate breast cancer occurrence.

Cancer type-specific modulation of mitochondrial haplogroups in breast, colorectal and thyroid cancer.

BACKGROUND: Mitochondrial DNA (mtDNA) haplogroups and single nucleotide polymorphisms (mtSNP) have been shown to play a role in various human conditions including aging and some neurodegenerative diseases, metabolic diseases and cancer. METHODS: To investigate whether mtDNA haplogroups contribute to the occurrence of cancer in a specific Chinese population, we have carried out a comprehensive case-control study of mtDNA from large cohorts of patients with three common cancer types, namely, colorectal cancer (n = 108), thyroid cancer (n = 100) and breast cancer (n = 104), in Wenzhou, a southern Chinese city in the Zhejiang Province. RESULTS: We found that patients with mtDNA haplogroup M exhibited an increased risk of breast cancer occurrence [OR = 1.77; 95% CI (1.03-3.07); P = 0.040], and that this risk was even more pronounced in a sub-haplogroup of M, D5 [OR = 3.11; 95%CI (1.07-9.06); p = 0.030]. In spite of this, in patients with breast cancer, haplogroup M was decreased in the metastatic group. On the other hand, our results also showed that haplogroup D4a was associated with an increased risk of thyroid cancer [OR = 3.00; 95%CI (1.09-8.29); p = 0.028]. However, no significant correlation has been detected between any mtDNA haplogroups and colorectal cancer occurrence. CONCLUSION: Our investigation indicates that mitochondrial haplogroups could have a tissue-specific, population-specific and stage-specific role in modulating cancer development.