Development Of Sporadic Breast Cancer Research Articles

Dietary phytochemicals/nutrients as promising protector of breast cancer development: a comprehensive analysis.

Genetic change, particularly epigenetic alteration, is one of the imperative factors for sporadic breast cancer development in the worldwide population of women. The DNA methylation process is essential and natural for human cellular renewal and tissue homeostasis, but its dysregulation contributes to many pathological changes, including breast tumorigenesis. Chemopreventive agents mainly protect the abnormal DNA methylation either by hindering the division of pre-malignant cells or looming the DNA damage, which leads to malignancy. The present review article is about understanding the potential role of dietary phytochemicals in breast cancer prevention. Accordingly, a literature search of the published article until August 2021 has been performed. Further, we have investigated the binding affinity of different phytochemicals isolated from diverse dietary sources against the various oncogenic proteins related to breast cancer initiation to understand the common target(s) in breast cancer prevention mechanisms. Various small phytochemicals, especially dietary phytochemicals including sulforaphane, mahanine, resveratrol, linolenic acid, diallyl sulfide, benzyl/phenethyl isothiocyanate, etc. are being investigated as the chemopreventive agent to manage breast cancer development, and some of them have shown promising outcomes in the cited research. In this present review, we discuss the recent advancement in acceptance of such types of potential dietary phytochemicals as a chemopreventive agent against breast cancer development and their inner lining mechanism. The critical clinical trials and cohort studies have also been considered to understand the progress in contemporary perspectives.

Homologous recombination deficiency in breast cancer: Implications for risk, cancer development, and therapy.

An underlying cause of breast cancers has been largely attributed to defects in the DNA damage response (DDR) pathway. In particular, the homologous recombination (HR) pathway repairs double-stranded breaks (DSBs) in DNA, ultimately protecting the cell from genomic instability and thus preventing the accumulation of transforming mutations. In line with this, mutations in a number of genes encoding HR proteins are a well-studied cause of HR deficiency (HRD), and, at the germline level, can confer risk to breast cancer but also occur somatically, contributing to sporadic breast cancer development, progression and response to therapy. Our understanding of the biological processes involved in HR and how these become compromised during breast cancer development has led to a better understanding of how HRD cells can be targeted with specific DNA damaging agents and/or with synthetic lethal targeting approaches such as PARP inhibition. Additionally, in vitro and preclinical modeling has supported the development of clinical trials to assess targeted therapies such as PARP inhibitors (PARPis), ultimately leading to development of therapies with greater clinical benefit. A number of challenges have been encountered, including resistance to therapy; however, addressing these challenges head-on and continually driving scientific research and clinical trials with innovative therapies will contribute to our ability to target HRD in breast cancers. Ongoing research efforts into HRD in breast cancer development are therefore essential, even in the era of targeted therapies, to provide innovative strategies for improved tumor responses.

Novel Clofarabine-Based Combinations with Polyphenols Epigenetically Reactivate Retinoic Acid Receptor Beta, Inhibit Cell Growth, and Induce Apoptosis of Breast Cancer Cells.

An epigenetic component, especially aberrant DNA methylation pattern, has been shown to be frequently involved in sporadic breast cancer development. A growing body of literature demonstrates that combination of agents, i.e. nucleoside analogues with dietary phytochemicals, may provide enhanced therapeutic effects in epigenetic reprogramming of cancer cells. Clofarabine (2-chloro-2′-fluoro-2′-deoxyarabinosyladenine, ClF), a second-generation 2′-deoxyadenosine analogue, has numerous anti-cancer effects, including potential capacity to regulate epigenetic processes. Our present study is the first to investigate the combinatorial effects of ClF (used at IC50 concentration) with epigallocatechin-3-gallate (EGCG, tea catechin) or genistein (soy phytoestrogen), at physiological concentrations, on breast cancer cell growth, apoptosis, and epigenetic regulation of retinoic acid receptor beta (RARB) transcriptional activity. In MCF7 and MDA-MB-231 cells, RARB promoter methylation and expression of RARB, modifiers of DNA methylation reaction (DNMT1, CDKN1A, TP53), and potential regulator of RARB transcription, PTEN, were estimated using methylation-sensitive restriction analysis (MSRA) and quantitative real-time polymerase chain reaction (qPCR), respectively. The combinatorial exposures synergistically or additively inhibited the growth and induced apoptosis of breast cancer cells, followed by RARB hypomethylation with concomitant multiple increase in RARB, PTEN, and CDKN1A transcript levels. Taken together, our results demonstrate the ability of ClF-based combinations with polyphenols to promote cancer cell death and reactivate DNA methylation-silenced tumor suppressor genes in breast cancer cells with different invasive potential.

Plant natural modulators in breast cancer prevention: status quo and future perspectives reinforced by predictive, preventive, and personalized medical approach.

In contrast to the genetic component in mammary carcinogenesis, epigenetic alterations are particularly important for the development of sporadic breast cancer (BC) comprising over 90% of all BC cases worldwide. Most of the DNA methylation processes are physiological and essential for human cellular and tissue homeostasis, playing an important role in a number of key mechanisms. However, if dysregulated, DNA methylation contributes to pathological processes such as cancer development and progression. A global hypomethylation of oncogenes and hypermethylation of tumor-suppressor genes are characteristic of most cancer types. Moreover, histone chemical modifications and non-coding RNA-associated multi-gene controls are considered as the key epigenetic mechanisms governing the cellular homeostasis and differentiation states. A number of studies demonstrate dietary plant products as actively affecting the development and progression of cancer. "Nutri-epigenetics" focuses on the influence of dietary agents on epigenetic mechanisms. This approach has gained considerable attention; since in contrast to genetic alterations, epigenetic modifications are reversible affect early carcinogenesis. Currently, there is an evident lack of papers dedicated to the phytochemicals/plant extracts as complex epigenetic modulators, specifically in BC. Our paper highlights the role of plant natural compounds in targeting epigenetic alterations associated with BC development, progression, as well as its potential chemoprevention in the context of preventive medicine. Comprehensive measures are stated with a great potential to advance the overall BC management in favor of predictive, preventive, and personalized medical services and can be considered as "proof-of principle" model, for their potential application to other multifactorial diseases.

Validation of Arid1a as a Mammary Tumor Driver in Mice

Distinguishing commonly deleted genes as drivers or passengers of human cancers are key to delineating mechanisms of tumor initiation. The “Chaos3” mouse model of spontaneous breast cancer carries a missense mutation in MCM4 (minichromosome maintenance 4), causing destabilization of the MCM2‐7 replicative helicase, which in turn causes elevated genomic instability. Approximately 80% of female mice homozygous for this mutation in the C3H/FeJ background develop mammary tumors with an average latency of 12 months. Genomic analysis of these tumors revealed that ~70% had monoallelic deletion of tumor suppressor Arid1a. Arid1a is a member of the SWI/SNF chromatin remodeling complex and is responsible for conferring specificity of SWI/SNF complexes to their targets. Previous studies in the lab have shown that introduction of a second Arid1a allele in monoallelically deleted, cultured tumor cells rescued the tumorgenic phenotype following transplantation into host mammary glands. We propose that deletion of Arid1a early in postnatal development is one driver of Chaos3 mammary tumors. Here, we will perform intraductal mammary injections of adeno‐cre virus into Chaos3 females bearing a floxed Arid1a allele. Loss of Arid1a has been implicated as a driver of tumorigenesis in many cancers such as clear cell ovarian carcinoma and endometrioid carcinoma, and is deleted in ~5–11% of human breast cancers. Identifying Arid1a as a driver of mammary tumors in Chaos3 mice would validate its potential role in development of sporadic breast cancer in people.Support or Funding InformationBreast Cancer Coalition of RochesterThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The role of low-penetrance alleles in predisposing the development of sporadic breast cancer

Breast cancer (BC) is one of the most common oncological diseases in the world and has a complex polygenic multifactorial character. The simultaneous analysis of a large number of medium- and low-penetrance genes in the genesis of the sporadic forms of BC makes it possible to more accurately predict the individual risk of this disease, and the analysis of their intergenic associations will help to identify the most significant interactions between several of them. This would significantly simplify further screening studies. In this study, we analyzed all possible combinations of pathogenetically significant polymorphic variants for the key genes involved in (1) repair systems (XRCC1, XRCC3, and PALB2); (2) biotransformation of xenobiotics (NAT2, EPHX1, GSTP1, GSTT1, and GSTM1); (3) cell cycle control (HMMR, TP53); and (4) folate cycle (MTHFR) among patients from Belarus (eastern European region) with the sporadic forms of BC and in the control group. The combinations of genotypes (genetic profile) significantly modifying the risk of sporadic BC were identified using the multifactor dimensionality reduction (MDR). The genetic profile (combinations of genotypes) leading to a significant increase in the risk of sporadic BC is the presence of the G allele in SNP p.I105V (GSTP1), the T allele in SNP p.T241M (XRCC3), and the AA genotype in SNP p.E429A (MTHFR).

BRCA1/FANCD2/BRG1-Driven DNA Repair Stabilizes the Differentiation State of Human Mammary Epithelial Cells

An abnormal differentiation state is common in BRCA1-deficient mammary epithelial cells, but the underlying mechanism is unclear. Here, we report aconvergence between DNA repair and normal, cultured human mammary epithelial (HME) cell differentiation. Surprisingly, depleting BRCA1 or FANCD2 (Fanconi anemia [FA] proteins) or BRG1, a mSWI/SNF subunit, caused HME cells to undergo spontaneous epithelial-to-mesenchymal transition (EMT) and aberrant differentiation. This also occurred when wild-type HMEs were exposed to chemicals that generate DNA interstrand crosslinks (repaired by FA proteins), but not in response to double-strand breaks. Suppressed expression of ΔNP63 also occurred in each of these settings, an effect that linksDNA damage to the aberrant differentiation outcome. Taken together with somatic breast cancer genome data, these results point to a breakdown in a BRCA/FA-mSWI/SNF-ΔNP63-mediated DNA repair and differentiation maintenance process in mammary epithelial cells that may contribute to sporadic breast cancer development.

Abstract 1585: Chronic induction of breast cell carcinogenesis by multiple environmental and dietary carcinogens

Abstract Breast cancer, the most common type of cancer among North American and European women, is mostly sporadic and attributable to long-term exposure to small quantities of multiple carcinogens. To understand how multiple carcinogens act together to induce breast cell carcinogenesis, we investigated the activity of the tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), the environmental carcinogen benzo[a]pyrene (B[a]P), and the dietary carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Non-cancerous human breast epithelial MCF10A cells were exposed to NNK, B[a]P, and PhIP sequentially or in combination and then analyzed for the acquisition of cancerous properties/endpoints. Transient endpoints included DNA damage, Ras-Erk-Nox pathway activation, reactive oxygen species (ROS) elevation, and increased cell proliferation. Constitutive endpoints included reduced dependence on growth factors, anchorage-independent growth, Ras-Erk-Nox pathway activation, and increased ROS and cell proliferation. To detect agents that can intervene with cellular carcinogenesis induced by NNK, B[a]P, and PhIP, we investigated the activity of green tea catechins effective in blocking these cancerous endpoints. Our study revealed, for the first time, that combined NNK and B[a]P enhanced breast cell carcinogenesis chronically induced by PhIP. Co-exposure was more potent than sequential exposure to induce initiation of cellular carcinogenesis measured by induction of transient endpoints in a single exposure and progression of carcinogenesis measured by cellular acquisition of constitutive endpoints in cumulative exposures. Our study also revealed that combined ECG and EGCG, at non-cytotoxic levels, was more effective than individual agents in intervention of cellular carcinogenesis induced by combined NNK, B[a]P, and PhIP. Thus, co-exposure to NNK, B[a]P, and PhIP should be critically examined in epidemiological studies to reveal the impact of these carcinogens in the development of sporadic breast cancer. Use of combined ECG and EGCG should be seriously considered for chemoprevention of breast cell carcinogenesis associated with long-term exposure to environmental and dietary carcinogens. Citation Format: Lenora A. Pluchino, Hwa-Chain R. Wang. Chronic induction of breast cell carcinogenesis by multiple environmental and dietary carcinogens. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1585. doi:10.1158/1538-7445.AM2014-1585

Abstract 561: A natural copy number variant in the GAEC1 oncogene is associated with breast cancer susceptibility

Abstract The recently discovered GAEC1 oncogene, located at 7q22, has been found to be amplified in esophageal and colorectal cancers and is associated with altered clinical characteristics in those diseases. Amplification studies in these cancers showed variation in copy number in normal tissues, indicating a potential natural copy number variant (CNV) of GAEC1. In this research, the presence of such a CNV and its association with sporadic breast cancer development was tested in a population of 190 Caucasian women with breast cancer and a population of age, sex and ethnicity matched controls. Data produced by qPCR confirmed the presence of a CNV for GAEC1 in both cancer and control populations, with three common copy number types and several uncommon values, representing up to a 64-fold difference in GAEC1 copies. In addition, Chi-square analysis of copy number types indicated that increased GAEC1 copy number is associated with cancer development. This includes analysis using only the common copy number types (p=0.05) as well as considering all genotypes on a High/Low gene dosage basis (p=0.03). Overall risk for breast cancer was found to be slightly increased in high dose individuals (OR 1.552 (95% CI 1.035-2.338)). These results indicate that GAEC1 may be an important gene in the development of breast cancer, and that examination of its copy number in patient DNA may be a useful addition to genetic risk markers in sporadic cases. Citation Format: Vinod Gopalan, Robert A. Smith, Suja Pillai, Lyn R. Griffiths, Alfred K-Y Lam. A natural copy number variant in the GAEC1 oncogene is associated with breast cancer susceptibility. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 561. doi:10.1158/1538-7445.AM2014-561

Rad51 supports triple negative breast cancer metastasis.

In contrast to extensive studies on familial breast cancer, it is currently unclear whether defects in DNA double strand break (DSB) repair genes play a role in sporadic breast cancer development and progression. We performed analysis of immunohistochemistry in an independent cohort of 235 were sporadic breast tumours. This analysis suggested that RAD51 expression is increased during breast cancer progression and metastasis and an oncogenic role for RAD51 when deregulated. Subsequent knockdown of RAD51 repressed cancer cell migration in vitro and reduced primary tumor growth in a syngeneic mouse model in vivo. Loss of RAD51 also inhibited associated metastasis not only in syngeneic mice but human xenografts and changed the metastatic gene expression profile of cancer cells, consistent with inhibition of distant metastasis. This demonstrates for the first time a new function of RAD51 that may underlie the proclivity of patients with RAD51 overexpression to develop distant metastasis. RAD51 is a potential biomarker and attractive drug target for metastatic triple negative breast cancer, with the capability to extend the survival of patients, which is less than 6 months.

Breast Cell Carcinogenesis Model for Intervention

Carcinogenesis is a multiyear, multistep, multipath disease process with progressive genetic and epigenetic alterations and associated tissue damage. More than 85% of breast cancers are sporadic and attributable to long-term exposure to small quantities of environmental carcinogenic substances. We have developed a chronically-induced cellular carcinogenesis model to mimic sporadic breast cancer development. This model allows us to identify carcinogenic substances, at physiologically-achievable low levels, capable of inducing breast cell carcinogenesis. With this model, we are able to identify cellular, biochemical, and molecular endpoints transiently and constitutively induced by single and cumulative exposures, respectively, thereby identifying carcinogenic substances involved in induction and progression of carcinogenesis. Using our model, we are also able to identify preventive agents effective in blocking these transient and constitutive carcinogenic endpoints. Thus, use of our model system will help accelerate development of novel strategies for targeted intervention of sporadic breast cancer in association with chronic exposure to low-dose carcinogenic substances, leading to a comprehensive reduction of breast cancer incidence and mortality.

Induction of human breast cell carcinogenesis by triclocarban and intervention by curcumin

More than 85% of breast cancers are sporadic and attributable to long-term exposure to environmental carcinogens and co-carcinogens. To identify co-carcinogens with abilities to induce cellular pre-malignancy, we studied the activity of triclocarban (TCC), an antimicrobial agent commonly used in household and personal care products. Here, we demonstrated, for the first time, that chronic exposure to TCC at physiologically-achievable nanomolar concentrations resulted in progressive carcinogenesis of human breast cells from non-cancerous to pre-malignant. Pre-malignant carcinogenesis was measured by increasingly-acquired cancer-associated properties of reduced dependence on growth factors, anchorage-independent growth and increased cell proliferation, without acquisition of cellular tumorigenicity. Long-term TCC exposure also induced constitutive activation of the Erk–Nox pathway and increases of reactive oxygen species (ROS) in cells. A single TCC exposure induced transient induction of the Erk–Nox pathway, ROS elevation, increased cell proliferation, and DNA damage in not only non-cancerous breast cells but also breast cancer cells. Using these constitutively- and transiently-induced changes as endpoints, we revealed that non-cytotoxic curcumin was effective in intervention of TCC-induced cellular pre-malignancy. Our results lead us to suggest that the co-carcinogenic potential of TCC should be seriously considered in epidemiological studies to reveal the significance of TCC in the development of sporadic breast cancer. Using TCC-induced transient and constitutive endpoints as targets will likely help identify non-cytotoxic preventive agents, such as curcumin, effective in suppressing TCC-induced cellular pre-malignancy.

The Unliganded Glucocorticoid Receptor Positively Regulates the Tumor Suppressor GeneBRCA1through GABP Beta

Loss of BRCA1 tumor suppressor function is a critical event in breast tumorigenesis. We have previously identified the stress hormone hydrocortisone as a negative regulator of BRCA1 expression in nonmalignant mammary cells. Here, we have identified a direct role for the unliganded glucocorticoid receptor (GR) in BRCA1 upregulation in the absence of hydrocortisone. The positive regulatory effect of GR is lost upon the addition of hydrocortisone. We have shown that GR interacts with the BRCA1 promoter only in the absence of hydrocortisone, and that this interaction is mediated through the β-subunit of the ets transcription factor GA-binding protein (GABP) at the RIBS promoter element. GR and GABPβ interact in both coimmunoprecipitation and mammalian two-hybrid assays, and this interaction involves the N-terminal to central regions of both proteins. This work presents the first evidence of a ligand-independent role for GR as a positive regulator of gene expression, and loss of GR from the BRCA1 promoter in response to stress hormones leads to decreased BRCA1 expression. Because low levels of BRCA1 have been implicated in the development of sporadic breast cancer, this may represent a novel mechanism through which prolonged stress signaling increases breast cancer risk.

303 Hypoxia-inducible factor 1a promotes gastric cancer chemoresistance via modulation of p53 and NF-κB

DNA sequence variations in hypoxia-inducible factor-1α (HIF-1α) gene, which have been demonstrated to be correlated with tumor angiogenesis, may yield changes both in the production outcomes and in the activities of the gene. In this study, we investigated the relationship between three single nucleotide polymorphisms (SNPs) [C1772T and G1790A in exon 12 and C111A in exon 2 of the HIF-1α gene] in the HIF-1α gene coding regions and development of sporadic breast cancer in the Turkish population. These three polymorphisms result in an amino acid change from proline 582 to serine, from alanine 588 to threonine and from serine 28 to tyrosine, respectively.Genomic DNA was isolated from 102 sporadic breast cancer patients and 102 healthy female controls. All three HIF-1α gene regions were amplified by PCR, and genotypes were determined by RFLP and DNA sequencing.There were no significant differences between patients and controls in terms of the distribution of C1772T and G1790A polymorphisms of HIF-1 gene (p >0.05). As for HIF-1α C111A polymorphism, we did not find CA and AA variants of the gene in either controls or patients. Multivariable logistic regression analysis was performed between CC and CT + TT genotypes of C1772T polymorphism. No significant differences were found between these two genotypes in terms of clinicopathological characteristics of the patients including age at enrollment, age at menarche and first delivery, number of full-term pregnancies, body mass index, use of oral contraceptives and postmenopausal hormones, family history of breast and ovarian cancers, menopausal status, histopathological features, oophorectomy, smoking habits, and alcohol consumption (p >0.05).Our results suggest that none of the polymorphisms studied in the HIF-1α gene influence susceptibility to sporadic breast cancer. The present study is the first case-control study that investigates the association of HIF-1α polymorphisms with sporadic breast cancer in the Turkish population.

An integrative hypothesis about the origin and development of sporadic and familial breast cancer subtypes

Do breast cancer tumours have a common cell origin? Do different breast cancer molecular phenotypes arise from distinct cell types? The studies we have performed during the last few years in familial breast tumours (BRCA1, BRCA2 and non-BRCA1/2) widen questions about the development of sporadic breast cancer to hereditary breast cancer. Array-comparative genomic hybridisation (CGH) studies show universal genomic aberrations in both familial and sporadic breast cancer subtypes that may be selected in the breast tumour development. The inactivation of BRCA1 seems to play a critical role in oestrogen receptor (ER)-negative cancer stem cells (CSCs), driving the tumour development mostly towards a basal-like or, in some cases, to a luminal B phenotype, but other carcinogenetic events are proposed to explain the remaining tumour subtypes. The existence of common genomic alterations in basal-like, ERBB2 and luminal B breast tumours may suggest a common cell origin or clonal selection of these tumour subtypes, arising from an ER-negative CSC or from a progenitor cell (PC). Finally, specific genomic aberrations in ER-positive tumours could provide cellular proliferation advantages when the cells are exposed to oestrogen. We propose a combination of the CSC hypothesis (for the carcinogenesis processes) and the clonal selection model (in terms of tumour development). We uphold that the basal-like-, ERBB2- and luminal B-sporadic and familial tumour subtypes have an ER-negative breast stem/PC origin, whereas luminal A tumours arise from an ER-positive PC, supporting a hierarchical breast carcinogenesis model, whereas crucial genomic imbalances are clonally selected during the tumour development.

Young women and fertility in breast cancer

DNA sequence variations in hypoxia-inducible factor-1α (HIF-1α) gene, which have been demonstrated to be correlated with tumor angiogenesis, may yield changes both in the production outcomes and in the activities of the gene. In this study, we investigated the relationship between three single nucleotide polymorphisms (SNPs) [C1772T and G1790A in exon 12 and C111A in exon 2 of the HIF-1α gene] in the HIF-1α gene coding regions and development of sporadic breast cancer in the Turkish population. These three polymorphisms result in an amino acid change from proline 582 to serine, from alanine 588 to threonine and from serine 28 to tyrosine, respectively.Genomic DNA was isolated from 102 sporadic breast cancer patients and 102 healthy female controls. All three HIF-1α gene regions were amplified by PCR, and genotypes were determined by RFLP and DNA sequencing.There were no significant differences between patients and controls in terms of the distribution of C1772T and G1790A polymorphisms of HIF-1 gene (p >0.05). As for HIF-1α C111A polymorphism, we did not find CA and AA variants of the gene in either controls or patients. Multivariable logistic regression analysis was performed between CC and CT + TT genotypes of C1772T polymorphism. No significant differences were found between these two genotypes in terms of clinicopathological characteristics of the patients including age at enrollment, age at menarche and first delivery, number of full-term pregnancies, body mass index, use of oral contraceptives and postmenopausal hormones, family history of breast and ovarian cancers, menopausal status, histopathological features, oophorectomy, smoking habits, and alcohol consumption (p >0.05).Our results suggest that none of the polymorphisms studied in the HIF-1α gene influence susceptibility to sporadic breast cancer. The present study is the first case-control study that investigates the association of HIF-1α polymorphisms with sporadic breast cancer in the Turkish population.

Single Nucleotide Polymorphisms in the Hypoxia-inducible Factor-1α (HIF-1α) Gene in Human Sporadic Breast Cancer

DNA sequence variations in hypoxia-inducible factor-1alpha (HIF-1alpha) gene, which have been demonstrated to be correlated with tumor angiogenesis, may yield changes both in the production outcomes and in the activities of the gene. In this study, we investigated the relationship between three single nucleotide polymorphisms (SNPs) [C1772T and G1790A in exon 12 and C111A in exon 2 of the HIF-1alpha gene] in the HIF-1alpha gene coding regions and development of sporadic breast cancer in the Turkish population. These three polymorphisms result in an amino acid change from proline 582 to serine, from alanine 588 to threonine and from serine 28 to tyrosine, respectively. Genomic DNA was isolated from 102 sporadic breast cancer patients and 102 healthy female controls. All three HIF-1alpha gene regions were amplified by PCR, and genotypes were determined by RFLP and DNA sequencing. There were no significant differences between patients and controls in terms of the distribution of C1772T and G1790A polymorphisms of HIF-1 gene (p >0.05). As for HIF-1alpha C111A polymorphism, we did not find CA and AA variants of the gene in either controls or patients. Multivariable logistic regression analysis was performed between CC and CT + TT genotypes of C1772T polymorphism. No significant differences were found between these two genotypes in terms of clinicopathological characteristics of the patients including age at enrollment, age at menarche and first delivery, number of full-term pregnancies, body mass index, use of oral contraceptives and postmenopausal hormones, family history of breast and ovarian cancers, menopausal status, histopathological features, oophorectomy, smoking habits, and alcohol consumption (p >0.05). Our results suggest that none of the polymorphisms studied in the HIF-1alpha gene influence susceptibility to sporadic breast cancer. The present study is the first case-control study that investigates the association of HIF-1alpha polymorphisms with sporadic breast cancer in the Turkish population.

Promoter polymorphism (−786t>C) in the endothelial nitric oxide synthase gene is associated with risk of sporadic breast cancer in non‐Hispanic white women age younger than 55 years

Nitric oxide (NO) is constitutively synthesized in the endothelium by endothelial nitric oxide synthase (eNOS) and acts as a pleiotropic regulator involved in carcinogenesis. Most breast cancers develop from mammary epithelial cells; therefore, NO may play a role in their development. It was hypothesized that eNOS polymorphisms are associated with risk of breast cancer. In the current hospital-based case-control study of 421 non-Hispanic white women with sporadic breast cancer and 423 frequency-matched control subjects, we genotyped 3 polymorphisms of eNOS (i.e., -786T>C, the 27-base pair [bp] variable number of tandem repeats [VNTR] in intron 4, and 894G>T [Glu298Asp]) and assessed their associations with risk of breast cancer. It was found that, compared with -786TT, the -786C variant genotypes were associated with a significantly increased risk of breast cancer in an allele dose-dependent manner (adjusted odds ratio [OR], 1.33 [95% confidence interval (95% CI)], 0.99-1.77 for -786TC; and OR, 1.79 [95% CI, 1.11-2.87] for -786CC; P(trend) = .007), but 27-bp VNTR and 894G>T genotypes were not. Stratification analysis demonstrated that the risk associated with -786C variant genotypes (-786TC/CC) was more pronounced in smokers and in those 50 years or older (OR, 1.82 [95% CI, 1.19-2.80] and OR, 2.08 [95% CI, 1.25-3.45], respectively), and in the estrogen and progesterone receptor-negative cases (OR, 1.70 [95% CI, 1.10-2.62] and OR, 1.57 [95% CI, 1.07-2.32], respectively). Furthermore, the C4G haplotype derived from the observed genotypes was also associated with a significantly increased risk of breast cancer (OR, 2.16; 95% CI, 1.07-4.36). The results suggest that eNOS polymorphisms (especially -786T>C) may play a role in the development of sporadic breast cancer.

Functional IFNG polymorphism in intron 1 in association with an increased risk to promote sporadic breast cancer

Interferon (IFN)-gamma is an important Th1 cytokine, which plays a role in immune surveillance and anti-tumor activity. A case-control study involving 54 sporadic breast cancer patients and 144 healthy controls was carried out to explore if the genotype variation of a proposed non-specific enhancer element with a dinucleotide (CA)n repeat in intron 1 has a role in the susceptibility to promote sporadic breast cancer. Genotype analysis carried out by single-strand length polymorphism and confirmed by sequencing showed an increased frequency of (CA)12 allele (P<0.001) and decreased frequencies of (CA)15 (P<0.01) and (CA)>15 (p<0.001) alleles in sporadic breast cancer patients as compared to controls. Further, in vitro reporter assays for (CA)12 and (CA)15 alleles suggested these to be associated with decreased and increased expressions, respectively, suggesting the (CA)12/(CA)12 background to act as one of the factors that could lead to low production of IFN-gamma. The study concludes that such genetic background for a proposed non-specific enhancer element with (CA)n repeat within intron 1 of the IFNG gene might put the individuals with this genotype at higher risk to promote the development of sporadic breast cancer due to a resultant compromised immune surveillance.

Roles of mismatch repair proteins hMSH2 and hMLH1 in the development of sporadic breast cancer

Defects in mismatch repair (MMR) genes, particularly the hMSH2 and hMLH1 genes, are associated with a variety of cancers including sporadic breast cancer. However, whether or not patient clinical background, e.g. age, progesterone receptor (PR), estrogen receptor (ER), tumor progression and stage, chemotherapy history, and menopausal status, influences MMR status is not understood. To address these issues, 83 archival breast cancer specimens were examined for expression of hMSH2 and hMLH1 by immunohistochemistry and the relationship between MMR protein expression and patient clinical background was analyzed. We detected lack of or reduced expression of hMSH2 and hMLH1 in 23 (27.7%) and 26 cases (31.3%), respectively, and hypermethylation of the hMLH1 promoter accounted for the majority of the cases with reduced expression of hMLH1. Statistical analysis revealed that (i) reduced expression of hMLH1 and hMSH2 seemed to confer advantage for the progression of breast tumors to more advanced stages; (ii) attenuated expression of hMLH1 correlated with history of chemotherapy, but not with age, menopause, or the status of PR and ER; (iii) hypermethylation of the hMLH1 promoter was linked with clinical stage and lymphatic metastasis. These analyses indicate that defective expression of MMR genes is closely associated with the development of sporadic breast cancer.