Identification of candidate polymorphisms on stress oxidative and DNA damage repair genes related with clinical outcome in breast cancer patients

Emerging Roles of Xanthine Oxidoreductase in Chronic Kidney Disease

Xanthine Oxidoreductase (XOR) is a ubiquitous, essential enzyme responsible for the terminal steps of purine catabolism, ultimately producing uric acid that is eliminated by the kidneys. XOR is also a physiological source of superoxide ion, hydrogen peroxide, and nitric oxide, which can function as second messengers in the activation of various physiological pathways, as well as contribute to the development and the progression of chronic conditions including kidney diseases, which are increasing in prevalence worldwide. XOR activity can promote oxidative distress, endothelial dysfunction, and inflammation through the biological effects of reactive oxygen species; nitric oxide and uric acid are the major products of XOR activity. However, the complex relationship of these reactions in disease settings has long been debated, and the environmental influences and genetics remain largely unknown. In this review, we give an overview of the biochemistry, biology, environmental, and current clinical impact of XOR in the kidney. Finally, we highlight recent genetic studies linking XOR and risk for kidney disease, igniting enthusiasm for future biomarker development and novel therapeutic approaches targeting XOR.

Variability of DNA Repair and Oxidative Stress Genes Associated with Worst Pain in Breast Cancer Survivors on Aromatase Inhibitors

Pain is a problem affecting women with breast cancer (HR+BrCa) receiving aromatase inhibitor (AI) therapy. We investigated the relationship between single-nucleotide polymorphisms (SNPs) in DNA repair and oxidative stress genes and perceived worst pain after 6 months of AI therapy. We explored 39 SNPs in genes involved in DNA repair (ERCC2, ERCC3, ERCC5, and PARP1) and oxidative stress (CAT, GPX1, SEPP1, SOD1, and SOD2) in women with HR+BrCa receiving adjuvant therapy (AI ± chemotherapy; n = 138). Pain was assessed via the Brief Pain Inventory. Hurdle regression was used to evaluate the relationship between each associated allele and (1) the probability of pain and (2) the severity of worst pain. ERCC2rs50872 and ERCC5rs11069498 were associated with the probability of pain and had a significant genetic risk score (GRS) model (p = 0.003). ERCC2rs50872, ERCC5rs11069498, ERCC5rs4771436, ERCC5rs4150360, PARP1rs3219058, and SEPP1rs230819 were associated with the severity of worst pain, with a significant GRS model (conditional mean estimate = 0.45; 95% CI = 0.29, 0.60; p < 0.001). These results suggest DNA repair and oxidative stress pathways may play a role in the probability of pain and the severity of worst pain. As healthcare delivery moves towards the model of precision healthcare, nurses may, in the future, be able to use these results to tailor patient care based on GRS.

Genetic variation at the catalytic subunit of glutamate cysteine ligase contributes to the susceptibility to sporadic colorectal cancer: a pilot study

BACKGROUND

Glutathione is a tripeptide detoxifying a variety of exogenous and endogenous free radicals and carcinogens, and a deficiency of glutathione is associated with an increased host susceptibility to oxidative stress, a pathological condition implicated in the development and progression of cancer. The catalytic subunit of glutamate-cysteine ligase (GCLC) is an enzyme responsible for the initial and rate-limiting step of glutathione biosynthesis.

METHODS AND RESULTS

The aim of this pilot study was to investigate whether genetic variation at the GCLC gene contributes to the risk of colorectal cancer (CRC). DNA samples from 681 unrelated Russian individuals (283 patients with CRC and 398 age- and sex-matched healthy controls) were genotyped for six common functional SNPs of the GCLC gene (SNPs) such as rs12524494, rs17883901, rs606548, rs636933, rs648595 and rs761142 of the GCLC gene using the MassARRAY-4 system. We found that genotype rs606548-C/T is significantly associated with increased risk of CRC regardless of sex and age (OR 2.24; 95% CI 1.24-4.03; P = 0.007, FDR = 0.04). Moreover, ten GCLC genotype combinations showed association with the risk of CRC (P < 0.05). Functional SNP annotation enabled establishing the CRC-associated polymorphisms are associated with a decreased GCLC expression that may be attributed to epigenetic effects of histone modifications operating in a colon-specific manner.

CONCLUSIONS

The present study was the first to show that genetic variation at the catalytic subunit of glutamate-cysteine ligase may contribute to the risk of colorectal cancer risk. However, further genetic association studies with a larger sample size are required to substantiate the role of GCLC gene polymorphisms in the development of sporadic colorectal cancer.

Genetic variants in XDH are associated with prognosis for gastric cancer in a Chinese population

OBJECTIVE

We explored the association between single nucleotide polymorphisms (SNPs) rs207454 and rs494852 located in xanthine dehydrogenase (XDH) and gastric cancer (GC) survival.

METHODS

A total of 940 patients with gastric cancer were enrolled and genotyped using TaqMan allelic discrimination method. The Kaplan-Meier test and log-rank examine were used to assess the effect of genetic variation.

RESULTS

Patients carrying rs207454 CC genotype had a longer survival time than those with the AA genotype (P = 0.042). The similar association was detected in the recessive model (P = 0.017). We conducted expression quantitative trait loci (eQTL) analysis and found that gastric cancer patients carrying rs207454 CC genotype had significant lower XDH levels than those with AA/AC genotype, suggesting that rs207454 polymorphism effected the expression of XDH. Additionally, the Kaplan-Meier curves showed that gastric cancer patients with high expression of XDH had remarkably poor survival outcome than those with low expression (hazard ratio [HR] = 1.53, 95% confidence interval [CI] = 1.29-1.82).

CONCLUSIONS

Genetic variants in XDH were associated with the survival of gastric cancer and may act as prognostic markers for individual suffered from gastric cancer.

Association study of TGFBR2 and miR-518 gene polymorphisms with age at natural menopause, premature ovarian failure, and early menopause among Chinese Han women

Age at natural menopause (ANM), a highly heritable phenotype, has been identified to be closely associated with major hormone-related diseases, including breast cancer and gynecological cancers. We previously identified an important role for the transforming growth factor, β receptor II (TGFBR2) gene polymorphisms in breast cancer susceptibility among Asian women. Considering the important role of ANM in breast carcinogenesis, we hypothesized that TGFBR2 signals were involved in the formation of natural menopause.In a population-based study of 1844 Chinese women, we evaluated the effect of the genetic polymorphisms of TGFBR2 and miR-518 to determine if they are associated with ANM, premature ovarian failure (POF), and early menopause (EM) risk.No significant differences in the distribution of body mass index, education levels, smoking, drinking, and hypertension were detected between POF and EM cases and controls except for POF cases that were older (P = 0.015) than controls and more likely to have dyslipidemia (P = 0.002). The results showed that miR-518 rs7256241 was significantly associated with ANM. The carriers of minor allele G of rs7256241 have significantly higher ANM than those of the major allele homozygotes TT (β = 0.385, P = 0.035). TGFBR2 rs3773661 was significantly associated with POF, with odds ratio (OR) (95% confidence intervals [CIs]) of 0.66 (0.47-0.94) associated with per minor allele C (P = 0.023). The quartiles of genetic risk score were significantly associated with POF (OR, 1.27; 95% CI, 1.02-1.58; Ptrend = 0.034). Sensitivity analyses confirmed the robustness of these findings and no significant interactions were detected.This study provides evidence to implicate TGFBR2 and miR-518 gene polymorphisms as novel susceptibility factors for ANM, POF, and EM in Asians. Further research on these genetic regions will enhance our understanding of the genetic basis of natural menopause.