In vivo and in vitro expression of steroid-converting enzymes in human breast tumours: associations with interleukin-6

The role of 17βHSDs in breast tissue and breast cancers

The family of seventeen beta hydroxysteroid dehydrogenase enzymes has a long and diverse history in breast and breast cancer research. Given the known dependence of the breast on steroid signalling and intracrine steroid metabolism these enzymes are considered to be essential local fine tuners of overall steroid balance in the tissue. This review will cover the current state of knowledge regarding the expression, clinical effect and biological regulation of enzymes in both cancerous and normal states. In addition we will also cover the current state of knowledge regarding 17βHSD actions in the often neglected adipose and stromal components of tumours.

Effects of modified Shu-Gan-Liang-Xue decoction combined with anastrozole on osteoblastic proliferation and differentiation of MC3T3-E1 cells

Aromatase inhibitors (AIs) are widely used in the treatment of hormone-dependent breast cancer and as a result, aromatase inhibitor-associated bone loss (AIBL) has become a major concern amongst patients receiving AI treatment. Modified Shu-Gan-Liang-Xue decoction (mSGLXD), a clinical prescription, has been used for ameliorating AIBL in patients with breast cancer for decades and has achieved good clinical efficacy. However, the mechanism underlying how mSGLXD influences bone homeostasis and alleviates AIBL has remained elusive. In the present study, mSGLXD was supplemented with Rhizoma Drynariae containing phytoestrogens, and the safety of mSGLXD was evaluated. mSGLXD did not possess estrogenic activity and significantly inhibited the proliferation of estrogen receptor-positive breast cancer cell line MCF-7, which suggested that mSGLXD was safe for postmenopausal patients with breast cancer. Subsequently, the effects of mSGLXD alone or in combination with anastrozole on osteoblastic MC3T3-E1 cell proliferation and differentiation were investigated. Cell counting kit-8, reverse transcription-polymerase chain reaction and biochemical methods, such as ELISA and alizarin red S staining, were used in the present study. It was revealed that mSGLXD not only stimulated MC3T3-E1 cell proliferation, but also upregulated alkaline phosphatase and osteocalcin gene and protein expression levels. High concentrations of anastrozole (10 or 100 μmol/l) markedly inhibited MC3T3-E1 cell proliferation, but this inhibitory effect was attenuated by mSGLXD. Furthermore, mSGLXD increased MC3T3-E1 cell mineralization following β-glycerophosphate and ascorbic acid induction. Therefore, the results of the present study suggested that mSGLXD may be a promising adjuvant therapy, with high safety and efficacy, for the prevention and treatment of AIBL in patients with breast cancer who receive AI treatment.

Anti-tumor effect of Shu-Gan-Liang-Xue decoction in breast cancer is related to the inhibition of aromatase and steroid sulfatase expression

ETHNOPHARMACOLOGICAL RELEVANCE

Shu-Gan-Liang-Xue Decoction (SGLXD), a traditional Chinese herbal formula used to ameliorate the hot flushes in breast cancer patients, was reported to have anti-tumor effect on breast cancer. Estrogen plays a critical role in the genesis and evolution of breast cancer. Aromatase and steroid sulfatase (STS) are key estrogen synthesis enzymes that predominantly contribute to the high local hormone concentrations. The present study was to evaluate the anti-tumor effect of SGLXD on estrogen receptor (ER) positive breast cancer cell line ZR-75-1, and to investigate its underlying mechanisms both in vitro and in vivo.

MATERIALS AND METHODS

The anti-tumor activity of SGLXD in vitro was investigated using the MTT assay. The in vivo anti-tumor effect of SGLXD was evaluated in non-ovariectomized and ovariectomized athymic nude mice. The effect of SGLXD on enzymatic activity of aromatase and STS was examined using the dual-luciferase reporter (DLR) based on bioluminescent measurements. Aromatase and STS protein level were assessed using Western blot assay.

RESULTS

SGLXD showed dose-dependent inhibitory effect on the proliferation of ZR-75-1 cells with IC50 value of 3.40 mg/mL. It also suppressed the stimulating effect on cell proliferation of testosterone and estrogen sulfates (E1S). Oral administration of 6 g/kg of SGLXD for 25 days resulted in a reduction in tumor volume in non-ovariectomized and ovariectomized nude mice. The bioluminescent measurements confirmed that SGLXD has a dual-inhibitory effect on the activity of aromatase and STS. Western blot assay demonstrated that the treatment of SGLXD resulted in a decrease in aromatase and STS protein levels both in vitro and in vivo.

CONCLUSION

Our results suggested that SGLXD showed anti-tumor effect on breast cancer cells both in vitro and in vivo. The anti-tumor activity of SGLXD is related to inhibition of aromatase and STS via decreasing their expression. SGLXD may be considered as a novel treatment for ER positive breast cancer.

Ratio of 17HSD1 to 17HSD2 protein expression predicts the outcome of tamoxifen treatment in postmenopausal breast cancer patients

PURPOSE

Estrogens have great significance in the development of breast cancer. After menopause, most estrogen biosynthesis is done in peripheral tissue, and the main enzymes involved in balancing the amount of estrone against estradiol are 17beta-hydroxysteroid dehydrogenases (17HSD). The aim of this study was to investigate the prognostic and tamoxifen predictive values of 17HSD1 and 17HSD2 expression.

EXPERIMENTAL DESIGN

Tumors from low-risk breast cancer patients randomized to adjuvant tamoxifen therapy or no adjuvant treatment were analyzed with immunohistochemistry to investigate protein expression of 17HSD1 and 17HSD2 in 912 cases. All patients had lymph node-negative breast cancer and were postmenopausal at the time of diagnosis.

RESULTS

Low 17HSD1 expression was associated with significant benefit from tamoxifen treatment among patients with estrogen receptor (ER)-positive tumors (P < 0.001). For patients with a 17HSD1 score not exceeding that of 17HSD2, tamoxifen increased the rate of distant recurrence-free survival (hazard ratio, 0.37; 95% confidence interval, 0.23-0.60) and breast cancer-specific survival (hazard ratio, 0.30; 95% confidence interval, 0.16-0.54), whereas no apparent effect was observed when the 17HSD1 score was higher than that of 17HSD2. The interaction was significant for both distant recurrence-free survival (P = 0.036) and breast cancer-specific survival (P = 0.014). In the cohort of systemically untreated patients, no prognostic importance was observed.

CONCLUSIONS

This is the first report that clearly distinguishes between the prognostic and predictive importance of 17HSD1 and 17HSD2 in ER-positive breast cancer treated with or without tamoxifen. Our data suggest that the 17HSD1/17HSD2 ratio might be useful as a predictive factor for tamoxifen treatment in ER-positive breast cancer patients.

17Beta-hydroxysteroid dehydrogenase enzymes and breast cancer

Sex steroids play an important role in the development and differentiation in several tissues. Biologically active hormones that are locally converted in endocrine organs in the tissue where they exert their effects without release into extracellular space is a field of endocrinology that has been called intracrinology. In pre-menopausal women the ovary is the main source of estrogens, but in post-menopausal women the estrogen production as main site of synthesis moves to peripheral tissues and almost all of the sex steroids are synthesised from precursors of adrenal origin. In breast cancer 60-80% of the tumors express high levels of oestrogen receptor (ER) alpha which gives estrogen a proliferative effect. Breast tumors tend to have a higher intratumoral estrogen concentration than normal breast tissue and plasma, and in situ synthesis and the metabolism of estrogens is believed to be of great importance for the development and progression of the disease. The activity of estrogen metabolizing enzymes in breast are mainly aromatase, estrone sulfatases and 17HSD enzymes. 17HSD1 and 17HSD2 are the family members known to be of main importance in breast cancer. High expression of 17HSD1 has been associated to poor prognosis in breast cancer and late relapse among patients with ER-positive tumors. One of the mechanisms behind high 17HSD1 expression is gene amplification. Low or absent expression of 17HSD2 is associated to decreased survival in ER-positive breast cancer. 17HSD14 is one of the latest discovered 17HSD enzymes, transfection of 17HSD14 in human breast cancer cells significantly decreased the levels of estradiol in the culture medium. Low expression of 17HSD14 mRNA expression in breast cancer was correlated to decreased survival. The understanding of intratumoral synthesis of sex steroids in breast cancer is crucial to understand the disease both in pre- and post-menopausal women. Further studies are desirable to state the direct role of these enzymes in breast cancer and which patients that may benefit from new therapeutic strategies targeting 17HSD enzymes. The new inhibitors targeting 17HSD1 have shown promising results in pre-clinical studies to have clinical potential in the future.

Amplification of HSD17B1 has prognostic significance in postmenopausal breast cancer

In situ synthesis of estrogens is believed to be of great importance for the progression of breast cancer. In postmenopausal women most estrogens are synthesized in peripheral hormone-target tissues from circulating precursor steroids, by the enzymes involved in formation of active estrogens. One of the enzymes involved in this process is 17beta-hydroxysteroid dehydrogenase (17beta-HSD) type 1. This enzyme catalyzes the interconversion of estrone (E1) to the biologically more potent estradiol (E2). The gene coding for 17beta-HSD type 1 (HSD17B1) is located at 17q12-21. The aim of this study was to investigate altered gene copy number of HSD17B1 in breast cancer. We used real-time PCR and examined 387 postmenopausal breast tumors for amplification of HSD17B1, and if an increased mRNA level of this enzyme is associated with amplification of the gene. We also investigated whether amplification of HSD17B1 has a prognostic value. There was a significant correlation between gene copy number of HSD17B1 and mRNA expression level (P = 0.00002). ER-positive patients with amplification of HSD17B1 showed lower breast cancer survival than patients without amplification (P = 0.025). Among ER-negative patients there was no significant correlation between increased gene copy number of HSD17B1 and prognosis. Furthermore, we found that amplification of the gene had prognostic significance in multivariate analysis adjusting for other clinicopathological variables.

Steroid sulfatase in breast carcinoma and change of serum estrogens levels after operation

Fifty-four breast carcinomas were studied for the expression of steroid sulfatase (STS) by immunohistochemistry. Correlations between the expression of STS and clinical parameters were determined. Concentrations of serum estrone (E1), estrone sulfate (E1S), estradiol (E2) and estradiol sulfate (E2S) in 12 postmenopausal patients with STS positive tumor were measured by radioimmunoassay. Positive expression of STS was obtained in 72% of tumors. The incidence of STS positive tumor was significantly more frequent in postmenopausal patients (p = 0.01). In our postmenopausal patients, serum E1, E1S, E2, E2S and E2S levels in STS high score group were decreased postoperatively, and those in both STS high and low score group were stabilized after operation. Results from this study suggest STS in breast carcinoma may play an important enzyme of the intratumoral estrogen synthesis in postmenopausal women, and it would be interesting that locally produced STS might be closely related to the control of estrogens environment in breast carcinoma.

17β-Hydroxysteroid Dehydrogenase 14 Affects Estradiol Levels in Breast Cancer Cells and Is a Prognostic Marker in Estrogen Receptor–Positive Breast Cancer

Estrogens have an important role in the progression of breast cancer. The 17beta-hydroxysteroid dehydrogenase (17HSD) family has been identified to be of significance in hormone-dependent tissues. 17HSD1 and 17HSD2 are the main 17HSD enzymes involved in breast cancer investigated this far, but it is possible that other hormone-regulating enzymes have a similar role. 17HSD5 and 17HSD12 are associated with sex steroid metabolism, and 17HSD14 is a newly discovered enzyme that may be involved in the estrogen balance. The mRNA expression of 17HSD5, 17HSD12, and 17HSD14 were analyzed in 131 breast cancer specimens by semiquantitative real-time PCR. The results were compared with recurrence-free survival and breast cancer-specific survival of the patients. The breast cancer cell lines MCF7, SKBR3, and ZR75-1 were transiently transfected with 17HSD14 to investigate any possible effect on estradiol levels. We found that high 17HSD5 was related to significantly higher risk of late relapse in estrogen receptor (ER)-positive patients remaining recurrence-free later than 5 years after diagnosis (P = 0.02). No relation to 17HSD12 expression was found, indicating that 17HSD12 is of minor importance in breast cancer. Patients with ER-positive tumors with high expression levels of 17HSD14 showed a significantly better prognosis about recurrence-free survival (P = 0.008) as well as breast cancer-specific survival (P = 0.01), confirmed by multivariate analysis (P = 0.04). Transfection of 17HSD14 in the human breast cancer cells MCF7 and SKBR3 significantly decreased the levels of estradiol, presenting an effect of high expression levels of the enzyme.

Differential response to phytoestrogens in endocrine sensitive and resistant breast cancer cellsin vitro

Women approaching menopause increasingly investigate alternatives to hormone replacement therapy. Plant phytoestrogens are being promoted as "natural" alternatives but there is a lack of substantive data to advocate their safe use in breast cancer patients receiving tamoxifen (TAM), or in those who have relapsed. The aim of our study was to investigate the proliferative effects and mode of action of the phytoestrogens genistein, daidzein and coumestrol on TAM-sensitive (-s) and resistant (-r) breast cancer cells under in vitro conditions designed to mimic the hormonal environment of the pre- and post-menopausal breast. At physiological concentrations (<10 microM) and under reduced estrogen (E2) conditions, genistein was mitogenic to TAM-s cells with TAM-r cells generally refractory. Daidzein and coumestrol were growth stimulatory irrespective of TAM sensitivity. Transcriptional activity was ERE-mediated. Combining phytoestrogens with E2 (simulating the pre-menopausal breast environment) had no effect on growth of TAM-s or TAM-r cells. Addition of 4-HT mimicked the hormonal environment in post-menopausal breast cancer patients receiving TAM. The growth inhibitory effects of 4-HT were abrogated in TAM-s cells when combined with genistein and coumestrol, and to a lesser extent, daidzein, where significant growth stimulatory effects were observed. In TAM-r cells, proliferation did not exceed control values. At phytoestrogen concentrations above 10 microM, growth inhibitory effects were seen, irrespective of estrogenic environment or cell sensitivity to TAM. Our in vitro data suggests that phytoestrogens could have potentially adverse mitogenic effects on tumour cells and should probably be avoided by patients who remain sensitive to TAM or in those with pre-existing and possibly undiagnosed breast tumours.

Evaluation of leukocyte arylsulphatase a, serum interleukin-6 and urinary heparan sulphate following tamoxifen therapy in breast cancer

Leukocyte arylsulphatase A (AS-A) was shown to be significantly high in newly-diagnosed breast cancer patients. Previous reports imply a connection between serum interleukin-6 (IL-6) and breast cancer, possibly through a modulation of enzymes involved in estrogen synthesis. Abnormal distribution of heparan sulphate proteoglycans (HSPGs) in malignant breast epithelial cells suggests that they play a key role in the regulation of cell growth. Estradiol is believed to be effective in modulating glycosaminoglycans (GAGs) and their depolymerizing enzymes. Therefore, in this study, attempts were made to evaluate the activity of leukocyte arylsulphatase A, serum interleukin-6, urinary GAGs and heparan sulphate (HS) in response to tamoxifen (TAM) therapy in mastectomised breast cancer patients. Thirty-four patients (aged 30-82 years) were administered TAM (20 mg twice daily). Blood and urine samples of each patient were collected three times (at the beginning, and in third and sixth month of TAM therapy), and biochemical parameters were measured. There was no difference between baseline leukocyte AS-A activity and that measured after three months. At the end of six months, enzyme activity was significantly higher than the former values (p=0.022), but within the reference intervals reported in the literature. Although this increase might imply a normalization, the duration of TAM therapy is not long enough to make a decision about either regression or aggravation of the disease. TAM did not have any effect on serum IL-6, urinary HS and GAG levels which may be due to insensitivity of these variables to TAM during the short period of therapy. Both urinary GAG and HS levels measured at sixth month exhibited a positive correlation with the baseline level of leukocyte AS-A (p=0.005 and 0.009, respectively), suggesting that positive responses to the drug might be seen in patients with low AS-A activity.

17beta-Hydroxysteroid dehydrogenases involved in local oestrogen synthesis have prognostic significance in breast cancer

The 17β-hydroxysteroid dehydrogenase (17HSD) enzymes are involved in the local regulation of sex steroids. The 17HSD type 1 enzyme catalyses the interconversion of the weak oestrone (E1) to the more potent oestradiol (E2), whereas 17HSD type 2 catalyses the oxidation of E2 to E1. The aim of this study was to correlate the expression of these enzymes in the tumour with the recurrence-free survival of tamoxifen-treated breast cancer patients. We used real-time reverse transcriptase PCR to investigate the mRNA expression of 17HSD types 1 and 2 in tumour samples from 230 postmenopausal patients. For the patients with oestrogen receptor (ER)-positive breast cancer, we found a statistically significant positive correlation between recurrence-free survival and expression of 17HSD type 2 (P=0.026). We examined the ratio of 17HSD types 2 and 1, and ER-positive patients with low ratios showed a significantly higher rate of recurrence than those with higher ratios (P=0.0047). ER positive patients with high expression levels of 17HSD type 1 had a significantly higher risk for late relapse (P=0.0051). The expression of 17HSD types 1 and 2 in breast cancer differs from the expression of these enzymes in normal mammary gland, and this study indicates that the expression has prognostic significance in breast cancer.

Effect of nomegestrol acetate on estrogen biosynthesis and transformation in MCF-7 and T47-D breast cancer cells

Although ovaries serve as the primary source of estrogen for pre-menopausal women, after menopause estrogen biosynthesis from circulating precursors occurs in peripheral tissues by the action of several enzymes, 17beta-hydroxysteroid dehydrogenase 1 (17beta-HSD1), aromatase and estrogen sulfatase. In the breast, both normal and tumoral tissues have been shown to be capable of synthesizing estrogens, and this local estrogen production can be implicated in the development of breast tumors. In these tissues, estradiol (E(2)) can be synthesized by three pathways: (1) estrone sulfatase transforms estrogen sulfates into bioactive estrogens, (2) 17beta-HSD1 converts estrone (E(1)) into E(2), (3) aromatase which converts androgens into estrogens is also present and contributes to the in situ synthesis of active estrogens but to a far lesser extent than estrone sulfatase. Quantitative assessment of E(2) formation in human breast tumors indicates that metabolism of estrone sulfate (E(1)S) via the sulfatase pathway produces 100-500 times more E(2) than androgen aromatization. Breast tissue also possesses the estrogen sulfotransferase involved in the conversion of estrogens into their sulfates that are biologically inactive. In the present review, we summarized the action of the 19-nor-progestin nomegestrol acetate (NOMAC) on the sulfatase, 17beta-HSD1 and sulfotransferase activities in the hormone-dependent MCF-7 and T47-D human breast cancer cell lines. Using physiological doses of substrates NOMAC blocks very significantly the conversion of E(1)S to E(2). It inhibits the transformation of E(1) to E(2). NOMAC has a stimulatory effect on sulfotransferase activity in both cell lines, with a strong stimulating effect at low doses but only a weak effect at high concentrations. The effects on the three enzymes are always stronger in the progesterone-receptor rich T47-D cell line as compared with the MCF-7 cell line. Besides, no effect is found for NOMAC on the transformation of androstenedione to E(1) in the aromatase-rich choriocarcinoma cell line JEG-3. In conclusion, the inhibitory effect provoked by NOMAC on the enzymes involved in the biosynthesis of E(2) (sulfatase and 17HSD pathways) in estrogen-dependent breast cancer, as well as the stimulatory effect on the formation of the inactive E(1)S, can open attractive perspectives for future clinical trials.

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.

Egr1 promotes growth and survival of prostate cancer cells. Identification of novel Egr1 target genes

In the majority of aggressive tumorigenic prostate cancer cells, the transcription factor Egr1 is overexpressed. We provide new insights of Egr1 involvement in proliferation and survival of TRAMP C2 prostate cancer cells by the identification of several new target genes controlling growth, cell cycle progression, and apoptosis such as cyclin D2, P19ink4d, and Fas. Egr1 regulation of these genes, identified by Affymetrix microarray, was confirmed by real-time PCR, immunoblot, and chromatin immunoprecipitation assays. Furthermore we also showed that Egr1 is responsible for cyclin D2 overexpression in tumorigenic DU145 human prostate cells. The regulation of these genes by Egr1 was demonstrated using Egr1 antisense oligonucleotides that further implicated Egr1 in resistance to apoptotic signals. One mechanism was illustrated by the ability of Egr1 to inhibit CD95 (Fas/Apo) expression, leading to insensitivity to FasL. The results provide a mechanistic basis for the oncogenic role of Egr1 in TRAMP C2 prostate cancer cells.

Expression of interleukin-6 and tumor necrosis factor alpha and histopathologic findings in painful and nonpainful breast tissue

Mastalgia is a common condition that is thought to be hormonally related, but the mechanisms of pain causation are unknown. Inflammatory cytokines are implicated in pain modulation, but have not been studied with regard to mastalgia. We compared the relationship of mastalgia to the expression of the cytokines interleukin (IL)-6, IL-1beta, and tumor necrosis factor (TNF)-alpha and the degree of tissue infiltration with inflammatory cells in breast tissue from 29 premenopausal women with breast pain and 29 age-matched pain-free controls. Paraffin sections from breast biopsy samples were scored for the presence of inflammatory infiltrate and were evaluated for the expression of IL-6, IL-1beta, and TNF-alpha using standard immunohistochemical procedures. TNF-alpha and IL-6 expression displayed a trend toward slightly lower values in patients with pain (median TNF-alpha score, 3 versus 5; median IL-6 score, 3 versus 4). In the luteal phase, patients with mastalgia showed a trend toward lower expression of IL-6 (p = 0.4) in comparison to those without pain. A similar trend was also seen with TNF-alpha expression (p = 0.4). IL-1beta expression was extremely scant in the first 30 samples and was not investigated further. The degree of inflammatory infiltrate in the tissue was unrelated to the presence of breast pain. These data suggest that the three cytokines tested in this study do not play a significant role in the causation of mastalgia and lend weight to the previous finding that there are no identifiable histologic correlates of this troubling condition. Further investigation of the role of cytokines in breast pain is warranted, especially in view of the possible association between mastalgia and breast cancer risk.

Amplification of HSD17B1 and ERBB2 in primary breast cancer

Estrogens play a crucial role in the development of breast cancer. Estradiol can be produced in the breast tissue in situ, and one of the enzymes involved in this process is 17beta-hydroxysteriod dehydrogenase (17beta-HSD) type 1 that catalyzes the interconversion of estrone (E1) to the biologically more potent estradiol (E2). The gene coding for 17beta-HSD type 1 (HSD17B1) is located at 17q12-21, close to the more studied ERBB2 and BRCA1. The aim of this study was to investigate if HSD17B1 shows an altered gene copy number in breast cancer. We used real-time PCR and examined 221 postmenopausal breast tumors for amplification of HSD17B1 and ERBB2. In all, 32 tumors (14.5%) showed amplification of HSD17B1 and 21% were amplified for ERBB2. Amplification of the two genes was correlated (P=0.00078) and in 14 tumors (44%) with amplification of HSD17B1, ERBB2 was co amplified. The patients with amplification in at least one of the genes had a significantly worse outcome than patients without (P=0.0059). For estrogen receptor (ER)-positive patients who received adjuvant tamoxifen, amplification of HSD17B1 was related to decreased breast cancer survival (P=0.017), whereas amplification of ERRB2 was not. Amplification of HSD17B1 might be an indicator of adverse prognosis among ER-positive patients, and possibly a mechanism for decreased benefit from tamoxifen treatment.

Possible co-regulation of genes associated with enhanced progression of mammary adenocarcinomas

Tumor progression is a multistep process in which alterations in the expression of numerous gene products may give rise to highly malignant cellular variants. In the present study, we analyzed the differential expression of several genes in cellular variants of mammary adenocarcinomas with high or low malignancy potential, which originated in a common ancestor. To assess the generality of our findings, high and low malignancy variants were derived from two different mammary adenocarcinoma cell lines, namely DA3 and CSML cells. Of major importance is the fact that the differences between high- and low-malignancy variants observed in one system of mammary adenocarcinoma cells (DA3 cells) were identically reproduced in the other system of mammary adenocarcinoma cells (CSML cells). The high malignancy variants of tumors both DA3-high and CSML-high (previously called CSML-100), expressed higher levels of factors that induce monocyte migration than the low malignancy DA3-low and CSML-low (previously called CSML-0) variants. In addition, it was found that DA3-high and CSML-high cell variants expressed higher levels of monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6) and matrix metalloproteinases (MMPs) than the low malignancy variants (DA3-low and CSML-low). These results suggest that MCP-1, IL-6 and MMPs potentially contribute to mammary adenocarcinoma progression and that their expression is regulated by a common pathway. The expression of MCP-1, IL-6 and MMPs in both DA3-high and CSML-high cells was up-regulated by tumor necrosis factor alpha (TNFalpha). The fact that TNFalpha exerted similar effects on the expression of these three factors in both cell systems raises the possibility of a coordinated co-regulation of tumor-promoting factors.

The influence of inflammatory cytokines on estrogen production and cell proliferation in human breast cancer cells

Estrogens play important roles in the development of breast cancer. Inflammatory cytokines such as interleukin-6 (IL-6) and interleukin-1 beta (IL-1 beta) exist at high concentrations in breast cancer tissue. Although these cytokines are thought to exert some effect on cancer growth, their precise mechanism is still unclear. In the present study, we investigated the effects of inflammatory cytokines on aromatase (Arom) and steroid sulfatase (STS), which are estrogen-producing enzymes, and cell proliferation using human breast cancer cell lines (SK-BR-3, MCF-7). IL-6 and IL-1 beta stimulated the activity of Arom and STS. Estrone sulfate (E1-S) had a stimulus effect on cell proliferation of MCF-7. Although IL-6 did not show significant effect on cell proliferation, cell proliferation was significantly increased when IL-6 and E1-S were simultaneously added to the incubation medium. This cell proliferative effect was apparently stronger than the addition of E1-S alone. Addition of IL-1 beta in the presence of E1-S also significantly enhanced cell proliferation though IL-1 beta alone did not show any effect. These results led us to the hypothesis that inflammatory cytokines such as IL-6 and IL-1 beta regulate proliferation of breast cancer cells through estrogen production by steroid-catalyzing enzymes in the tissue.

Deletion mapping of chromosome 16q24 in hepatocellular carcinoma in Taiwan and mutational analysis of the 17-beta-HSD gene localized to the region

Human chromosome band 16q24 commonly undergoes loss of heterozygosity (LOH) in human hepatocellular carcinoma (HCC). To further localize the region of deletion on 16q24 and to evaluate the genetic role of 17-beta-HSD, which is near 16q24, in HCC, we examined the pattern of loss of heterozygosity in 88 HCC patients. DNAs from 88 pairs of HCCs and corresponding non-tumor parts were prepared. Loss of heterozygosity on chromosomes 16q24 was investigated by 11 sets of microsatellite markers. Mutation analysis of type II 17-beta-HSD was performed by automatic sequencing. LOH on 16q24 for at least 1 locus was found in 43 of the 88 tumor DNAs (49%). Three non-overlapping regions of frequent LOH were defined in these 43 tumors with partial deletions. The first region was between D16S516 loci and D16S507, encompassed by a 1-cM region, defined by the D16S504. The second region was defined by the 17HSDB2 locus between D16S505 and D16S422, encompassed approximately by a 1-cM region. The third region was between D16S520 and D16S413, defined by D16S3048, encompassed approximately by a 4-cM region. Homozygous deletions of any exons in 17HSDB2 gene were identified in 7 of 27 cases (26%). Automated sequencing analysis of 17HSDB2 failed to demonstrate mutations in any of these specimens. Our data suggest that the 17HSDB2 locus is a frequent target of deletion in HCC but the inactivation of 17HSDB2 may not involve sequence mutations. Furthermore, the presence of the other 2 frequent LOH regions suggest that the putative tumor suppressor genes at these locations might be involved in the development of HCC.

Regulation of interleukin-6 secretion from breast cancer cells and its clinical implications

Interleukin (IL)-6 may play possible roles in the proliferation and metastasis of cancer cells, in the development of osteolysis and humoral hypercalcemia, and in the regulation of estrogen production in breast cancer tissues. IL-6 is also suggested to be a cachectic factor in cancer patients. A decrease in serum IL-6 levels induced by medroxyprogesterone acetate (MPA) has been reported to correlate with a reversion of body weight loss in patients with advanced breast cancer. To elucidate the mechanisms of action of the anti-cachectic effect of MPA its effects on IL-6 secretion from the KPL-4 cell line, the first human breast cancer cell line to secrete IL-6 and to induce cachexia, were explored. It has been suggested that an inhibitory effect of MPA on IL-6 secretion from breast cancer cells causes the anti-cachectic effect of MPA. Our other studies have revealed that 5'-fluorouridine (5'-DFUR) inhibits the growth of KPL-4 tumors and decreases IL-6 levels in both serum and tumor tissues. Decreasing serum IL-6 levels resulted in alleviation of body weight loss. Docetaxel increased IL-6 levels in both serum and KPL-4 tumors, but combined treatment with docetaxel and 5'-DFUR resulted not only in a potent antitumor effect but also in a drastic decrease of serum IL-6 levels. In the present paper the possible roles of IL-6 in the development and progression of breast cancer are reviewed, and the regulatory mechanisms of IL-6 secretion from breast cancer cells and the possible clinical implications of decreasing IL-6 secretion by therapeutic agents are discussed.

Direct activation of oestrogen receptor-alpha by interleukin-6 in primary cultures of breast cancer epithelial cells

Interleukin 6 (IL-6) is secreted by breast tumours and shows synergistic activity with 17beta-oestradiol (E2), leading to increases in reductive 17beta-hydroxysteroid dehydrogenase activity in breast cancer epithelial cells. However, the mechanisms involved are poorly understood. Using short-term epithelial cultures established from primary breast tumours, we have examined whether IL-6 could directly affect transcriptional activity of oestrogen reception alpha (ERalpha). Tumour epithelial cultures were established from 15 breast tumours, grown to 70% confluence and transiently transfected with a plasmid reporter containing the vitellogenin oestrogen response element and the luciferase coding sequence (ERE-TK-LUC). Following transfection, cells were incubated with E2, IL-6, the pure anti-oestrogen ZM 182780 or combinations of these substances for 48 h. Luciferase activity was then measured in cell lysates. E2 caused a dose-dependent increase in luciferase expression, causing a maximum threefold stimulation at 100 pM. In the presence of IL-6, transcriptional activity was increased by up to 2.5-fold in ERalpha+ cultures (11/15). In combination with E2, synergistic effects were observed with increases in luciferase activity of up to sixfold over controls. This effect could be blocked by treatment with ZM 182780. Pre-incubation of cells with an antibody directed against the signalling component of IL-6, gp130, was ineffective in blocking the E2 response. This antibody reduced, but did not completely block the effect of IL-6 either alone or in combination with E2, suggesting cross-talk between the two signalling pathways. In conclusion, these results provide evidence for direct transcriptional activation of ERalpha by IL-6.