Steroid profile in patients with breast cancer and in mice treated with mifepristone.

Progesterone receptors (PRs) are biomarkers used as prognostic and predictive factors in breast cancer, but they are still not used as therapeutic targets. We have proposed that the ratio between PR isoforms A and B (PRA and PRB) predicts antiprogestin responsiveness. The MIPRA trial confirmed the benefit of 200 mg mifepristone, administered to patients with tumors with a high PRA/PRB ratio, but dose-ranging has not been conducted. The aim of this study was to establish the plasma mifepristone levels of patients from the MIPRA trial, along with the resultant steroid profiles, and compare these with those observed in mifepristone-treated mice using therapeutic schemes able to induce the regression of experimental mammary carcinomas with high PRA/PRB ratios: 6 mg pellets implanted subcutaneously, or daily doses of 12 mg/kg body weight. The plasma levels of mifepristone and other 19 plasma steroids were measured by liquid chromatography-tandem mass spectometry. In mifepristone-treated mice, plasma levels were lower than those registered in mifepristone-treated patients (i.e. day 7 after treatment initiation, pellet-treated mice: 8.4 ± 3.9 ng/mL; mifepristone-treated patients: 300.3 ± 31.7 ng/mL (mean ± s.d.; P < 0.001)). The increase in corticoid related steroids observed in patients was not observed in mifepristone-treated mice. The increase in progesterone levels was the most significant side effect detected in mifepristone-treated mice after 14 or 21 days of treatment, probably due to an ovarian compensatory effect not observed in postmenopausal patients. We conclude that in future clinical trials using mifepristone, the possibility of lowering the standard daily dose of 200 mg should be considered.

The Beta2-adrenergic agonist salbutamol synergizes with paclitaxel on cell proliferation and tumor growth in triple negative breast cancer models.

PURPOSE: Globally breast cancer accounts for 24.5% in incidence and 15.5% in cancer deaths in women. The triple-negative subtype lacks any specific therapy and is treated with chemotherapy, resulting in significant side-effects. We aimed to investigate if the dose of chemotherapeutic drugs could be diminished by co-administering it with the ß2-agonist salbutamol. METHODS: Cell proliferation was measured by thymidine incorporation; gene expression, by real-time PCR and protein phosphorylation by WB. Apoptosis was assessed by acridine orange / ethidium bromide and TUNEL tests. Public patient databases were consulted. Cells were inoculated to nude mice and their growth assessed. RESULTS: The ß2-agonist salbutamol synergizes in MDA-MB-231 cells in vitro with paclitaxel and doxorubicin on cell proliferation through ADRB2 receptors, while the ß-blocker propranolol does not. The expression of this receptor was assessed in patient databases and other cell lines. Triple negative samples had the lowest expression. Salbutamol and paclitaxel decreased MDA-MB-231 cell proliferation while their combination further inhibited it. The pathways involved were analyzed. When these cells were inoculated to nude mice, paclitaxel and salbutamol inhibited tumor growth. The combined effect was significantly greater. Paclitaxel increased the expression of MDR1 while salbutamol partially reversed this increase. CONCLUSION: While the effect of salbutamol was mainly on cell proliferation, suboptimal concentrations of paclitaxel provoked a very important enhancement of apoptosis. The latter enhanced transporter proteins as MDR1, whose expression were diminished by salbutamol. The expression of ADRB2 should be assessed in the biopsy or tumor to eventually select patients that could benefit from salbutamol repurposing.

Adrenergic receptors in breast cancer.

Breast cancer is the most diagnosed malignancy in women worldwide and in the majority of the countries. Breast cancers are classified on the expression of estrogen and progesterone receptor expression and overexpression of human epidermal growth factor receptor 2 (HER2) as luminal, HER2+ and triple negative breast cancer. The intrinsic molecular subtypes match this classification. Cancer diagnosis and treatment cause distress. In both acute and chronic stress, the secreted catecholamines adrenaline and noradrenaline trigger the "fight-or-flight" response. This chapter focuses on the actions of the ß2 and α2 adrenergic receptors in several models of breast cancer. The actions of these receptors depend on the model used to investigate them. The ß2-adrenergic receptors seem to exert a dual action. They can directly act on the epithelial cells inhibiting cell proliferation and migration/invasion and indirectly upon the immune microenvironment. The proportion of ß2 receptors in each compartment could, therefore, lean the scale to an inhibition or to an exacerbation of tumor growth, invasion and metastasis. All the work points to a beneficial or neutral action of ß-blockers on breast cancer. With respect to α2-adrenergic receptors, the investigation performed by our group suggest that the α2B and the α2C receptors are linked to enhanced cell proliferation and tumor growth acting through both the epithelial and the stromal (fibroblastic) compartments while α2A could be beneficial for patients. Some adrenergic compounds could be repurposed for breast cancer treatment due to their very low side effects and very well-known pharmacology.

Agonist Effects of Propranolol on Non-Tumor Human Breast Cells.

The ß-blocker propranolol (PROP) has been proposed as a repurposed treatment for breast cancer. The similarity of action between ß-agonists and antagonists found on breast cells encouraged us to compare PROP and isoproterenol (ISO, agonist) signaling pathways on a human breast cell line. Cell proliferation was measured by cell counting and DNA-synthesis. Cell adhesion was measured counting the cells that remained adhered to the plastic after different treatments. Changes in actin cytoskeleton were observed by fluorescence staining and Western Blot. ISO and PROP caused a diminution of cell proliferation and an increase of cell adhesion, reverted by the pure ß-antagonist ICI-118551. ISO and PROP induced a reorganization of actin cytoskeleton increasing F-actin, p-COFILIN and p-LIMK. While ISO elicited a marked enhancement of cAMP concentrations and an increase of vasodilator-stimulated phosphoprotein (VASP) and cAMP response element-binding protein (CREB) phosphorylation, PROP did not. Clathrin-mediated endocytosis inhibition or ß-arrestin1 dominant-negative mutant abrogated PROP-induced cell adhesion and COFILIN phosphorylation. The fact that PROP has been proposed as an adjuvant drug for breast cancer makes it necessary to determine the specific action of PROP in breast models. These results provide an explanation for the discrepancies observed between experimental results and clinical evidence.

Prognostic significance of α- and ß2-adrenoceptor gene expression in breast cancer patients.

AIMS: Breast cancer is the most frequently diagnosed and leading cause of cancer death among women worldwide. It was classified within molecular intrinsic subtypes: luminal A, luminal B, human epidermal growth factor receptor 2-enriched and basal-like. Epinephrine and norepinephrine, released during stress, bind to adrenoceptors. α2 -adrenoceptors are encoded by the ADRA2A, ADRA2B and ADRA2C genes and ß2 by ADRB2. METHODS: We compiled several publicly available Affymetrix gene expression datasets, obtaining a large cohort of 1924 patients with distant metastasis-free survival (DMFS) data and evaluated the association between adrenoceptor expression, clinicopathological markers and outcome. RESULTS: ADRA2A high expressing tumours also expressed hormone receptors and presented diminished tumour size, grade and not compromised lymph nodes. ADRB2 high expression was found in smaller, low grade, oestrogen receptor-positive tumours. Both were significantly associated with the absence of metastasis. High expression of ADRA2C was positively associated with increased tumour size and metastatic relapse. We observed a significant increase in DMFS of patients with high ADRA2A (hazard ratio 0.54, 95% CI 0.45-0.65, P < .001) and ADRB2 (0.77, 0.64-0.93, P = .006) expression and a decrease with ADRA2C high expression (1.45, 1.16-1.81, P = .001). For patients with luminal tumours, ADRA2A was the only factor that retained its significance as an independent predictor of DMFS while ADRA2C expression was an independent predictor for worse prognosis in basal-like tumours. CONCLUSIONS: We herein provide new insight for a potential role of ADRA2A and ADRA2C in breast cancer. In low- and medium-income countries, their incorporation to routine immunohistochemistry analysis of biopsies or tumour samples, could provide additional low-cost prognostic factors.

The ß 2-Adrenergic Agonist Salbutamol Inhibits Migration, Invasion and Metastasis of the Human Breast Cancer MDA-MB- 231 Cell Line.

BACKGROUND: Breast cancer is the most diagnosed and the major cause of cancer death in women worldwide. Metastasis is the main cause of these deaths. The metastatic cascade involves multiple steps and it has been described that adrenergic receptors can modulate this process at multiple levels. However, ß -adrenergic action in breast cancer is controversial. We have previously shown that ß-adrenergic agonists inhibit cell proliferation and tumor growth of numerous breast cancer models. OBJECTIVE: The purpose of the present investigation was to evaluate adrenergic effect in parameters related to tumor progression (migration, invasion and metastases) in two human breast cancer cell lines. METHODS: Migration was assessed in IBH-6 and MDA-MB-231 cells by time-lapse videomicroscopy and modified Boyden chambers. Invasion was evaluated by Transwells coated with Matrigel and expression of pro-metastatic genes was determined by RT-qPCR. Experimental metastases studies were performed by injection of the cells in the tail vein of NSG immuno-deficient mice. RESULTS: In both cell lines, salbutamol (ß2-agonist) and propranolol (ß-blocker) significantly diminished cell migration while epinephrine exerted opposite effects. Moreover, salbutamol inhibited invasion of both breast cancer cell lines and enhanced adhesion to extracellular matrix. Salbutamol treatment was also able to decrease the expression of pro-metastatic genes in MDA-MB-231 cells. Finally, this compound decreased the number and size of MDA-MB-231 lung experimental metastases in NSG immuno- deficient mice. No effect on the establishment of IBH-6 metastases was observed. CONCLUSION: Our results suggest that salbutamol could be an effective adjuvant drug for the treatment of metastatic breast cancer.

Alpha2-adrenoceptor agonists trigger prolactin signaling in breast cancer cells.

Breast cancer is the most frequent malignancy among women worldwide. We have described the expression of α2-adrenoceptors in breast cancer cell lines, associated with increased cell proliferation and tumor growth. A mitogenic autocrine/paracrine loop of prolactin (Prl) has been described in breast cancer cells. We hypothesized that the α2-adrenergic enhancement of proliferation could be mediated, at least in part, by this Prl loop. In both T47D and MCF-7 cell lines, the incubation with the α2-adrenergic agonist dexmedetomidine significantly increased Prl release into the culture medium (measured by the Nb2 bioassay), this effect being reversed by the α2-adrenergic antagonist rauwolscine. No change in Prl receptors (PrlR) was observed by RT-qPCR in these cell lines. In IBH-6 cells a decrease in Prl secretion was observed at the lower dexmedetomidine concentration. The signaling pathways involved in ovine Prl (oPrl) and dexmedetomidine action were also assessed. Both compounds significantly activated STAT5 and ERK in all three cell lines. In T47D and MCF-7 cell lines also AKT was activated by both Prl and dexmedetomidine. We therefore describe the STAT5 phosphorylation by an α2-adrenergic agonist, dexmedetomidine. In T47D cells, the α2-adrenergic stimulation of cell proliferation is probably mediated, at least in part, by the Prl autocrine/paracrine loop, because this effect is abrogated by the specific PrlR antagonist Δ1-9-G129R-hPrl. The implication of Prl loop describes a novel mechanism of action of this GPCR.

Expression analysis of epithelial cadherin and related proteins in IBH-6 and IBH-4 human breast cancer cell lines.

Epithelial cadherin (E-cadherin) is a 120 kDa cell-cell adhesion molecule involved in the establishment of epithelial adherens junctions. It is connected to the actin cytoskeleton by adaptor proteins such as beta-catenin. Loss of E-cadherin expression/function has been related to tumor progression and metastasis. Several molecules associated with down-regulation of E-cadherin have been described, within them neural cadherin, Twist and dysadherin. Human breast cancer cell lines IBH-6 and IBH-4 were developed from ductal primary tumors and show characteristic features of malignant epithelial cells. In this study expression of E-cadherin and related proteins in IBH-6 and IBH-4 cell lines was evaluated. In IBH-6 and IBH-4 cell extracts, only an 89 kDa E-cadherin form (Ecad89) was detected, which is truncated at the C-terminus and is present at low levels. Moreover, no accumulation of the 86 kDa E-cadherin ectodomain and of the 38 kDa CTF1 fragment was observed. IBH-6 and IBH-4 cells showed an intracellular scattered E-cadherin localization. beta-catenin accompanied E-cadherin localization, and actin stress fibers were identified in both cell types. E-cadherin mRNA levels were remarkably low in IBH-6 and IBH-4 cells. The E-cadherin mRNA and genomic sequence encoding exons 14-16 could not be amplified in either cell line. Neither the mRNA nor the protein of neural cadherin and dysadherin were detected. Up-regulation of Twist mRNA was found in both cell lines. In conclusion, IBH-6 and IBH-4 breast cancer cells show down-regulation of E-cadherin expression with aberrant protein localization, and up-regulation of Twist; these features can be related to their invasive/metastatic characteristics.

Novel human breast cancer cell lines IBH-4, IBH-6, and IBH-7 growing in nude mice.

Breast cancer is the most frequent cancer in women. However, in vivo hormone receptor positive and metastatic models are scarce. The aim of the present manuscript was to assess if the novel steroid receptor positive human cell lines IBH-4, IBH-6, and IBH-7 developed in our laboratory from primary infiltrant ductal carcinomas are good models to study in vivo human breast cancer. Cell lines or tumors were inoculated to nude mice in the presence or absence of hormone supplementation. Growth was analyzed by ANOVA followed by Tukey-Kramer's test. Steroid hormone expression was assessed by immunohistochemistry and Western blotting. The histology of the tumors was analyzed. IBH-4 and IBH-6 cells were inoculated to nude mice and 100% of the injected mice developed tumors in the presence or absence of hormone treatment, although tamoxifen inhibited growth. IBH-4 and IBH-6 cell lines in vivo gave rise to poorly differentiated carcinomas with areas of solid growth and sarcomatoid areas showing no morphological signs of epithelial differentiation. Distinct features of malignancy were observed. IBH-7 tumors in animals receiving estradiol were semi-differentiated adenocarcinomas. IBH-7 cells grew only in the presence of estradiol, but even with hormone addition, the tumor take was 20%. These tumors metastasized to the uterus and lung and vascular tumor emboli were evident. IBH-7 tumors were invasive and able to break through the peritoneum. As a conclusion, IBH-4 and IBH-6 are good models for studying tumor progression, whereas IBH-7 is a good model for tumor take, being metastatic and strictly estrogen-dependent.

Contribution of alpha2-adrenoceptors to the mitogenic effect of catecholestrogen in human breast cancer MCF-7 cells.

Catecholestrogens are estrogen metabolites formed by hydroxylation of 17beta-estradiol and estrone at either the C-2 or C-4 position, rivaling the parent estrogens in concentration. The objective of the present work was to assess if their catechol group could make them induce proliferation of human breast cancer cells via alpha(2)-adrenoceptors. In competition studies in human breast cancer MCF-7 cells, high concentrations of 2-hydroxy-estradiol (2-OH-E(2)), 2-hydroxy-estrone (2-OH-E(1)) and 4-hydroxy-estrone (4-OH-E(1)) competed for [(3)H]-rauwolscine binding, whereas 4-hydroxy-estradiol (4-OH-E(2)) did not. The contribution of alpha(2)-adrenoceptors and estrogen receptors (ERs) in proliferation enhancement was analyzed with specific antagonists. The specific alpha(2)-adrenergic antagonist yohimbine partially reversed the effect of catecholestrogens except 4-OH-E(2). The selective ER downregulator ICI-182780 or fulvestrant partially or totally reversed the effect of all hydroxylated catecholestrogens. When analyzing the effect of the combination of both antagonists in MCF-7, the contribution of the alpha(2)-adrenoceptors and ERs for 2-OH-E(2), 2-OH-E(1) and 4-OH-E(1) was mixed, whereas for 4-OH-E(2), the only receptor implied was an ER. In MDA-MB-231 cells (ER-alpha negative) the proliferation stimulation by these three catecholestrogens and reversal by the adrenergic antagonist was also observed. It can be concluded that alpha(2)-adrenoceptors contribute at least in part to the mitogenic effect of 2-OH-E(2), 2-OH-E(1) and 4-OH-E(1).

Human breast cell lines exhibit functional alpha2-adrenoceptors.

Adrenergic compounds (epinephrine and norepinephrine) are the most important hormones released during stress. Several different receptors are associated with their action in different tissues. However, alpha(2)-adrenoceptors have not yet been described in either normal or tumour human breast tissue. The aim of this work was to describe and characterize these receptors in several tumour and non-tumour human cell lines. The expression of alpha(2)-adrenoceptors was analyzed at the RNA (RT-PCR) and protein ([(3)H]-rauwolscine binding and immunocytochemistry) levels in different human breast cell lines, and the biological activity assessed by [(3)H]-thymidine incorporation. The cancer IBH-6, IBH-7 and MCF-7 and the non-tumour HBL-100 cells line, expressed both alpha(2B)- and alpha(2C)-adrenoceptor-subtypes. A single subtype was expressed in malignant HS-578T (alpha(2A)) and MDA-MB-231 and non-tumour MCF-10A cells (alpha(2B)). All cell lines exhibited significant binding for the specific antagonist [(3)H]-rauwolscine. The alpha-, alpha(2)-, and the alpha(1)-compounds with known affinity for alpha(2)-adrenoceptors, including epinephrine, norepinephrine, yohimbine, clonidine, rauwolscine and prazosin, competed significantly with binding in MCF-7 cells. In addition, IBH-6, IBH-7 and MCF-7 cells showed significant staining with specific antibodies against alpha(2B)- and alpha(2C)-adrenoceptor-subtypes, when tested by immunocytochemistry. In all cell lines, the specific agonist clonidine or oxymetazoline stimulated [(3)H]-thymidine incorporation. EC(50) values were in the range of 20-50 fM for IBH-6, IBH-7, and HS-578T; 0.14 pM for MCF-7; 2-82 pM for HBL-100 and MCF-10A cells, and a biphasic behaviour with a maximum value at 38.0 pM, was observed for MDA-MB-231 cells. The specific alpha(2)-adrenergic antagonist rauwolscine always reversed this stimulation at 0.1 nM. In conclusion, this study describes for the first time, the presence of alpha(2)-adrenoceptors in human epithelial breast cell lines. Moreover, activation of these receptors was associated with an enhancement of cell proliferation.

Three novel hormone-responsive cell lines derived from primary human breast carcinomas: functional characterization.

Human breast cancer primary cultures are useful tools for the study of several aspects of cancer biology, including the effects of chemotherapy and acute gene expression in response to different hormonal/chemotherapy treatments. The present study reports the conditions for primary culture of breast cancer samples from untreated patients and the most effective collagenization method to dissociate human samples consisting in an overnight incubation with 1 mg/ml types II or IV collagenase and further incubation in DMEM:F12 (1:1) medium supplemented with glutamine, bovine insulin, penicillin-streptomycin, HEPES, estradiol, cortisol (F), tri-iodothyronine (T(3)), transferrine (TR), and 10% fetal calf serum (FCS). These conditions proved to be appropriate for both primary culture and the development of stable cell lines. Of the seven cell lines obtained, three fast growing and estrogen receptor (ER)+/progesterone receptor (PgR)+/EGF receptor (EGFR)+ have been characterized. The cells are able to grow both in soft agar and in nude mice, and express cytokeratins, all parameters characteristic of malignant epithelial cell lines. The cells also exhibit an increased proliferation rate in the presence of estradiol, progesterone, and EGF, suggesting the presence of the corresponding receptors. The mRNA expression of type alpha- and beta-ER as well as EGFR, was confirmed by RT-PCR. In conclusion, the novel cell lines described, arose from primary tumors and are sensitive to estradiol, progesterone, and EGF. This not only expands the repertoire of breast cancer cells available as potentially useful tools for examining most parameters in breast cancer "in vitro", but also provides unique new models to explore the complex regulation by steroids as well as growth factors in such cells.