Alok Deoraj

Estrogen-induced reactive oxygen species-mediated signalings contribute to breast cancer

Elevated lifetime estrogen exposure is a major risk factor for breast cancer. Recent advances in the understanding of breast carcinogenesis clearly indicate that induction of estrogen receptor (ER) mediated signaling is not sufficient for the development of breast cancer. The underlying mechanisms of breast susceptibility to estrogens carcinogenic effect remain elusive. Physiologically achievable concentrations of estrogen or estrogen metabolites have been shown to generate reactive oxygen species (ROS). Recent data implicated that these ROS induced DNA synthesis, increased phosphorylation of kinases, and activated transcription factors, e.g., AP-1, NRF1, E2F, NF-kB and CREB of non-genomic pathways which are responsive to both oxidants and estrogen. Estrogen-induced ROS by increasing genomic instability and by transducing signal through influencing redox sensitive transcription factors play important role (s) in cell transformation, cell cycle, migration and invasion of the breast cancer. The present review discusses emerging data in support of the role of estrogen induced ROS-mediated signaling pathways which may contribute in the development of breast cancer. It is envisioned that estrogen induced ROS mediated signaling is a key complementary mechanism that drives the carcinogenesis process. ROS mediated signaling however occurs in the context of other estrogen induced processes such as ER-mediated signaling and estrogen reactive metabolite-associated genotoxicity. Importantly, estrogen-induced ROS can function as independent reversible modifiers of phosphatases and activate kinases to trigger the transcription factors of downstream target genes which participate in cancer progression.

Integrated Bioinformatics, Environmental Epidemiologic and Genomic Approaches to Identify Environmental and Molecular Links between Endometriosis and Breast Cancer.

We present a combined environmental epidemiologic, genomic, and bioinformatics approach to identify: exposure of environmental chemicals with estrogenic activity; epidemiologic association between endocrine disrupting chemical (EDC) and health effects, such as, breast cancer or endometriosis; and gene-EDC interactions and disease associations. Human exposure measurement and modeling confirmed estrogenic activity of three selected class of environmental chemicals, polychlorinated biphenyls (PCBs), bisphenols (BPs), and phthalates. Meta-analysis showed that PCBs exposure, not Bisphenol A (BPA) and phthalates, increased the summary odds ratio for breast cancer and endometriosis. Bioinformatics analysis of gene-EDC interactions and disease associations identified several hundred genes that were altered by exposure to PCBs, phthalate or BPA. EDCs-modified genes in breast neoplasms and endometriosis are part of steroid hormone signaling and inflammation pathways. All three EDCs–PCB 153, phthalates, and BPA influenced five common genes—CYP19A1, EGFR, ESR2, FOS, and IGF1—in breast cancer as well as in endometriosis. These genes are environmentally and estrogen responsive, altered in human breast and uterine tumors and endometriosis lesions, and part of Mitogen Activated Protein Kinase (MAPK) signaling pathways in cancer. Our findings suggest that breast cancer and endometriosis share some common environmental and molecular risk factors.

Redox signalling to nuclear regulatory proteins by reactive oxygen species contributes to oestrogen-induced growth of breast cancer cells

Background:17β-Oestradiol (E2)-induced reactive oxygen species (ROS) have been implicated in regulating the growth of breast cancer cells. However, the underlying mechanism of this is not clear. Here we show how ROS through a novel redox signalling pathway involving nuclear respiratory factor-1 (NRF-1) and p27 contribute to E2-induced growth of MCF-7 breast cancer cells.Methods:Chromatin immunoprecipitation, qPCR, mass spectrometry, redox western blot, colony formation, cell proliferation, ROS assay, and immunofluorescence microscopy were used to study the role of NRF-1.Results:The major novel finding of this study is the demonstration of oxidative modification of phosphatases PTEN and CDC25A by E2-generated ROS along with the subsequent activation of AKT and ERK pathways that culminated in the activation of NRF-1 leading to the upregulation of cell cycle genes. 17β-Oestradiol-induced ROS by influencing nuclear proteins p27 and Jab1 also contributed to the growth of MCF-7 cells.Conclusions:Taken together, our results present evidence in the support of E2-induced ROS-mediated AKT signalling leading to the activation of NRF-1-regulated cell cycle genes as well as the impairment of p27 activity, which is presumably necessary for the growth of MCF-7 cells. These observations are important because they provide a new paradigm by which oestrogen may contribute to the growth of breast cancer.

Association between Exposure to Estrogenic Endocrine Disruptors - Polychlorinated Biphenyls, Phthalates, and Bisphenol A and Gynecologic Cancers- Cervical, Ovarian, Uterine Cancers

Introduction: Estrogen is a driver in the growth and progression of gynecologic cancers (cervical, ovarian, and uterine). A number of estrogenically active chemicals are suspected to contribute in the development of gynecologic lesions, including an increased risk of estrogen-dependent cancer in women. Humans are exposed to estrogenic endocrine disruptors (EEDs), such as- polychlorinated biphenyls (PCBs), phthalates and bisphenol A (BPA). Therefore, we examined the cross-sectional relationship between exposure to PCBs, phthalates, and BPA and gynecologic cancers (cervical, ovarian, and uterine). Methods: We analyzed data from female participants (20 years of age and older) who provided blood and urine samples for the Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey (NHANES) between 1999 and 2010. Exposure was examined based on lipid adjusted serum levels of 6 individual PCB congeners (74, 99, 118, 138, 153, and 180), the sum of dioxin-like PCBs (074 and 118), the sum of non-dioxin-like PCBs (099+138+153+187), 8 urinary phthalate metabolites (MNP, MEP, MEHP, MBzP, MCPP, MEHHP, MEOHP, and MIB), the sum of DEHP metabolites (MHP+MHH+MOH), the sum of total phthalates, and urinary BPA in conjunction with data obtained from the medical and reproductive health questionnaires. We calculated geometric means to compare EEDs concentrations in women who self-reported a cervical, ovarian, or uterine cancer diagnosis vs. women who self-reported never being diagnosed with cancer. We used logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between exposure to EEDs and r gynecologic cancers. We also evaluated age, race/ethnicity, body mass index (BMI; kg/m2), and age at menarche as potential confounding variables in our final models. Results: Separate analyses showed weighted geometric mean (GM) levels of individual PCB congeners to be significantly higher among women with ovarian cancer, and uterine cancer when compared to the rest of the study population. Mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) was found to be significantly higher and BPA was higher among women with ovarian cancer compared to women never diagnosed with any gynecologic cancer. After adjusting for age, race, BMI, and age at menarche, we found that PCB 138 was significantly associated with cervical cancer, and uterine cancer [odds ratios of 3.05, 95% CI: 1.21-7.69; and 5.83, 95% CI: 1.63-20.9], respectively. PCB 74 and 118 however, were significantly associated with ovarian cancer with an odds ratios of 6.47, 95% CI: 1.23-3.41 (for PCB 74) and 6.68, 95% CI: 1.39-32.3 (for PCB 118). We also found the sum of non-dioxin-like PCBs to be significantly associated with uterine cancer (OR of 1.12, 95% CI: 1.03-1.23) and the sum of dioxin-like PCBs to be significantly associated with ovarian cancer (OR of 2.02, 95% CI: 1.06-3.85). We did not find significant associations between urinary phthalates and BPA and gynecologic cancers. Conclusions: Our findings point to a possible association between environmental exposure to PCBs and an increased risk of cervix, ovarian and uterine cancer. However, these findings should be interpreted cautiously because of self-reported cross sectional data and a limited sample size of gynecologic cancers.

Approaches to Identify Environmental and Epigenomic Components or Covariates of Cancer and Disease Susceptibility

A complex disease such as cancer is one of the major public health burdens for the United States and developing societies. A combination of variations in multiple genes and environmental factors contribute to the susceptibility and progression of different diseases. Comprehensive understanding of the interactions between multiple genetic and environmental factors will more accurately predict a risk of contracting a disease or a particular cancer and treatment response to explain the etiology than any single genetic or environmental factor. Although advances in the knowledge of measuring genetic variants and the amount of data available has steadily been increasing, a major barrier to further the success of molecular epidemiology studies, especially those with a environment-gene interactions, is to determine an appropriate methodological strategy for analysis and interpretation of results. Here we describe approaches to measure genome wide genetic variation and suggest resources to conduct gene × environment (G×E) interaction analysis. We also describe epigenomics that how it may play an important role in enhancing the risk for complex diseases such as cancer. Study of G×E interactions aim to describe how genetic and environmental factors jointly influence the risk of developing a disease. Analysis of G×E interactions take into account the various ways in which genetic effects are modified due to environmental exposures. The number of levels of these exposures and the model on which the genetic effects can be based are also discussed in this chapter. Choice of study design, sample size and genotyping technology influence the analysis and interpretation of observed G×E interactions. Current systems for reporting epidemiological studies make it difficult to assess whether the observed interactions are reproducible. Suggestions are made for improvements in this area.

Abstract 3433: Association between serum concentrations of polychlorinated biphenyls (PCBs) and increased risk of breast cancer among US women

The main objective of this study was to examine the cross-sectional relationship between exposure to PCBs or their congeners and breast cancer among US women. There is limited information on the association of specific PCB congener or their combination levels in blood serum with increased breast cancer risk. PCBs are weak estrogens which has been shown to act as endocrine disrupters by increasing or blocking estrogen like activities in animals and humans. We analyzed National Health and Nutrition Examination Survey (NHANES) data from 1999-2004 in the lipid adjusted blood samples of female participants (>20 years of age). Exposure assessment was based on lipid adjusted serum levels of 6 individual PCB congeners (PCB 074, 099, 118, 138, 153, and 180), the sum of dioxin-like PCBs (074 and 118), and the sum of non-dioxin-like PCBs (099 + 138 + 153+187) in conjunction with data obtained from the medical and reproductive health questionnaires. We calculated geometric means to compare PCB concentrations in women9s blood samples who also self-reported a breast cancer diagnosis and women who were never diagnosed with cancer. Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CI) for the association between PCB, their congener or their combinations and breast cancer. We evaluated age, race/ethnicity, age at menarche, body mass index (BMI; kg/m2), and lactation as potential confounders. Our results show a weighted geometric mean levels of 6 PCB congeners to be significantly higher in blood serum among women with breast cancer when compared to the rest of the study population. After adjusting for age, race, BMI, lactation, and age at menarche we found significant association of PCB 138 with breast cancer [odds ratios of 2.88; 95% confidence interval (CI): 1.14-7.30; 2.93, 95% CI: 1.04-8.26; and 3.43, 95% CI: 1.12-10.4] in women with higher body burdens of individual PCB congeners (> 50th percentile, 50th-75th percentile, and ≥75th percentile), respectively. After adjusting for age and race, it was also found that the sum of non-dioxin-like PCBs (074 and 118) in blood serum is significantly associated with breast cancer [OR of 1.14; 95% CI: 1.00-1.29]. In summary, our results suggest a possible link between environmental exposures to PCBs and increased risk of breast cancer among U.S. women. Citation Format: Marisa Morgan, Alok Deoraj, Deodutta Roy. Association between serum concentrations of polychlorinated biphenyls (PCBs) and increased risk of breast cancer among US women. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3433.

Abstract 4559: Phosphodeficient NRF1 mutant suppresses the susceptibility of the breast epithelial cells to develop tumors when exposed to estrogen - a major breast cancer risk factor

Although several nuclear regulatory proteins may be targeted by estrogen, our efforts have focused on the redox nuclear respiratory factor-1 (NRF-1), because our recent study showed that NRF-1 gene expression significantly increases with the progression of breast tumor grades. NRF-1 overexpression supported in vitro tumor formation. To determine if NRF-1 is required for 17 beta estradiol (E2)-induced neoplastic phenotype, we have generated NRF-1 mutants by site directed mutagenesis. We have generated stable clones that express NRF-1 mutant. The in vitro tumor formation was detected by anchorage independent growth and 3D spheroid assays. NRF-1 overexpression enhanced in vitro tumor spheroid formation, cell migration and cell invasion. Our flow cytometry analysis showed that overexpression of wild-type NRF-1 increased the percent of transformed MCF-10A cells in S phase compared to vector alone. Dominant negative NRF-1 protein showed reduction in the tumor formation. In addition, shRNA targeting NRF-1 resulted in the inhibition of anchorage independent growth of MCF-10A cells in both vehicle control and E2-treated cells. Since NRF-1 is a substrate of the kinase AKT, we determined whether NRF-1 phosphorylation was increased in MCF-10A cells after treatment with a carcinogenic regimen of E2. We observed more than a 2-fold increase in phospho-NRF-1 in E2 treated (100pg/ml for 30 min) MCF-10A cells and phosphorylation of NRF-1 was inhibited by co-treatment with either biological (CAT or MnSOD) or chemical (20μM ebselen) ROS modifiers. These results suggest that E2-induced phosphorylation of NRF-1 is influenced by ROS signaling messengers. We found that E2 treated MCF-10A cells showed increased NRF-1 binding to the promoters of Cdc2, PRC1, PCNA, Cyclin B1, and CDC25C genes. NRF-1 binding induced by E2 treatment was inhibited by the overexpression of CAT and MnSOD. NRF-1 phosphorylation site specific to kinase AKT, Thr-109, was mutated to Asp (D) or Ala (A), and the NRF-1 acetylation site specific to acetyl-transferase PCAF, Lys- 89, was mutated to Gln (glutamine)-Q or Ala (A). We examine the effect of one of the NRF-1 mutants on E2-induced in vitro tumor formation. We observed that the expression of NRF-1 (T109A) phosphodeficient mutant (NRF-1PMT) significantly inhibited E2-induced cell transformation, whereas empty vector did not influence E2-induced colony formation. Together these findings support the idea that NRF-1 may play an important role in E2-induced malignant transformation of breast epithelial cells. Thus, our data is consistent with the hypothesis that in addition to the estrogen receptor activity, NRF-1 activation contributes to the susceptibility to develop malignant phenotype in response to exposure to estrogen. This work was in part supported by a VA MERIT Review (VA BX001463) grant to DR Citation Format: Lazaro Mesa, Jayanta Das, Alok Deoraj, Victor Okoh, Deodutta Roy. Phosphodeficient NRF1 mutant suppresses the susceptibility of the breast epithelial cells to develop tumors when exposed to estrogen - a major breast cancer risk factor. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4559. doi:10.1158/1538-7445.AM2015-4559