Association of NQO1 polymorphism with spontaneous breast cancer in two independent populations

Impact of NQO1 dysregulation in CNS disorders

NAD(P)H Quinone Dehydrogenase 1 (NQO1) plays a pivotal role in the regulation of neuronal function and synaptic plasticity, cellular adaptation to oxidative stress, neuroinflammatory and degenerative processes, and tumorigenesis in the central nervous system (CNS). Impairment of the NQO1 activity in the CNS can result in abnormal neurotransmitter release and clearance, increased oxidative stress, and aggravated cellular injury/death. Furthermore, it can cause disturbances in neural circuit function and synaptic neurotransmission. The abnormalities of NQO1 enzyme activity have been linked to the pathophysiological mechanisms of multiple neurological disorders, including Parkinson's disease, Alzheimer's disease, epilepsy, multiple sclerosis, cerebrovascular disease, traumatic brain injury, and brain malignancy. NQO1 contributes to various dimensions of tumorigenesis and treatment response in various brain tumors. The precise mechanisms through which abnormalities in NQO1 function contribute to these neurological disorders continue to be a subject of ongoing research. Building upon the existing knowledge, the present study reviews current investigations describing the role of NQO1 dysregulations in various neurological disorders. This study emphasizes the potential of NQO1 as a biomarker in diagnostic and prognostic approaches, as well as its suitability as a target for drug development strategies in neurological disorders.

Upregulation of p53 by tannic acid treatment suppresses the proliferation of human colorectal carcinoma

The present study's objective is to clarify the molecular mechanisms of tannic acid effects on the viability of human colorectal carcinoma (CRC). Tannic acid is stable for up to 48 h and is localized in both cytoplasm and nucleus. It dose-dependently inhibited the viability of CRC cell lines; SW-620 and HT-29 with IC ₅₀ values of 7.2 ± 0.8 and 37.6 ± 1.4 µmol L^-1. Besides, metastatic, invasive, and colony formation properties of CRC cells were significantly inhibited following the tannic acid treatment (p < 0.001). Tannic acid has been found to modulate enzyme, protein, and gene expressions of NQO1 in different levels and the upregulation of protein/gene expressions of p53 (p < 0.001), which leads the cells to trigger apoptosis. In conclusion, the present in vitro study may supply a significant background for in vivo studies in which the molecular mechanisms of antioxidant and chemopreventive activities of tannic acid will completely clarify.

Genetic polymorphisms on the effectiveness or safety of breast cancer treatment: Clinical relevance and future perspectives

Breast cancer (BC) is the most frequent neoplasm and one of the main causes of death in women. The pharmacological treatment of BC consists of hormonal therapy, chemotherapeutic agents and targeted therapy. The response to BC therapy is highly variable in clinical practice. This variability can be explained by the presence of genetic polymorphisms in genes involved in the pharmacokinetics, pharmacodynamics or immune response of patients. The abundant evidence of associations between low-activity alleles CYP2D6*3, *4, *5, *6, *10 and *41 and poor results with tamoxifen therapy, and between DPYD gene polymorphisms rs3918290, rs55886062, rs67376798 and rs75017182 and increased risk of toxicity to fluoropyrimidine therapy, justify the existence of clinical pharmacogenetic guidelines. The NQO1 rs1800566 polymorphism is related to poorer results in BC therapy with chemotherapy agents. The polymorphism rs1695 of the GSTP1 gene has been associated with the effectiveness and toxicity of fluorouracil, cyclophosphamide and epirubicin therapy. Finally, the HLA-DQA1*02:01 allele is significantly associated with the occurrence of liver toxicity events in patients receiving lapatinib. There is moderate evidence to support the aforementioned associations and, therefore, a high probability of these being considered as future predictive genetic biomarkers of response. However, further studies are required to reinforce or clarify their clinical relevance.

Impact of xenobiotic-metabolizing gene polymorphisms on breast cancer risk in South Indian women

BACKGROUND

Functional variants of the xenobiotic-metabolizing genes (XMG) might modulate breast cancer (BC) risk by altering the rate of metabolism and clearance of myriad types of potent carcinogens from the breast tissue. Despite mounting evidence on the role of XMG variants on BC risk, the current knowledge regarding their influence on BC development is still fragmentary.

METHODS

The present study examined the candidate genetic variants in CYP1A1, NQO1, GST-T1, GST-M1, and GST-P1 in 1002 subjects (502 BC patients and 500 disease-free women). PCR-RFLP was employed to genotype the mono-nucleotide variation in CYP1A1, NQO1, and GST-P1, and allele-specific PCR was used to detect the deletion polymorphism in GST-T1 and GST-M1 genes.

RESULTS

Regarding CYP1A1-M1 polymorphism, the heterozygous TC and mutant CC genotype conferred 1.47-fold (95% CI 1.13-1.91, p = 0.004) and 1.84-fold (95% CI 1.17-2.91, p = 0.009) elevated risk of BC. GST-T1 null genotype was associated with increased BC risk (OR 1.47; 95% CI 1.02-2.11, p = 0.037). For the NQO1 C609T variant, the mutant T allele was associated with BC risk with an odds ratio of 1.22 (95% CI 1.02-1.48, p = 0.034). Combinatorial analysis indicated that the presence of NQO1*2 (CT), CYP1A1-M1 (CC), and GST-P1 rs1695 (AG) genotypes conferred 16.7-fold elevated risk of BC (95% CI 3.65-76.85; p < 0.001). Moreover, GST-M1 null genotype was associated with the development of larger primary breast tumors.

CONCLUSION

Xenobiotic-metabolizing gene polymorphisms may play a crucial role in mammary carcinogenesis in South Indian women.

p.Arg72Pro polymorphism of P53 and breast cancer risk: a meta-analysis of case-control studies

Background

The effect of the p.Arg72Pro variant of the P53 gene on the risk of development ofbreast cancer remains variable in populations. However, the use ofstrategies such aspoolingage-matched controls with disease may provide a consistent meta-analysis. Our goal was to perform a meta-analysis in order to assess the association of p.Arg72Pro variant of P53 gene with the risk of breast cancer.

Methods

Databases such as PubMed, Genetics Medical Literature, Harvard University Library, Web of Science and Genesis Library were used to search articles. Case-control studies with age-matched on breast cancer havingevaluated the genotype frequencies of the TP53 p.Arg72Pro polymorphism were selected. The fixed and random effects (Mantel-Haenszel) were calculated using pooled odds ratio of 95% CI to determine the risk of disease. Inconsistency was calculated to determine heterogeneity among the studies. The publication bias was estimated using the funnel plot.

Results

Twenty-one publications with 7841 cases and 8876 controls were evaluated in this meta-analysis. Overall, our results suggested that TP53 p.Arg72Pro was associated with the risk of breast cancer for the dominant model (OR = 1.09, 95% CI = 1.02–1.16, P = 0.01) and the additive model (OR = 1.09, 95% CI = 1.01–1.17, P = 0.03), but not for the recessive model (OR = 1.07, 95% CI = 0.97–1.18, P = 0.19). According to the ethnic group analysis, Pro allele was associated with the risk of breast cancer in Caucasians for the dominant model and additive model (P = 0.02), and Africans for the recessive model and additive model (P = 0.03).

Conclusions

This meta-analysis found a significant association between TP53 p.Arg72Pro polymorphism and the risk of breast cancer. Individuals carrying at least one Pro allele were more likely to have breast cancer than individuals harboring the Arg allele.

Keap1/Nrf2 Signaling: A New Player in Thyroid Pathophysiology and Thyroid Cancer

The Keap1/Nrf2 pathway is a key mediator of general redox and tissue-specific homeostasis. It also exerts a dual role in cancer, by preventing cell transformation of normal cells but promoting aggressiveness, and drug resistance of malignant ones. Although Nrf2 is well-studied in other tissues, its roles in the thyroid gland are only recently emerging. This review focuses on the involvement of Keap1/Nrf2 signaling in thyroid physiology, and pathophysiology in general, and particularly in thyroid cancer. Studies in mice and cultured follicular cells have shown that, under physiological conditions, Nrf2 coordinates antioxidant defenses, directly increases thyroglobulin production and inhibits its iodination. Increased Nrf2 pathway activation has been reported in two independent families with multinodular goiters due to germline loss-of-function mutations in KEAP1. Nrf2 pathway activation has also been documented in papillary thyroid carcinoma (PTC), due to somatic mutations, or epigenetic modifications in KEAP1, or other pathway components. In PTC, such Nrf2-activating KEAP1 mutations have been associated with tumor aggressiveness. Furthermore, polymorphisms in the prototypical Nrf2 target genes NQO1 and NQO2 have been associated with extra-thyroidal extension and metastasis. More recently, mutations in the Nrf2 pathway have also been found in Hürthle-cell (oncocytic) thyroid carcinoma. Finally, in in vitro, and in vivo models of poorly-differentiated, and undifferentiated (anaplastic) thyroid carcinoma, Nrf2 activation has been associated with resistance to experimental molecularly-targeted therapy. Thus, Keap1/Nrf2 signaling is involved in both benign and malignant thyroid conditions, where it might serve as a prognostic marker or therapeutic target.

Joint effect of smoking and NQO1 C609T polymorphism on undifferentiated nasopharyngeal carcinoma risk in a North African population

BACKGROUND

Nasopharyngeal carcinoma (NPC) has a higher incidence in North Africa than in most parts of the world. In addition to environmental factors such as Epstein-Barr virus infection and chemical carcinogen exposure, genetic susceptibility has been reported to play a key role in the development of NPC. NAD(P)H: quinone oxidoreductase 1 is a cytosolic enzyme that protects cells from oxidative damage. A C to T transition at position 609 in the NQO1 gene (OMIM: 125860) has been shown to alter the enzymatic activity of the enzyme and has been associated with increased risk to several cancers. This study investigates for the first time the effect of this polymorphism on NPC susceptibility in a North African population.

METHODS

The NQO1 C609T polymorphism was genotyped using PCR-RFLP in 392 NPC cases and 365 controls from Morocco, Algeria, and Tunisia.

RESULTS

The allele frequencies and distributions of genotypes did not differ between cases and controls (p > 0.05). When stratifying according to smoking status, we observed two-fold higher NPC risk in ever-smokers carrying the CT or TT genotype. Multiple logistic regression analysis revealed that there was a significant interaction between T allele and smoking status (OR = 1.95, 95% CI = 1.20-3.19; interaction p = 0.007).

CONCLUSION

In this North African population, the functional NQO1 polymorphism was associated with a significantly higher risk of NPC among smokers and did not affect the risk among nonsmokers.

Association between the BRCA2 rs144848 polymorphism and cancer susceptibility: a meta-analysis

The BRCA2 gene plays an important role in cancer carcinogenesis, and polymorphisms in this gene have been associated with cancer risk. The BRCA2 rs144848 polymorphism has been associated with several cancers, but results have been inconsistent. In the present study, a meta-analysis was performed to assess the association between the rs144848 polymorphism and cancer risk. Literature was searched from the databases of PubMed, Embase and Google Scholar before April 2016. The fixed or random effects model was used to calculate pooled odd ratios on the basis of heterogeneity. Meta-regression, sensitivity analysis, subgroup analysis and publication bias assessment were also performed using STATA 11.0 software according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2009. A total of 40 relevant studies from 30 publications including 34,911 cases and 48,329 controls were included in the final meta-analysis. Among them, 22 studies focused on breast cancer, seven on ovarian cancer, five on non-Hodgkin lymphoma, and the remaining six studies examined various other cancers. The meta-analysis results showed that there were significant associations between the rs144848 polymorphism and cancer risk in all genetic models. Stratified by cancer type, the rs144848 polymorphism was associated with non-Hodgkin lymphoma. Stratified by study design, the allele model was associated with breast cancer risk in population-based studies. The meta-analysis suggests that the BRCA2 rs144848 polymorphism may play a role in cancer risk. Further well-designed studies are warranted to confirm these results.

Using a novel NQO1 bioactivatable drug, beta-lapachone (ARQ761), to enhance chemotherapeutic effects by metabolic modulation in pancreatic cancer

Novel, tumor-selective therapies are needed to increase the survival rate of pancreatic cancer patients. K-Ras-mutant-driven NAD(P)H:quinone oxidoreductase 1 (NQO1) is over-expressed in pancreatic tumor versus associated normal tissue, while catalase expression is lowered compared to levels in associated normal pancreas tissue. ARQ761 undergoes a robust, futile redox cycle in NQO1+ cancer cells, producing massive hydrogen peroxide (H2 O2 ) levels; normal tissues are spared by low NQO1 and high catalase expression. DNA damage created by ARQ761 in pancreatic cancer cells "hyperactivates" PARP1, causing metabolic catastrophe and NAD ± keresis cell death. NQO1: catalase levels (high in tumor, low in normal tissue) are an attractive therapeutic window to treat pancreatic cancer. Based on a growing body of literature, we are leading a clinical trial to evaluate the combination of ARQ761 and chemotherapy in patients with pancreatic cancer.

The relationship between apolipoprotein E gene ε2/ε3/ε4 polymorphism and breast cancer risk: a systematic review and meta-analysis

Objective

We conducted a systematic review and meta-analysis aiming to assess the relationship between apolipoprotein E (APOE) gene ε2/ε3/ε4 polymorphism and breast cancer risk.

Methods

Yun-Long Liu and Hao-Min Zhang independently completed literature retrieval and data collection, and statistical analyses were performed by Stata. Individual odds ratio (OR) and 95% confidence interval (CI) were pooled in a random-effects model using the DerSimonian–Laird method. Heterogeneity was evaluated by I² statistic at a significance level of 50%. Publication bias was assessed by Egger’s test.

Results

Eleven articles including 2,074 breast cancer patients and 2,372 controls were summarized. Using the most common allele ε3 as a reference, the ε2 (OR =0.87, 95% CI =0.72–1.05, P=0.154, I²=0.0%) and ε4 (OR =1.07, 95% CI =0.80–1.42, P=0.654, I²=71.8%) alleles were not found to be significantly associated with breast cancer risk in the overall analyses. Subgroup analyses revealed that the comparison of allele ε4 with ε3 was significant in Asians (OR =1.58, 95% CI =1.17–6.32, P=0.003, I²=12.1%) and in studies that used the restriction fragment length polymorphism (RFLP) genotyping method (OR =1.27; 95% CI =1.01–1.61, P=0.045, I²=34.3%), and was marginally significant in hospital-based studies (OR =1.33; 95% CI =0.98–1.79, P=0.065, I²=30.2%), without heterogeneity. Moreover, the presence of the ε2 allele was significantly associated with breast cancer in small studies (total sample size <500) (OR =0.73, 95% CI =0.54–1.00, P=0.052, I²=0.0%) without heterogeneity. The Egger’s test indicated low probabilities of publication bias.

Conclusion

We observed a significant association between APOE gene ε4 allele and breast cancer risk in Asian populations. Moreover, the findings of our subgroup analyses suggest that source of controls, genotyping platform, and sample size might be the potential causes of heterogeneity.

The C609T (Pro187Ser) Null Polymorphism of the NQO1 Gene Contributes Significantly to Breast Cancer Susceptibility in North Indian Populations: a Case Control Study

BACKGROUND

Worldwide, breast cancer is the most common cancer among women and is a leading cause of cancer death. In the present study, we investigated the NQO1 C609T genotypic and allelic distribution in north Indian breast cancer patients.

MATERIALS AND METHODS

The genotypic distribution of the NQ01 C609T polymorphism was assessed in 100 invasive ductal carcinoma (IDC) breast cancer patients and 100 healthy controls using allele specific PCR (AS-PCR).

RESULTS

A lower frequency of the CC genotype was found in breast cancer patients (24%) than in the controls. On the other hand, TT genotype frequency was also found to be higher in female healthy controls (32%) than the female breast cancer patients (20%). The frequencies of all three genotypes CC, CT, TT in patients were 24%, 56% and 20% and in healthy controls 50%, 22% and 32% respectively. We did not find any significant correlation between the NQO1 C609T polymorphism and age group, grading, menopausal status and distant metastasis. A less significant association was found between the NQ01 C609T polymorphism and the stage of breast cancer (X2=5.931, P=0.05).

CONCLUSIONS

The present study shows a strong association between NQO1 C609T polymorphism with the breast cancer risk in the north Indian breast cancer patients so that possible use as a risk factor should be further explored.

Implications of NQO1 in cancer therapy

NAD(P)H

quinone oxidoreductase (NQO1), an obligatory two-electron reductase, is a ubiquitous cytosolic enzyme that catalyzes the reduction of quinone substrates. The NQO1- mediated two-electron reduction of quinones can be either chemoprotection/detoxification or a chemotherapeutic response, depending on the target quinones. When toxic quinones are reduced by NQO1, they are conjugated with glutathione or glucuronic acid and excreted from the cells. Based on this protective effect of NQO1, the use of dietary compounds to induce the expression of NQO1 has emerged as a promising strategy for cancer prevention. On the other hand, NQO1-mediated two-electron reduction converts certain quinone compounds (such as mitomycin C, E09, RH1 and -lapachone) to cytotoxic agents, leading to cell death. It has been known that NQO1 is expressed at high levels in numerous human cancers, including breast, colon, cervix, lung, and pancreas, as compared with normal tissues. This implies that tumors can be preferentially damaged relative to normal tissue by cytotoxic quinone drugs. Importantly, NQO1 has been shown to stabilize many proteins, including p53 and p33ING1b, by inhibiting their proteasomal degradation. This review will summarize the biological roles of NQO1 in cancer, with emphasis on recent findings and the potential of NQO1 as a therapeutic target for the cancer therapy.

Causal relevance of circulating high-density lipoprotein cholesterol with cancer: a Mendelian randomization meta-analysis

We summarized published data on the associations of apolipoprotein E (APOE) gene ε2/ε3/ε4 polymorphism with both cancer risk and circulating lipid profiles, aiming to examine the causal relevance between lipids and cancer risk. Article identification and data abstraction were conducted in duplicate and independently by two authors. Data were analyzed by STATA software. Twenty-five articles that examined the associations of APOE gene ε2/ε3/ε4 polymorphism with either cancer risk (n = 22) or circulating lipid changes (n = 4) were eligible. The presence of ε2 and ε4 alleles showed no overall associations with overall cancer risk when compared with ε3 allele. The ε4 allele was significantly associated with 1.40-fold (odds ratio or OR = 1.40; 95% confidence interval or CI: 1.00–1.94; P = 0.047) increased risk of developing cancer in Asian populations, and the presence of heterogeneity was low (I² = 37.6%). Carriers of ε3/ε4 genotype had a significant reduction in circulating HDL-C (WMD = −2.62; 95% CI: −4.19 to −1.04; P = 0.001) without heterogeneity (I² = 16.6%). The predicted odds of having cancer for 1 mg/dL reduction in circulating HDL-C was 1.14 (95% CI: 1.00 to 1.89). The findings of this Mendelian randomization meta-analysis demonstrate that reduced circulating HDL-C might be a potentially causal risk factor for the development of overall cancer in Asians.

Interactive effect of smoking and NQO1 haplotypes on lung cancer risk

The role of genetic polymorphisms of

NAD(P)H

quinone oxidoreductase 1 (NQO1), which is known to be related to carcinogen metabolism and oxidative status, was evaluated for lung cancer development. The genotypes of two NQO1 polymorphisms, namely, IVS1-27C>G and Ex6+40C>T, were determined in 616 lung cancer cases and 616 lung cancer-free controls and haplotypes composed of the two polymorphisms were estimated. In the evaluation of the effect of the NQO1 genotypes or diplotypes, we did not find any significant association with lung cancer risk after adjusting for body mass index and smoking status. However, when we evaluated the effect of the NQO1 diplotypes for lung cancer risk in combination with smoking, smokers without the C-T/C-T diplotype showed a significantly increased risk of lung cancer compared with nonsmokers without the C-T/C-T diplotype (adjusted OR, 2.2; 95% CI, 1.67-3.02), and smokers with the C-T/C-T diplotype showed the highest OR of lung cancer (adjusted OR, 2.7; 95% CI, 1.78-4.21). Moreover, a trend test showed an additive interaction between smoking and the NQO1 C-T/C-T diplotype (P trend < 0.01). The additive effect of smoking and the NQO1 C-T/C-T diplotype was more apparent in squamous cell carcinoma, although this effect was statistically significant in all lung cancer cell types (all cell types, P trend < 0.05). This result suggests that haplotypes of the NQO1 gene play an important role in the development of lung cancer by interaction with smoking.

GSTM1, GSTT1, and NQO1 polymorphisms in cervical carcinogenesis

The aim of the study is to investigate the clinical significance of glutathione-S-transferase GSTM1, GSTT1, and NQO1 c.609C>T (rs1800566) genetic polymorphisms in cervical carcinogenesis. GSTM1, GSTT1, and NQO1 polymorphisms together with human papillomavirus (HPV) types were examined in a total of 192 cervical smear in exfoliated cervical cell samples using polymerase chain reaction (PCR) system and real-time polymerase chain reaction (PCR) system. The 19 patients with high-grade squamous intraepithelial lesion had statistically higher frequency of null GSTT1 genotype than 9 with low-grade squamous intraepithelial lesion (LSIL) among the 67 patients with high-risk HPV (P = 0.024). The 24 patients with HSIL had also statistically higher frequency of NQO1 (CT+TT) genotype than 14 with LSIL among the 67 patients with high-risk HPV (P = 0.024). GSTT1 null and NQO1 genotype in cervical cell samples may be associated with more severe precancerous lesions of the cervix in a Japanese population.

Oxidative stress-related genetic polymorphisms are associated with the prognosis of metastatic gastric cancer patients treated with epirubicin, oxaliplatin and 5-fluorouracil combination chemotherapy

Background

Oxidative stress genes are related to cancer development and treatment response. In this study, we aimed to determine the predictive and prognostic roles of oxidative stress-related genetic polymorphisms in metastatic gastric cancer (MGC) patients treated with chemotherapy.

Methods

In this retrospective study, we genotyped nine oxidative stress-related single nucleotide polymorphisms (SNPs) in NQO1, SOD2, SOD3, PON1, GSTP1, GSTT1, and NOS3 (rs1800566, rs10517, rs4880, rs1799895, rs662, rs854560, rs1695, rs2266637, rs1799983, respectively) in 108 consecutive MGC patients treated with epirubicin, oxaliplatin, and 5-fluorouracil (EOF) regimen as the first-line chemotherapy and analyzed the association between the genotypes and the disease control rate (DCR), progression-free survival (PFS), and overall survival (OS).

Results

We found that, in addition to a lower pathological grade (p = 0.017), NQO1 rs1800566 CT/TT genotype was an independent predictive factor of poor PFS (hazard ratio [HR] = 1.97, 95% confidence interval [CI] = 1.23–3.16; p = 0.005). PON1 rs662 AA/AG genotype was significantly associated with poor OS (HR = 1.95, 95% CI = 1.07–3.54; p = 0.029). No associations were detected between the nine SNPs and DCR.

Conclusions

NQO1 rs1800566 is an independent predictive factor of PFS for MGC patients treated with EOF chemotherapy, and PON1 rs662 is a noteworthy prognostic factor of OS. Information on oxidative stress-related genetic variants may facilitate optimization of individualized chemotherapy in clinical practice.

Association of the TP53 codon 72 polymorphism and breast cancer risk: a meta-analysis

This study was conducted in order to investigate the implications of the R72P polymorphism in the TP53 gene in breast cancer risk. The enlightenment of this matter might provide a piece of information about the potential implications of this polymorphism in patient risk. A meta-analysis was conducted considering a large sample size from studies with conflicting results on the R72P polymorphism in breast cancer patients. Relevant studies were selected from PubMed and SciELO databases for data extraction and statistical analysis. Database was built according to the continent and considering the genotype frequencies, sample size and genotyping methodology. The dominant models (RR vs RP + PP and RR + RP vs. PP), homozygous (RR vs. PP), heterozygous (RR vs. RP and RP vs. PP) and the allele (R vs. P) were used. Genotype frequencies were summarized and evaluated by χ² test of heterogeneity in 2×2 contingency tables with 95% CIs. Odds Ratios (OR) were calculated with a fixed-effect model (Mantel-Haenszel) or a random-effect model (DerSimonian-Laird) if the studies were considered homogeneous (P > 0.05) or heterogeneous (P < 0.05), respectively, using BioEstat® 5.0 software. Supported by a large sample size composed by 25,629 cases and 26,633 controls from 41 studies, we found significant association between the R72P polymorphism in the TP53 gene and the breast cancer risk. The overall data shows an increased risk due to the P allele dominant model, but not in Asia where the risk was associated with the R allele and R dominant model.

Association of BRCA2 N372H polymorphism with cancer susceptibility: a comprehensive review and meta-analysis

BRCA2 gene plays an important role in homologous recombination. Polymorphic variants in this gene has been suggested to confer cancer susceptibility. Numerous studies have investigated association between BRCA2 N372H polymorphism and risk of several cancers, especially breast cancer. However, the results were inconsistent. We performed a comprehensive meta-analysis to provide a more precise assessment of the association between N372H and cancer risk, following the latest meta-analysis guidelines (PRISMA). Forty six studies involving 36299 cases and 48483 controls were included in our meta-analysis. The crude ORs and the 95% CIs were used to evaluate the strength of the association. The results indicated that the BRCA2 N372H variant was significantly associated with an increased risk of overall cancer (dominant model: OR = 1.07, 95% CI = 1.01-1.13; recessive model: OR = 1.12, 95% CI = 1.02-1.23). Moreover, stratified analyses by the cancer type and source of control observed significantly increased risk associated with BRCA2 N372H in subgroups with ovarian cancer, non-Hodgkin lymphoma and population-based controls, but not breast cancer or hospital-based controls. We also found such association among Africans. Overall, the meta-analysis suggested that BRCA2 N372H may be a cancer susceptibility polymorphism. Well-designed and large-scale studies are needed to substantiate the association between BRCA2 N372H polymorphism and cancer risk.

The NQO1 Pro187Ser polymorphism and breast cancer susceptibility: evidence from an updated meta-analysis

Background

NAD(P)H: quinone oxidoreductase 1 (NQO1) plays a central role in catalyzing the two-electron reduction of quinoid compounds into hydroquinones. The NQO1 Pro187Ser polymorphism was found to correlate with a lower enzymatic activity, which may result in increased incidence of carcinomas including breast cancer. Previous studies investigating the association between NQO1 Pro187Ser polymorphism and breast cancer risk showed inconsistent results. We performed a meta-analysis to summarize the possible association.

Methods

All studies published from January 1966 to February 2014 on the association between NQO1 Pro187Ser polymorphism and breast cancer risk were identified by searching electronic databases PubMed, EMBASE, Cochrane library, and Chinese Biomedical Literature database (CBM). The association between NQO1 Pro187Ser polymorphism and breast cancer risk was assessed by odds ratios (ORs) together with their 95% confidence intervals (CIs).

Results

Ten studies with 2,773 cases and 4,076 controls were finally included in the meta-analysis. We did not observe a significant association between NQO1 Pro187Ser polymorphism and breast cancer risk when all studies were pooled into the meta-analysis. In subgroup analysis by ethnicity, significant increased breast cancer risk was found in Caucasians (Ser/Pro vs. Pro/Pro: OR = 1.145, 95% CI = 1.008–1.301, P = 0.038; Ser/Ser + Ser/Pro vs. Pro/Pro: OR = 1.177, 95% CI = 1.041–1.331, P = 0.009). When stratified by source of control, significant increased breast cancer risk was found in population-based studies (Ser/Pro vs. Pro/Pro: OR = 1.180, 95% CI = 1.035–1.344, P = 0.013; Ser/Ser + Ser/Pro vs. Pro/Pro: OR = 1.191, 95% CI = 1.050–1.350, P = 0.007). However, in subgroup analyses according to menopausal status, quality score, and HWE in controls, no any significant association was detected.

Conclusions

Our meta-analysis provides the evidence that the NQO1 Pro187Ser polymorphism contributed to the breast cancer susceptibility among Caucasians. Further large and well-designed studies are needed to confirm this association.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1248639991252504

The NQO1 polymorphism C609T (Pro187Ser) and cancer susceptibility: a comprehensive meta-analysis

Background:

Evidence is increasingly emerging about multiple roles for the NAD(P)H quinone oxidoreductase 1 enzyme in cancer. The C609T (rs1800566, Pro187Ser) null polymorphism of the NQO1 gene contributes significantly to the variation in enzymatic activity across different populations. NQO1 C609T polymorphism was thoroughly investigated with respect to cancer susceptibility. The results were inconsistent partly due to low sample sizes. The aim of the present work was to perform a meta-analysis to assess association for all common cancer sites separately and in combination.

Methods:

Our meta-analysis involved 92 studies including 21 178 cases and 25 157 controls. Statistical analysis involved individual cancer sites and the combined cancer risk. Association was tested under different genetic models.

Results:

We found a statistically significant association between the variant T allele and overall cancer risk in the worldwide population (for the TT vs CC model, OR=1.18 (1.07–1.31), P=0.002, I²=36%). Stratified analysis revealed that this association was largely attributed to the Caucasian ethnicity (for the TT vs CC model, OR=1.28 (1.12–1.46), P=0.0002, I²=1%). Stratification by tumour site showed significant association for bladder cancer in the worldwide population (for the TT vs CC model, OR=1.70 (1.17–2.46), P=0.005, I²=0%), and in the Asian population (for the TT vs CC model, 1.48 (1.14–1.93), P=0.003, I²=16%). Positive association was also found for gastric cancer in the worldwide population under the dominant model (OR=1.34 (1.09–1.65), P=0.006, I²=15%).

Conclusion:

Our results indicate that the C609T polymorphism of the NQO1 gene is an important genetic risk factor in cancer.

BRCA1 polymorphisms and breast cancer epidemiology in the Western New York exposures and breast cancer (WEB) study

Results of studies for the association of BRCA1 genotypes and haplotypes with sporadic breast cancer have been inconsistent. Therefore, a candidate single nucleotide polymorphism (SNP) approach was used in a breast cancer case-control study to explore genotypes and haplotypes that have the potential to affect protein functions or levels. In a breast cancer case-control study, genotyping of BRCA1 polymorphisms Q356R, D693N, and E1038G was performed on 1,005 cases and 1,765 controls. Unconditional, polytomous logistic regression and χ(2) -tests were used to examine the associations of breast cancer with genotypes and haplotypes. In addition, interactions between genotype and smoking, benign breast disease, family history of breast cancer, body mass index (BMI), alcohol consumption, and hormonal risk factors, hormone receptor status, and breast cancer pathology were calculated also using logistic regression and χ(2) . Although sporadic breast cancer was not associated with BRCA1 genotypes or haplotypes overall or by menopausal status, there was evidence of an interaction between the E1038G BRCA1 genotype, smoking, and BMI among premenopausal women (P for interaction = 0.01 and 0.045, respectively) and between E1038G and D693N BRCA1 genotypes and hormone therapy use among postmenopausal women (P for interaction = 0.01 and 0.02, respectively). There were no other associations found between BRCA1 genotypes and stage, histological grade, or nuclear grade. However, the D693N SNP was associated with the risk of triple negative breast cancer (odds ratio = 2.31 95% confidence interval 1.08-4.93). The BRCA1 variants studied may play a role in the etiology of triple negative breast cancer and may interact with environmental factors such as hormone therapy or smoking and increase sporadic breast cancer risk.

p53 codon 72 polymorphism and breast cancer risk: A meta-analysis

p53 is a tumor suppressor gene and plays important roles in the etiology of breast cancer. Studies have produced conflicting results concerning the role of p53 codon 72 polymorphism (G>C) on the risk of breast cancer; therefore, a meta-analysis was performed to estimate the association between the p53 codon 72 polymorphism and breast cancer. Screening of the PubMed database was conducted to identify relevant studies. Studies containing available genotype frequencies of the p53 codon 72 polymorphism were selected and a pooled odds ratio (OR) with 95% confidence interval (CI) was used to assess the association. Sixty-one published studies, including 28,539 breast cancer patients and 32,788 controls were identified. The results suggest that variant genotypes are not associated with breast cancer risk (Pro/Pro + Arg/Pro vs. Arg/Arg: OR=1.016, 95% CI=0.931–1.11, P=0.722). The symmetric funnel plot, Egger’s test (P=0.506) and Begg’s test (P=0.921) were all suggestive of the lack of publication bias. This meta-analysis suggests that the p53 codon 72 Pro/Pro + Arg/Pro genotypes are not associated with an increased risk of breast cancer. To validate the association between the p53 codon 72 polymorphism and breast cancer, further studies with larger numbers of participants worldwide are required.

Association between polymorphisms in apoptotic genes and susceptibility for developing breast cancer in Syrian women

Apoptosis is a major protective mechanism against cancer. The tumor suppressor protein p53 is the central protein in the apoptotic pathway and was shown to harbor mutations in a considerable fraction of breast cancer tumors. The NQO1 was shown to act as a p53 stabilizer and was suggested to play an important role in the protection against carcinogenic catechol estrogens. Functional polymorphisms in TP53 and NQO1 were investigated in relation to breast cancer susceptibility in several studies, primarily involving Asian and Caucasian populations. The aim of the present study was to investigate TP53 and NQO1 polymorphisms and their combined effects with respect to breast cancer susceptibility in a Syrian study cohort. The study cohort consisted of 122 cases and 139 controls. The tetra-primer ARMS-PCR method was used to genotype three TP53 polymorphisms; namely, exon 4 G>C Arg72Pro, IVS3 16 bp Del/Ins, and MspI IVS6+62A>G, and NQO1 C609T (Pro187Ser) polymorphism. Association was tested under six genetic models. We found a significant association for the heterozygous Arg/Pro genotype when combined with heterozygosity for IVS3 16 bp Del/Ins and MspI IVS6+62A>G (OR = 2.05 (1.22-3.47), P = 0.006). No significant association was found for NQO1 C609T or its combinations with TP53 polymorphisms. Our results support an association for TP53 polymorphisms with breast cancer susceptibility in the Syrian population.

NQO1 C609T polymorphism correlated to colon cancer risk in farmers from western region of Inner Mongolia

OBJECTIVE

To investigate the relationship between NAD(P)H:quinone oxidoreductase 1 (NQO1) C609T polymorphism and colon cancer risk in farmers from western region of Inner Mongolia.

METHODS

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed to analyze NQO1 C609T polymorphism from 160 healthy controls and 76 colon cancer patients.

RESULTS

Among the colon cancer patients, the incidence of NQO1 T allele (53.29%) was significantly higher than it in control group (33.75%, P<0.001). The individuals with NQO1 T allele had higher risk [2.239 (95% CI: 
1.510-3.321) times] to develop colon cancer than individuals with NQO1 C allele. The incidence of NQO1
 (T/T) (34.21%) in colon cancer patients was higher than that in control group (15.62%, P<0.001). Odds ratios (OR) analysis suggested that NQO1 (T/T) and NQO1 (T/C) genotype carriers had 3.813 (95% CI: 1.836-7.920) times and 2.080 (1.026-4.219) times risk compared with wild-type NQO1 (C/C) gene carriers in developing colon cancer. Individuals with NQO1 (T/T) genotype had 2.541 (95% CI: 0.990-6.552) times, 3.713 (95% CI: 1.542-8.935) times, and 3.471 (95% CI: 1.356-8.886) times risk than individuals with NQO1 (T/C) or NQO1 (C/C) genotype in well-differentiated, moderately-differentiated, and poorly-differentiated colon cancer patients, respectively.

CONCLUSIONS

NQO1 gene C609T could be one of risk factors of colon cancer in farmers from western region of Inner Mongolia.

Null association of NQO1 609C>T and NQO2 -3423G>A polymorphisms with susceptibility and prognosis of Esophageal cancer in north Indian population and meta-analysis

INTRODUCTION

NAD(P)H:quinone oxidoreductase 1 (NQO1) and NRH:quinone oxidoreductase 2 (NQO2), involved in detoxification of environmental carcinogens and activation of chemotherapeutic agents, are supposed to play critical role in carcinogenesis. So, we aimed to investigate the association of NQO1 609C>T and NQO2 -3423G>A polymorphisms with susceptibility and prognosis of Esophageal cancer (EC) in north Indian population. We also performed Meta analysis of published literatures on NQO1 609C>T polymorphism to systematically evaluate its association with EC.

METHODS

We genotyped NQO1 609C>T and NQO2 -3423G>A polymorphisms in 200 incident EC cases (including 150 follow-up cases) and 200 controls using PCR RFLP based methods. Binary logistic regression was applied for risk estimation, while Kaplan Meier and Cox regression tests were applied for survival analysis. All Meta analysis tests were performed using MIX 2.0 software.

RESULTS

The present study did not find any significant association of NQO1 609C>T and NQO2 -3423G>A polymorphisms with susceptibility to EC or its clinical phenotypes (histopathology, tumor location or lymph node metastasis) or interactions with lifestyle risk factors (tobacco usage, smoking, alcohol habit and occupational exposures). Meta analysis of NQO1 polymorphism also indicated null association of the polymorphism with EC overall or with cancer cases stratified by tumor histopathology/ethnicity. Moreover, no prognostic implication of both polymorphisms was observed in EC.

CONCLUSION

NQO1 609C>T and NQO2 -3423G>A polymorphisms do not seem to play any significant role in susceptibility or prognosis of EC in north Indian population and results of Meta-analysis further reinforces null association of NQO1 609C>T polymorphism with EC susceptibility.

Apolipoprotein E (APOE) Polymorphisms and Susceptibility to Breast Cancer: A Meta-Analysis

Purpose

Apolipoprotein E (APOE, MIM: 107741) has three functionally distinct isoforms of the protein (E2, E3, and E4), encoded by corresponding alleles ε2, ε3, and ε4, which have been well described. Findings from previous studies investigating association between APOE polymorphisms and breast cancer risk have been inconsistent. The present meta-analysis was conducted in order to investigate association of APOE polymorphisms with risk of breast cancer.

Materials and Methods

Several electronic databases were used for identification of studies containing information on APOE polymorphisms and breast cancer risk published up to January 2012. We identified 10 eligible studies, including 3,835 subjects (2008 patients, and 1,827 healthy controls), that reported on polymorphisms of APOE and risk of breast cancer. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were obtained using a fixed and random-effects models.

Results

Among studies reported from Asia, an association of the ε4 allele with increased risk of breast cancer, in comparison with the ε3 allele, was observed (OR, 1.56; 95% CI, 1.19 to 2.04; p=0.001). It should be noted that allele ε2 showed no association with breast cancer risk. Among Caucasians, neither the ε4 (OR, 0.99; 95% CI, 0.83 to 1.17; p=0.917) nor the ε2 (OR, 0.92; 95% CI, 0.72 to 1.17; p=0.514) allele showed an association with susceptibility to breast cancer, when compared with the ε3 allele. Carriers of the ε4 allele (E4E4, E4E3, and E4E2 genotypes), in comparison with the E3E3 genotype, showed an association with elevated risk of breast cancer only among Asians (OR, 1.75; 95% CI, 1.23 to 2.47; p=0.002). No publication bias was detected.

Conclusion

This meta-analysis suggest that the APOEε4 allele is a low-penetrant risk factor for development of breast cancer.

Two minor NQO1 and NQO2 alleles predict poor response of breast cancer patients to adjuvant doxorubicin and cyclophosphamide therapy

OBJECTIVE

A SNP in the NQO1 gene has been implicated in the response of patients with breast cancer to anthracycline containing regimens. NQO1, and its homologue NQO2, share many substrates yet retain distinct functional differences, with NQO2 being a more permissive molecule for electron accepting substrates. We aimed to determine whether functional NQO2 variants are associated with altered response to adjuvant doxorubicin and cyclophosphamide therapy, with or without tamoxifen, in the treatment of breast cancer.

METHODS

Genomic DNA samples from 227 women with early breast cancer were genotyped for NQO1 and NQO2 polymorphisms. All participants were treated with an AC adjuvant therapy regimen. The functional implications of NQO2 polymorphisms were validated in in-vitro ectopic expression models.

RESULTS

The NQO1 SNP (rs1800566) was associated with a poorer outcome and a lower likelihood of having a treatment delay. Patients who had ER and PR negative disease and were wild type for both the NQO1 and an NQO2 SNP (rs1143684) had 100% 5-year overall survival compared with 88% for carriers of one minor allele and 70% for carriers of two or more minor alleles (P=0.018, log rank). Carriers of minor alleles of a triallelic NQO2 promoter polymorphism were more likely to be withdrawn from tamoxifen therapy prematurely due to intolerance (P=0.009, log rank). MCF-7 cells were sensitized to growth inhibition by doxorubicin and 4OH tamoxifen, but not cyclophosphamide, by ectopic expression of NQO2.

CONCLUSION

This study suggests that both NQO1 and NQO2 modulate the efficacy of AC therapy and that NQO2 is associated with tamoxifen toxicity.

A quadruplex tetra-primer ARMS-PCR method for the simultaneous detection of TP53 Arg72Pro, IVS3 16bp Del/Ins and IVS6+62A>G, and NQO1 C609T polymorphisms

The apoptotic pathway has been shown to be crucial in the development of cancers in addition to a variety of neurodegenerative disorders. The tumor suppressor gene (TP53) encodes p53, the central protein in the apoptotic pathway. The NAD(P)H:quinone oxidoreductase 1, which is encoded by the NQO1 gene and, plays a direct role in apoptosis in addition to its recently discovered role as a regulator for p53. Three most commonly studied polymorphisms that were shown to affect the biochemical functions of p53 protein are the exon 4 Arg72pro, Intron 3 16bp Del/Ins, and Intron 6 A>G polymorphisms. The exon 6 C609T polymorphism was shown to significantly affect NQO1 enzymatic activity. The currently used methods for the separate detection of the four polymorphisms are either slow and laborious or extremely expensive. In this paper, a new highly optimized method for the simultaneous detection of the four polymorphisms is described. The proposed method utilizes 13 primers in a single PCR reaction to detect the four polymorphisms simultaneously based on the principle of tetra-primer ARMS-PCR (also known as PCR-CTPP). The proposed method offers extremely fast, economical, and simple detection. The proposed method was successfully applied to a sample of the Syrian population (n=144), where we found a unique distribution for TP53 polymorphisms that differed from the major ethnic groups. The proposed method is the first to simultaneously detect four polymorphisms including 3 SNPs in a single PCR reaction based on tetra-primer ARMS-PCR or PCR-CTPP, and can serve as an invaluable tool for the investigation of TP53 haplotypes and the combined effects of the TP53 and NQO1 genes with respect to apoptosis and susceptibility for various types of cancers and neurodegenerative disorders.

Reduced prevalence of the C825T polymorphism of the G-protein beta subunit gene in women with breast cancer

OBJECTIVE

To evaluate the prevalence of the C825T polymorphism in the GNB3 gene in women with and without breast cancer and its possible association with clinical or pathological features of breast disease.

SUBJECTS AND METHODS

We included 134 women with breast cancer and a control group of 129 healthy women. The case group responded to a questionnaire on lifestyle, reproductive factors and family history. Clinical data were also evaluated. The risk for cancer was calculated and PCR was carried out for the detection of the polymorphism. Statistical analysis was performed using the package R Environment, with confidence intervals of 95% and a significance level of 5% (p and lt;0.05).

RESULTS

The frequency of the TT genotype was significantly greater in women of the control group (30.2%) than women with breast cancer (14.9%) (p=0.02). The polymorphism was not associated with clinical features, age at diagnosis (p=0.07), age at menarche (p=0.17), and age at menopause (p=0.60). The TT genotype did not have a higher frequency in patients with high BMI (p=0.98). The risk for cancer showed no correlation with the presence of the polymorphism.

CONCLUSIONS

Our data indicate that the C825T polymorphism in the GNB3 gene has no relationship to the risk for breast cancer or the characteristics of the disease.

Association between the p53 polymorphisms and breast cancer risk: meta-analysis based on case-control study

p53 is a tumor suppressor gene and plays an important role in the etiology of breast cancer. However, studies on the association between p53 polymorphisms and breast cancer risk have yielded conflicting results. We performed a meta-analysis to investigate the association between breast cancer and the p53 polymorphisms codon 72 (27,046 cases and 30,998 controls), IVS3 16 bp (3,332 cases and 3,700 controls) and IVS6+62A>G (8,787 cases and 9,869 controls) in different inheritance models. When all the eligible studies of codon 72 polymorphism were pooled into this meta-analysis, there was no evidence of significant association between breast cancer risk and p53 codon 72 polymorphism in any genetic model. However, in the stratified analysis for Indian population, significantly association was observed in additive model (OR = 0.62, 95% CI = 0.46-0.82, P value of heterogeneity test [P (h)] = 0.153) and recessive model (OR = 0.70, 95% CI = 0.50-0.92, P (h) = 0.463). IVS3 16 bp was significantly associated with breast cancer risk in a pooled 15 studies dataset (dominant model: OR = 1.14, 95% CI = 1.02-1.27, P (h) = 0.30; recessive model: OR = 1.61, 95% CI = 1.21-2.25, P(h) = 0.25; additive model: OR = 1.66, 95% CI = 1.24-2.21, P (h) = 0.28). No significant association was found between IVS6+62A>G polymorphism and breast cancer risk in a total of 14 studies. In summary, these results indicate that IVS3 16 bp is likely an important genetic marker contributing to susceptibility of breast cancer, and codon 72 homozygous mutants may be associated with decreased breast cancer risk in Indian population.

Global gene expression profiling of endothelium exposed to heme reveals an organ-specific induction of cytoprotective enzymes in sickle cell disease

BACKGROUND

Sickle cell disease (SCD) is characterized by hemolysis, vaso-occlusion and ischemia reperfusion injury. These events cause endothelial dysfunction and vasculopathies in multiple systems. However, the lack of atherosclerotic lesions has led to the idea that there are adaptive mechanisms that protect the endothelium from major vascular insults in SCD patients. The molecular bases for this phenomenon are poorly defined. This study was designed to identify the global profile of genes induced by heme in the endothelium, and assess expression of the heme-inducible cytoprotective enzymes in major organs impacted by SCD.

METHODS AND FINDINGS

Total RNA isolated from heme-treated endothelial monolayers was screened with the Affymetrix U133 Plus 2.0 chip, and the microarray data analyzed using multiple bioinformatics software. Hierarchical cluster analysis of significantly differentially expressed genes successfully segregated heme and vehicle-treated endothelium. Validation studies showed that the induction of cytoprotective enzymes by heme was influenced by the origin of endothelial cells, the duration of treatment, as well as the magnitude of induction of individual enzymes. In agreement with these heterogeneities, we found that induction of two major Nrf2-regulated cytoprotective enzymes, heme oxygenase-1 and NAD(P)H:quinone oxidoreductase-1 is organ-specific in two transgenic mouse models of SCD. This data was confirmed in the endothelium of post-mortem lung tissues of SCD patients.

CONCLUSIONS

Individual organ systems induce unique profiles of cytoprotective enzymes to neutralize heme in SCD. Understanding this heterogeneity may help to develop effective therapies to manage vasculopathies of individual systems.

Polymorphism of xenobiotic-metabolizing genes and breast cancer susceptibility in North Indian women

NAD(P)H:quinone oxidoreductase 1 (NQO1) and cytochrome P450 1A2 (CYP1A2) are involved in the metabolism of estrogens. Genetic polymorphisms in these genes may lead to interindividual variation in breast cancer susceptibility. This study was undertaken to investigate the association of NQO1 exon 6 proline187serine (C609T) and CYP1A2 exon 2 phenylalanine21leucine (C63G) polymorphisms with breast cancer susceptibility in North Indian women. Polymorphisms were analyzed by polymerase chain reaction amplification of the desired segment of NQO1 and CYP1A2 genes followed by restriction fragment length polymorphism. NQO1 mRNA expression was analyzed by semiquantitative reverse transcription-polymerase chain reaction and its enzyme activity was estimated spectrofluorophotometrically. Odds ratios for NQO1 C609T heterozygous and homozygous variants were 0.66 (95% confidence interval: 0.39-1.13; p-value: 0.141) and 1.07 (95% confidence interval: 0.46-2.46; p-value: 0.976). All cases and controls were monomorphic for the CYP1A2 exon 2 phenylalanine21leucine (C63G) genotype. NQO1 mRNA expression and its catalytic activity among wild-type genotype, homozygous variant, and heterozygous variant were not significantly altered, except for catalytic activity of the NQO1 homozygous variant, which was observed extremely low. The results of the study suggest that NQO1 exon 6 proline187serine (C609T) and CYP1A2 exon 2 phenylalanine21leucine (C63G) polymorphisms do not play a significant role in breast cancer susceptibility in North Indian women.

E3 ligase STUB1/CHIP regulates NAD(P)H:quinone oxidoreductase 1 (NQO1) accumulation in aged brain, a process impaired in certain Alzheimer disease patients

NAD(P)H:quinone oxidoreductase 1 (NQO1) is a flavoenzyme that is important in maintaining the cellular redox state and regulating protein degradation. The NQO1 polymorphism C609T has been associated with increased susceptibility to various age-related pathologies. We show here that NQO1 protein level is regulated by the E3 ligase STUB1/CHIP (C terminus of Hsc70-interacting protein). NQO1 binds STUB1 via the Hsc70-interacting domain (tetratricopeptide repeat domain) and undergoes ubiquitination and degradation. We demonstrate here that the product of the C609T polymorphism (P187S) is a stronger STUB1 interactor with increased susceptibility to ubiquitination by the E3 ligase STUB1. Furthermore, age-dependent decrease of STUB1 correlates with increased NQO1 accumulation. Remarkably, examination of hippocampi from Alzheimer disease patients revealed that in half of the cases examined the NQO1 protein level was undetectable due to C609T polymorphism, suggesting that the age-dependent accumulation of NQO1 is impaired in certain Alzheimer disease patients.

DCPIP (2,6-dichlorophenolindophenol) as a genotype-directed redox chemotherapeutic targeting NQO1*2 breast carcinoma

Accumulative experimental evidence suggests feasibility of chemotherapeutic intervention targeting human cancer cells by pharmacological modulation of cellular oxidative stress. Current efforts aim at personalization of redox chemotherapy through identification of predictive tumour genotypes and redox biomarkers. Based on earlier research demonstrating that anti-melanoma activity of the pro-oxidant 2,6-dichlorophenolindophenol (DCPIP) is antagonized by cellular NAD(P)H:quinone oxidoreductase (NQO1) expression, this study tested DCPIP as a genotype-directed redox chemotherapeutic targeting homozygous NQO1*2 breast carcinoma, a common missense genotype [rs1800566 polymorphism; NP_000894.1:p.Pro187Ser] encoding a functionally impaired NQO1 protein. In a panel of cultured breast carcinoma cell lines and NQO1-transfectants with differential NQO1 expression levels, homozygous NQO1*2 MDA-MB231 cells were hypersensitive to DCPIP-induced caspase-independent cell death that occurred after early onset of oxidative stress with glutathione depletion and loss of genomic integrity. Array analysis revealed upregulated expression of oxidative (GSTM3, HMOX1, EGR1), heat shock (HSPA6, HSPA1A, CRYAB) and genotoxic stress response (GADD45A, CDKN1A) genes confirmed by immunoblot detection of HO-1, Hsp70, Hsp70B', p21 and phospho-p53 (Ser15). In a murine xenograft model of human homozygous NQO1*2-breast carcinoma, systemic administration of DCPIP displayed significant anti-tumour activity, suggesting feasibility of redox chemotherapeutic intervention targeting the NQO1*2 genotype.

Evidence on the association between NQO1 Pro187Ser polymorphism and breast cancer risk in the current studies: a meta-analysis

Several molecular epidemiological studies were conducted in recent years to evaluate the association between NQO1 Pro187Ser polymorphism and breast cancer risk in diverse populations. However, the results remain conflicting rather than conclusive. This meta-analysis on 3177 cases with breast cancer and 4038 controls from seven published case-control studies showed that the 187Ser allele was not associated with a significantly increased risk of breast cancer (Ser versus Pro: P = 0.33, OR = 1.08, 95% CI = 0.92-1.28; Ser/Ser versus Pro/Pro: P = 0.58, OR = 1.16, 95% CI = 0.68-2.00; Ser/Ser versus Pro/Ser + Pro/Pro: P = 0.62, OR = 1.14, 95% CI = 0.68-1.90; Ser/Ser + Pro/Ser versus Pro/Pro: P = 0.30, OR = 1.07, 95% CI = 0.94-1.22). In the stratified analysis by ethnicity, we found that the Pro187Ser polymorphism was associated with increased breast cancer risk in Caucasians in the additive genetic model and dominant genetic model (P = 0.03, OR = 1.13, 95% CI = 1.01-1.26; P = 0.03, OR = 1.15, 95% CI = 1.01-1.30, respectively), whereas no significant in Asians (P = 0.44, OR = 0.94, 95% CI = 0.80-1.10) and postmenopausal women (P = 0.99, OR = 1.00, 95% CI = 0.84-1.19). The results suggest that NQO1 Pro187Ser polymorphism may contribute to breast cancer development in Caucasians.

BRCA2 N372H polymorphism and breast cancer susceptibility: a meta-analysis involving 44,903 subjects

Published data on the association between BRCA2 N372H polymorphism and breast cancer risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. Crude ORs with 95% CIs were used to assess the strength of association between them. A total of 22 studies including 22,515 cases and 22,388 controls were involved in this meta-analysis. Overall, no significant associations were found between BRCA2 N372H polymorphism and breast cancer risk when all studies pooled into the meta-analysis (NH versus NN: OR = 1.01, 95% CI = 0.97-1.05; HH versus NN: OR = 1.05, 95% CI = 0.97-1.13; dominant model: OR = 1.01, 95% CI = 0.98-1.05; and recessive model: OR = 1.05, 95% CI = 0.98-1.13). In the subgroup analysis by ethnicity, still no significant associations were found for Caucasians, Asians, or Africans. When stratified by study design, statistically significantly elevated risk was found for 372H allele based on population-based studies (HH versus NN: OR = 1.11, 95% CI = 1.01-1.21; dominant model: OR = 1.05, 95% CI = 1.00-1.10; recessive model: OR = 1.09, 95% CI = 1.00-1.18). In conclusion, this meta-analysis suggests that the BRCA2 372H allele may be a low-penetrant risk factor for developing breast cancer. However, large sample and representative population-based studies with homogeneous breast cancer patients and well matched controls are warranted to confirm this finding.

Missense polymorphisms in BRCA1 and BRCA2 and risk of breast and ovarian cancer

PURPOSE

BRCA1 and BRCA2 are key tumor suppressors with a role in cellular DNA repair, genomic stability, and checkpoint control. Mutations in BRCA1 and BRCA2 often cause hereditary breast and ovarian cancer; however, missense polymorphisms in these genes pose a problem in genetic counseling, as their impact on risk of breast and ovarian cancer is unclear.

EXPERIMENTAL DESIGN

We resequenced BRCA1 and BRCA2 in 194 women with a familial history of breast and/or ovarian cancer and identified nine possibly biologically relevant polymorphisms (BRCA1 Gln356Arg, Pro871Leu, Glu1038Gly, Ser1613Gly, and Met1652Ile. BRCA2 Asn289His, Asn372His, Asp1420Tyr, and Thr1915Met). [corrected] We evaluated risk of breast and/or ovarian cancer by these polymorphisms in a prospective study of 5,743 women from the general population followed for 39 years and in a case-control study of 1,201 breast cancer cases and 4,120 controls.

RESULTS

We found no association between heterozygosity or homozygosity for any of the nine polymorphisms and risk of breast and/or ovarian cancer in either study. We had 80% power to exclude hazard/odds ratios for heterozygotes and/or homozygotes for all nine missense polymorphisms above 1.3 to 3.3 in the prospective study, and above 1.2 to 3.2 in the case-control study.

CONCLUSIONS

Heterozygosity and homozygosity of any of the examined nine BRCA1 and BRCA2 missense polymorphisms cannot explain the increased risk of breast and/or ovarian cancer observed in families with hereditary breast and/or ovarian cancer. Therefore, genetic counseling of such families safely can disregard findings of these missense polymorphisms.

NAD(P)H:quinone oxidoreductase 1 Arg139Trp and Pro187Ser polymorphisms imbalance estrogen metabolism towards DNA adduct formation in human mammary epithelial cells

Estrogens (estrone, E(1); estradiol, E(2)) are oxidized in the breast first to catechols and then to form two ortho-quinones (E(1/2)-3,4-Q) that react with DNA to form depurinating adducts, which lead to mutations associated with breast cancer. NAD(P)H:quinone oxidoreductase 1 (NQO1) reduces these quinones back to catechols, and thus may protect against this mechanism. We examined whether the inheritance of two polymorphic variants of NQO1 (Pro187Ser or Arg139Trp) would result in poor reduction of E(1/2)-3,4-Q in normal human mammary epithelial cells (MCF-10F) and increased depurinating adduct formation. An isogenic set of stably transfected normal human breast epithelial cells (MCF-10F) that express a truncated (135Stop), the wild-type, the 139Trp variant or the 187Ser variant of human NQO1 cDNA was constructed. MCF-10F cells showed a low endogenous NQO1 activity. NQO1 expression was examined by RT-PCR and Western blotting, and catalytic activity of reducing E(2)-3,4-Q to 4-hydroxyE(1/2) and associated changes in the levels of quinone conjugates (4-methoxyE(1/2), 4-OHE(1/2)-2-glutathione, 4-OHE(1/2)-2-Cys and 4-OHE(1/2)-2-N-acetylcysteine) and depurinating DNA adducts (4-OHE(1/2)-1-N3Ade and 4-OHE(1/2)-1-N7Gua) were examined by HPLC with electrochemical detection, as well as by ultra-performance liquid chromatography with tandem mass spectrometry. The polymorphic variants transcribed comparably to the wild-type NQO1, but produced approximately 2-fold lower levels of the protein, suggesting that the variant proteins may become degraded. E(1/2)-3,4-Q toxicity to MCF-10F cells (IC50=24.74 microM) was increased (IC50=3.7 microM) by Ro41-0960 (3 microM), a catechol-O-methyltransferase inhibitor. Cells expressing polymorphic NQO1 treated with E(2)-3,4-Q with or without added Ro41-0960, showed lower ability to reduce the quinone ( approximately 50% lower levels of the free catechols and approximately 3-fold lower levels of methylated catechols) compared to the wild-type enzyme. The increased availability of the quinones in these cells did not result in greater glutathione conjugation. Instead, there was increased (2.5-fold) formation of the depurinating DNA adducts. Addition of Ro41-0960 increased the amounts of free catechols, quinone conjugates and depurinating DNA adducts. NQO1 polymorphic variants (Arg139Trp and Pro187Ser) were poor reducers of estrogen-3,4-quinones, which caused increased formation of estrogen-DNA adduct formation in MCF-10F cells. Therefore, the inheritance of these NQO1 polymorphisms may favor the estrogen genotoxic mechanism of breast cancer.

An empirical comparison of meta-analyses of published gene-disease associations versus consortium analyses

PURPOSE

Consortia of investigators currently compile sufficiently large sample sizes to investigate the effects of low-risk susceptibility genetic variants. It is not clear how the results obtained by consortia compare with those derived from meta-analyses of published studies.

METHODS

We performed meta-analyses of published data for 16 genetic polymorphisms investigated by the Breast Cancer Association Consortium, and compared sample sizes, heterogeneity, and effect sizes. PubMed, Web of Science, and Human Genome Epidemiology Network databases were searched for breast cancer case-control association studies.

RESULTS

We found that meta-analyses of published data and consortium analyses were based on substantially different data. Published data by non-consortium teams amounted on average to 26.9% of all available data (range 3.0 -50.0%). Both approaches showed statistically significant decreased breast cancer risks for CASP8 D302H. The meta-analyses of published data demonstrated statistically significant results for five other genes and the consortium analyses for two other genes, but the strength of this evidence, evaluated on the basis of the Venice criteria, was not strong.

CONCLUSIONS

Because both approaches identified the same gene out of 16 candidates, the methods can be complimentary. The expense and complexity of consortium-based studies should be considered vis-à-vis the potential methodological limitations of synthesis of published studies.

Functional polymorphisms, altered gene expression and genetic association link NRH:quinone oxidoreductase 2 to breast cancer with wild-type p53

We hypothesized that NRH:quinone oxidoreductase 2 (NQO2) is a candidate susceptibility gene for breast cancer because of its known enzymatic activity on estrogen-derived quinones and its ability to stabilize p53. We performed case-control studies to investigate the contributions of genetic variants/haplotypes of the NQO2 gene to breast cancer risk. In the first hospital-based study (n = 1604), we observed significant associations between the incidence of breast cancer and a 29 bp-insertion/deletion polymorphism (29 bp-I/D) and the rs2071002 (+237A>C) polymorphism, both of which are located within the NQO2 promoter region. Decreased risk was associated with the D-allele of 29 bp-I/D [odds ratio (OR), 0.76; P = 0.0027] and the +237C-allele of rs2071002 (OR, 0.80; P = 0.0031). Specifically, the susceptibility variants within NQO2 were notably associated with breast carcinomas with wild-type p53 (the most significant P-value: 3.3 x 10(-6)). The associations were successfully replicated in an independent population set (familial/early-onset breast cancer cases and community-based controls, n = 1442). The combined P-values of the two studies (n = 3046) are 3.8 x 10(-7) for 29 bp-I/D and 2.3 x 10(-6) for rs2071002. Furthermore, we revealed potential mechanisms of pathogenesis of the two susceptibility polymorphisms. Previous work has demonstrated that the risk-allele I-29 of 29 bp-I/D introduces transcriptional-repressor Sp3 binding sites. Using promoter reporter-gene assays and electrophoretic-mobility-shift assays, our present work demonstrated that the other risk-allele, +237A-allele of rs2071002, abolishes a transcriptional-activator Sp1 binding site. Furthermore, an ex vivo study showed that normal breast tissues harboring protective genotypes expressed significantly higher levels of NQO2 mRNA than those in normal breast tissues harboring risk genotypes. Taken together, the data presented here strongly suggest that NQO2 is a susceptibility gene for breast carcinogenesis.

Investigation of an NQO1 polymorphism as a possible risk and prognostic factor for chronic lymphocytic leukemia

NAD(P)H:quinoneoxidoreductase 1 (NQO1) inhibits some cancers and increases p53 and apoptosis in cells. Due to an inactivating polymorphism, 10% of humans have no NQO1 activity. A case:control study suggested that chronic lymphocytic leukemia (CLL) patients may have an increased incidence of the NQO1 null genotype compared with controls. NQO1 genotype did not correlate with various CLL prognostic factors, but we observed a trend toward lower drug response in patients with the NQO1 null genotype. Inhibiting NQO1 activity decreased p53 levels and drug induced apoptosis in CLL cells. These results raise the possibility that the NQO1 polymorphism may be a risk factor for CLL and a predictor of response to chemotherapy.