Contrasting actions of estradiol on the growth of human gastric cancer xenografts in nude mice

Sex hormone receptor expression and survival in esophageal adenocarcinoma: a prospective cohort study

INTRODUCTION

A striking epidemiological feature of esophageal adenocarcinoma (EAC) is its strong, unexplained male predominance but few studies have evaluated the prevalence of sex hormone receptor expression in EAC.

RESULTS

A low proportion of EAC tumors stained positive for ERα (4%) and AR (3%) while approximately one third stained positive for ERβ (31%). After a mean follow-up of 3 years (max 9 years), no significant associations were seen for ERα, ERβ or AR expression and EAC recurrence or survival. A non-significant reduction in mortality was observed for positive ERβ tumor expression, when restricting to patients with gastro-esophageal junctional (GEJ) cancer (HR 0.58, 95% CI 0.33, 1.03, p = 0.06).

MATERIALS AND METHODS

We identified all EAC patients who underwent neo-adjuvant chemotherapy prior to surgical resection between 2004-2012 in the Northern Ireland Cancer Centre. Immunohistochemical expression of ERα, ERβ and AR was scored on triplicate cores to generate H-scores. Cox proportional hazards regression was used to evaluate the association between sex hormone receptor expression and overall, cancer-specific and recurrence-free survival.

CONCLUSION

We found little evidence of ERα or AR expression in EAC. A moderate proportion expressed ERβ and there was suggestive evidence that its expression was associated with improved survival in GEJ cancer patients.

Effects of 17β-estradiol and estrogen receptor antagonists on the proliferation of gastric cancer cell lines

Purpose

The aims of this study were as follow: 1) to de scribe the expression status of estrogen receptor-α and -β mRNAs in five gastric carcinoma cell lines; 2) to evaluate in vitro the effects of 17β-estradiol and estrogen receptor antagonists on the proliferation of the cell lines.

Materials and Methods

Detection of estrogen receptor-α and estrogen receptor-β mRNA in five human gastric cancer cell lines (AGS, KATO III, MKN28, MKN45 and MKN74) was made by the reverse transcription-polymerase chain reaction system. To evaluate the effect of 17β-estradiol and estrogen receptor antagonists on the proliferation of gastric cancer cell line, the cell lines which expressed both es trogen receptors were chosen and treated with 17β-estradiol and estrogen receptor antagonists (methyl-piperidino-pyrazole and pyrazolo [1,5-a] pyrimidine). Cell proliferation was assessed with the methylthiazol tetrazolium test.

Results

Estrogen receptor-α and estrogen receptor-β mRNAs were expressed in three (KATO III, MKN28 and MKN45) and all of the five gastric cancer cell lines, respectively. At higher concentrations, 17β-estradiol inhibited cell growth of MKN28, MKN45 and KATO III cell lines. Neither estrogen receptor-α nor estrogen receptor-β antagonist blocked the anti-proliferative effect of 17β-estradiol.

Conclusions

Our results indicate that estrogen receptor-β mRNAs are preferentially expressed in gastric cancers and also imply that hormone therapy rather than estrogen receptor blockers may be a useful strategy for the treatment of estrogen receptor-β positive gastric cancer. Its therapeutic significance in gastric cancer are, however, limited until more evidence of the roles of estrogen receptors in the gastric cancer are accumulated.

Effect of estrogen on growth and apoptosis in esophageal adenocarcinoma cells

The epidemiology of esophageal adenocarcinoma demonstrates a strong gender bias with a sex ratio of 8-9:1 in favor of males. A potential explanation for this is that estrogen might protect against esophageal adenocarcinoma. Estrogen has previously been shown to stimulate apoptosis in esophageal squamous cancer cells. However, the effect of estrogen on esophageal adenocarcinoma cells has not been determined. We used immunoblotting analysis to determine the expression of estrogen receptors, cell adhesion marker E-cadherin, and proliferation marker Ki-67 in cell lines derived from esophageal adenocarcinoma (OE-19, OE-33) and Barrett's esophagus (QhTRT, ChTRT, GihTRT). Estrogen and selective estrogen receptor modulator (SERM)-dependent effects on cell growth were determined by the CellTiter-96 Aqueous Proliferation Assay. Apoptosis was determined by Annexin V/Propidium Iodide cell labeling and flow cytometry. We detected that physiological and supra-physiological concentrations of 17β-estradiol and SERM decreased cell growth in esophageal adenocarcinoma cells. In Barrett's esophagus cells (QhTRT, ChTRT), decreased growth was also detected in response to estrogen/SERM. The level of estrogen receptor expression in the cell lines correlated with the level of anti-growth effects induced by the receptor agonists. Flow cytometry analysis confirmed estrogen/SERM stimulated apoptosis in esophageal adenocarcinoma cells. Estrogen/SERM treatments were associated with a decrease in the expression of Ki-67 and an increase in E-cadherin expression in esophageal adenocarcinoma cells. This study suggests that esophageal adenocarcinoma and Barrett's esophagus cells respond to treatment with selective estrogen receptor ligands, resulting in decreased cell growth and apoptosis. Further research to explore potential therapeutic applications is warranted.

Oestrogen and the enigmatic male predominance of gastric cancer

Gastric cancer is the second most common cause of cancer death worldwide, and annually it causes over 150,000 deaths in Europe and 700,000 deaths globally. The incidence of gastric cancer shows an enigmatic male dominance with a male-to-female ratio of about 2:1. This sex ratio cannot be entirely attributed to the differences in the prevalence of known risk factors between the sexes. This review focuses on the potential role of oestrogen in explaining the male predominance in gastric cancer. Some data argue in favour of sex hormonal influence. Women with a longer fertility life and those on hormone replacement therapy seem to have a decreased risk of gastric cancer, and men who have been treated with oestrogen for prostate cancer have a decreased risk. Use of tamoxifen in women seems to increase their risk of gastric cancer. Animal studies indicate that oestrogen may offer protection against the development of this cancer as for example ovariectomised mice are at an increased risk, whilst administration of female sex hormones decreases the incidence of gastric cancer. Oestrogen may exert its effect by acting on oestrogen receptors (ERs). Both ERalpha, ERbeta and the latest discovered ERbetacx have been identified in gastric tissue. The biological means behind this is not yet clear but various mechanisms have been suggested. There are indications that oestrogen may lead to an increased expression of trefoil factor proteins, which protect mucous epithelia or inhibit the expression of c-erb-2 oncogene.

Epidermal growth factor and 17beta-estradiol effects on proliferation of a human gastric cancer cell line (AGS)

BACKGROUND

Recent evidence suggests that both estrogens and growth factors play an important role in the growth of gastrointestinal tumors. The expression of estrogen receptors (ER) and epidermal growth factor receptors (EGFR) in the gastrointestinal tract might therefore result in functional cross-talk between estrogens and EGF. The aim of the present study was to evaluate in vitro the effects of 17beta-estradiol and EGF administration on cell proliferation of a human gastric adenocarcinoma cell line (AGS) and investigate whether any interaction of these compounds may play a role in regulating gastric cancer cell proliferation.

METHODS

Estrogen and EGFRs were detected by enzyme immunoassay. Cell proliferation was assessed with the MTT test.

RESULTS

Exposure of AGS cells to increasing concentrations of 17beta-estradiol showed an anti-proliferative action at concentrations of 2 microM or higher. The addition of increasing concentrations of EGF stimulated cell growth, with a maximal response at 50 ng/ml EGF. The effect of increasing 17beta-estradiol concentrations combined with 50 ng/ml EGF was to increase cell growth at the lower estradiol concentrations. At the highest estradiol concentration the EGF proliferative effect was suppressed, and a decrease in proliferation rates occurred. Moreover, a significant negative correlation was found between 17beta-estradiol concentrations and EGFR expression.

CONCLUSIONS

These findings suggest that growth of cultured gastric cancer cells (AGS) might be modulated by sex steroid hormones through interaction with EGF.

Gastric cancer in pregnancy: do pregnancy, age or female sex alter the prognosis? Case reports and review

The coincidence of gastric cancer and pregnancy is a rare event. By literature research of the last three decades only 31 cases from outside Japan were identified including two own patients. The analysis of these and another 61 cases from Japan revealed the same predominance of poorly differentiated diffuse carcinomas with peritoneal and lymphatic metastases as in other young patients (<40 years). The survival rate is not obviously affected by pregnancy, young age or female sex. Experimental and epidemiological data suggest a protective effect of oestrogen against the induction of (intestinal) gastric cancer, while the cancer growth itself seems to be enhanced. Oestrogen receptors (ER) are found in about 22% of gastric cancer cells, especially in the poorly differentiated type. In contrast to target organs like the breast, ER in gastric cancer seem to be a sign of tumour adaptation involving e.g. the pathway of the epidermal growth factor. The results of treatment with anti-oestrogen are controversial in experimental and clinical settings. Due to the very common epigastric complaints early diagnosis of gastric cancer is even more difficult in pregnancy, so that early gastroscopy is advisable in patients on risk. Main effort should be given, however, to primary prevention.

Inhibitory effect of 17beta-estradiol on growth and the polyamine metabolism of a human gastric carcinoma cell line (HGC-27)

BACKGROUND

Estrogens may, by means of their receptors, modulate the growth of several tumors including gastrointestinal neoplasms. This control may occur through interaction with other molecules such as polyamines. An inverse relation between polyamine levels and the estrogen receptorial content has previously been demonstrated in vivo in human gastric carcinoma. The aim of the present study was to evaluate the effects of 17beta-Estradiol administration on the in vitro cell proliferation rates and the polyamine metabolism of an estrogen receptor-positive human gastric cancer cell line (HGC-27).

METHODS

Estrogen receptors were detected with enzyme immunoassay. Cell proliferation was assessed by means of [3H]-thymidine incorporation and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test. The polyamine content was evaluated with high-performance liquid chromatography and the ornithine decarboxylase activity with a radiometric technique.

RESULTS

Exposure of HGC-27 cells to increasing concentrations of 17beta-Estradiol showed that an antiproliferative action became evident at concentrations of 8 microM or higher. At such concentrations, ornithine decarboxylase (ODC) activity was also significantly reduced, as were all polyamine levels, compared with the untreated control. These findings suggest that one of the mechanisms underlying 17beta-Estradiol inhibition of HGC-27 cell proliferation is a decrease in ODC activity and, hence, in polyamine production.

Steroid hormone receptors in three human gastric cancer cell lines

Steroid hormone receptors in three human gastric adenocarcinoma cell lines and their transplanted tumors (except nontumorigenic KATO-III) in nude mice were determined by dextran-coated charcoal assay. Progesterone receptors (PgR) were found in all cell lines, transplanted NUGC-3, and AZ 521 tumors. Estrogen receptors (ER) were found in KATO-III cells, transplanted NUGC-3, and AZ 521 tumors, whereas glucocorticoid receptors (GR) were found only in NUGC-3 tumor and no androgen receptor was found in any cell lines or transplanted tumors. Since NUGC-3 cells had ER, PgR, and GR, it was used for the study of the effects of steroid hormones on growth. The results showed the cell cycle phase distributions and growth rate of transplanted tumors were similar in hormone-treated and nontreated groups. The persistent expression of PgR in gastric cancer cell lines and tumors, and the slight increase of tumor volumes in the progesterone-treated group suggests that progesterone and its receptors may be important in the pathogenesis of gastric cancer, but their biological function remains to be elucidated.

Interrelationship between estradiol and tamoxifen responses for clinical breast carcinoma cells cultured on contact-sensitive plates

An in vitro assay system for predicting the estradiol (E2) sensitivity of clinical cancer cells was applied to 54 patients with breast carcinoma to compare the responses to E2 and tamoxifen (TAM) with the estrogen receptor (ER) status. We found that 18 of the 35 cases in the ER-positive group and 6 of the 19 cases in the ER-negative group were stimulated by E2. It is suggested that ER status alone can not predict the response of cultured cells to E2 in clinical breast cancer. Cell growth of 11/35 (31%) of the ER-positive cases and that of 8/19 (42%) of the ER-negative cases was inhibited by E2. Since the cases inhibited by E2 could not be distinguished by ER status alone, an assay system based on a quantitative proliferative response was considered necessary. There were 20 (83%) cases of inhibition by TAM among the 24 stimulated by E2. Only 18/35 (51%) of the ER-positive group exhibited growth inhibition by TAM. In our (CSP) assay, 20 (83%) of the 24 cases stimulated by E2 were inhibited by TAM, 10 (91%) of the 11 E2-insensitive cases were insensitive to TAM and 13 (68%) of the 19 cases inhibited by E2 were stimulated by TAM. In short, TAM response and E2 response tended to be inversely related (43/54 = 80%, P < 0.01). Furthermore, the E2-response rate showed a good correlation with the TAM-response rate (R2 = 0.825). These results indicate the feasibility of predicting individual tumor responses to either E2 or TAM by using CSPs.

In vivo mitogenic effects of estradiol on colon cancers: role of gastrin and gastrin receptors

We have previously reported mitogenic effects of gastrin on a mouse colon cancer (MC-26) cell line in vivo. The present studies were undertaken to determine if gonadal hormones can influence the mitogenic response of MC-26 cells to gastrin. The female gonadal hormone, estradiol (E2), was determined to be as mitogenic as pentagastrin (PG) for the growth of MC-26 tumors in mice; the mitogenic effects of E2 and PG were not additive. Female gonadal hormones were furthermore as effective as PG in maximally up-regulating gastrin receptor (GR) concentrations on MC-26 tumor membranes, which was confirmed in autoradiographic studies. Since PG and E2 had similar and non-additive trophic effects it was hypothesized that gastrin may be mediating the trophic effects of E2. Serum gastrin concentrations were significantly increased in E2 treated ovariectomized mice that correlated with an increase in tumor weights; E2 however was ineffective in stimulating the release of gastrin from perfused rat stomachs indicating that the increase in serum gastrin concentration on long-term treatment with E2 was mediated by some other mechanism. Saturable high-affinity E2 binding sites were not measured in MC-26 cells and tumors, supporting the possibility that mitogenic effects of E2 were probably mediated via indirect mechanisms. In summary our results indicate that both E2 and PG are equally mitogenic for colon cancer cells in vivo which may explain the sex- and age-related discrepancy in the incidence of human colon cancers.

Estradiol is trophic for colon cancer in mice: effect on ornithine decarboxylase and c-myc messenger RNA

The mitogenic role of estradiol on the growth of colon cancer was examined in mice. Sham-operated or ovariectomized mice were injected with cancer cells and received estradiol treatment. Tumor growth was noted: tumor weights were higher in female than male mice. The growth of the tumors was least in ovariectomized mice and highest in estradiol-treated ovariectomized mice. Tumor messenger RNA (mRNA) levels for ornithine decarboxylase (ODC) and proto-oncogenes c-myc, c-fos, and H-ras were examined. Two transcripts (2.2 and 2.7 kilobase pairs) of ODC were observed. The steady-state mRNA levels for ODC paralleled the changes observed in the weight of the tumors in all groups of animals. Less dramatic changes were observed in c-myc mRNA levels. No significant differences were observed in the mRNA levels for H-ras and c-fos. It thus appears likely that an increase in the ODC mRNA levels and, to a lesser extent, an increase in c-myc mRNA levels may be some of the important mechanisms by which estradiol mediates its growth effects on colon cancer cells in vivo.

The correlation of epidermal growth factor with invasion and metastasis in human gastric cancer

We examined the localization of epidermal growth factor (EGF) in 185 specimens of primary human gastric cancer using the avidin-biotin peroxidase complex immunohistochemical method on formalin-fixed paraffin-embedded sections. Thirty-four per cent of the gastric cancer specimens were positive for EGF, which was mainly located in the cytoplasm of the cancer cells and occasionally in the stromal cells, but was not detected in non-cancerous gastric epithelium. Moreover, the presence of EGF in gastric cancer was correlated with gastric wall invasion and lymph node metastasis. EGF was found more often in advanced cancers than in early ones (p less than 0.01), and also more often in cancers with lymph node metastasis than in those without (p less than 0.05). The five-year survival of patients with EGF-positive tumors was worse than that of patients with EGF-negative tumors (p less than 0.05). The presence of EGF in human gastric cancer may thus represent higher malignant potential.