afimoxifene and Carcinoma

Premenopausal women are at highest risk for papillary and follicular thyroid carcinoma, implicating a role for estrogens in thyroid cancer. The expression of estrogen receptors alpha and beta (ER), the effects of estradiol (E2), selective estrogen receptor modulators (SERMs) 4-hydroxytamoxifen and raloxifene, and ER subtype selective agonists were examined in NPA87 and KAT5 papillary and WRO follicular thyroid carcinoma cell lines. All three thyroid cancer cell lines expressed full-length ERalpha and ERbeta proteins with cytoplasmic localization that was unaffected by E2. ICI 182,780 (Fulvestrant, an ER antagonist), and inhibitors of non-genomic E2-activated MAPK and PI3K signaling blocked E2-induced cell proliferation. SERMs acted in a cell line-specific manner. No E2-induced estrogen response element (ERE)-driven reporter activity was observed in transiently transfected thyroid cancer cells. However, E2 increased transcription of established endogenous E2-target genes, i.e., cathepsin D in WRO and cyclin D1 in both KAT5 and WRO cells in an ER-dependent manner as validated by inhibitor and siRNA experiments. In contrast, E2 did not increase progesterone receptor expression in the thyroid cancer cell lines. E2 stimulated phosphorylation of ERK1/2 in KAT5 and WRO cells and siERalpha or siERbeta inhibited E2-induced ERK phosphorylation. Expression of the putative membrane estrogen receptor GPR30 was detected in WRO, but not NPA87 or KAT5 cells. GPR30 expression was lower in WRO than MCF-7 human breast cancer cells. Overall, these findings suggest E2-mediated thyroid cancer cell proliferation involves ERalpha and ERbeta transcriptional and non-genomic signaling events.

Topics: Carcinoma; Cell Line, Tumor; Cell Proliferation; Estradiol; Estrogen Receptor alpha; Estrogen Receptor beta; Fulvestrant; Humans; Phosphorylation; Raloxifene Hydrochloride; RNA, Small Interfering; Signal Transduction; Tamoxifen; Thyroid Neoplasms

Estrogen exerts a primary regulatory role on a wide variety of physiological processes in different tissues and organs. Agonistic ad antagonistic compounds are widely used in human health and, therefore, a deep understanding of their mechanisms of action at the molecular level is mandatory. The effect of 17beta-estradiol and three antiestrogenic drugs, comprising two selective estrogen receptor modulator (SERM, 4-OH-tamoxifen, Raloxifene) and the pure antiestrogen ICI 182,780, on genome-wide gene expression levels was evaluated in breast carcinoma cell lines by DNA microarray analysis. Different clusters of genes, showing specific coregulation patterns, were found. First, several groups of genes displaying temporal-specific up- or down-regulation were characterized. Second, clusters of genes responding to different antiestrogenic drugs in either antagonstic or agonistic fashion, were found. Genes responding specifically to antiestrogens, but not to estrogen, were also identified. In addition, each individual compound exhibited a very specific gene regulation. Bioinformatic analysis was applied to the regulatory sequences of different groups of genes and confirmed that specific pathways and secondary responses are activated at each temporal point and in response to different compounds. Our results underline the complexity of genomic responses to estrogen in breast cancer cells and strongly suggest that the molecular characterization of estrogen agonists and antagonists used in human therapy should be carefully studied.

Topics: Breast Neoplasms; Carcinoma; Down-Regulation; Estradiol; Estrogen Antagonists; Female; Fulvestrant; Gene Expression Regulation, Neoplastic; Humans; Raloxifene Hydrochloride; Selective Estrogen Receptor Modulators; Tamoxifen; Tumor Cells, Cultured; Up-Regulation

The formation of reactive oxygen species (ROS) plays a critical role in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced toxicities in mammalian cells since it promotes cell proliferation, growth arrest, and apoptosis. In this study, we investigated whether TCDD induces oxidative stress and DNA damage in human ERalpha(+)/MCF-7 and ERalpha(-)/MDA-MB-231 breast cancer cells and whether this is accompanied by the initiation of DNA repair events. Results indicated that viability of MCF-7 and MDA-MB-231 cells was concentration- and time-dependently reduced by TCDD. Further, we observed significant increases in ROS formation and decreases in intracellular glutathione (GSH) in these two cell lines after TCDD treatment. Overall, the extent of cell death was greater in MCF-7 cells than in MDA-MB-231 cells whereas the magnitude of ROS formation and GSH depletion was greater in MDA-MB-231 cells than in MCF-7 cells. In addition, we observed that at non-cytotoxic concentration (1nM for 5h), TCDD induced decreases in intracellular NAD(P)H and NAD(+) in MCF-7 and MDA-MB-231 cells. These decreases were completely blocked by three types of poly(ADP-ribose) polymerase-1 (PARP-1) inhibitors. The catalytic activation of PARP-1 in cells treated with TCDD was confirmed by detection of the presence of polymers of ADP-ribose-modified PARP-1 using Western blotting. Moreover, we demonstrated increases in the number of DNA strand breaks in MCF-7 and MDA-MB-231 cells exposed to TCDD as measured by the single-cell gel electrophoresis (Comet) assay. Overall, this evidence confirms that TCDD induces decreases in intracellular NAD(P)H and NAD(+) through PARP-1 activation mediated by formation of DNA strand breaks. In addition, we demonstrated that the extent of oxidative stress and DNA damage was greater in MDA-MB-231 cells than in MCF-7 cells, with a strong correlation to estrogen receptor (ER) status. In conclusions, our findings add further support to the theme that ROS formation is a significant determinant factor in mediating the induction of oxidative DNA damage and repair in human breast cancer cells exposed to TCDD and that the TCDD-induced oxidative stress and DNA damage may, in part, contribute to TCDD-induced carcinogenesis.

Topics: Benzamides; Benzoflavones; Breast Neoplasms; Carcinoma; Cell Line, Tumor; Cell Survival; Coumarins; DNA Breaks; Environmental Pollutants; Estrogen Receptor alpha; Glutathione; Humans; NAD; NADP; Oxidative Stress; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Polychlorinated Dibenzodioxins; Reactive Oxygen Species; Receptors, Aryl Hydrocarbon; Tamoxifen

The higher incidence of thyroid carcinoma (TC) in women during reproductive years compared with men and the increased risk associated with the therapeutic use of estrogens have suggested a pathogenetic role exerted by these steroids in the development of TC. In the present study, we evaluated the potential of 17beta-estradiol (E2), genistein (G), and 4-hydroxyta-moxifen (OHT) to regulate the expression of diverse estrogen target genes and the proliferation of human WRO, FRO, and ARO thyroid carcinoma cells, which were used as a model system. We have ascertained that ARO cells are devoid of estrogen receptors (ERs), whereas both WRO and FRO cells express a single variant of ERalpha that was neither transactivated, modulated, nor translocated into the nucleus upon treatment with ligands. However, E2, G, and OHT were able either to induce the transcriptional activity of c-fos promoter constructs, including those lacking the estrogen-responsive elements, or to increase c-fos, cyclin A, and D1 expression. It is noteworthy that we have demonstrated that the G protein-coupled receptor 30 (GPR30) and the mitogen-activated protein kinase (MAPK) pathway mediate both the up-regulation of c-fos and the growth response to E2, G, and OHT in TC cells studied, because these stimulatory effects were prevented by silencing GPR30 and using the MEK inhibitor 2'-amino-3'-methoxyflavone (PD 98059). Our findings provide new insight into the molecular mechanisms through which estrogens may induce the progression of TC.

Topics: Antineoplastic Agents; Carcinoma; Cell Line, Tumor; Cell Proliferation; Cyclin A; Cyclin D1; Estradiol; Gene Expression Regulation, Neoplastic; Genistein; Humans; Promoter Regions, Genetic; Proto-Oncogene Proteins c-fos; Receptors, Estrogen; Receptors, G-Protein-Coupled; RNA, Messenger; Signal Transduction; Tamoxifen; Thyroid Neoplasms; Transfection

Vascular endothelial growth factor D (VEGF-D) induces angiogenesis and lymphangiogenesis. Nodal metastasis is recognised as a powerful prognostic marker in breast carcinoma, but the molecular mechanisms underlying this process are unknown. Although it has been suggested that VEGF-D may regulate nodal metastasis, this is based largely on animal models, its role in human disease being unclear.. To measure the pattern and degree of VEGF-D protein expression in normal and neoplastic human breast tissues.. The pattern and degree of VEGF-D expression was measured in normal tissue and invasive carcinomas, and expression was correlated with clinicopathological parameters, hypoxia markers, and survival. Because other VEGF family members are affected by oestrogen, whether VEGF-D is regulated by oestrogen in breast cancer cell lines was also assessed.. VEGF-D was significantly positively associated with hypoxia inducible factor (HIF-1alpha) (p = 0.03) and the HIF-1alpha regulated gene DEC1 (p = 0.001), but not lymph node status, the number of involved lymph nodes, patient age, tumour size, tumour grade, lymphovascular invasion, oestrogen receptor, progesterone receptor, c-erb-B2, or tumour histology (all p>0.05). There was no significant relation between tumour VEGF-D expression and relapse free (p = 0.78) or overall (p = 0.94) survival. VEGF-D expression was enhanced by oestrogen in MCF-7 and T47D breast cancer cells, and was blocked by hydroxytamoxifen.. These findings support a role for hypoxia and oestrogen induced VEGF-D in human breast cancer and also suggest that tamoxifen and related oestrogen antagonists may exert some of their antitumour effects through the abrogation of VEGF-D induced function.

Topics: Breast Neoplasms; Carcinoma; Case-Control Studies; Cell Line, Tumor; Chi-Square Distribution; Disease-Free Survival; Estradiol; Estrogen Antagonists; Female; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Immunohistochemistry; Lymphatic Metastasis; Middle Aged; Survival Rate; Tamoxifen; Transcription Factors; Tumor Suppressor Proteins; Vascular Endothelial Growth Factor D

Tamoxifen is an estrogen receptor (ER)-antagonist that is widely used for the treatment of breast cancer, although it increases the risk of endometrial cancer. The mechanism mediating the stimulatory effect of tamoxifen on endometrial cancer is presently unknown. In this study we examined the effects of tamoxifen on Ishikawa 3H-12 endometrial cancer cells and MCF-7 breast cancer cells. Ishikawa cell growth was stimulated by 4-hydroxytamoxifen and accompanied by increased transcriptional activity of the endogenous ER. These stimulatory effects did not occur in MCF-7 cells. The relative transcriptional activity of the activation function (AF) 1 domain of ERalpha compared with that of the AF2 domain was 4-fold higher in Ishikawa cells than in MCF-7 cells. Mitogen-activated protein (MAP) kinase, which stimulates the transcriptional activity of AF1, was constitutively activated in Ishikawa cells, but not in MCF-7 cells. These observations suggest that the constitutively activated MAP kinase-signaling pathway in Ishikawa cells enhances the transcriptional activity of ERalpha via the AF1 domain. This ERalpha activation pathway may be involved in the stimulatory effect of tamoxifen on the development and/or progression of endometrial cancer.

Topics: Adenocarcinoma; Breast Neoplasms; Carcinoma; Endometrial Neoplasms; Endometrium; Estradiol; Estrogen Receptor alpha; Female; Gene Expression Regulation, Neoplastic; Humans; MAP Kinase Signaling System; Models, Biological; Neoplasms, Hormone-Dependent; Nuclear Receptor Coactivator 3; Protein Structure, Tertiary; Receptors, Estrogen; Selective Estrogen Receptor Modulators; Signal Transduction; Tamoxifen; Transcription Factors; Transcriptional Activation; Tumor Stem Cell Assay

Tamoxifen is the endocrine treatment of choice for all stages of estrogen receptor (ER)-positive breast cancer, and it is the first drug approved to reduce the incidence of breast cancer in high-risk women. Unfortunately, tamoxifen also possesses some estrogen-like effects in the uterus that cause a modest increase in the risk of endometrial cancer. GW5638 is a tamoxifen derivative with a novel carboxylic acid side chain with no uterotropic activity in the rat (Willson et al., J Med Chem, 1994, 37:1550-1552). We have compared and contrasted the actions of 4-hydroxytamoxifen (4-OHT, the active metabolite of tamoxifen) with GW7604 [the presumed metabolite of GW5638 in breast (MCF-7) and endometrial (ECC-1) cell lines in vitro]. GW7604 did not cause the growth of ECC-1 cells at any concentration (10(-11)-10(-6) M), but 4-OHT was weakly estrogen-like at low concentrations (10(-11)-10(-10) M). Compounds (10(-7) M) blocked the growth promoting action of estradiol (10(-10) M) in both ECC-1 and MCF-7 cells. Western blotting was used to show that GW7604 and raloxifene did not affect ER levels significantly, compared with controls, in MCF-7 cells; whereas the pure antiestrogen ICI182,780 decreased ER levels (P < 0.05). An assay system was used that can classify compounds into tamoxifen-like, raloxifene-like, or pure antiestrogens. The assay depends on the activation of the transforming growth factor alpha (TGFalpha) gene in situ by wild-type or D351Y mutant ER stably transfected into MDA-MB-231 cells (MacGregor-Schafer et al., Cancer Res, 1999, 59:4308-4313). GW7604 inhibited both estradiol (10(-9) M) and 4-OHT (10(-8), 10(-7) M) induction of TGFalpha in a concentration related manner (10(-9)-10(-6) M). GW7604 and raloxifene stimulated TGFalpha with the D351Y ER. In contrast, ICI 182,780 (10(-6) M) did not initiate TGFalpha and blocked the induction of TGFalpha with GW7604, raloxifene, and 4-OHT in D351Y-transfected cells. Using computer-assisted molecular models of ER complexes, we found that the antiestrogenic side chain of 4-OHT weakly interacted with the surface amino acid 351 (aspartate), but the carboxylic acid of GW7604 caused a strong repulsion of aspartate 351. We propose that GW7604 is less estrogen-like than 4-OHT, because it disrupts the surface charge around aa351 required for coactivator docking in the 4-OHT:ER complex. This charge is restored in the D351Y ER, thus converting GW7604 from an antiestrogen to an estrogen-like molecule.

Topics: Carcinoma; Cell Division; Cinnamates; Endometrial Neoplasms; Estrogen Receptor alpha; Estrogen Receptor Modulators; Estrogens; Female; Gene Expression Regulation; Humans; Models, Molecular; Receptors, Estrogen; RNA, Messenger; Selective Estrogen Receptor Modulators; Stilbenes; Tamoxifen; Transforming Growth Factor alpha; Tumor Cells, Cultured

Expression of parathyroid hormone-related protein (PTHrP) in breast carcinoma is a frequent cause of the paraneoplastic syndrome of hypercalcemia. In response to treatment with estrogen or tamoxifen, some breast cancer patients also develop a transient hypercalcemia. Therefore, the effect of 17beta-estradiol (E2), tamoxifen, or its more potent metabolite, 4-hydroxytamoxifen (OH-tamoxifen), on PTHrP expression in an estrogen receptor (ER)-positive breast carcinoma cell line (MCF-7) was evaluated. E2 increased PTHrP mRNA levels in MCF-7 cells and stimulated PTHrP(1-86) release in a dose-dependent fashion (10(-10)-10(-6) M). Tamoxifen and OH-tamoxifen also stimulated PTHrP release in a concentration-dependent fashion that paralleled their relative ER binding affinities (10(-6) or 10(-8)-10(-6) M, respectively). Combined treatment with the partial estrogen agonist, OH-tamoxifen, and E2 decreased E2-stimulated PTHrP secretion in MCF-7 cells to the levels seen with OH-tamoxifen treatment alone. These results suggest that transient estrogen- or tamoxifen-induced hypercalcemia in patients with breast carcinoma may be a PTHrP-mediated effect that is a marker of ER positivity.

Topics: Breast Neoplasms; Carcinoma; Dose-Response Relationship, Drug; Estradiol; Estrogen Antagonists; Female; Humans; Hypercalcemia; Parathyroid Hormone-Related Protein; Protein Biosynthesis; Proteins; RNA, Messenger; Tamoxifen; Tumor Cells, Cultured

The effect of 4-hydroxytamoxifen (4OH-TAM), the potent anti-estrogenic metabolite of tamoxifen, on the radiosensitivity of MCF-7 cells irradiated in vitro was determined. Radiation dose response curves were generated for MCF-7 cells maintained and irradiated in phenol red-free medium containing 10(-10) M estradiol (E2) with or without 10(-7) M 4OH-TAM. Immediately after irradiation cells were transferred to medium containing 10(-10) ME2 supplemented with bovine serum to stimulate colony formation. Estradiol-stimulated cell proliferation was inhibited by 10(-7) M 4OH-TAM, but radiation sensitivity was not significantly altered (p > 0.3). Continued incubation in the absence of E2 for an additional 24 hours after irradiation likewise failed to alter the radiosensitivity of 4OH-TAM-treated MCF-7 cells. These studies indicate that growth-inhibitory concentrations of the anti-estrogen 4OH-TAM do not modify the in vitro radiation sensitivity of this line of human breast carcinoma cells.

Topics: Breast Neoplasms; Carcinoma; Cell Division; Female; Humans; Radiation Dosage; Radiation Tolerance; Tamoxifen; Tumor Cells, Cultured

The influence of estrogen (E) and antiestrogen (AES) on the in vitro growth of BG-1 ovarian carcinoma cells, which express steroid receptors was examined (K. R. Geisinger, T. E. Kute, M. J. Pettenati, C. E. Welander, Y. Dennard, L. A. Collins, and M. E. Berens, Characterization of a human ovarian carcinoma cell line with estrogen and progesterone receptors, Cancer 63, 280-288, 1989). All determinations were simultaneously referenced under similar conditions to MCF-7 cells, a well-established cell line for modeling hormonal responses in breast cancer. In "complete" media containing fetal calf serum (FCS, 10%), MCF-7 cell numbers increased approximately 7 x in 7 days, remaining at this level Days 8-15. In contrast, BG-1 cells achieved similar numbers by Day 7, but showed apparent exponential growth over Days 8-15 to 15-20 x. Phenol red-free media containing 10% FCS (less than 20 pg estradiol (E2)/ml by RIA) was used to assess responses to E and AES. Growth of both MCF-7 and BG-1 cells slowed in E-free media. E2 (10 nM) stimulated the growth of both cell lines, yet was responsible for exponential increases during Days 8-15 only in BG-1 cell numbers (50-70 x). The metabolically active AES (4OH-tamoxifen, 50 nM) reduced E2-stimulated MCF-7 growth to 3-4 x, while tamoxifen (50 nM) had no effect. Rescue with 10 microM E2 fully overcame the AES inhibition of MCF-7 proliferation. In contrast, BG-1 cells experienced significant E2-stimulated growth reductions in the presence of either 4OH-tamoxifen or tamoxifen. E2 was observed to rescue BG-1 cells from both of these antagonists. We conclude that BG-1 ovarian carcinoma cells respond in vitro to E and AES. Moreover, by virtue of responses to tamoxifen, BG-1 cells may have an intrinsic capacity to hydroxylate tamoxifen to its active metabolite. This property of ovarian carcinoma cells might be worth exploiting in the design of more effective combination chemotherapy regimens.

Topics: Carcinoma; Cell Division; Culture Media; Estradiol; Estrogen Antagonists; Estrogens; Female; Humans; Ovarian Neoplasms; Tamoxifen; Tumor Cells, Cultured

Methods and evaluation of the human tumor stem cell assay (HTSCA) are described. Advantages and disadvantages of the test system are elaborated. The in vitro/in vivo correlation in the drug screening of human ovarian carcinomas shows that the prediction of sensitivity to a cytotoxic agent is only possible in 64%. Prediction of drug resistance, however, seems to be possible in 95%. The number of patients that profit from the HTSCA seems to be only less than 10%. Our investigations describe the influence of various hormones and antiestrogens on the colony formation of human ovarian carcinoma cells. Tamoxifen and his major metabolite 4-hydroxy-tamoxifen were the most active agents. Both compounds inhibit the colony survival (70% at pharmacological concentrations) of 60% of the screened ovarian carcinomas. A significant correlation to the quantitative level of estrogen or progesterone receptors could not be proved. Colony formation of ovarian carcinoma cells was compared in the HTSCA as described by Hamburger and Salmon and in a methylcellulose-monolayer system. Our results show that the colony formation corresponds to the results of the original HTSCA: Cloning ovarian carcinoma cells in the methylcellulose-monolayer, however, seems to be technically easier and faster.

Topics: Agar; Antineoplastic Agents; Carcinoma; Cells, Cultured; Colony-Forming Units Assay; Drug Resistance; Estradiol; Female; Hormones; Humans; Medroxyprogesterone; Medroxyprogesterone Acetate; Methylcellulose; Ovarian Neoplasms; Progesterone; Prognosis; Tamoxifen; Tumor Stem Cell Assay