Common single-nucleotide polymorphisms in the estrogen receptor β promoter are associated with colorectal cancer survival in postmenopausal women

The Influence of ESR2 Gene Polymorphisms on Susceptibility to Hepatitis B Virus-Related Chronic Hepatitis, Liver Cirrhosis, and Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) represents an estrogen-dependent tumor. The action of estrogen is regulated via estrogen receptor (ER). Polymorphisms in ERα gene, ESR1, are known to be related to HCC susceptibility among people carrying chronic hepatitis B (CHB). But the effect of ERβ on HCC is still largely unclear, and studies about the genetic variability of ESR2 and HCC are rare. For understanding ESR2's effect on HCC, this work tested two polymorphisms in the ESR2 gene promoter as well as the associations with CHB, HCC, and hepatitis B virus (HBV)-related liver cirrhosis (LC) among the Guangxi population. This work enrolled a total of 137 CHB, 136 LC, and 149 HBV-related HCC patients, together with 146 normal subjects. ESR2 polymorphisms rs3020449 and rs2978381 were examined using the SNaPshot genotyping technique. The AG genotype and dominant model of rs3020449 were related to the decreased CHB susceptibility. In both the overall and subgroup analyses, no associations were observed with the remaining models in all patient groups (those with CHB, HBV-related LC, and HCC), but associations were found between the dominant (TC+CC vs TT) and allele models (C vs T) of rs2978381 and increased HBV-related LC and HCC susceptibility, but not CHB. These findings suggest that rs3020449 polymorphism of ESR2 gene makes great contribution to the decreased CHB risk and that rs2978381 significantly contributed to higher risks of HBV-related LC and HCC.

Association Study of rs2987983 Polymorphism in the Promoter Region of ESR2 Gene and Susceptibility to Nodular Thyroid in Women of Markazi Province, Iran

Background: The risk of thyroid disease has been increased during recent years; more than 200 million people are suffering from various types of thyroid diseases. The rate of thyroid nodules in women is 4 times more than that of men. Epidemiological findings and experimental evidence of thyroid lesions suggest that sex hormones, especially estrogen, may affect this gland and its neoplasms. Objectives: Considering the prevalence of benign and malignant thyroid disease in women, we investigated the association between rs2987983 polymorphism in the estrogen receptor beta gene and nodular thyroid disease. Methods: In this case-control study, 146 patients with thyroid nodules from Amir- Almomenin Hospital in Arak were compared with 151 healthy individuals. The diagnosis was performed by ultrasonography and confirmed by an endocrinologist. After DNA extraction, genotyping was performed with T-ARMS PCR. Finally, statistical analysis was carried out. Results: The frequencies of AA, AG, and GG genotypes in the case group were 48 (32.9%), 83 (56.8%), and 15 (10.3%), respectively. These values in the control group were 64 (42.4%), 64 (42.4%), and 23 (15.2%), respectively. Overall, a statistically significant association (P = 0.042, χ2 = 6.3, df = 2) was observed between rs2987983 polymorphism and thyroid nodules. Conclusions: Considering the significant association between rs2987983 polymorphism and thyroid nodules, it can be suggested that the mentioned polymorphism may be used as a diagnostic biomarker. Because this polymorphism is in the promoter region of the gene, it probably alters gene expression levels.

Is the beta estradiol receptor receiving enough attention for its metabolic importance in postmenopause?

The relationship between menopause and the development of metabolic diseases is well established. In postmenopause women, there is an expansion of visceral white adipose tissue (WATv), which highly contributes to the rise of circulating lipids. Meanwhile, muscle glucose uptake decreases and hepatic glucose production increases. Consequently, in the pancreas, lipotoxicity and glycotoxicity lead to deficient insulin production. These factors initiate an energy imbalance and enhance the probability of developing cardiovascular and metabolic diseases. Although the activation of estradiol receptors (ER) has been shown to be beneficial for the WAT stock pattern, leading to the insulin-sensitive phenotype, authors have described the risk of these receptors' activation, contributing to neoplasia development. The selective activation of beta-type ER (ERβ) seems to be a promising strategy in the treatment of energy imbalance, acting on several tissues of metabolic importance and allowing an intervention with less risk for the development of estrogen-dependent neoplasia. However, the literature on the risks and benefits of selective ERβ activation still needs to increase. In this review, several aspects related to ERβ were considered, such as its physiological role in tissues of energy importance, beneficial effects, and risks of its stimulation during menopause. PubMed, SciELO, Cochrane, and Medline/Bireme databases were used in this study.

Estrogen Receptor Beta: The Promising Biomarker and Potential Target in Metastases

The discovery of the Estrogen Receptor Beta (ERβ) in 1996 opened new perspectives in the diagnostics and therapy of different types of cancer. Here, we present a review of the present research knowledge about its role in endocrine-related cancers: breast, prostate, and thyroid, and colorectal cancers. We also discuss the reasons for the controversy of its role in carcinogenesis and why it is still not in use as a biomarker in clinical practice. Given that the diagnostics and therapy would benefit from the introduction of new biomarkers, we suggest ways to overcome the contradictions in elucidating the role of ERβ.

Intestinal estrogen receptor beta suppresses colon inflammation and tumorigenesis in both sexes

Estrogen hormones protect against colorectal cancer (CRC) and a preventative role of estrogen receptor beta (ERβ) on CRC has been supported using full knockout animals. However, it is unclear through which cells or organ ERβ mediates this effect. To investigate the functional role of intestinal ERβ during colitis-associated CRC we used intestine-specific ERβ knockout mice treated with azoxymethane and dextran sodium sulfate, followed by ex vivo organoid culture to corroborate intrinsic effects. We explored genome-wide impact on TNFα signaling using human CRC cell lines and chromatin immunoprecipitation assay to mechanistically characterize the regulation of ERβ. Increased tumor formation in males and tumor size in females was noted upon intestine-specific ERβ knockout, accompanied by enhanced local expression of TNFα, deregulation of key NFκB targets, and increased colon ulceration. Unexpectedly, we noted especially strong effects in males. We corroborated that intestinal ERβ protects against TNFα-induced damage intrinsically, and characterized an underlying genome-wide signaling mechanism in CRC cell lines whereby ERβ binds to cis-regulatory chromatin areas of key NFκB regulators. Our results support a protective role of intestinal ERβ against colitis-associated CRC, proposing new therapeutic strategies.

Sexual dimorphism in hepatitis B and C and hepatocellular carcinoma

The incidence of viral hepatitis B or C (HBV/HCV) infection and hepatocellular carcinoma is higher in male compared to female populations, showing a faster disease progression and results in a worse overall survival. Indeed, women are in general better protected from viral infections and show a lower risk of death from malignant cancer in comparison to men. Females mount stronger innate and adaptive immune responses than males, and therefore, most of the autoimmune diseases occur predominantly in females. Next to occupational and/or behavioral factors, cellular and molecular differences between the two sexes contribute to this observation. In this review, we will discuss underlying mechanisms that are important for the observed sex-related differences in liver diseases. A better appreciation of these differences between the two sexes might be of value for better and gender-specific treatment options.

ASSOCIATION OF TESTOSTERONE WITH COLORECTAL CANCER (HT29), HUMAN GLIOBLASTOMA (A172) AND HUMAN EMBRYONIC KIDNEY (HEK293) CELLS PROLIFERATION

Testosterone influences cancer development. This in vitro experiment was exerted to determine the association of testosterone with human colorectal cancer(HT29), glioblastoma (A172) and human embryonic kidney(HEK293) cells proliferation. HT-29, A172 and HEK293 cell lines were cultured in standard growth medium, then randomly divided into control group (not exposed to testosterone) and groups exposed to 1, 10, 100 and 1000 μg/mL of testosterone. Cell viability was quantified by MTT assay. Statistical analysis was performed using ANOVA. Viability of HEK293 cells significantly increased in groups exposed to 1 μg/mL and decreased in groups exposed to 100 and 1000 μg/mL of testosterone compared to control group (P<0.05, P<0.05 and P<0.001, respectively). Viability of HT29 cells significantly increased in groups exposed to 10 and 100 μg/mL of testosterone and significantly decreased when exposed to 1000 μg/mL of testosterone compared to control group (P<0.05, P<0.001 and P<0.001, respectively). Viability of A172 cells significantly decreased in groups exposed to 100 and 1000 μg/mL of testosterone compared to control group (P<0.001). In conclusion, different doses of testosterone have enhancing or suppressive effects on HEK293, HT29 and A172 cells proliferation; according to which, considering clinical use of testosterone therapy for cancer treatment is a highly controversial issue.

Polymorphisms in the estrogen receptor alpha gene (ESR1), daily cycling estrogen and mammographic density phenotypes

Background

Single nucleotide polymorphisms (SNPs) involved in the estrogen pathway and SNPs in the estrogen receptor alpha gene (ESR1 6q25) have been linked to breast cancer development, and mammographic density is an established breast cancer risk factor. Whether there is an association between daily estradiol levels, SNPs in ESR1 and premenopausal mammographic density phenotypes is unknown.

Methods

We assessed estradiol in daily saliva samples throughout an entire menstrual cycle in 202 healthy premenopausal women in the Norwegian Energy Balance and Breast Cancer Aspects I study. DNA was genotyped using the Illumina Golden Gate platform. Mammograms were taken between days 7 and 12 of the menstrual cycle, and digitized mammographic density was assessed using a computer-assisted method (Madena). Multivariable regression models were used to study the association between SNPs in ESR1, premenopausal mammographic density phenotypes and daily cycling estradiol.

Results

We observed inverse linear associations between the minor alleles of eight measured SNPs (rs3020364, rs2474148, rs12154178, rs2347867, rs6927072, rs2982712, rs3020407, rs9322335) and percent mammographic density (p-values: 0.002–0.026), these associations were strongest in lean women (BMI, ≤23.6 kg/m^2.). The odds of above-median percent mammographic density (>28.5 %) among women with major homozygous genotypes were 3–6 times higher than those of women with minor homozygous genotypes in seven SNPs. Women with rs3020364 major homozygous genotype had an OR of 6.46 for above-median percent mammographic density (OR: 6.46; 95 % Confidence Interval 1.61, 25.94) when compared to women with the minor homozygous genotype. These associations were not observed in relation to absolute mammographic density. No associations between SNPs and daily cycling estradiol were observed. However, we suggest, based on results of borderline significance (p values: 0.025–0.079) that the level of 17β-estradiol for women with the minor genotype for rs3020364, rs24744148 and rs2982712 were lower throughout the cycle in women with low (<28.5 %) percent mammographic density and higher in women with high (>28.5 %) percent mammographic density, when compared to women with the major genotype.

Conclusion

Our results support an association between eight selected SNPs in the ESR1 gene and percent mammographic density. The results need to be confirmed in larger studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2804-1) contains supplementary material, which is available to authorized users.

Sexual dimorphism in cancer

The incidence of many types of cancer arising in organs with non-reproductive functions is significantly higher in male populations than in female populations, with associated differences in survival. Occupational and/or behavioural factors are well-known underlying determinants. However, cellular and molecular differences between the two sexes are also likely to be important. In this Opinion article, we focus on the complex interplay that sex hormones and sex chromosomes can have in intrinsic control of cancer-initiating cell populations, the tumour microenvironment and systemic determinants of cancer development, such as the immune system and metabolism. A better appreciation of these differences between the two sexes could be of substantial value for cancer prevention as well as treatment.

Estrogen receptor beta as target for colorectal cancer prevention

Colorectal cancer (CRC) is a leading cause of death in the United States. Despite its slow development and the capacity for early diagnosis, current preventive approaches are not sufficient. However, a role for estrogen has been demonstrated in multiple epidemiologic studies, which may benefit CRC prevention. A large body of evidence from preclinical studies indicates that expression of the estrogen receptor beta (ERβ/ESR2) demonstrates an inverse relationship with the presence of colorectal polyps and stage of tumors, and can mediate a protective response. Natural compounds, including phytoestrogens, or synthetic ERβ selective agonists, can activate or upregulate ERβ in the colon and promote apoptosis in preclinical models and in clinical experience. Importantly, this activity has been associated with a reduction in polyp formation and, in rodent models of CRC, has been shown to lower incidence of colon adenocarcinoma. Collectively, these findings indicate that targeted activation of ERβ may represent a novel clinical approach for management of colorectal adenomatous polyps and prevention of colorectal carcinoma in patients at risk for this condition. In this review, we discuss the potential of new chemopreventive or dietary approaches based on estrogen signaling.

Delay discounting, genetic sensitivity, and leukocyte telomere length

In a graying world, there is an increasing interest in correlates of aging, especially those found in early life. Leukocyte telomere length (LTL) is an emerging marker of aging at the cellular level, but little is known regarding its link with poor decision making that often entails being overly impatient. Here we investigate the relationship between LTL and the degree of impatience, which is measured in the laboratory using an incentivized delay discounting task. In a sample of 1,158 Han Chinese undergraduates, we observe that steeper delay discounting, indexing higher degree of impatience, is negatively associated with LTL. The relationship is robust after controlling for health-related variables, as well as risk attitude-another important determinant of decision making. LTL in females is more sensitive to impatience than in males. We then asked if genes possibly modulate the effect of impatient behavior on LTL. The oxytocin receptor gene (OXTR) polymorphism rs53576, which has figured prominently in investigations of social cognition and psychological resources, and the estrogen receptor β gene (ESR2) polymorphism rs2978381, one of two gonadal sex hormone genes, significantly mitigate the negative effect of impatience on cellular aging in females. The current results contribute to understanding the relationship between preferences in decision making, particularly impatience, and cellular aging, for the first time to our knowledge. Notably, oxytocin and estrogen receptor polymorphisms temper accelerated cellular aging in young females who tend to make impatient choices.

Association of estrogen and progesterone receptor gene polymorphisms and their respective hormones in uterine leiomyomas

The steroid hormones estradiol and progesterone play an important role in the pathophysiology of fibroids that occurs in 20-25 % of women in the reproductive age. Our study examines the risk imposed by estrogen and progesterone plasma levels in correlation with the ERβ (-13950T/C) and PGR (+331G/A) receptor gene polymorphisms. The study population included 296 individuals (146 UL cases and 150 female controls). Hormonal levels were estimated by ELISA and genotyping was carried out by PCR-RFLP analysis, and the obtained results were statistically analyzed. Estrogen levels were found to be high in cases with the "TC" genotype of ERβ receptor polymorphism compared to controls, whereas individuals with "GA" and "AA" genotype of PGR receptor polymorphism showed high progesterone levels for cases when compared to controls. The TC genotype of the ERβ receptor polymorphism and the GA and AA genotypes of the PGR receptor polymorphism and their respective hormonal levels can be developed as markers in the prediction of uterine fibroids.

Estrogen receptor-beta genetic variations and overall survival in patients with locally advanced gastric cancer

Estrogen has been shown not only to reduce the incidence of colorectal cancer but also gastric cancer (GC). Polymorphisms in estrogen receptor β gene, ESR2, correlate with colorectal cancer survival. To better understand the role of ESR2 in GC, genomic DNA extracted from 169 Japanese patients and 172 patients from Los Angeles County (LAC) was analyzed for association of overall survival (OS) with three ESR2 polymorphisms, which are of biological significance using multivariable Cox proportional hazard regression. ESR2 rs1271572 (C>A) and rs3020443 (T>G) had univariate and multivariable associations with OS in the Japanese cohort, whereas the C allele of ESR2 rs2978381 (T>C) predicted favorable OS in the Japanese cohort but worse OS in the LAC cohort. The interaction term of the ESR2 rs2978381 and cohort group reached statistical significance. Our study provides evidence that genetic variations in ESR2 gene are significantly associated with survival in patients with locally advanced GC.

Estrogen receptors and their implications in colorectal carcinogenesis

Upon binding their cognate receptors, ERα (ESR1) and ERβ (ESR2), estrogens activate intracellular signaling cascades that have important consequences for cellular behavior. Historically linked to carcinogenesis in reproductive organs, estrogens have also been implicated in the pathogenesis of different cancer types of non-reproductive tissues including the colon. ERβ is the predominant estrogen receptor expressed in both normal and malignant colonic epithelium. However, during colon cancer progression, ERβ expression is lost, suggesting that estrogen signaling may play a role in disease progression. Estrogens may in fact exert an anti-tumor effect through selective activation of pro-apoptotic signaling mediated by ERβ, inhibition of inflammatory signals and modulation of the tumor microenvironment. In this review, we analyze the estrogen pathway as a possible therapeutic avenue in colorectal cancer, we report the most recent experimental evidence to explain the cellular and molecular mechanisms of estrogen-mediated protection against colorectal tumorigenesis, and we discuss future challenges and potential avenues for targeted therapy.

Gene variations in oestrogen pathways, CYP19A1, daily 17β-estradiol and mammographic density phenotypes in premenopausal women

INTRODUCTION

High mammographic density is an established breast cancer risk factor, and circulating oestrogen influences oestrogen-regulating gene expression in breast cancer development. However, less is known about the interrelationships of common variants in the CYP19A1 gene, daily levels of oestrogens, mammographic density phenotypes and body mass index (BMI) in premenopausal women.

METHODS

Based on plausible biological mechanisms related to the oestrogen pathway, we investigated the association of single nucleotide polymorphisms (SNPs) in CYP19A1, 17β-estradiol and mammographic density in 202 premenopausal women. DNA was genotyped using the Illumina Golden Gate platform. Daily salivary 17β-estradiol concentrations were measured throughout an entire menstrual cycle. Mammographic density phenotypes were assessed using a computer-assisted method (Madena). We determined associations using multivariable linear and logistic regression models.

RESULTS

The minor alleles of rs749292 were positively (P = 0.026), and the minor alleles of rs7172156 were inversely (P = 0.002) associated with daily 17β-estradiol. We observed an 87% lower level of daily 17β-estradiol throughout a menstrual cycle in heavier women (BMI >23.6 kg/m(2)) of rs7172156 with minor genotype aa compared with major genotype AA. Furthermore, the rs749292 minor alleles were inversely associated with absolute mammographic density (P = 0.032). Lean women with rs749292 minor alleles had 70 to 80% lower risk for high absolute mammographic density (>32.4 cm(2)); Aa: odds ratio (OR) = 0.23 (95% CI 0.07 to 0.75). Lean women with rs7172156 minor homozygous genotype had OR 5.45 for high absolute mammographic density (aa: OR = 5.45 (95% CI 1.13 to 26.3)).

CONCLUSION

Our findings suggest that two SNPs in CYP19A1, rs749292 and rs7172156, are associated with both daily oestrogen levels and mammographic density phenotypes. BMI may modify these associations, but larger studies are needed.

Repeat polymorphisms in ESR2 and AR and colorectal cancer risk and prognosis: results from a German population-based case-control study

Background

Evidence has accumulated which suggests that sex steroids influence colorectal cancer development and progression. We therefore assessed the association of repeat polymorphisms in the estrogen receptor β gene (ESR2) and the androgen receptor gene (AR) with colorectal cancer risk and prognosis.

Methods

The ESR2 CA and AR CAG repeat polymorphisms were genotyped in 1798 cases (746 female, 1052 male) and 1810 controls (732 female, 1078 male), matched for sex, age and county of residence. Colorectal cancer risk associations overall and specific for gender were evaluated using multivariate logistic regression models adjusted for sex, county of residence and age. Associations with overall and disease-specific survival were evaluated using Cox proportional hazard models adjusted for established prognostic factors (diagnosis of other cancer after colorectal cancer diagnosis, detection by screening, treatment with adjuvant chemotherapy, tumour extent, nodal status, distant metastasis, body mass index, age at diagnosis and year of diagnosis) and stratified for grade of differentiation. Heterogeneity in gender specific associations was assessed by comparing models with and without a multiplicative interaction term by means of a likelihood ratio test.

Results

The average number of ESR2 CA repeats was associated with a small 5% increase in colorectal cancer risk (OR = 1.05, 95% CI 1.01-1.10) without significant heterogeneity according to gender or tumoural ESR2 expression. We found no indication for an association between the AR CAG repeat polymorphisms and risk of colorectal cancer. The ESR2 CA and AR CAG repeat polymorphisms were not associated with overall survival or disease specific survival after colorectal cancer diagnosis.

Conclusions

Higher numbers of ESR2 CA repeats are potentially associated with a small increase in colorectal cancer risk. Our study does not support an association between colorectal cancer prognosis and the investigated repeat polymorphisms.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-817) contains supplementary material, which is available to authorized users.

PELP1 suppression inhibits colorectal cancer through c-Src downregulation

Proline-, glutamic acid-, and leucine-rich protein 1 (PELP1), a coregulator of estrogen receptors alpha and beta, is a potential protooncogene implicated in several human cancers, including sexual hormone-responsive or sexual hormone-nonresponsive cancers. However, the functions of PELP1 in colorectal cancer remain unclear. In this study, western blot and bioinformatics revealed that PELP1 expression was higher in several colorectal cancer cell lines than in immortalized normal colorectal epithelium. PELP1 silencing by short hairpin RNA promoted the senescence and inhibited the proliferation, colony formation, migration, invasion, and xenograft tumor formation of the CRC cell line HT-29. Moreover, PELP1 silencing was accompanied by c-Src downregulation. c-Src upregulation partly alleviated the damage in HT-29 malignant behavior induced by PELP1 RNA interference. In conclusion, PELP1 exhibits an oncogenic function in colorectal cancer through c-Src upregulation.

No association between germline variation in catechol-O-methyltransferase and colorectal cancer survival in postmenopausal women

OBJECTIVE

Sex steroid hormones play a role in colorectal cancer (CRC) development, but little is known about their influence on tumor progression and metastasis. Because catechol-O-methyltransferase (COMT; 22q11.21) activity is an important component of estrogen-mediated carcinogenesis, we hypothesized that germline variation in COMT may be associated with CRC survival.

METHODS

We identified 10 single nucleotide polymorphisms that tagged variation across two isoforms of COMT in 2,458 women with CRC from the Nurses' Health Study, Postmenopausal Hormones Supplementary Study to the Colon Cancer Family Registry, VITamins And Lifestyle Study, and Women's Health Initiative. All four studies participated in the Genetics and Epidemiology of Colorectal Cancer Consortium.

RESULTS

During a median follow-up of 7 years across all studies, there were 799 deaths, including 566 deaths from CRC. Based on multiple comparisons, no associations between single nucleotide polymorphisms and CRC-specific or overall survival reached statistical significance, including the well-characterized Val108/158Met polymorphism (rs4680; CRC-specific survival: hazard ratio per minor allele, 1.04; 95% CI, 0.92-1.17; overall survival: hazard ratio per minor allele, 1.01; 95% CI, 0.90-1.14).

CONCLUSIONS

In this large study of women with CRC, we find no evidence that common inherited variation in COMT is associated with survival time after diagnosis.

Genetic polymorphisms of ESR1, ESR2, CYP17A1, and CYP19A1 and the risk of breast cancer: a case control study from North India

Estrogen is a key driver of breast cancer and genes involved in its signaling and biosynthesis are crucial in breast cancer progression. In this study, we investigated the role of estrogen signaling and synthesis related genes polymorphism in susceptibility to breast cancer risk in North India population in a case-control approach. We examined the association of single nucleotide polymorphism (SNP) in estrogen receptors, ESR1 (rs2234693) and ESR2 (rs2987983); estrogen biosynthesis enzymes, CYP17A1 (rs743572); and aromatase, CYP19A1 (rs700519) with breast cancer risk. Cases (n = 360) were matched to controls (n = 360) by age, sex, ethnicity, and geographical location. Results provided evidence that all the genetic variants were significantly associated with breast cancer risk among North Indian women. Furthermore, on performing stratified analysis between breast cancer risk and different clinicopathological characteristics, we observed strong associations for menopausal status, estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) status, clinical stage, and histological grade. Our results suggest that these genes could be used as molecular markers to assess breast cancer susceptibility and predicting prognosis in North India population.

Targeted re-sequencing identified rs3106189 at the 5' UTR of TAPBP and rs1052918 at the 3' UTR of TCF3 to be associated with the overall survival of colorectal cancer patients

Recent studies have demonstrated the power of deep re-sequencing of the whole genome or exome in understanding cancer genomes. However, targeted capture of selected genomic whole gene-body regions, rather than the whole exome, have several advantages: 1) the genes can be selected based on biology or a hypothesis; 2) mutations in promoter and intronic regions, which have important regulatory roles, can be investigated; and 3) less expensive than whole genome or whole exome sequencing. Therefore, we designed custom high-density oligonucleotide microarrays (NimbleGen Inc.) to capture approximately 1.7 Mb target regions comprising the genomic regions of 28 genes related to colorectal cancer including genes belonging to the WNT signaling pathway, as well as important transcription factors or colon-specific genes that are over expressed in colorectal cancer (CRC). The 1.7 Mb targeted regions were sequenced with a coverage ranged from 32× to 45× for the 28 genes. We identified a total of 2342 sequence variations in the CRC and corresponding adjacent normal tissues. Among them, 738 were novel sequence variations based on comparisons with the SNP database (dbSNP135). We validated 56 of 66 SNPs in a separate cohort of 30 CRC tissues using Sequenom MassARRAY iPLEX Platform, suggesting a validation rate of at least 85% (56/66). We found 15 missense mutations among the exonic variations, 21 synonymous SNPs that were predicted to change the exonic splicing motifs, 31 UTR SNPs that were predicted to occur at the transcription factor binding sites, 20 intronic SNPs located near the splicing sites, 43 SNPs in conserved transcription factor binding sites and 32 in CpG islands. Finally, we determined that rs3106189, localized to the 5′ UTR of antigen presenting tapasin binding protein (TAPBP), and rs1052918, localized to the 3′ UTR of transcription factor 3 (TCF3), were associated with overall survival of CRC patients.

Estrogen receptor β expression induces changes in the microRNA pool in human colon cancer cells

There is epidemiological, animal and in vitro evidence that estrogen receptor β (ERβ) can mediate protective effects against colon cancer, but the mechanism is not completely understood. Previous research has indicated critical pathways whereby ERβ acts in an antitumorigenic fashion. In this study, we investigate ERβ's impact on the microRNA (miRNA) pool in colon cancer cells using large-scale genomic approaches, bioinformatics and focused functional studies. We detect and confirm 27 miRNAs to be significantly changed following ERβ expression in SW480 colon cancer cells. Among these, the oncogenic miR-17-92 cluster and miR-200a/b are strongly downregulated. Using target prediction and anticorrelation to gene expression data followed by focused mechanistic studies, we demonstrate that repression of miR-17 is a secondary event following ERβ's downregulatory effect on MYC. We show that re-introduction of miR-17 can reverse the antiproliferative effects of ERβ. The repression of miR-17 also influences cell death upon DNA damage and mediates regulation of NCOA3 (SRC-3) and CLU in colon cancer cells. We further determine that the downregulation of miR-200a/b mediates increased ZEB1 while decreasing E-cadherin levels in ERβ-expressing colon cancer cells. Changes in these genes correspond to significant alterations in morphology and migration. Our work contributes novel data of ERβ and miRNA in the colon. Elucidating the mechanism of ERβ and biomarkers of its activity has significant potential to impact colon cancer prevention and treatment.