Keratinocyte growth factor-induced motility of breast cancer cells.

Endogenous growth factors and cytokines are known to have a major influence on the progression, motility and invasiveness of tumor cells. We have reported previously that conditioned media from mouse fibroblasts increases the motility of breast cancer cells. Further, we determined that keratinocyte growth factor (KGF) was an active factor from mouse fibroblasts responsible for most of the motility response in breast cancer cells. The present study examined the effect of Human KGF on the motility of estrogen receptor (ER)-positive and ER-negative human breast cancer cell lines in culture using time-lapse videomicroscopy to quantify cell motility. In the present study we observed that recombinant human KGF enhanced several parameters of cellular motility in ER-positive cells but not in ER-negative cell lines. Further, we observed that the level of KGF receptor (KGFR) expression in ER-positive cells was much greater than in the ER-negative cell lines. The motility response to KGF was found to be both dose-and time-dependent. Of the three ER-positive breast cancer cell lines tested. MCF-7 cells were the most responsive to KGF stimulation. Finally, MCF-7 cells grown in estrogen-depleted media did not respond to KGF. These results suggest that KGF from stromal tissue surrounding a primary tumor mass can enhance tumor cell motility and may be an early signal in the progression of breast cancer cells to a more motile and metastatic phenotype. Thus, KGF, KGFR and/or the KGF signaling pathway may be important therapeutic targets for the treatment or prevention of breast cancer metastasis.

Differential influence of antiestrogens on the in vitro release of gelatinases (type IV collagenases) by invasive and non-invasive breast cancer cells.

Matrix metalloproteinases (MMPs) play an important role in tumor cell invasion and cancer metastasis. Accordingly, a higher level of these enzymes has been associated with the invasive phenotype. In the present study the effect of the antiestrogens, Analog II (AII), ICI-182,780 (ICI), and tamoxifen (TAM), on the in vitro release of MMPs, particularly gelatinases A and B by the MDA-MB-231 (MDA) and MCF-7 (MCF) human breast cancer cell lines was investigated using a solid-phase radioassay and substrate gel zymography. Quantitatively, the enzyme activity was found to be higher in the incubation medium from estrogen receptor (ER)-negative and more metastatic MDA cells compared to ER-positive and less metastatic MCF cells. Tissue inhibitor of metalloproteinases-1 (TIMP-1) reduced the enzyme activity in media from both MDA (56.36%) and MCF (71.03%) cells. Differential antiestrogen effects on the two cell lines were observed following 4 days of treatment of cells at a concentration of 10(-6)M. The enzyme activity from MDA cells was not influenced by treatment with any of the antiestrogens, whereas, in MCF cells, ICI produced the greatest enzyme inhibition (47.93%), followed by AII (36.51%) and TAM (24.05%). Concurrent treatment of MCF cells with 17-beta-estradiol (10(-9)M) partially reversed the AII- and TAM-induced but did not alter ICI-induced inhibition of enzyme activity. Substrate gel zymography revealed that among the MMPs, the MDA cells released predominantly progelatinase A (72 kDa) along with minor bands of activated forms, 62 kDa and 59 kDa, whereas progelatinase B (92 kDa) was detected predominantly in the medium from MCF cells. Comparison of the overall antiestrogen effect indicates that ICI is the most potent inhibitor of enzyme activity in ER-positive MCF cells and that antiestrogen treatment may limit the metastatic potential of ER-positive breast cancer.

The influence of antiestrogens on the release of plasminogen activator (uPA) by MDA-MB-231 and MCF-7 breast cancer cells.

Plasminogen activators are known to be involved in the metastatic spread of breast cancer. In the present study we examined the effects of antiestrogens [Analog II (1,1-dichloro-cis-2,3-diphenyl cyclopropane) (AII), ICI-182,780 (ICI) and tamoxifen (TAM)], on the in vitro release of uPA from estrogen receptor (ER)-positive MCF-7 (MCF) and ER-negative MDA-MB-231 (MDA) human breast cancer cell lines. Using a solid-phase radioassay, uPA activity was found to be higher in the culture medium from MDA cells compared to MCF cells. Aminocaproic acid, a specific plasmin inhibitor, produced a 50-60% reduction in the degradation of labeled substrate, in the solid phase assay, using culture medium from both cell lines, thus indicating that most of the proteolysis observed was due to uPA-mediated plasmin generation from plasminogen. In the absence of plasminogen, the enzyme activity was not detected in either the quantitative assay or by zymography. In MDA cells, uPA release was not altered by any of the antiestrogens used alone or in the presence of estradiol. In contrast, in MCF cells, ICI alone produced maximal inhibition (40%) of enzyme release, while estradiol alone produced a 120% increase in enzyme activity. When co-administered with estradiol, in MCF cultures, each antiestrogen reduced enzyme activity to control levels. Substrate gel zymography revealed that the urokinase-type PA is the predominant form of PA released by both cell lines. Comparison of the activity of all three antiestrogens used in this study indicates that ICI is the most potent inhibitor of enzyme activity in ER-positive MCF cells.

Influence of antiestrogens on the migration of breast cancer cells using an in vitro wound model.

The metastasis of malignant tumor cells to other organs in the body is the major cause of cancer-related patient mortality. Therefore, the inhibition of tumor cell motility is critical in the prevention or control of tumor malignancy. In the present study, the antimetastatic potential of antiestrogens [tamoxifen (TAM); ICI-182,780 (ICI); and Analog II (AII)] on highly invasive, estrogen receptor (ER)-negative MDA-MB-231 (MDA) and non-invasive, ER-positive MCF-7 (MCF) human breast cancer cell lines was investigated using an in vitro wound model. Wounds were created in confluent cell cultures and repopulation of the wound space was evaluated by counting the number of cells that migrated into the wound area and by measuring the maximum distance traveled. In addition, the number of cells that were passively seeded into the wounded area was determined. ICI and AII reduced the number of MCF cells that migrated into the wounded area and reduced the number of viable passively seeded MDA cells. Unlike ICI and AII, TAM appeared to enhance MCF and MDA cell movement. This study indicates that the in vitro wound technique is applicable to the study of breast cancer cell movement in response to antiestrogens and other antimetastatic agents. It also demonstrates that antiestrogens differ in their influence on breast cancer cell migration.

Synthesis and biological evaluation of a series of 1,1-dichloro-2,2,3-triarylcyclopropanes as pure antiestrogens.

A series of 1,1-dichloro-2,2,3-triarylcyclopropanes (DTACs) was synthesized and evaluated as pure antiestrogens. Addition of 4-methoxy- or 4-(benzyloxy)phenyl Grignard reagents to p-methoxy, p-benzyloxy, or unsubstituted deoxybenzoins, followed by dehydration of the resulting carbinols produced a mixture of E and Z olefins, which were reacted with dichlorocarbene to give O-protected DTACs. The E and Z isomers were separated by fractional crystallization and the central or geminal phenyl ring was deprotected to provide phenolic DTACs. Alkylation with (N,N-dimethylamino)ethyl chloride yielded basic cyclopropanes. Two chlorodiarylindenes were isolated as thermolysis products of the DTACs, and one was converted to a phenol by hydrogenolysis. All DTACs and indenes were competitive inhibitors of [3H]estradiol binding in the immature rat uterine cytosol receptor assay, with relative binding affinities of 0.1-3.6% of estradiol. None of the new compounds were estrogenic in the 3-day immature mouse uterotrophic assay at doses up to 750 micrograms. In the 3-day immature mouse antiuterotrophic assay, five DTACs with either a methoxy (5a), benzyloxy (4d, 5c), or (dimethylamino)ethoxy (7a, 7b) central ring side chain produced significant decreases in uterine weight at doses up to 750 micrograms. One compound, (Z)-1,1-dichloro-2-[4-[2-(dimethylamino)ethoxy]-phenyl]-2-(4- methoxyphenyl)-3-phenylcyclopropane (7b), elicited a dose-dependent decrease in vivo comparable to MER 25. These same five compounds, as well as the lead compound Analog II, were active in vitro against the estrogen-dependent MCF-7 human breast tumor cell line in a dose-dependent fashion.

Influence of the calcium ionophores A23187 and X537A on calcitonin secretion from the isolated perfused porcine thyroid.

The present study examined the influence of the calcium ionophores A23187 and X537A on the calcitonin (CT) secretory process. The isolated perfused porcine thyroid was used to evaluate ionophore effects on CT secretion and thyroid slices were used to measure 45Ca uptake. Both A23187 and X537A enhanced the rate of CT release from the perfused thyroid. A23187 at a concentration of 19 microM (10 micrograms/ml) produced a maximal increase in CT secretion of 325% above control levels. X537A at a concentration of 16 microM (10 micrograms/ml) produced a peak rise in CT release of approximately 2000% over control levels. The CT secretory response to A23187 was found to be completely calcium dependent; however, the secretory response to X537A was partially, but not completely dependent upon the presence of perfusate calcium. The results demonstrate that these calcium ionophores are very potent CT secretagogues which vary considerably in their calcium dependency.

Characteristics of calcitonin degradation in vitro produced by incubation with procine thyroid tissue.

The possibility of calcitonin (CT) degradation by thyroid tissue in vitro was investigated. Tissue slices or a thyroid supernatant solution was incubated with 131I-labeled porcine CT for 30--60 min at 37 degrees C. Calcitonin degradation and deiodination were determined by chromatoelectrophoresis and/or quso adsorption. Degradation of ]131I]CT occurred rapidly in the presence of 50--200 mg porcine thyroid tissues; however, little or no hormone deiodination was observed. Porcine liver, kidney and lung slices also degraded [131I]CT. The data indicate that a nonspecific proteolytic enzyme, capable of rapid CT degradation, is liberated from thyroid tissue slices in vitro. This substance, which is found in the cytosol fraction of thyroid tissue, is heat labile, has a molecular weight between 25,000 and 100,000, displays an acidic pH maximum for CT degradation and is inhibited by sulfhydryl enzyme inhibitors. The liberation of this substance from thyroid slices may explain the relative unresponsiveness of CT secretion observed in previous in vitro studies.

Antitumor mechanism of action of a cyclopropyl antiestrogen (compound 7b) on human breast cancer cells in culture.

Cyclopropyl compound 7b [(Z)-1,1-dichloro-2-[4-[2-(dimethylamino)ethoxy] phenyl]-2-(4-methoxyphenyl)-3-cyclopropane] has been shown to be a pure antiestrogen in mouse uterine tissue. Antitumor activity was examined by evaluating the influence of 7b on the proliferation, estrogen receptor (ER) affinity and cell-surface morphology of ER-positive and ER-negative human breast cancer cells in culture. The antiproliferative potency of 7b was found to be equal to tamoxifen in ER-positive MCF-7 human breast cancer cells. Further, the antiproliferative activities of 7b and tamoxifen were reversed by coadministration of estradiol. Accordingly, the antiproliferative activity of compound 7b appears to be estrogen-mediated since it did not influence the growth of either ER-negative MDA-MB-231 human breast cells or A-549 human lung cancer cells in culture. An ER-dependent mechanism of action is also supported by the specific binding affinity of 7b for ER in MCF-7 cells. Further, a study of cell surface morphology using scanning electron microscopy (SEM) revealed that 7b reduced the density and distribution of microvilli (MV) on MCF-7 cells, which was reversed by coadministration of estradiol. Compound 7b did not alter the cell surface morphology of ER-negative MDA-MB-231 cells. In conclusion, 7b inhibited the growth of ER-positive MCF-7 cells in an estradiol-reversible manner, and had no effect on either ER-negative MDA-MB-231 cells or A-549 lung cancer cells. The results of this study confirm an antiestrogenic mechanism of action for 7b as previously observed in vivo and suggest that 7b would be effective in the treatment of estrogen-dependent breast cancer or as a prophylactic treatment for women with a high risk of breast cancer development.

Influence of lanthanum on calcium transport and retention in the rat duodenum.

The present study examined the effects of lanthanum on calcium retention and transport in rat duodenal segments in vitro. Increasing the concentration of lanthanum from 0.1 to 10 mM in both the serosal and mucosal media produced a progressive decrease in tissue calcium retention and calcium transport. The addition of 10 mM lanthanum to the mucosal media alone reduced both calcium retention and transport. The addition of 10 mM lanthanum to the serosal media alone decreased calcium transport but did not alter total calcium retention by the duodenal segments. The results of this study indicate that lanthanum at a concentration of 1--10 mM acts at calcium transport sites in rat duodenum to reduce both calcium uptake and extrusion, with the net result that the addition of lanthanum to either the mucosal media, serosal media or both significantly reduced calcium transport.

The influence of interrrupted vitamin D metabolism on acute low calcium adaptation in the rat.

The small intestine of animals place on a low calcium diet adapts to the dietary restriction by transporting calcium more efficiently. Adaptation has been observed in most mammalian species; however, the mechanism of adaptation has not been well defined. Recent evidence indicates that 1,25-dihydroxycholecalciferol [1,25(OH)2-D3], the active metabolite of vitamin D, may be involved in the process of adaptation. The present study was designed to examine the inflluence of experimental interruption of vitamin D metabolism on acute low calcium adaptation. Partial hepatectomy, cortisone treatment and dietary strontium supplements were used to inhibit the production of 1,25(OH)2-D3. In separate experiments partial hepatectomy produced a 38% reduction in adaptation; cortisone treatment (5 mg/day, s.c.) caused a 88% reduction and dietary strontium abolished adaptation completely. The possible roles of parathyroid hormone and 1,25(OH)2-D3 and their relationships in the process of adaptation are discussed.

Cell-growth quantitation methods for the evaluation of antiestrogens in human breast cancer cells in culture.

The antiproliferative activity of the antiestrogen, tamoxifen, on the growth of MCF-7 human breast cancer cells was evaluated using the hemocytometric trypan blue exclusion method, [3H]-thymidine incorporation, and a total protein determination. Tamoxifen was evaluated over a concentration range from 10(-9) to 10(-6) M. The hemocytometric trypan blue exclusion method and [3H]-thymidine incorporation were sensitive enough to demonstrate the inhibitory influence of tamoxifen on the proliferation of MCF-7 cells at a concentration as low as 10(-9) M. A very good correlation of these two methods was observed in the submicromolar concentration range of tamoxifen. The total protein determination method was only sensitive enough to detect the antiproliferative influence of tamoxifen at concentrations above 10(-6) M. In conclusion, the [3H]-thymidine incorporation method was found to be effective and much less time consuming than the hemocytometric trypan blue exclusion method for evaluating the antiproliferative effects of antiestrogens in cultured MCF-7 cells. However, when evaluating antiestrogens, which are cell-cycle specific, the results of the [3H]-thymidine incorporation method should be interpreted with caution.

Antiestrogenic effects of Z-1, 1-dichloro-2,3 diphenyl-2-(4-methoxyphenyl)cyclopropane(5a) on human breast cancer cells in culture.

Compound 5a ([Z]-1, 1-Dichloro-2,3 diphenyl-2-(4-methoxyphenyl)cyclopropane) is a novel cyclopropyl compound which was shown to be a pure antiestrogen. In the present study, the antiproliferative activity of 5a was examined on estrogen receptor (ER)-positive MCF-7 and ER-negative MDA-MB-231 human breast cancer cells and A-549 human lung cancer cells using the hemocytometric trypan blue exclusion method. Compound 5a inhibited the growth of MCF-7 cells in a dose-related manner over a concentration range of 10(-9) to 10(-5) M, but did not alter the growth of MDA-MB-231 or A-549 cells. Co-administration of estradiol (10(-8) M) reversed the antiproliferative activity of 5a (10(-7) M) on MCF-7 cells. Further, an ER-dependent mechanism of action is supported by the specific ER binding of 5a in MCF-7 cells observed in this study. The influence of 5a on the cell surface morphology of MCF-7 and MDA-MB-231 cells was studied using scanning electron microscopy (SEM). Compound 5a at 10(-6) M reduced the length and density of microvilli (MV) on MCF-7 cells, which was reversed by co-administration of estradiol (10(-8) M). This compound did not alter the cell surface morphology of ER-negative MDA-MB-231 cells. In conclusion, 5a and tamoxifen inhibited the growth of ER-prositive MCF-7 cells in an estradiol-reversible manner, and had no effect on ER-negative MDA-MB-231 cells. The results of this study with human breast cancer cells suggest that 5a may be highly effective in the treatment of estrogen-dependent breast cancer and/or in the prophylactic treatment of women with a high risk of breast cancer development.

Influence of cyclopropyl antiestrogens on the cell cycle kinetics of MCF-7 human breast cancer cells.

Five cyclopropyl compounds, previously shown to exhibit pure antiestrogenic activity in the mouse uterotropic assay and antiproliferative activity of MCF-7 human breast cancer cells in culture, were examined for their influence on the cell cycle kinetics of MCF-7 cells. The DNA-histogram of a single cell suspension was obtained on Coulter Epics V after fixing the cells in 70 % ethyl alcohol and staining in propidium iodide. Tamoxifen increased the percentage of cells in G1-phase with a concomitant decrease in percentage of cells in S-phase, in an estradiol reversible manner. Cyclopropyl compound 7a increased the percentage of cells in G1-phase, in an estradiol-irreversible manner. Further, compounds 5a, 5c, 7a and 7b decreased the percentage of cells in S-phase and increased percentage of cells in the G2M-phase, in an estradiol-irreversible manner. Of the five cyclopropyl compounds tested, only 4d had no influence on the cytokinetic parameters, even though this compound was found to exhibit antiproliferative activity on MCF-7 cells equal to that of tamoxifen. In conclusion, all of the cyclopropyl compounds, except 4d, altered cell cycle parameters of MCF-7 cells in a manner different than that of tamoxifen. Thus, the results of this study indicate that, although these cyclopropyl compounds are antiestrogenic, they produce antiproliferative activity by a distinct mechanism of action in estrogen receptor positive breast cancer cells.

The influence of antiestrogens on pS2 and cathepsin D mRNA induction in MCF-7 breast cancer cells.

Tamoxifen, although widely used in the treatment of estrogen-dependent tumors, is a partial estrogen agonist producing undesirable effects in breast cancer patients. ICI 182,780 a steroidal antiestrogen displays pure antagonist activity which is due to its ability to prevent dimerization of the estrogen receptor (ER). Our previous studies have shown that 1,1-dichloro-cis-2,3-diaryl cyclopropane (Analog II), a diarylcyclopropyl compound is devoid of estrogenic activity, has a weak binding affinity for the estrogen receptor in the mouse uterine tissue and inhibits the growth of breast cancer cells in culture. These findings suggest that Analog II may not inhibit tumor cell growth at the cellular level by an ER-mediated mechanism of action. Since these three antiestrogens appear to have different mechanisms of antiestrogenic activity, the purpose of this study was to compare the influence of the three antiestrogens on estradiol-induced expression of pS2 and cathepsin D (cath-D). These genes are known to be primarily under the influence of estrogen in ER positive MCF-7 human breast cancer cells. The results of this study demonstrate different mechanisms of regulation of the cath-D and pS2 genes by antiestrogens in MCF-7 cells. This study indicates that ICI 182,780 is a pure antagonist at the levels of gene regulation and cell proliferation. The relative order of inhibitory action was found to be ICI 182,780 > tamoxifen > Analog II.

Enhancement of intestinal glucose transport following chronic parathion poisoning.

Chronic administration of parathion to male rats stimulated glucose (p less than 0.05) but not calcium (p greater than 0.05) transport in the everted duodenal gut sac preparation. Chronic parathion stimulation was not reduced by concurrent administered of atropine. Acutely applied parathion or paraoxon, its active metabolite, did not increase glucose transport in this preparation.

Estrogenic and antiestrogenic activity of novel selenosteroids.

An assay for estrogenic and antiestrogenic activity of seven selenoestrogens has been carried out in immature female rats. The estrogenic activity was compared to the in vitro binding affinity data. The study reveals that introduction of selenium substituents on C-16 or C-17 of the steroid nucleus produced a marked reduction in the estrogenic activity. The selenium analogues of ethynylestradiol produced the highest estrogenic activity. None of the compounds produced antiestrogenic activity.

Synthesis and biological evaluation of gem-dichlorocyclopropyl and cyclopropyl analogs of stilbene congeners as potential antiestrogens.

A series of gem-cichlorocyclopropyl and cyclopropyl analogs of stilbene congeners was synthesized and examined for estrogenic and antiestrogenic activity using the uterotropic assay in the immature mouse. The relative receptor affinity in vitro was determined by measuring [3H]estradiol displacement from the rat uterine cytosol receptor. The 11 test compounds synthesized in this study did not produce estrogenic or antiestrogenic activity at the dosage levels used (1-25 micrograms), but did produce a significant displacement of [3H]estradiol in the rat uterine receptor binding assay with analog XVIII possessing the greatest binding affinity and compound XI the lowest affinity. Structure-affinity relationships of this series were established from the receptor binding assay and comparisons between these analogs and a previously reported series are summarized.

Biological evaluation of novel cyclopropyl analogues of stilbene, stilbenediol, and phenanthrene for estrogenic and antiestrogenic activity.

The triphenylethylene-type antiestrogens, such as tamoxifen, are known to be useful in the treatment of estrogen-dependent tumors. However, these compounds display mixed estrogen agonist/antagonist activity which may limit their therapeutic effectiveness. This problem of mixed activity led to the synthesis and identification of a cyclopropyl derivative of cis-stilbene which we have named Analog I. This compound (1,1-dichloro-cis-2,3-diphenylcyclopropane) displayed only antiestrogenic activity in the mouse. The present study was designed to evaluate cyclopropyl derivatives of Analog II for estrogenic and antiestrogenic activity in the rat using the standard 3-d uterotropic assay and the uterine cytoplasmic estrogen receptor assay. Five compounds (B-F) which are cyclopropyl derivatives of stilbene, stilbenediol, and phenanthrene were evaluated in this study. Three of the compounds (B-D) displayed neither estrogenic nor antiestrogenic activity in the rat. The relative estrogenic activities of E and F were 11.3 and 1.5%, respectively, of diethylstilbestrol in the uterotropic assay, and 39 and 6.2%, respectively, of estradiol in the estrogen receptor assay. Neither E nor F was found to display antiestrogenic activity in the rat. The results indicate that the relative estrogenic and receptor binding activities of E and F are similar to those previously observed in the mouse, while B-D appear to be inactive in both species.

Nonsteroidal estrogens and antiestrogens: biological activity of cyclopropyl analogs of stilbene and stilbenediol.

The estrogenic, antiestrogenic, and receptor binding activity of a series of cyclopropyl analogs of stilbene and stilbenediol were determined using the uterotropic assay in the mouse and the receptor binding assay with rat uterine cytosol. One compound, 1,1-dichloro-cis-2,3-diphenylcyclopropane (II), displayed antiestrogenic activity in vivo with a low affinity for the estrogen receptor in vitro and showed tumor remission activity on 7,12-dimethylbenz(a)anthracene-induced estrogen-dependent rat mammary tumors. Compounds VIII, IV, and V (in that order) exhibited the greatest estrogen activity in the mouse and the greatest receptor binding activity in vitro. Compound VIII exhibited antifertility activity in the mouse.

Growth medium for the evaluation of antiestrogenic compounds in MCF-7 cell culture.

The primary aim of the present study was to define a set of cell culture conditions that would be optimal for the evaluation of antiestrogens using estrogen dependent MCF-7 human breast cancer cells in culture. Therefore, the present study examined for the influence of media supplements which are known to alter the growth rate and estrogen receptor content of MCF-7 cells in culture. In this study, MCF-7 cell proliferation was evaluated using the hemocytometric trypan blue exclusion method. The results of this study clearly indicate that 1) charcoal-dextran stripped serum offers no advantage over low estradiol (less than 100 fM) calf serum which is available commercially, and 2) calf serum is as effective as fetal calf serum, in the presence or absence of insulin, in time-dependent growth of MCF-7 cells. Thus, growth media containing 5% non-stripped low estradiol (less than 100 fM) calf serum without insulin supplementation was found to be optimal for the evaluation of the antitumor activity of antiestrogenic compounds using MCF-7 cells in culture.