Therapeutic effect of green tea extract on alcohol induced hepatic mitochondrial DNA damage in albino wistar rats

The present study principally sought to investigate the effect of green tea extract (GTE) supplementation on hepatic mitochondrial DNA (mtDNA) damage in alcohol receiving rats. MtDNA was isolated from hepatic tissues of albino wistar rats after alcohol treatment with and without GTE supplementation. Entire displacement loop (D-loop) of mtDNA was screened by PCR-Sanger’s sequencing method. In addition, mtDNA deletions and antioxidant activity were measured in hepatic tissue of all rats. Results showed increased frequency of D-loop mutations in alcoholic rats (ALC). DNA mfold analysis predicted higher free energy for 15507C and 16116C alleles compared to their corresponding wild alleles which represents less stable secondary structures with negative impact on overall mtDNA function. Interestingly, D-loop mutations observed in ALC rats were successfully restored on GTE supplementation. MtDNA deletions were observed in ALC rats, but intact native mtDNA was found in ALC + GTE group suggesting alcohol induced oxidative damage of mtDNA and ameliorative effect of GTE. Furthermore, markedly decreased activities of glutathione peroxidise, superoxide dismutase, catalase and glutathione content were identified in ALC rats; however, GTE supplementation significantly (P < 0.05) restored these levels close to normal. In conclusion, green tea could be used as an effective nutraceutical against alcohol induced mitochondrial DNA damage

Mitochondrial Control Region Alterations and Breast Cancer Risk: A Study in South Indian Population

<div><p>Background</p><p>Mitochondrial displacement loop (D-loop) is the hot spot for mitochondrial DNA (mtDNA) alterations which influence the generation of cellular reactive oxygen species (ROS). Association of D-loop alterations with breast cancer has been reported in few ethnic groups; however none of the reports were documented from Indian subcontinent.</p><p>Methodology</p><p>We screened the entire mitochondrial D-loop region (1124 bp) of breast cancer patients (n = 213) and controls (n = 207) of south Indian origin by PCR-sequencing analysis. Haplotype frequencies for significant loci, the standardized disequilibrium coefficient (D′) for pair-wise linkage disequilibrium (LD) were assessed by Haploview Software.</p><p>Principal Findings</p><p>We identified 7 novel mutations and 170 reported polymorphisms in the D-loop region of patients and/or controls. Polymorphisms were predominantly located in hypervariable region I (60%) than in II (30%) of D-loop region. The frequencies of <i>310‘C’</i> insertion (<i>P</i> = 0.018), <i>T16189C</i> (<i>P</i> = 0.0019) variants and <i>310‘C’ins/16189C</i> (<i>P</i> = 0.00019) haplotype were significantly higher in cases than in controls. Furthermore, strong LD was observed between nucleotide position 310 and 16189 in controls (D′ = 0.49) as compared to patients (D′ = 0.14).</p><p>Conclusions</p><p>Mitochondrial D-loop alterations may constitute inherent risk factors for breast cancer development. The analysis of genetic alterations in the D-loop region might help to identify patients at high risk for bad progression, thereby helping to refine therapeutic decisions in breast cancer.</p></div

Graphical representation of minor allele frequencies of significant D-loop SNPs in breast cancer patients with different clinical parameters:

<p>(A) breast cancer stage; (B) menopausal status; (C) estrogen receptor status; (D) progesterone receptor status; (E) human epidermal growth factor receptor 2 status. Asterisk (*) indicates the significant difference (<i>P</i><0.05, as determined by the Student’s t-test) between patient groups with different clinical parameters. Percentage values were used for statistical analysis.</p

Linkage disequilibrium (LD) analysis of significant D-loop SNPs in cases and controls:

<p>Haploview plots are presented along the single nucleotide polymorphisms studied. The pair-wise linkage disequilibrium values (D′ = 0–100) of all significant SNPs are given in each diamond. A value of 100 represents maximum possible linkage disequilibrium.</p

Novel mutations detected in mitochondrial D-loop region of breast cancer patients.

<p>rCRS: Revised Cambridge Reference Sequence.</p><p>IUPAC: International Union of Pure and Applied Chemistry.</p

Novel mutations observed in D-loop region of breast cancer patients:

<p>(A) 12 ‘C’ insertion; (B) A37G transition; (C) A238G transition; (D) C463T transition; (E) C566G transversion; (F) T16445C transition; (G) G16485A transition.</p