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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Estrogens and thyroid hormones contribute importantly to cell proliferation and tumor transformation in the pituitary gland. We found that methylene blue antagonized estrogen-promoted adenohypophyseal enlargement and the enhancement of prolactin secretion. The purpose of the present article is to provide a review about neurotransmitters and their receptors involved in estrogen-induced anterior pituitary growth and in the antagonistic effects of triiodothyronine (T3) and methylene blue (MB). Central dopaminergic and noradrenergic systems are the most important factors regulating pituitary growth and function. Recently nitric oxide (NO) was added to the list of the neurotransmitters and neuropeptides involved in the control of the anterior pituitary secretion. Our data suggest that estrogen-induced anterior pituitary growth is associated with decreased synthesis and metabolism of central catecholamines, reduction of adenohypophyseal beta-adrenergic receptors and increase of dopamine DA-2 receptors. We found that the treatment with T3 or MB prevented both estrogen-induced catecholaminergic inhibition and dopamine DA-2 receptor increment in the anterior pituitary. In contrast to T3, MB given alone also slightly decreased the anterior pituitary weight. Serum levels and anterior pituitary content of prolactin were increased after treatment with estradiol benzoate (EB), whereas T3 or MB partially attenuated prolactin hypersecretion after estrogen administration. This is in accord with the attenuation of EB-induced inhibition of dopaminergic system by T3 and MB. MB given in combination with EB also partially attenuated EB-promoted rise of adenohypohyseal NO synthase activity which plays an important role in the regulation of prolactin secretion. Further studies on central catecholaminergic systems, pituitary receptors, the nitrergic system and mechanisms of intracellular signal transduction are necessary for better understanding of pituitary tumor transformation and possibly for the discovery of new approaches towards treating patients with these diseases.
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PMID:The regulation of adenohypophyseal prolactin secretion: effect of triiodothyronine and methylene blue on estrogenized rat adenohypophysis. 1098 69

Alpha-fetoprotein (AFP) is a transporter of various serum ligands and regulator of cellular growth during pregnancy. Estrogens modify AFP to exhibit growth suppressive properties. We recently synthesized a peptide (P149) from human AFP that suppresses the growth of mouse uterus and MCF-7 breast cancer cells. Here it is shown that molar excess treatment of native AFP with estradiol-17 beta (E2) exposes the P149 site on AFP. The anti-estrogenic and anti-tumor activities of AFP-peptides were tested in vivo in the immature mouse uterine assay and mammary tumor (6WI-101)-induced ascites assay, and in vitro in a cytostatic assay using five different human breast tumor cell lines. AFP-peptide P149, and fragments of P149, P149A and P149C but not P149B, suppressed the growth in both in vivo assays. P149 also suppressed the in vitro growth of MCF-7, MDA-MB-231, MDA-MB435 breast cancer cells by more than 75%. P149 and P149A bound the estrogen receptor-alpha (ER) with low affinities compared to E2 and tamoxifen, while P149B bound 3H-E2 with 10(5) fold less affinity compared to ER. The recent epidemiologic observation that high AFP levels in young pregnant women reduce their subsequent risk of postmenopausal breast cancer may be related to the growth suppressive property of AFP with the exposed P149 epitope.
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PMID:Human alpha-fetoprotein peptides bind estrogen receptor and estradiol, and suppress breast cancer. 1107 58

Estrogens are involved in anterior pituitary (AP) growth and tumor transformation of AP. Central dopaminergic and noradrenergic systems are probably most important systems in regulation of AP growth. Estrogen-induced AP growth is associated with decreased metabolism of central catecholamines and increased dopaminergic DA-2 receptors. Application of thyroid hormones or methylene blue prevents both estrogen-induced catecholaminergic inhibition and dopamine DA-2 receptors increment in the AP. The alone given methylene blue increases the dopaminergic activity and the binding sites for dopamine. The study of interaction of natural regulators or synthetic compounds with estrogen-induced pituitary growth will be of value to understand better mechanisms of pituitary tumor formation and possibly find new approaches towards treating patients with these tumors.
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PMID:[Pharmacologic control of hypophyseal tumors: interactions of estrogens, thyroid hormones, growth and anti-growth factors]. 1126 96

The ability of breast tumors to synthesize sex steroid hormones is well recognized and their local production is thought to play a role in breast cancer development and growth. The aim of this study was to estimate local intra-tumoral and circulating levels of Estrone (E1), Estrone Sulfate (E1S), Estradiol (E2), Estriol (E3), and Testosterone (T) in 33 pre- and postmenopausal women with primary breast cancer in comparison to 12 pre- and postmenopausal women with benign breast tumors. The mean levels of the studied sex hormones were higher in serum and tumor tissue of breast cancer women than those with benign breast tumors apart from Testosterone which showed a significant decrease in pre- and postmenopausal women with breast cancer (P<0.001for follicular phase, P<0.05 for luteal phase, and P<0.005 for postmenopausal). The levels of the five hormones were significantly higher intra-tumoral than in serum of both benign and malignant breast tumor women with E1S as the predominant estrogen. There was only a positive significant correlation between serum and tumor tissue levels of E1 (rs=0.52, P<0.05 for follicular; rs=0.63, P<0.05 for luteal and rs=0.58, P<0.05 for postmenopausal) and a significant correlation between serum and tumor tissue of T (rs=0.64, P<0.05 for follicular; rs=-0.51, P<0.05 for luteal and rs=-0.81, P<0.04 for postmenopausal).
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PMID:Sex steroid hormones in serum and tissue of benign and malignant breast tumor patients. 1138 Nov 98

Estrogens administered in high doses were commonly used for therapy of advanced breast cancer before the introduction of contemporary endocrine therapy. While the mechanism of the antitumor effect is unknown, in vitro investigations have shown estrogens in high concentrations to be toxic to cell growth. Further, it has been shown that exposure of MCF-7 cells to estrogens in low concentrations may enhance the sensitivity and also lower the toxicity threshold to estrogens. This study was designed to evaluate treatment with diethylstilbestrol (DES) in postmenopausal women with advanced breast cancer becoming resistant to estrogen deprivation. Thirty-two patients with advanced breast cancer previously exposed to multiple endocrine treatment regimens (median 4, range 2-10) were enrolled. Their tumor should have revealed evidence of endocrine sensitivity (previous partial response or at least stable disease for > or = 6 months to therapy). Each patient received DES 5 mg t.i.d. Four patients terminated therapy after < or = 2 weeks on therapy due to side effects; another two patients terminated therapy before progression for similar reasons (one patient after SD for 15 weeks and one with a PR after 39 weeks). Four patients obtained CR and six patients PR. In addition, two patients had SD for > or = 6 months duration. Five patients had an objective response and one patient a SD lasting for > or = 1 year. Our results reveal estrogens administered in high doses may have antitumor effects in breast cancer patients heavily pretreated with endocrine therapy. Such treatment represents a valuable alternative to chemotherapy in selected patients.
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PMID:High-dose estrogen treatment in postmenopausal breast cancer patients heavily exposed to endocrine therapy. 1151 59

Estrogens have been widely used for the treatment of advanced prostatic adenocarcinoma. However, their direct effect to prostatic cancer cells via estrogen receptors remains unclear. We investigated expression of ERalpha, wild-type ERbeta (wtERbeta), and a C-terminal truncated splice variant of ERbeta (ERbetacx) in 50 benign and 100 malignant human prostatic tissue samples by immunohistochemistry. While strong immunostaining of ERalpha was consistently identified in the stromal compartment, wtERbeta was expressed in epithelial cells in both the benign and malignant foci. However, wtERbeta expression was significantly lower in the cancers than in the benign epithelium and inversely correlated with Gleason tumor grade (P < 0.0001 and P = 0.0099, respectively). In contrast, ERbetacx was significantly more expressed in the high-grade cancers (83%) compared with the low-grade tumors (22%) and the benign sites (11%) (P < 0.0001, both). Cancer-specific survival of patients with lower wtERbeta expression was significantly worse than those with higher expression of wtERbeta (P = 0.0018). Conversely, higher ERbetacx expression significantly correlated with poor cancer-specific survival (P = 0.0058). These results suggest that differential expressions of wtERbeta and ERbetacx may be prognostic predictors for prostatic cancer.
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PMID:Differential expression of estrogen receptor beta (ERbeta) and its C-terminal truncated splice variant ERbetacx as prognostic predictors in human prostatic cancer. 1172 3

Estrogens, alone or in combination with androgens, can induce aberrant growth and/or malignancy of the prostate gland. Squamous metaplasia is an abnormal form of prostatic epithelial differentiation elicited by exogenous estrogen alone. Estrogens elicit their effects via estrogen receptors (ER) in the prostate. Experiments using ERalpha and ERbeta null mice demonstrated that ERalpha, but not ERbeta is essential in the induction of prostatic squamous metaplasia. To determine the respective roles of epithelial versus stromal ERalpha in this response, the following tissue recombinants were constructed with prostatic epithelium (PRE) and stroma (S) from wild-type (wt) and ERalpha knockout (alphaERKO) mice: wt-S + wt-PRE, alphaERKO-S + alphaERKO-PRE, wt-S + alphaERKO-PRE and alphaERKO-S + wt-PRE. A metaplastic response to diethylstilbestrol (DES) was only observed in wt-S + wt-PRE tissue recombinants. Tissue recombinants containing alphaERKO-PRE and/or alphaERKO-S (alphaERKO-S + alphaERKO-PRE, wt-S + alphaERKO-PRE and alphaERKO-S + wt-PRE) failed to respond to DES. Therefore, full and uniform epithelial squamous metaplasia requires ERalpha in both the epithelium and stroma. Estradiol (E2) in combination with testosterone (T) was shown to be effective in inducing prostatic carcinogenesis in a tissue recombinant model composed of rat urogenital sinus mesenchyme plus mouse prostatic epithelium. A particularly efficient model of prostatic carcinogenesis in mice involves T + E2 treatment of mice bearing grafts of wild-type rat urogenital mesenchyme (rUGM) plus retinoblastoma gene (Rb) knockout (Rb-KO) prostatic epithelium (rUGM + Rb-KO-PRE). Such rUGM + Rb-KO-PRE tissue recombinants developed hyperplasia, atypical hyperplasia and invasive prostatic carcinoma with high efficiency. During carcinogenesis in rUGM + Rb-KO-PRE tissue recombinants, epithelial E-cadherin almost totally disappeared and epithelial PCNA labeling was elevated. These epithelial changes were associated with almost total loss of smooth muscle cells in the stroma. The results of this study demonstrate that the absence of the Rb tumor suppressor gene predisposes prostatic epithelial cells to hormonal carcinogenesis.
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PMID:Estrogenic effects on prostatic differentiation and carcinogenesis. 1180 Jan 67

Granulosa cell tumors (GCT) of the ovary are prepubertal in 5% of the patients. In girls less than 20 years old, 80% of GCTs differ from those among adults. These juvenile granulosa cell tumors (JGCTs) are usually benign. GCTs belong to ovarian sex cord-stromal tumors, the more common ovarian tumors being epidermal and germinal. The etiology of GCT remains unknown. Most young children with GCT present with precorious pseudopuberty. Among adolescents GCT often causes menstrual irregularities, virilization, abdominal swelling, and pain. When JGCT is limited to the ovaries the outcome is excellent with only salpingo-oophorectomy. However, more widely spread tumors are difficult to treat and cause mortality. Cisplatin-containing chemotherapy can induce remissions in adult GCTs. Estrogens and peptide hormones, i.e., inhibin, are useful in the follow-up of the patients. The authors describe 3 children with GCT and review current data on this rare tumor from molecular biology to clinical aspects.
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PMID:Ovarian granulosa cell tumors in childhood. 1193 27

The effects of dose and duration of estrogen treatment on cholestasis, hepatic regeneration, and the genesis of liver tumors are evaluated in this work. Estrogens, especially at high doses during pregnancy or after long use of oral contraceptives (OCs), cause a constant diminution of bile secretion which remains subclinical in the great majority of cases. Ethinyl estradiol causes a constant but reversible cholestasis in the rat. 2 categories of cholestasis related to estrogens are distinguished in clinical practice; cholestasis induced by estrogens in pregnancy or in OCs, and cholestasis aggravated or revealed by estrogens, such as primitive biliary cirrhosis. Cholestasis induced by estrogens is dose-dependent, but few clinical data are available on this point. Experience has shown that a woman predisposed to cholestasis due to condition even with low-dose combined OCs. OCs are contraindicated for women genetically predisposed to cholestasis. Evidence has been found of an interaction between estrogen and DNA in the initiation of regenerative processes after experimental hepatectomy. 2 benign liver tumors, hepatic adenomas and focal nodular hyperplasias, have become more common with widespread diffusion of OCs. The role of estrogens in the genesis of hepatic adenomas is well established, but is more controversial with focul nodular hyperplasia. The appearance of low- dose OCs does not seem to have decreased the incidence of benign liver tumors. On the other hand, 2 series totalling 113 cases have demonstrated that the risk of adenoma increases significantly with the duration of treatment, and another study of 32 cases of focal nodular hyperplasia and 12 adenomas showed that most of the women had used OCs for more than 5 years. Both types of tumor carry risks of hemorrhagic accidents, and adenomas at least also carry carcinoma appears more significant in a country like Great Britain with a very low prevalence of such cancers. Benign liver tumors are very rare and should not affect prescription of OCs. A hepatobiliary sonogram should be obtained for women seeking OCs. A sonographic image of a tumor less than 5 cm in diameter with the characteristics of a benign tumor should prompt termination of OCs and reexamination in 4 weeks. If the tumor is over 5 cm in diameter the diagnosis should be confirmed by another technique. The nodular hyperplasias that are large, painful, and easily accessible. Recent epidemiologic studies suggest that the prevalence of asymptomatic lithiases is not very different in OC users and nonusers, but the frequency of complications leading to cholecystectomy is greater in women receiving longterm estrogen treatment. An asymptomatic lithiasis in a young OC user does not necessarily require termination of OCs.
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PMID:[Hepatic and biliary repercussions of estrogens: dose or duration of treatment effect]. 1231 61

Estrogens have been shown to regulate vascular endothelial growth factor-A (VEGF-A) for physiological and patho-physiological functions. However, estrogen action on VEGF-A mRNA expression has not been completely elucidated. We have identified two phases of activation of VEGF-A mRNA transcription, one early and one late response, induced by 17beta-estradiol (17beta-E2) in ER+ MCF-7 breast tumor cells, depending upon the length of exposure. VEGF-A mRNA level was significantly higher than control in tumor cells after 2 h of 17beta-E2 exposure. Furthermore this induction was not inhibited by cycloheximide, indicating that it was a direct effect of estrogen. In contrast VEGF-A mRNA expression was back at basal level in MCF-7 cells exposed to 17beta-E2 for 6 h. However, expression levels were again significantly augmented after 24 h of exposure, and this induction was unaltered by cycloheximide indicating that de novo protein synthesis was not required and like early response, it was a direct effect of estrogen. The antiestrogen ICI 182,780 was a pure antagonist for the early response phase of VEGF-A mRNA induction, but it had partial but significant effect on the late response phase, further suggesting that both early and late phases were ER dependent. In human mammary epithelial cells (HMEC) lacking estrogen receptor (ER-alpha) the early and late response phase of VEGF-A mRNA induction in response to 17beta-E2 was not found, but significant inductions were seen in the early and late phases when ER-alpha transfected HMEC were exposed to 17beta-E2 for 2 or 24 h. Taken together, these studies suggest that VEGF-A is an estrogen responsive gene and modulation of this gene expression by estrogen is biphasic and can be mediated through ER-alpha dependent pathway.
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PMID:Estradiol-induced vascular endothelial growth factor-A expression in breast tumor cells is biphasic and regulated by estrogen receptor-alpha dependent pathway. 1257 15


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