Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0376358 (prostate cancer)
 59,338 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Female hormones, especially estrogens, play an important role in the pathogenesis of breast neoplasms and are a principal determinant of their biological behavior. Endocrine manipulation through medical or surgical means can often lead to objective shrinkage of breast tumors. Tamoxifen, a triphenylethylene estrogen receptor modulator, is currently the most widely used hormonal treatment for breast cancer. It has been conclusively demonstrated to reduce the risk of relapse following definitive local therapy (and systemic chemotherapy, when indicated) of invasive or noninvasive breast cancer. Recently, it has also been shown to reduce the incidence of breast cancer in healthy women who are at high risk of developing the disease. In addition, it can prevent osteoporosis and reduce the risk of fractures in postmenopausal women. However, its use is also complicated by an increased incidence of endometrial hyperplasia/carcinoma, venous thromboembolism, cataracts, and in some cases, emergence of tamoxifen-dependent clones of breast cancer. These side effects (except cataracts) are believed to be related to estrogen-agonist effects of tamoxifen. Newer drugs, which are "pure antiestrogens" or inhibitors of estrogen biosynthesis, are devoid of such estrogen-agonist activity and may not have the liability of many of these side effects. However, these agents would also be expected to lack the potentially beneficial effects of tamoxifen on lipids and skeletal system. The ability of tamoxifen to act as an estrogen-agonist or estrogen-antagonist in a tissue-specific fashion has led to the concept of selective estrogen-receptor modulation. Selective estrogen receptor modulators (SERMs), which are devoid of estrogen-agonist effects on the uterus or breast cancer cells but retain potentially beneficial effects on bones and lipids, have been described as "ideal" SERMs. A number of such compounds are currently being tested. Raloxifene is already approved for prevention of osteoporosis and has potential efficacy for prevention and treatment of breast cancer. An analogue of raloxifene, LY353381, is currently in Phase II clinical trials for treatment of breast cancer, with promising early results. EM800 and CP336156 are other promising ideal SERMs in clinical trials. These compounds may provide better treatment and chemoprevention alternatives for breast cancer as compared to tamoxifen, aromatase inhibitors, and pure antiestrogens. In addition, they may also prove to be useful for the treatment and prevention of prostate cancer as well as for treating benign gynecological diseases such as fibroids and endometriosis. Future laboratory efforts should focus on further broadening the efficacy profile of SERMs (e.g., prevention of Alzheimer's disease and elevation of high-density lipoproteins to improve the likelihood of cardiovascular benefit) and narrowing their side-effect profile (e.g., risk of thromboembolism and hot flashes).
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PMID:Selective estrogen receptor modulation: the search for an ideal hormonal therapy for breast cancer. 1148 8

Unregulated expression of wild-type BRCA1 (wtBRCA1) confers an altered phenotype in cultured human prostate cancer cells, characterized by chemosensitivity, susceptibility to apoptosis, decreased DNA repair activity, and alterations of key cell regulatory proteins. We now report that the expression of truncated or mutant full-length BRCA1 genes can abrogate certain phenotypic characteristics and/or confer the opposite phenotype to the wild-type BRCA1 gene. In particular, several carboxyl-terminal truncated BRCA1 proteins conferred chemoresistance, decreased susceptibility to apoptosis, and decreased ability to suppress in vivo tumor growth. These truncated BRCA1 proteins also blocked the ability of ectopically expressed wtBRCA1 to induce chemosensitivity and to inhibit estrogen receptor transcriptional activity. Studies using epitope-tagged truncated proteins confirmed their expression, nuclear localization, and functionality. On the other hand, in cells with no endogenous wild-type BRCA1 (HCC1937 human breast cancer cells), the wtBRCA1 gene enhanced cellular DNA repair activity and rendered the cells resistant to DNA damage; while truncated BRCA1 proteins blocked the wtBRCA1-induced chemoresistance. Our findings suggest that truncated BRCA1 proteins can inhibit the function of wild-type BRCA1. They raise the possibility that some inherited BRCA1 mutations may actively promote oncogenesis by blocking the function of the remaining wild-type BRCA1 allele, although this hypothesis remains to be proved.
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PMID:Mutant BRCA1 genes antagonize phenotype of wild-type BRCA1. 1178 37

We previously reported that expression of the breast cancer susceptibility gene BRCA1 strongly inhibits the transcriptional activity of the estrogen receptor (ER-alpha) in human breast and prostate cancer cell lines but only weakly inhibits ER-alpha activity in cervical cancer cells (S. Fan et al., Science (Wash. DC), 284: 1354-1356, 1999). We now report that the ability of BRCA1 to repress ER-alpha activity correlates with its ability to induce down-regulation of the cellular levels of the transcriptional coactivator p300 in breast and prostate, but not in cervical cancer cells. On the other hand, BRCA1 failed to alter the expression of the CREB binding protein (CBP), the structural and functional homologue of p300, in any of these cell types. Ectopic expression of either p300 or CBP "rescued" (i.e., reversed) the BRCA1 inhibition of ER-alpha activity, whereas two other nuclear receptor coactivators, the p300/CBP-associated factor (PCAF) and the glucocorticoid receptor-interacting protein-1 (GRIP1), failed to rescue the ER-alpha activity. The rescue function mapped to the cysteine-histidine rich domain CH3, a region of p300/CBP that we found to interact directly with the conserved COOH-terminal activation domain (AF-2) of ER-alpha. p300 and ER-alpha were also found to interact in vivo and to colocalize within the nucleus in breast cancer cells. These findings suggest that the cofactors p300 and CBP modulate the ability of the BRCA1 protein to inhibit ER-alpha signaling. They further suggest that the BRCA1 inhibition of ER-alpha activity may be attributable, at least in part, to the down-regulation of p300.
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PMID:p300 Modulates the BRCA1 inhibition of estrogen receptor activity. 1178 71

Housing adult rats on ground corncob bedding impedes male and female mating behavior and causes acyclicity in females. The suppressive effects on ovarian cyclicity are mimicked by a mitogenic agent purified from the ground corncob bedding material (corn mitogen; CM), which stimulates the proliferation of estrogen receptor (ER)-positive (MCF-7 cells) and ER-negative (MDA-MD-231 cells) breast cancer cells. Purified CM does not compete for [(3)H]estradiol binding to ER or nuclear type II sites, and its effects on MCF-7 breast cancer cell proliferation are not blocked by the antiestrogen ICI-182,780. These results suggest that the active component is unlikely to be a phytoestrogen, bioflavonoid, mycotoxin, or other known endocrine-disrupting agent that modifies cell growth via ER or type II [(3)H]estradiol binding sites. CM also stimulates the proliferation of PC-3 human prostatic cancer cells in vitro, and the growth rate of PC-3 cell xenografts is accelerated in nude male mice housed on ground corncob as opposed to pure cellulose bedding. Consequently, this endocrine-disrupting agent in ground corncob bedding may influence behavioral and physiologic reproductive response profiles and malignant cell proliferation in experimental animals. Fresh corn (kernels and cob) or corn tortillas also contain CM, indicating that human exposure is likely; consequently, CM and/or related mitogens in corn products may influence human health and development.
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PMID:A novel endocrine-disrupting agent in corn with mitogenic activity in human breast and prostatic cancer cells. 1452 57

The estrogen receptor-alpha (ER-alpha) is a ligand-dependent transcription factor that regulates the growth, differentiation, and development of hormone-responsive target organs. While ER-alpha has been reported to play critical role in the pathogenesis and prognosis of breast and prostate cancers, its possible functional role in regulating prostate cancer cell growth in a ligand-dependent or -independent manner is poorly understood. We addressed this question by stably transfecting wild type (wt) ER-alpha cDNA into an invasive estrogen receptor-negative human prostate cancer cell line ARCaP. We isolated several clonal lines of transfected cells expressing varying levels of ER-alpha. The ectopic expression of wt ER-a markedly inhibited the growth of ARCaP cells in vitro in an ER-a dose-dependent but ligand-independent manner. Flow cytometric analysis of the wt ER-alpha-transfected ARCaP cells revealed that wt ER-alpha expression arrested cell growth in G1 phase. Our results suggest that ER-alpha may regulate prostate cell growth and participate in the pathogenesis of prostate cancer. ER-alpha may be delivered and expressed ectopically to target prostate cancer progression.
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PMID:Inhibition of growth and cell cycle arrest of ARCaP human prostate cancer cells by ectopic expression of ER-alpha. 1185 35

We investigated the potential of genistein, the primary isoflavone of soy, to protect against breast and prostate cancers in animal models. For mammary cancer studies, Sprague-Dawley rats were fed AIN-76A diet plus minus 250 mg genistein/kg diet. Dimethylbenz[a]anthracene was administered by gavage at d 50 postpartum to induce mammary tumors. Mammary cancer chemoprevention was demonstrated after prepubertal and combined prepubertal and adult genistein treatments but not after prenatal- or adult-only treatments, demonstrating that the timing of exposure to genistein is important for mammary cancer chemoprevention. The cellular mechanism of action was found to be mammary gland and cell differentiation, as shown by whole-mount analysis and beta-casein expression. An imprinting effect was shown for epidermal growth factor receptor expression in mammary terminal end buds. For prostate cancer studies, we used two models. The first was a chemically (N-methylnitrosourea) induced prostate cancer rat model. Genistein in the diet inhibited the development of invasive adenocarcinomas in a dose-dependent manner. The second model was a transgenic mouse model that resulted in spontaneously developing adenocarcinoma tumor of the prostate. Genistein in the diet reduced the incidence of poorly differentiated prostatic adenocarcinomas in a dose-dependent manner and down-regulated androgen receptor, estrogen receptor-alpha, progesterone receptor, epidermal growth factor receptor, insulin-like growth factor-I, and extracellular signal-regulated kinase-1 but not estrogen receptor-beta and transforming growth factor-alpha mRNA expressions. We conclude that dietary genistein protects against mammary and prostate cancers by regulating specific sex steroid receptors and growth factor signaling pathways.
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PMID:Genistein chemoprevention: timing and mechanisms of action in murine mammary and prostate. 1188 May 92

The chemopreventive efficacy of toremifene, an antiestrogen, was evaluated in the transgenic adenocarcinoma of mouse prostate (TRAMP) model. TRAMP mice were segregated into three groups: (a) the low-dose toremifene group (6.6 mg/kg/day); (b) the high-dose toremifene group (33 mg/kg/day); and (c) the control placebo group. Efficacy of treatment was measured by the absence of palpable tumor. To extend these studies using more sensitive techniques, TRAMP mice were then treated with placebo, flutamide (an antiandrogen; 33 mg/kg/day), or toremifene (10 mg/kg/day). Animals from each treatment group were sacrificed at 7, 10, 15, 20, 25, and 30 weeks of age, and prostate tissues and seminal vesicles were harvested. Tissues from animals (n = 5) in each group were evaluated by wholemount dissections of genitourinary tracts, histology, immunohistochemistry, and Western blot analyses. Blood was pooled per group to measure estradiol and testosterone hormonal levels. Tumors formed at week 17 in the placebo group (n = 10), at week 21 in the high-dose toremifene group (n = 12), and at week 29 in the low-dose toremifene group (n = 12). This represents an increased tumor latency of up to 12 weeks. By 33 weeks, all animals in the placebo group had tumors compared with only 35% of the animals treated with toremifene. Although both flutamide and toremifene decreased tumor incidence compared with the placebo, toremifene was more effective than flutamide. High-grade prostatic intraepithelial neoplasia was observed in animals in the placebo group, but not in animals treated with toremifene. Moreover, toremifene-treated animals had prolonged survival compared with placebo-treated animals. By 33 weeks of age, 100% of the placebo-treated animals had developed palpable tumors and died, whereas 60% of the toremifene-treated animals were tumor free. T antigen levels in the prostate of toremifene-treated animals were similar to those of placebo-treated, age-matched animals. Whereas serum estradiol levels remained unchanged, the total and free testosterone levels were elevated in the toremifene-treated group. Toremifene treatment did not affect androgen receptor levels. Because toremifene prevented prostate cancer in a milieu of elevated blood free testosterone levels with no change in prostate androgen receptor expression, the mechanism of toremifene's chemopreventive activity may be through nonandrogenic pathways, such as estrogen receptor signaling.
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PMID:Toremifene prevents prostate cancer in the transgenic adenocarcinoma of mouse prostate model. 1188 7

Osteoporosis in women has received a substantial amount of attention, but its impact in men is also significant and noteworthy. Those men who benefit from treatment for prostate cancer with androgen deprivation therapy (ADT) may also be at a higher risk for osteoporosis. Pharmacologic approaches to reduce this risk have received some attention. For example, agents such as bisphosphonates, estrogen receptor-binding drugs (diethylstilbestrol, tamoxifen, and raloxifene), calcitonin, and fluoride are some of the more promising interventions that have been previously outlined. In addition, statin drugs, or hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, have recently been hypothesized to lower osteoporosis risk. However, complementary therapies, which may also have an impact on reducing osteoporosis risk, have not received attention. Dietary and supplemental calcium and vitamin D have been shown, in some preliminary investigations, to maintain bone density in women and men. Numerous healthy and affordable dietary sources of this mineral and vitamin exist, and large intakes can be realistically achieved through proper education. Similarly, the supplemental dosages required to impact risk have been moderate, appear to be safe, are of low cost, and thus may provide an additional route for reducing risk, especially if these interventions are initiated at the start of medical treatment. More studies in men receiving ADT are needed because the existing work has mostly focused on men without castrate levels of male hormone. Additionally, many studies with conventional and nonconventional agents have only focused on individuals with baseline osteoporosis, rather than normal bone mineral densities or osteopenia. Other promising complementary therapies, such as weight-bearing exercise and abstaining from smoking, may also be of benefit. Newer estrogenic-type supplements (eg, ipriflavone) appear interesting and have some preliminary data, but more research is desperately required to determine their actual impact and potential for adverse effects (such as lymphocytopenia from a recent trial). Simple, inexpensive, and potentially effective dietary and supplemental approaches to reduce the risk of osteoporosis in men exist, and they should be discussed with patients. Whether these approaches effectively reduce the risk of osteoporosis in men receiving androgen ablation remains to be determined. The possibility is intriguing, and future research is needed. In the meantime, it is important to keep in mind that these complementary approaches are, at the very least, an integral part of the conventional options used today to the reduce the risk of osteoporosis in men and women.
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PMID:Complementary therapies for reducing the risk of osteoporosis in patients receiving luteinizing hormone-releasing hormone treatment/orchiectomy for prostate cancer: a review and assessment of the need for more research. 1193 34

Ligand-activated receptors are extensively used as targets for developing tissue-selective drugs for treatment of multiple diseases including cancers. The aryl hydrocarbon receptor (AhR) is a basic helix-loop-helix transcription factor that binds both synthetic chemicals such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and naturally-occurring phytochemicals, sterols and heme breakdown products. The high affinity ligand TCDD induces several AhR-mediated changes in gene expression, tissue/species-specific toxicities, and both tumorigenic and anticarcinogenic responses including inhibition of estrogen-dependent mammary and uterine tumor formation and growth. Research in this laboratory has demonstrated that TCDD inhibits E2-induced responses in the rodent uterus and mammary tumors (growth inhibition) and in breast and endometrial cancer cell lines through complex inhibitory AhR-estrogen receptor (ER) crosstalk. 6-Alkyl-1,3,8-trichlorodibenzofurans and substituted diindolylmethanes represent two structural classes of selective AhR modulators (SAhRMs). These compounds are relatively non-toxic and inhibit ER-positive and ER-negative mammary tumor growth, and synergize with tamoxifen to inhibit breast cancer growth and block tamoxifen-induced estrogenic activity in the uterus. Preliminary studies also indicate that SAhRMs inhibit prostate cancer cell growth, and there is evidence for inhibitory AhR-androgen receptor crosstalk. SAhRMs represent a novel class of drugs for treatment of hormone-dependent cancers, and combined therapies of SAhRMs with tamoxifen and other selective ER modulators (SERMs) provides a new approach for treating women with breast cancer.
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PMID:Mechanism of action and development of selective aryl hydrocarbon receptor modulators for treatment of hormone-dependent cancers (Review). 1201 88

We present a very rare case of metachronous triple cancers, including small cell carcinoma of the lung, as well as prostate and male breast cancer. To our knowledge, this is the first documented case of its kind. A 64-year-old man was referred to our hospital with left nipple retraction. He had previously undergone lobectomy of the right lung as treatment for small cell lung cancer at 57 years of age, and at 61 years of age, he had undergone prostatectomy and bilateral orchiectomy for prostate cancer, histologically determined to be moderately or poorly differentiated adenocarcinoma. Physical examination identified a painless irregular hard tumor in the left breast. Ultrasonography and magnetic resonance imaging (MRI) showed a nodular mass, and fine needle aspiration cytology of the mass revealed adenocarcinoma. Modified radical mastectomy was performed. Histological examination revealed that the breast tumor was scirrhous carcinoma, t1, n0, m0, stage T. Immunohistochemistry demonstrated that the prostate tumor was positive for prostatic specific antigen (PSA) and negative for estrogen receptor (ER), while the breast tumor was positive for ER and negative for PSA. Primary breast cancer was diagnosed. At present, 1 year and 8 months after surgical removal of the breast cancer, the patient has had no recurrence of breast cancer, small cell lung cancer, or prostate cancer. We discuss the possible causes of the triple cancers in this case with reference to the literature.
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PMID:A male patient with metachronous triple cancers of small cell lung, prostate and breast. 1201 98


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