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PubMed2001

Metastatic breast cancer: understanding current management options.

PURPOSE/OBJECTIVES: To review the standard treatment options for metastatic breast cancer, present recently approved chemotherapeutic and hormonal approaches, and describe novel biologic therapies, particularly the use of monoclonal antibodies. DATA SOURCES: Published articles, abstracts, and conference proceedings. DATA SYNTHESIS: Standard treatment options available to women with metastatic breast cancer include surgery, radiation therapy, hormonal therapy, chemotherapy, and palliative approaches. New chemotherapeutic approaches for the management of metastatic breast cancer include the recently approved agents paclitaxel, docetaxel, and capecitabine. New hormonal agents such as toremifene, letrozole, and exemestane also have been approved. Finally, an agent from a new class of agents--biologic response modifiers (BRMs)--now. Is available. Trastuzumab, a monoclonal antibody (one class of BRMs), is a new and promising approach available to a subpopulation of women with metastatic breast cancer. CONCLUSION: Although standard treatment options for the management of metastatic breast cancer may prolong survival for some, they have not resulted in a cure for the majority of women. Recent advances in the understanding of cancer cellular biology have led to newer approaches such as monoclonal antibodies and other BRMs that may offer hope of extended survival and improved quality of life for certain women. This field is growing quickly, and new targets for breast cancer therapy are being studied. IMPLICATIONS FOR NURSING PRACTICE: Nurses who become familiar with newer treatment options available for the management of metastatic breast cancer, including new chemotherapeutic and hormonal approaches and monoclonal antibody therapy, are better able to provide information and support for their patients. Clinicians must understand the criteria for patient selection for newer agents, particularly trastuzumab. In addition, recognizing adverse effects and knowing the management strategies for treatment-related toxicities help to ensure positive patient outcomes.

Antineoplastic Agents↗
PubMed2001

Ethyl side-chain modifications in novel flexible antiestrogens--design, synthesis and biological efficacy in assay against the MCF-7 breast tumor cell line.

To examine the efficacy of ethyl side-chain modifications in a family of flexible non-steroidal modulators of the estrogen receptor, a series of novel compounds was prepared and their antiproliferative effects on human MCF-7 breast tumor cells evaluated. These flexible antiestrogens consisted of members wherein the ethyl portion of the parent compound, a flexible analogue of tamoxifen, had been modified so as to introduce halogens or a nitro group, or to extend the side-chain length from ethyl to propyl or butyl. The compounds demonstrated potency at low micromolar concentrations in antiproliferative assays against an MCF-7 human breast cancer cell line with low associated cytotoxicity. Tested compounds exhibited nanomolar binding affinity (Ki) for the estrogen receptor (ER) as determined through displacement of radiolabelled estradiol. Semiempirical calculations predict an inherent lower oxidative potential at the allylic position, similar to that calculated for the established analogue toremifene, indicating a lesser propensity of such compounds towards metabolic oxidative carbocation generation and consequent DNA adduct formation. Computational studies predict these compounds to bind in a typical estrogen antagonist mode within the ER-ligand binding domain (LBD). Ethyl side-chain modification in this compound class is well tolerated within the ER and is not detrimental to compound efficacy, with additional potential anti-carcinogenic properties imbued to the molecule.

Adult↗
PubMed2001

Future use of selective estrogen receptor modulators and aromatase inhibitors.

Selective estrogen receptor modulators (SERMs) may act as estrogens or antiestrogens depending on the cell and tissue targets. The triphenylethylene SERMs are represented by tamoxifen and toremifene and a new agent with a novel carboxylic acid side chain (GW5638). Because of isomerization in the triphenylethylene molecule, "fixed ring" SERMs were introduced. The major one in development is the benzothiophene arzoxiphene (LY353381), which is now in Phase III clinical trial versus tamoxifen. A fourth group of SERMs is based on the estrogen molecule and comprises the so-called "pure" antiestrogen ICI 182,780 (fulvestrant, Faslodex) and a new oral analogue just entering trials, SR16234. The steroidal aromatase inhibitors [AIs (40H androstenedione 'and exemestane)] inactivate aromatase, whereas the triazole AIs (anastrozole and letrozole) inhibit the enzyme via the heme prosthetic group. Thus, there are two groups of AIs that show relative non-cross-resistance in advanced breast cancer and four groups of SERMs that also show a high degree of non-cross-resistance. With six different treatments and six or more clinical situations (prevention, neoadjuvant, adjuvant, and first- and second-line treatments for advanced disease) in which they may be used, the possible combinations of treatment are enormous. At present, we have few clinical pointers to optimal sequence of treatments. Now that most of the appropriate comparative trials have been performed, it may be the time to initiate novel approaches. These include alternating and sequential treatments, preferably with treatments changed before overt progression occurs.

Aromatase Inhibitors↗
PubMed2003

Reversal of breast cancer resistance protein-mediated drug resistance by estrogen antagonists and agonists.

Breast cancer resistance protein (BCRP), an ATP-binding cassette transporter, confers resistance to a series of anticancer agents such as SN-38, mitoxantrone, and topotecan. In a previous study, we found that estrogens reverse drug resistance of BCRP-expressing cells. In this study, estrogen antagonists, estrogen agonists, and their derivatives were evaluated for BCRP-reversing activity. First, compounds were tested for effects on the cellular accumulation of topotecan in BCRP-transduced K562 cells (K562/BCRP). Next, these compounds were examined for their ability to reverse SN-38 and mitoxantrone resistance in K562/BCRP cells. Among commercially available estrogen antagonists and agonists tested, diethylstilbestrol showed the strongest BCRP-reversing activity. Diethylstilbestrol increased the cellular accumulation of topotecan and reversed drug resistance in K562/BCRP cells but showed marginal or no effect in parental K562 cells. The reversal activities of estrone and diethylstilbestrol were more prominent for mitoxantrone than for SN-38. Tamoxifen and toremifene were also found to enhance topotecan uptake in K562/BCRP cells. Next, various tamoxifen derivatives were screened for anti-BCRP activity. In the first cycle of screening with 14 compounds, TAG-11 showed the strongest effect. In the second cycle of screening of 25 TAG-11-related compounds, TAG-139 showed the strongest effect. Reversal of SN-38 and mitoxantrone resistance in K562/BCRP cells by TAG-139 was 5-fold stronger than that by estrone. Dose-dependent characteristics of drug resistance reversal with estrone and TAG-139 were very similar, suggesting that estrone and tamoxifen derivatives interact with the same drug-binding site of BCRP. Derivatives of antiestrogens that exhibit no other biological effects promise to be useful in overcoming BCRP-mediated drug resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

[Tamoxifen-induced severe hypertriglyceridemia--report of 3 cases].

Tamoxifen, an anti-estrogen, has been used for a long time as an adjuvant therapy in cases of estrogen receptor positive breast cancer. Tamoxifen also demonstrates some weak estrogenic activity. A small increase in serum triglycerides is commonly found after tamoxifen administration. Herein we report 3 cases of sever hypertriglyceridemia due to tamoxifen. Case 1 recovered with tamoxifen withdrawal. Tamoxifen was replaced with toremifene in case 2. The level of triglyceride decreased significantly after the change of agent. Tamoxifen was discontinued and anastrozole administration was started in the third patient. Her triglyceride levels improved. Tamoxifen-induced severe hypertriglyceridemia seen in these patients was an effect of its estrogen action. Anastrozole has been used to treat postmenopausal metastatic breast cancer, and several clinical trials in the adjuvant setting are ongoing. Anastrozole does not affect lipid metabolism. Therefore, anstrozole might be safe for patiens with abnormal triglyceride profiles during tamoxifen treatment. We recommended that a periodic serum triglyceride check is needed for patients treated with tamoxifen.

Adult↗
PubMed2004

Use of estrogen antagonists and aromatase inhibitors in breast cancer and hormonally sensitive tumors of the uterine body.

The new anti-estrogens, including the selective estrogen receptor modulators (e.g., toremifene, droloxifene, idoxifene, raloxifene and arzoxifene), the selective estrogen receptor downregulators (e.g., fulvestrant), and the new steroidal (e.g., exemestane) and non-steroidal (anastrozole and letrozole) aromatase inhibitors have been investigated in the treatment of breast cancer and hormonally sensitive tumors of the uterine body. In postmenopausal women, anastrozole, letrozole and exemestane appear to have superior efficacy and an improved toxicity profile than tamoxifen, and fulvestrant seems to be at least as effective as anastrozole in patients in whom tumors have progressed after prior endocrine treatment. Preliminary data showed a high response rate and a favorable toxicity profile for arzoxifene in endometrial cancer, whereas letrozole could represent a new interesting therapeutic tool for endometrial cancer as well as for low-grade endometrial stromal sarcoma.

Aromatase Inhibitors↗
PubMed2004

[Safety profile of raloxifene].

Selective estrogen receptor modulators (SERMs) are a diverse group of non-steroidal (non hormonal) compounds developed to offer the postmenopausal women many of the advantages of estrogen therapy (ET) while avoiding undesired effects on reproductive and other tissues. Tamoxifen and toremifene, first generation SERMs are used for the adjuvant treatment of breast cancer worldwide, but their stimulatory effect on the uterus prevents their widespread use in other indications. A second generation SERM, raloxifene hydrochloride, a benzothiophene SERM is fully safe for the uterus and significantly reduces the risk of vertebral fractures in postmenopausal women with osteoporosis. The safety and efficacy of raloxifene in postmenopausal women have been studied extensively in more than 40,000 women over 50 clinical trials in 30 countries. The majority of the trials have been large double-blind placebo-controlled trials, including Asia and Japan. Raloxifene is well tolerated, with the only common side effects significantly higher than placebo being hot flushes and minor leg cramps. Venous thromboembolism was the only adverse events of clinical significance but rare associated with raloxifene in Caucasian women, but was not observed so far in Asian countries.

Asian People↗
PubMed2006

[A case of cryptogenic organizing pneumonia after postoperative irradiation for breast cancer].

The patient was a 69-year-old woman who had undergone breast-conserving surgery of the right breast, followed by tangential irradiation of 50 Gy to the remaining breast. Her subsequent progress was monitored by endocrine therapy with toremifene. Symptoms consisting of cough and slight fever developed 5 months after completion of radiation therapy. A chest X-ray image revealed an infiltrating shadow in the right middle and lower pulmonary fields, and the patient visited our hospital. BOOP was diagnosed by thoracoscopic biopsy. Spontaneous remission was observed during monitoring of the patient's progress. A shadow subsequently reappeared, for which a steroid was administered. Improvement was rapid. This case suggests that when tangential irradiation with or without endocrine therapy is provided, subsequent to breast-conserving treatment, patients should be monitored for the occurrence of BOOP.

Aged↗
PubMed2006

Estrogen receptors as therapeutic targets in breast cancer.

The estrogen receptor alpha (ERalpha) has proven to be the single most important target in breast cancer over the last 30 years. The use of the selective ER modulator (SERM) tamoxifen for the treatment and prevention of breast cancer has changed therapeutics. The SERM raloxifene, approved for the treatment of osteoporosis, lacks tamoxifen's increased risk for endometrial cancer and is being evaluated for the prevention of breast cancer. Other SERMs approved or under development for use against breast cancer or osteoporosis include toremifene, GW5638, GW7604 (the active metabolite of GW5638), idoxifene, lasofoxifene, arzoxifene, bazedoxifene, EM-800 and acolbifene (the active metabolite of EM-800). Aromatase inhibitors (AIs) have recently proven to be more efficacious than tamoxifen as first-line therapy, efficacious for second-line therapy (e.g. against tamoxifen-resistant disease), and useful for extended adjuvant therapy after tamoxifen. The AIs include the non-steroidal agents letrozole and anastrole, and the steroidal agent exemestane. The pure antiestrogen fulvestrant has proven to be just as effective as AIs. Other pure antiestrogens, ZK-703, ZK-253, RU 58668 and TAS-108 show great promise. The development of resistance to endocrine therapy remains a clinically important problem, and laboratory models based on human breast cancer cells grown as tumors in immune-compromised mice have led to important insights into this problem. Progesterone receptor-negative status of ER-positive breast cancers may reflect altered growth factor receptor signaling, and helps to explain why this subclass of tumors exhibits lower response rates to tamoxifen compared to cancers typed progesterone receptor-positive. Crosstalk among plasma membrane-localized ER, growth factor receptor signaling, and nuclear-localized ER provide further insights into antihormonal-resistant breast cancer.

Animals↗
PubMed2006

[SERM].

SERM is the abbreviation of the selective estrogen receptor modulator which is the synthetic ligands of estrogen receptor (ER) acting estrogenically or anti-estrogenically among various tissues through modifying the ER function. Clomifene, tamoxifen, toremifene and raloxifene are generally classified as SERM in the clinical use. The main cause of postmenopausal osteoporosis is estrogen deficiency and it was revealed that the continuous combined use of conjugated estrogen and medroxyprogesterone acetate reduced the relative risk of femoral neck fracture to 0.66, however increased the relative risk of cardiovascular event and breast cancer to 1.29 or 1.26, respectively. From the standpoint of safe and clinical compliance for the breast and uterine tissue, raloxifene is recommendable for middle aged postmenopausal osteoporosis.

Female↗
PubMed2005

Drug therapies for eradicating high-grade prostatic intraepithelial neoplasia in the prevention of prostate cancer.

High-grade prostatic intraepithelial neoplasia (HGPIN) is a precursor to invasive prostate cancer observed as an isolated entity in a growing subset of men undergoing prostate biopsy. The presence of HGPIN predicts an increased risk of 1) coexisting occult prostate cancer at baseline and 2) delayed progression to prostate cancer. As such, men with HGPIN represent a population at high risk for the development of prostate cancer. Because the current recommended therapy is observation and delayed-interval biopsies until cancer develops, a well-tolerated therapeutic agent capable of interrupting the progression of HGPIN to cancer is highly desirable. Given the known cancer-stimulatory effects of estrogens in the prostate, the use of selective estrogen receptor modulators (SERMs) to provide an antiestrogen effect represents a novel strategy for prostate cancer prevention. Recent phase II data from trials using toremifene in the treatment of men with HGPIN validate the use of SERMs as a rational and provocative strategy for the prevention of prostate cancer.

Journal Article↗
PubMed1993

Hormone regulation of human prostate in organ culture.

We have established organ cultures of human prostate for in vitro analysis of the hormone responsiveness of prostatic carcinoma. Tissue samples were obtained from total prostatectomies for localized cancer. Normal prostate tissues with age-related hyperplastic changes were obtained from cystoprostatectomies of bladder cancer patients representing the same age group, and they wer cultivated as controls. The explants of prostates were cultured for 7 days in basal medium containing 5% dextran charcoal-treated fetal calf serum, insulin (0.08 IU/ml), and dexamethasone (10(-7) M) with or without dihydrotestosterone (DHT) (10(-7) M) or estradiol (10(-9) M). Control prostates showed involutive changes of morphology when cultured in basal medium. These changes were prevented by DHT, which also maintained a strong epithelial immunostaining for PSA (prostate specific antigen), which was used as a marker for tissue-specific functions. The concentration of PSA in the medium was high. The rate of [3H]thymidine incorporation into DNA was stimulated by DHT in some cultures of control prostates, but no increase was seen in the others. Androgen stimulation of [3H]thymidine incorporation was consistently inhibited by the antihormone cyproterone acetate. The main morphological response of cultured control prostates to estradiol was induction of squamous metaplasia. This was associated with increased incorporation of [3H]thymidine, which was radioautographically localized to the basal layer of epithelium. Estradiol effects were counteracted by the antihormone toremifene. The expression of androgen receptor mRNA and protein in cultured control prostate was demonstrated by Northern blotting and immunohistochemistry, respectively. Also, the expression of estrogen receptor was demonstrated by the polymerase chain reaction analysis of total mRNA from cultured control and cancer prostate. The cultured explants of prostate cancer maintained the overall morphology of the original carcinoma. However, the presence of DHT improved the morphology of cancerous acini in all better differentiated carcinomas (3 grade I and 5 grade II), and corresponding responses to DHT were observed in the rate of DNA labeling with [3H]thymidine. In 2 of 3 grade I carcinomas, DHT increased DNA synthesis, but in grade II cancers the patterns of hormone responses were more variable. The poorly differentiated grade III prostatic carcinomas did not respond to either hormone as measured by [3H]thymidine uptake, and no hormone effects could be seen in morphology. Immunostaining for PSA differed from that in control prostates: besides cancerous acini, the surrounding stroma was also intensively stained, which suggests unpolarized and impaired secretion of PSA by the cancer cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1994

Endocrine management of breast cancer.

Hormonal therapy for breast cancer began more than a century ago with the observation that bilateral oophorectomy caused tumor regression in selected premenopausal patients. In the first half of this century, besides extending ablation of ovarian function to photon irradiation, surgical adrenalectomy and hyophysectomy were introduced, and hormonal additive therapy was established. Regression rates for advanced breast cancer with all types of endocrine therapy at this point did not exceed 35%. The demonstration that adjuvant systemic therapy can prolong the disease-free interval and improve overall survival has been a major advance in the management of breast cancer, the rationale was to control or eliminate micrometastases before tumor recurrence. The nonsteroidal antiestrogen tamoxifen was chosen for the majority of studies since the mid-1970s. Since the first report of successful treatment of metastatic breast cancer, the number of treated women worldwide has reached over 3,000,000. Objective response rate (CR+PR following UICC) in unselected patients is 34%. Tamoxifen has been used successfully to treat both pre- and postmenopausal women with all stages of the disease. In an overview analysis of 30,000 patients from 40 trials of adjuvant tamoxifen, a significant increase was found in both disease-free and overall survival. When patients were separated by nodal status, statistically significant increases were observed in disease-free and overall survival for both node-positive and node-negative patients. Women over 50 appear to benefit most from tamoxifen treatment experiencing highly significant increases in disease-free and overall survival regardless of nodal status. However, since tamoxifen primarily acts as a cytostatic and not cytotoxic agent, most patients ultimately experience disease recurrence or progression during or after therapy. Newer antiestrogens include trioxifene, toremifene, and droloxifene (3-OH-tamoxifen). Randomized, prospective studies are still under way to establish their clinical superiority (or lack of it). Progestins exert direct antiproliferative effects on human breast cancer cell lines. They may also exert direct antiestrogenic action by increasing the oxidative activity of 17 beta-hydroxy-steroid-dehydrogenase, thereby facilitating the conversion of estradiol to estrone. Progestins may exert additional antiestrogenic effects by suppressing estrogen receptor levels. As they also cause estrogen deprivation indirectly through suppression of pituitary ACTH secretion, resulting in reduced production of adrenal androgen precursors, both low- and high-dose regimens have been studied. Aromatase inhibition in premenopausal women interrupts estrogen biosynthesis; the reflex rise in FSH then stimulates production of new aromatase enzyme, and the LH increment results in enhanced ovarian steroidogenesis, counteracting the inhibitory action of aromatase-blocking drugs on the ovary.(ABSTRACT TRUNCATED AT 400 WORDS)

Antineoplastic Agents↗
PubMed1995

Hormonal treatment of advanced breast cancer.

Endocrine therapy for breast cancer has been used for almost a century, but because of the enormous success of tamoxifen there has been a resurgence of interest by the pharmaceutical industry to develop new and innovative endocrine therapies. Overall, the strategy is quite simple. Estrogen stimulates growth; therefore, the goal is to deny the breast tumor estrogens. Tamoxifen accomplishes this by blocking the estrogen receptor. The new antiestrogens, toremifene and droloxifene, however, appear to have no greater activity than tamoxifen in the treatment of advanced disease and therefore may ultimately offer no advantages over current therapy. In contrast, the pure antiestrogens hold additional promise as they may produce a more profound inhibitory effect on the tumor, and the response may be maintained longer. An orally active, pure antiestrogen, however, would be an important advance. The strategy of using GnRH agonists for premenopausal patients clearly has merit to produce a chemical oophorectomy. The strategy could be integrated into the general treatment plan for the young premenopausal patient taking tamoxifen who may not have had her menstrual cycles stopped by combination chemotherapy. The GnRH agonists would block the reflex rise in estradiol caused by tamoxifen therapy and ultimately produce a more efficient antihormonal therapy. Indeed, the different specific aromatase inhibitors can also be integrated into the treatment plan to produce a complete estrogen blockade. Whether the use will be found to be superior to pure antiestrogens, however, must await the completion of comparative clinical studies. If all the results of endocrine therapy are therapeutically similar, the final strategy may depend on the acceptability by the patient of an individual delivery method for each pharmaceutical approach.

Antineoplastic Agents, Hormonal↗
PubMed1997

Increasing effectiveness of interferon-alpha for malignancies.

Alpha-interferons (IFN-alphas) have been shown to be effective agents in inducing the regression of various malignancies, including leukemias and lymphomas as well as solid tumors, and are the first human therapeutic proteins to result in increased survival in cancer patients. Based on their pleiotropic activities, IFNs have the potential for interacting synergistically with other anticancer agents. For example, preclinical in vitro and animal data suggest a synergistic antitumor interaction between IFN-alpha2 and the antiestrogens toremifene and tamoxifen. Further studies are required to elucidate the molecular basis for such synergistic interactions, particularly with respect to IFN-stimulated genes.

Combined Modality Therapy↗
PubMed2001

Cell-transforming activity and estrogenicity of bisphenol-A and 4 of its analogs in mammalian cells.

Estrogenicity is an important mechanism in hormonal carcinogenesis but not sufficient to explain the carcinogenic activity of all estrogens. Additional mechanisms, related to genetic alterations, in conjunction with estrogenicity mediated through the estrogen receptor, have been suggested. An environmental estrogen bisphenol-A (BP-A) and its analogs are widespread in our living environment. Because of the potential for human exposure, the possible relationship between carcinogenicity and estrogenicity of these bisphenols was studied using mammalian cells. We quantitatively compared the cell-transforming activity of BP-A and 4 of its analogs (BP-2, BP-3, BP-4 and BP-5) in Syrian hamster embryo (SHE) cells lacking estrogen-receptor expression. The transforming activity determined by the morphological transformation frequencies in SHE cells treated with the bisphenols ranked: BP-4 > BP-5 > BP-3 > BP-A > BP-2. We also compared the estrogenicity of the 5 bisphenols in MCF7 human breast cancer cells as determined by cell proliferation or progesterone receptor (PgR) expression assayed by RT-PCR. When MCF7 cells were treated with the bisphenols, the proliferative potency ranked: BP-A > BP-5 > BP-4 > BP-3 = BP-2. The level of mRNA for PgR in cells treated with the bisphenols was BP-A > BP-5 > BP-4 > BP-3 > BP-2. These indicate that the transforming activity does not correlate with the estrogenicity of the bisphenols, except for BP-2 that has the weakest activity at the both endpoints. In addition, our results suggest that bisphenols with few, if any, transforming and estrogenic activities could be altered by a modification of the chemical structure. Published 2001 Wiley-Liss, Inc.

Animals↗
PubMed2001

3,3'-diindolylmethane, a major condensation product of indole-3-carbinol, is a potent estrogen in the rainbow trout.

Indole-3-carbinol (I3C), a compound found in Brassica vegetables has been widely studied for its chemopreventive properties. I3C has been shown to block tumor initiation and promotion; however, it also acts as a tumor promoter. I3C and some of its acid condensation products, particularly 3,3'-diindolylmethane (I33'), have exhibited antiestrogenic properties. We report that I33' acts as an estrogen in the rainbow trout liver in vitro and in vivo by inducing vitellogenin (Vg), a well-characterized biomarker for estrogens. Precision-cut liver slices from male rainbow trout, Oncorhynchus mykiss, were incubated at 14 degrees C for 96 h in media containing I3C, I33', or a mixture of I3C acid condensation products (RXN) (0-250 microM). I33' and RXN increased Vg levels in rainbow trout liver slices by over 300- and 20-fold, respectively, vs vehicle. The efficacy of I33' induction of Vg was comparable to 17 beta-estradiol (E(2)) with 2500-fold less potency. I33' and E(2) cotreatment resulted in additive Vg induction. Tamoxifen completely inhibited I33'-induced Vg induction, suggesting that Vg induction by I33' is entirely through the estrogen receptor. In vivo, juvenile male rainbow trout were fed I3C, RXN (0-2000 mg/kg), or I33' (0-250 mg/kg) for 2 weeks. At 2000 mg/kg, I3C induced Vg by over 100,000-fold compared to controls, which was comparable to 5 mg/kg 17 beta-estradiol (the dose resulting in maximum induction). I33' was five times as potent as I3C with equal efficacy. The potency of RXN was only 5% of I3C. Again, I33' and E(2) cotreatment resulted in additive Vg induction. I33' may have accounted for Vg increases observed in trout fed I3C as it is present in liver after oral dosing at concentrations (70 microM) expected to maximally induce Vg. In trout, results in vitro and in vivo document that I33' is estrogenic, consistent with our hypothesis that I3C promotes liver cancer in trout by estrogenic pathways.

Adenosine Triphosphate↗
PubMed1986

A new triphenylethylene compound, Fc-1157a. I. Hormonal effects.

The basic pharmacological and biochemical properties of a new antiestrogen, Fc-1157a, are described. Fc-1157a is bound specifically and with high affinity to estrogen receptors. The binding is competitive with estradiol. Fc-1157a treatment induces translocation of estrogen receptors from cytoplasm to nucleus. The turnover rate of nuclear estrogen receptors is markedly lower than with estradiol, but is more rapid than after tamoxifen. Fc-1157a is an almost pure antiestrogen in rat uterus, but has intrinsic estrogenic activity in mouse uterus. In animal experiments Fc-1157a has shown antitumor properties, which are described in the companion paper.

Animals↗