Loss of estrogen inactivation in colonic cancer

Estrogen induces the expression of EBV lytic protein ZEBRA, a marker of poor prognosis in nasopharyngeal carcinoma

Several epidemiological studies have suggested that Epstein-Barr virus (EBV) lytic infection is essential for the development of nasopharyngeal carcinoma (NPC), as elevation of antibody titers against EBV lytic proteins is a common feature of NPC. Although ZEBRA protein is a key trigger for the initiation of lytic infection, whether its expression affects the prognosis and pathogenesis of NPC remains unclear. In this study, 64 NPC biopsy specimens were analyzed using immunohistochemistry. We found that ZEBRA was significantly associated with a worsening of progression-free survival in NPC (adjusted hazard ratio, 3.58; 95% confidence interval, 1.08-11.87; P = 0.037). Moreover, ZEBRA expression positively correlated with key endocrinological proteins, estrogen receptor α, and aromatase. The transcriptional level of ZEBRA is activated by estrogen in an estrogen receptor α-dependent manner, resulting in an increase in structural gene expression levels and extracellular virus DNA copy number in NPC cell lines, reminiscent of lytic infection. Interestingly, it did not suppress cellular proliferation or increase apoptosis, in contrast to cells treated with 12-O-tetradecanoylphorbol-13-acetate and sodium butyrate, indicating that viral production induced by estrogen is not a cell lytic phenomenon. Our results suggest that intratumoral estrogen overproduced by aromatase could induce ZEBRA expression and EBV reactivation, contributing to the progression of NPC.

Oestrogen and colorectal cancer: mechanisms and controversies

AIM

The role of oestrogen metabolism and action in colorectal cancer (CRC) is controversial. An extensive review of the current literature, encompassing epidemiological evidence, systemic and peripheral oestrogen concentrations, 17β-hydroxysteroid dehydrogenase (17β-HSD) and aromatase in CRC, steroid sulphatase (STS)/oestrone sulphotransferase (EST) and in vitro and in vivo genomic effects was therefore undertaken.

METHODS

A literature search (key words: colorectal cancer, oestrogen, oestrogen receptor, 17β-HSD, STS, organic anion transporter) was performed using Embase, Medline, and Pubmed and papers were evaluated on scientific relevance on an individual basis.

RESULTS

Epidemiological data highlights that premenopausal women, or postmenopausal women taking hormone replacement therapy, are significantly less likely than males to develop CRC. This implies that oestrogen signalling is most likely involved in CRC physiology and aetiology. Little is known about oestrogen metabolism in the colon. However, the expression of 17β-HSD, STS, and EST, enzymes involved in oestrogen metabolism, have shown prognostic significance. Evidence also suggests that protective effects are modulated through oestrogen receptor beta, although which metabolite of oestrogen, oestradiol (E2) or oestrone (E1), is more active remains undefined. To complicate matters, the changes in the peripheral ratios of these enzymes, oestrogens and receptors most likely influences CRC progression.

CONCLUSION

Epidemiological evidence, now supported by in vitro and in vivo studies, strongly associates oestrogen action and metabolism with CRC. Initially protective against CRC, once developed, results suggests that oestrogens increase proliferation. Consequently, hormone-ablation therapy, already successful against breast and prostate cancer, may be effective against CRC.

Molecular cloning and expression of 17β-hydroxysteroid dehydrogenase type 2 gene in Hu sheep

17β-Hydroxysteroid dehydrogenase type 2 (17β-HSD2) catalyzes the NADP+-dependent oxidation of the most potent estrogen 17β-estradiol into the weak estrogen estrone, and the conversion of testosterone to androstenedione. It has been reported that 17β-HSD2 was expressed in many tissues in human, rats, however, the full-length sequence of 17β-HSD2 gene and its expression in ewe were still unknown. In this study, we cloned the full-length cDNA sequence and investigated mRNA differential expression in 28 tissues of 12 adult Hu-Sheep which were fed with high- and low- dietary intake. The 1,317 bp full-length cDNA sequence was first cloned. The coding region was 1,167 bp in length, and the monomer was estimated to contain 389 amino acid residues. It shares high AA sequence identity with that of bos Taurus (96.13 %), sus scrofa (77.06 %), canis lupus familiaris (70.44 %), Callithrix jacchus (65.72 %), Nomascus leucogenys (65.46 %), pan troglodytes (65.21 %), human (64.69 %), mus musculus (58.35 %), and a comparatively lower identity to danio rerio (37.85 %). 17β-HSD2 gene was high expressed in gastrointestinal (GI) tract, liver, but weakly expressed in other tissues. No detected expression was examined in lung. 17β-HSD2 gene expression was significantly difference in rumen, omasum, duodenum, cecum, hypophysis after high- and low- dietary intake. Results from the present study suggested that 17β-HSD2 plays a crucial role in almost all tissues protecting against excessive levels of active steroid hormone, and GI tract maybe an important steroid hormone metabolizing organ in Hu-Sheep. This present study is the first to provide the primary foundation for further insight into this ovine gene.

Estrogen in obesity-associated colon cancer: friend or foe? Protecting postmenopausal women but promoting late-stage colon cancer

Obesity is associated with the increased incidence of colon cancer. Many cancer risk factors have been identified including increased blood levels of insulin, leptin, interleukin-6, interleukin-17, tumor necrosis factor-alpha, and decreased blood levels of adiponectin. However, the role of blood levels of estrogen in obesity-associated colon cancer is controversial. Evidence showed that obesity affected men more strongly than women in the carcinogenesis of colon cancer, indicating protective effect of estrogen which is increased in obesity. However, an epidemiological study has also shown that endogenous estradiol level is an independent risk factor for colon cancer, positively associated with colon cancer after normalizing insulin, IGF-1. The controversial opinions may be caused by different effects of ER-alpha and ER-beta. ER-alpha can increase colon cancer cell proliferation and increase cancer incidence. ER-beta has the opposite effect to ER-alpha, and it causes apoptosis of colon cancer cells. The normal colonocytes mainly express ER-beta. Therefore, increased estrogen in obesity may have protective effect via ER-beta in obesity-associated colon cancer. However, with the development of colon cancer, ER-alpha is increased and ER-beta is decreased. In the late stage of colon cancer, estrogen may promote cancer development via ER-alpha. The different effects and expression of ER-alpha and ER-beta may explain the different results observed in several epidemiological studies as well as several animal experiments. Therefore, manipulation of estrogen-caused signal pathways to inhibit ER-alpha and stimulate ER-beta may have preventive and therapeutic effect for obesity-associated colon cancer.

Dietary, endocrine, and metabolic factors in the development of colorectal cancer

INTRODUCTION

Colorectal cancer is the third cause of death in industrialized countries. Genetic susceptibility and diet are determinant of cancer risk and tumor behavior. Variation in cancer incidence among and within populations with similar dietary patterns suggests that an individual response may reflect interactions with genetic factors, which may modify gene, protein, and metabolite expression patterns. Nutrigenomics, defined as the interaction between nutrition and an individual genome, will likely provide important clues about responders and non-responders to nutritional intervention.

DISCUSSION

Epidemiological and experimental studies suggest a protective role of some normal components of daily diet (fish oil, milk, and vegetables), estrogens, and phytoestrogens in colorectal cancer. The effect of estrogen seems to be mediated by their binding to estrogen receptor beta (ER-β), one of the two estrogen receptors with high affinity for these hormones. Very recently, the demonstration of an involvement of ER-β in the development of adenomatous polyps of the colon has also been documented, suggesting the use of selective ER-β agonists in primary colorectal cancer prevention. Phytoestrogens are plant-derived compounds that structurally and functionally act as estrogen agonists in mammals. They are characterized by a higher binding affinity to ER-β as compared to estrogen receptor alpha (ER-α), the other estrogen receptor subtype. These biological characteristics explain why the administration of phytoestrogens does not produce the classical side effects associated to estrogen administration (cerebro- and cardiovascular accidents, higher incidence of endometrial and breast cancer) and makes these substances potential candidates for colorectal cancer prevention.

Effect of butyrate on aromatase cytochrome P450 levels in HT29, DLD-1 and LoVo colon cancer cells

Epidemiological studies suggest that colonic production of butyrate and estrogen may be involved in human susceptibility to colorectal cancer (CRC). Estrone (E1) can be produced by the aromatase pathway during the conversion of androstenedione (A) to E1. Therefore, we studied the effect of sodium butyrate (NaBu) on the CYP19A1 transcript and protein levels and on the conversion of A to E1 in HT29, DLD-1 and LoVo CRC cells. We found that NaBu significantly downregulated CYP19A1 transcript and protein levels, a phenomenon that was associated with reduced conversion of A to E1 in HT29, DLD-1 and LoVo cells. Our studies demonstrated that, although butyrate exhibited a protective role in CRC development, this compound may reduce aromatase activity and the production of E1 in colon cancer cells.

Epistasis between the HSD17B4 and TG polymorphisms is associated with premature ovarian failure

OBJECTIVE

To identify whether epistasis between TG and HSD17B4 and whether polymorphisms in HSD17B4 are associated with premature ovarian failure (POF).

DESIGN

Case-control genetic association study.

SETTING

Research laboratory of a university.

PATIENT(S)

Female patients with POF (98) and controls (218) of Korean ethnicity participated in this study.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Genotype distribution, haplotype (HT) inference, and gene-gene interaction.

RESULT(S)

Distribution of one haplotype (A-G-A-A-G-G) on the HSD17B4 gene was significantly different between the POF group and the control group in a dominant model. In addition, the combined effect of the single nucleotide polymorphisms (SNPs) HSD17B4 rs28943592 and TG rs2076740 was significantly associated with POF (odds ratio = 7.74, 95% confidence interval = 1.67-35.94), although a significant association was not observed in the single SNP model.

CONCLUSION(S)

A haplotype in the HSD17B4 gene was identified that was significantly associated with resistance to POF. In addition, epistasis between two missense SNPs (rs28943592, rs2076740) located in HSD17B4 and TG was significantly associated with susceptibility to POF.

Reproductive history and risk of colorectal cancer in postmenopausal women

BACKGROUND

There are conflicting data regarding the role of sex hormones in colorectal cancer development. Whereas clinical trials data indicate that hormone therapy use reduces the risk of colorectal cancer, data from prospective cohort studies suggest that circulating estrogen levels are positively associated with colorectal cancer risk. A surrogate measure of lifetime estrogen exposure is reproductive history. We investigated the relationship between reproductive factors and the risk of colorectal cancer.

METHODS

Subjects were postmenopausal women enrolled in the National Institutes of Health-American Association of Retired Persons Diet and Health Study, a cohort of 214,162 individuals (aged 50-71 years) that included 2014 incident cases of colorectal cancer that occurred over a mean follow-up of 8.2 years. Questionnaires were used to collect data on reproductive factors, including ages at menarche, birth of first child, and menopause; parity, and use of oral contraceptives. Multivariable Cox proportional hazards models were constructed to examine associations between these reproductive factors and the risk of colorectal cancer, with adjustment for established colorectal cancer risk factors. All statistical tests were two-sided.

RESULTS

Age at menopause (≥ 55 vs < 40 years: hazard ratio [HR] = 1.50, 95% confidence interval [CI] = 1.23 to 1.83; P(trend) = .008) and age at birth of first child (≥ 30 vs ≤ 19 years: HR = 1.26, 95% CI = 1.01 to 1.58; P(trend) = .05) were positively associated with the risk of colorectal cancer. Among women with no history of hormone therapy use, age at menarche (≥ 15 vs 11-12 years: HR = 0.73, 95% CI = 0.57 to 0.94; P(trend) = .02) and parity (≥ 5 children vs no children: HR = 0.80, 95% CI = 0.63 to 1.02; P(trend) = .10) were inversely associated with the risk of colorectal cancer.

CONCLUSION

These data support a role for sex hormones in colorectal tumorigenesis and suggest that greater endogenous estrogen exposure may increase the risk of colorectal cancer in postmenopausal women.

Advances in understanding the relationship between estrogen and colorectal cancer

Colorectal cancer is a common malignancy. Its incidence and mortality significantly increase in recent years in China. Since McMichael and Potter proposed that exogenous estrogen could reduce the incidence of colon cancer in women in 1980s, the relationship between estrogen use and the incidence of colorectal cancer has been extensively studied. This paper reviews the recent advances in understanding the relationship between estrogen and colorectal cancer.

Integrated view on 17beta-hydroxysteroid dehydrogenases

17beta-Hydroxysteroid dehydrogenases (17beta-HSDs) are important enzymes in steroid metabolism. Long known members of the protein family seemed to be well characterised concerning their role in the regulation of the biological potency of steroid hormones, but today more and more evidence points to pivotal contributions of these enzymes in a variety of other metabolic pathways. Therefore, studies on 17beta-HSDs develop towards metabolomic survey. Latest research results give new insights into the complex metabolic interconnectivity of the 17beta-HSDs. In this paper metabolic activities of 17beta-HSDs will be compared, their interplay with endogenous substrates summarised, and interlacing pathways depicted. Strategies on deciphering the physiological role of 17beta-HSDs and the genetic predisposition for associated diseases will be presented.

Estrone and progesterone inhibit the growth of murine MC38 colon cancer line

The unsatisfactory effectiveness of reference chemotherapy in colon cancer (fluorouracil - FU) results in continuous search for agents, which could enhance the action of FU. Some epidemiological data such as a decreased risk of colorectal cancer among menopausal women receiving hormonal replacement therapy indicate the role of female sex hormones in the pathogenesis of this disease. The aim of this study was to examine the direct effects of various concentrations of estrone and progesterone (10(-4) to 10(-12)M) applied alone or together with FU on the growth of murine MC38 colon cancer in vitro. Estrone inhibited MC38 cancer growth in a wide range of concentrations (10(-12) to 10(-4)M) with similar potency and at some concentrations (10(-6) and 10(-4)M) augmented also the cytotoxic action of FU. Progesterone induced MC38 cancer growth inhibition at high concentrations (10(-5) to 10(-4)M) in dose- and time-dependent manner but it did not intensify antineoplastic effect of FU. A weak inhibitory effect of progesterone was also observed for lower concentrations (10(-5) to 10(-10)M) in long lasting cultures (72h). The results indicate that estrone and progesterone inhibit the MC38 cancer growth and that estrone increases also the cytotoxic effect of FU, what confirms the role of female sex steroids in modulation of colon cancer growth.

17beta-Estradiol rapidly stimulates c-fos expression via the MAPK pathway in T84 cells

In this study, we show that 17beta-Estradiol (E2) induced the proliferation of T84 colonic carcinoma cells. We, further, investigated the mechanisms underlying this proliferation and show that E2 induced c-fos protooncogene expression in T84 cells in a timescale consistent with a rapid non-genomic action of the hormone. Furthermore, E2 rapidly phosphorylated both CREB and ELK1, transcription factors that bind to the c-fos promoter and stimulate transcription. Pretreatment with PD98059 and H89, mitogen-activated protein kinase (MAPK) pathway and protein kinase A (PKA) inhibitors, respectively showed that phosphorylation of CREB and ELK1 and subsequent c-fos induction was mediated by the MAPK pathway only. Finally, the estrogen receptor (ER) antagonist, ICI 182,780, blocked the activation of MAPK pathway, subsequent CREB and ELK1 phosphorylation and c-fos induction in T84 cells suggesting an ER dependent mechanism. Consistent with this finding, ICI 182,780 caused a substantial reduction in the proliferative effects of E2 on T84 cells.

The role of 17 beta-hydroxysteroid dehydrogenases

The biological activity of steroid hormones is regulated at the pre-receptor level by several enzymes including 17 beta-hydroxysteroid dehydrogenases (17 beta -HSD). The latter are present in many microorganisms, invertebrates and vertebrates. Dysfunctions in human 17 beta-hydroxysteroid dehydrogenases result in disorders of biology of reproduction and neuronal diseases, the enzymes are also involved in the pathogenesis of various cancers. 17 beta-hydroxysteroid dehydrogenases reveal a remarkable multifunctionality being able to modulate concentrations not only of steroids but as well of fatty and bile acids. Current knowledge on genetics, biochemistry and medical implications is presented in this review.

17 beta-hydroxysteroid dehydrogenases--their role in pathophysiology

17 beta-Hydroxysteroid dehydrogenases (17HSDs) regulate the biological activity of sex steroid hormones in a variety of tissues by catalyzing the interconversions between highly active steroid hormones, e.g. estradiol and testosterone, and corresponding less active hormones, estrone and androstenedione. Epidemiological and endocrine evidence indicates that estrogens play a role in the etiology of breast cancer, while androgens are involved in mechanisms controlling the growth of normal and malignant prostatic cells. Using LNCaP prostate cancer cell lines, we have developed a cell model to study the progression of prostate cancer. In the model LNCaP cells are transformed in culture condition into more aggressive cells. Our data suggest that substantial changes in androgen and estrogen metabolism occur in the cells, leading to increased production of active estrogens during the process. In breast cancer, the reductive 17HSD type 1 activity is predominant in malignant cells, while the oxidative 17HSD type 2 mainly seems to be present in non-malignant breast epithelial cells. Deprivation of an estrogen response by using specific 17HSD type 1 inhibitors is a tempting approach in treating estrogen-dependent breast cancer. Our recent studies demonstrate that in addition to sex hormone target tissues, estrogens may be important in the development of cancer in some other tissues previously not considered to be estrogen target tissues, such as the gastrointestinal tract.

Estrogen metabolism in human colorectal cancer cells

Epidemiological and "in vitro" studies support a direct role of estrogens in the pathogenesis and/or progression of colorectal cancer (CRC). Recent observations suggest a local synthesis of 17beta-estradiol (E(2)). In the present study, the CRC estrogen receptor beta (ERbeta) positive HCT8, HCT116, DLD-1 and LoVo cell lines were evaluated for expression of functional 17beta-hydroxysteroid dehydrogenase (17betaHSD) types 1, 2, 3, and 4. RT-PCR analysis revealed that while 17betaHSD1 and 17betaHSD4 were expressed in all the four cell lines, 17betaHSD2 and 17betaHSD3 were expressed in a cell-specific manner. The interconversion of tritiated estrone (E(1)) or E(2) evaluated by thin layer chromatography of conditioned media revealed that in HCT8, HCT116, and DLD-1 cells both reductive and oxidative activities were present, the latter showing K(m) values (approximately 10 microM) 40-fold higher than the former (approximately 250 nM). On the contrary, in LoVo cells, estrogens were almost (approximately 90%) completely metabolized to hydrophile compounds. Charcoal-dextrane (DC) stripped fetal calf serum (FCS) (10%), E(2) (10nM), Vitamin D(3) (100nM) and the combined E(2) and Vitamin D(3) treatment were evaluated for modulation of 17betaHSD isoenzymes gene expression and activity. Gene expression and activity of 17betaHSD reductive and oxidative isoenzymes were respectively inhibited and enhanced by Vitamin D(3) in HCT8 and LoVo cells. Surprisingly, DC-FCS induced a marked increase of estrogen metabolism toward hydrophile metabolites in all four cell lines. In conclusion, our results clearly show that metabolism of estrogens by 17betaHSD isoenzymes is functional and modulated by external stimuli in continuous neoplastic colonic epithelial cell lines.

Estrogen metabolism and malignancy: analysis of the expression and function of 17beta-hydroxysteroid dehydrogenases in colonic cancer

Age and sex differences in the incidence of gastrointestinal cancers suggest the involvement of sex steroids. Post-menopausal loss of estrogen in women appears to be associated with a lower risk of colonic cancer, and studies in vitro have shown that estradiol (E2) stimulates the growth of colonic cancer cell lines. Paradoxically more recent epidemiological data have shown that hormone replacement therapy (HRT) is associated with a lower risk of colonic cancer, although this may reflect differences in the composition and route of administration of HRT regimes. The precise mechanism by which estrogens influence colonic cancer in vivo remains unclear, although E2-induced growth of colonic cancer cells in vitro appears to be dependent on estrogen receptor (ER) expression. We have previously demonstrated differential responses to E2 in pre-malignant and malignant colonic cancer cell lines, without any apparent difference in ER expression. Analogous to well documented studies in breast cancer, we have postulated that local steroid metabolism in the colon may play a key role in modulating the effects of oestrogens by determining the tissue availability of active E2. Using biopsy material we have shown that the normal colonic mucosa has a high level of 17beta-hydroxysteroid dehydrogenase (17beta-HSD)-mediated E2 metabolism. Furthermore, the predominant enzyme activity, inactivation of E2 to estrone (E1), was significantly decreased in paired tumor biopsies. The presence of 17beta-HSD activity in the colon appears to be due to expression of the type 2 and 4 isozymes of 17beta-HSD (17beta-HSD2 and 4), and expression of mRNA for the latter was shown to be significantly decreased in tumours compared to normal mucosa. Further studies have characterised the expression of 17beta-HSD2 and 4 in colonic epithelial cells and in colonic cancer cell lines, and have suggested a link between estrogen metabolism and colonic cell proliferation. Data reviewed here provide evidence for the importance of 17beta-HSD isozymes as attenuators of E2 bioavailability in the colon, and emphasise a possible role for 17beta-HSD2 and 4 in the pathogenesis of colon cancer.