Female-specific association among I, J and K mitochondrial genetic haplogroups and cancer: A longitudinal cohort study

No association of the common Asian mitochondrial DNA haplogroups with lung cancer in East Indian population

OBJECTIVES

Mitochondrial dysfunction has long been associated with the pathogenesis of lung cancer (LC). Mitochondrial DNA (mtDNA) haplogroups have been reported to modify the risk of LC in a few different populations; however, no study has been done among the Indians. Here, we explore the relationship between mtDNA haplogroups and LC in a representative eastern Indian sample set.

METHODS

Different combinations of six mtDNA SNPs, which define the major Asian mtDNA haplogroups M and N, and their sub-haplogroups D, G, M7, R, and F were genotyped via polymerase chain reaction (PCR) - restriction fragment length polymorphism (RFLP) - sequencing approach in 94 smoker LC patients and 100 healthy smoker controls from an eastern Indian cohort.

RESULTS

The distribution of 7 mtDNA haplogroups did not show any significant differences between patients and controls (p<0.05). We did not find sub-haplogroup M7 in our study population.

CONCLUSIONS

Our study is the first to indicate that the major Asian mtDNA haplogroups have no significant (p<0.05) association with LC in East Indian population.

Maternal ancestry and hematological cancer risk: case-control study in an Argentinean population

Aim: We investigated the role of maternal ancestry in neoplastic hematological malignancies (HMs) risk in a population from Central Argentina. Materials & methods: We analyzed 125 cases with HMs and 310 controls from a public hospital, and a set of 202 colorectal, breast, lung, and hematologic cancer patients from a private hospital. Results: A decreased risk for HMs was associated with the Native American haplogroup B2 (odds ratio = 0.49; 95% CI: 0.25-0.92; p = 0.02). The sub-Saharan African parahaplogroup L was associated with higher susceptibility for disease (odds ratio = 3.10; 95% CI: 1.04-9.31; p = 0.043). Although the mean ancestral proportions in the total studied population was as published (61.7% Native American, 34.6% European and 3.7% African), an unequal distribution was observed between hospitals. Conclusion: We confirmed the tri-hybrid nature of the Argentinean population, with proportions varying within the country. Our finding supports the notion that associated haplogroup is population and cancer specific.

Mitochondrial DNA Haplotypes as Genetic Modifiers of Cancer

Mitochondria play an essential role in cellular metabolism, generation of reactive oxygen species (ROS), and the initiation of apoptosis. These properties enable mitochondria to be crucial integrators in the pathways of tumorigenesis. An open question is to what extent variation in the mitochondrial genome (mtDNA) contributes to the biological heterogeneity observed in human tumors. In this review, we summarize our current understanding of the role of mtDNA genetics in relation to human cancers.

Reduced mitochondrial DNA copy number is associated with the haplogroup, and some clinical features of breast cancer in Mexican patients

Mitochondrial DNA (mtDNA) copy number and mitochondrial DNA haplogroups have been associated with different types of cancer, including breast cancer, because they alter cellular energy metabolism. However, whether mtDNA copy number or haplogroups are predictors of oxidative stress-related risks in human breast cancer tissue in Mexican patients remains to be determined. Using quantitative real-time PCR assays and sequencing of the mtDNA hypervariable region, analysis of mtDNA copy numbers in 82 breast cancer tissues (BCT) and matched normal adjacent tissues (NAT) was performed to determine if copy number correlated with clinical features and Amerindian haplogroups (A2, B2, B4, C1 and D1) . The results showed that the mtDNA copy number was significantly decreased in BCT compared with NAT (p = 0.010); it was significantly decreased in BCT and NAT in women > 50 years of age, compared with NAT in women < 50 years of age (p = 0.032 and p = 0.037, respectively); it was significantly decreased in NAT and BCT in the postmenopausal group and in BCT in the premenopausal group compared with NAT in the premenopausal group (p = 0.011, p = 0.010 and, p = 0.018; respectively); and it was also significantly decrease in members of the BCT group classified as having invasive ductal carcinoma I-III (IDC-I, IDC-II and IDC-III) and IDC-II for NAT compared to IDC-I of NAT (p = 0.025, p = 0.022 and p = 0.031 and p = 0.020; respectively). The mtDNA copy number for BCT from patients with haplogroup B2 was decreased compared to patients with haplogroup D1 (p = 0.01); for BCT from patients with haplogroup C1 was also decreased compare with their NAT counterpart (p = 0.006) and with BCT patients belonging to haplogroups A2 and D1 (p = 0.01 and p = 0.03; respectively). In addition, the mtDNA copy number was decrease in the sequences with three deletions relative to the rCRS at nucleotide positions A249del, A290del and A291del, or C16327T polymorphism with the same p = 0.019 for all four variants. Contrary, the copy number increased in sequences containing C16111T, G16319A or T16362C polymorphisms (p = 0.021, =0.048, and = 0.001; respectively). In conclusion, a decrease in the copy number of mtDNA in BCT compared with NAT was shown by the results, which suggests an imbalance in oxidative phosphorylation (OXPHOS) that can affect the apoptosis pathway and cancer progression. It was also observed an increase of the copy number in samples with specific polymorphisms, which may be a good sign of favourable prognosis.

Cross-sectional associations between angiotensin-converting enzyme inhibitor use and cancer diagnosis in US adults

The objective of the present study was to investigate the association between angiotensin-converting enzyme (ACE) inhibitor use and cancer incidence (overall, and breast, prostate, and colorectal cancers specifically) in a large representative sample of US adults. Cross-sectional data on cancer diagnosis, timing of cancer diagnosis, ACE inhibitor use, and other characteristics were extracted from 49 512 adults aged ≥ 20 years participating in the National Health and Nutrition Examination Survey (1999-2016). Multivariable-logistic and propensity score matching (PSM) regressions examined the relationship between pre-diagnosis use of ACE inhibitors and diagnosis of all cancers, and breast, prostate, and colorectal cancers specifically. Overall, we observed an increased likelihood of cancer diagnosis [odds ratio (OR) 1.269, 95% confidence interval (CI) 1.088-1.480] among those who used ACE inhibitors compared to non-ACE inhibitor use, and for prostate cancer diagnosis (OR 1.438, 95% CI 1.090-1.897), after adjusting for age, sex, body mass index, race/ethnicity, educational attainment, physical activity, alcohol drinking status, smoking status, and high blood pressure. PSM regression retrieved more conservative estimates such that the increased likelihood of cancer diagnosis was only observed when comparing ACE inhibitor users with non-drug users (OR 1.022, 95% CI 1.016-1.027). Compared with non-ACE inhibitor use, ACE inhibitor use was associated with an increased risk of prostate cancer. In conclusion, in this large representative sample of US adults, it was found that ACE inhibitor use may have a marginal influence on some cancers.

Whole mitochondrial genome sequencing highlights mitochondrial impact in gastric cancer

Mitochondria are organelles that perform major roles in cellular operation. Thus, alterations in mitochondrial genome (mtGenome) may lead to mitochondrial dysfunction and cellular deregulation, influencing carcinogenesis. Gastric cancer (GC) is one of the most incident and mortal types of cancer in Brazil, particularly in the Amazon region. Here, we sequenced and compared the whole mtGenome extracted from FFPE tissue samples of GC patients (tumor and internal control – IC) and cancer-free individuals (external control – EC) from this region. We found 3-fold more variants and up to 9-fold more heteroplasmic regions in tumor when compared to paired IC samples. Moreover, tumor presented more heteroplasmic variants when compared to EC, while IC and EC showed no significant difference when compared to each other. Tumor also presented substantially more variants in the following regions: MT-RNR1, MT-ND5, MT-ND4, MT-ND2, MT-DLOOP1 and MT-CO1. In addition, our haplogroup results indicate an association of Native American ancestry (particularly haplogroup C) to gastric cancer development. To the best of our knowledge, this is the first study to sequence the whole mtGenome from FFPE samples and to apply mtGenome analysis in association to GC in Brazil.