Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P04626 (erbB-2)
 5,251 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Attempts were made to correlate growth effects induced by oestradiol and tamoxifen with the hormonal regulation of c-erbB-2 protein in experiments in vivo. We report here the responsiveness of four xenotransplanted oestrogen-receptor(ER)-positive and four ER-negative human mammary carcinomas to oestradiol and tamoxifen. Oestradiol in a dose of 0.5 mg/kg significantly increased the growth of the ER-positive mammary carcinomas 3366, MCF-7, 4134 and 4049, but not the ER-negative tumours 4000, 4296 and MT-3. However, within the group of the ER-negative breast carcinomas the tumour 4151 ES deviates from this growth behaviour, as we could prove an estrogen induced growth. The stimulation of tumour growth by oestradiol was always accompanied by a down-regulation of c-erbB-2 protein both in the ER-positive mammary carcinomas and in the ER-negative mammary carcinoma 4151 ES. Tamoxifen significantly inhibited the growth of the ER/PR-positive mammary carcinomas 3366 and MCF-7 but not the ER-positive/PR-negative mammary carcinomas 4049 and 4134. In the group of ER-negative mammary carcinomas only the growth of the oestrogen-responsive tumour 4151 ES was significantly inhibited by tamoxifen. The inhibition of tumour growth by tamoxifen was correlated with a reversion of the oestradiol-induced down-regulation of c-erbB-2, also in the ER-negative/oestradiol-responsive mammary carcinoma 4151 ES. From our results we hypothesize that the oestrogen-dependent growth of ER-negative breast carcinoma 4151 ES could also be correlated with the oestradiol-regulated expression of c-erbB-2 protein.
 ...
PMID:Relation of oestradiol-mediated growth stimulation with the expression of c-erbB-2 protein in xenotransplanted oestradiol-receptor-positive and -negative breast carcinomas. 854 87

We have established and characterized 3 new breast-cancer cell lines from pleural effusions of patients with advanced breast cancer. All 3 cell lines, designated IBEP-1, IBEP-2 and IBEP-3, showed typical ultrastructural characteristics of epithelial mammary tumor cells. Electron microscopy showed, among other characteristics, the presence of numerous microvilli, desmosomal junctions, intracytoplasmic duct-like vacuoles, well-developed endoplasmic reticulum and large nuclei. Immunohistochemical and biochemical studies revealed that the 3 cell lines expressed cytokeratin, epithelial membrane antigen, CEA and CA 15-3, but all showed negative immunoreaction for vimentin. On the other hand, other antigens (LEU-M1, GCDFP 15, c-erbB-2) were expressed by some of the cell lines, but in a variable manner. Ploidy studies confirmed the neoplastic origin of the cell lines. The doubling times were 68 hr for IBEP-1, 29 hr for IBEP-2 and 39 hr for IBEP-3. Only IBEP-2 cells expressed estrogen receptors (ER+), which were down-regulated after preincubation with E2, but they did not express progesterone receptors (PgR-). IBEP-1 and IBEP-3 cells were ER- but expressed PgR (PgR+). In these 2 cell lines, PgR were down-regulated after pre-incubation of the cells with progesterone (10(-8) M) for 24 hr. Estradiol (E2) increased the proliferation rate of IBEP-2 cells and progesterone increased the proliferation of IBEP-I and -3 cell lines. S.C. injection of the 3 IBEP cell lines into nude mice resulted in the growth of solid tumors between 11 and 16 weeks after inoculation. These cell lines could thus be new models for studying various aspects of the biology and the tumorigenicity of breast-cancer cells. A major interest of these new cell lines is that 2 of them were ER- and PgR+, which is an exceptional phenotypic feature. These 2 cell lines could be interesting models for studying the regulation of PgR and the effects of progestins and antiprogestins independently of the presence of ER.
 ...
PMID:Establishment and characterization of three new breast-cancer cell lines. 961 Jul 25

Oestrogen stimulates the proliferation of pituitary cells. The present study was designed to clarify the involvement of transforming growth factor-alpha (TGF-alpha) in the oestrogen-induced growth of mouse pituitary cells in vitro. Anterior pituitary cells obtained from ICR male mice were cultured in a primary serum-free culture system. Proliferation of pituitary cells was detected by monitoring the cellular uptake of bromodeoxyuridine. Secretory cell types were immunocytochemically determined. Treatment with TGF-alpha (0.1 and 1 ng/ml) for 5 days stimulated cell proliferation. Since TGF-alpha binds to the epidermal growth factor (EGF) receptor, this action may be exerted through the EGF receptor. Oestradiol-17beta (OE(2), 10(-)(9) M) stimulated mammotrophic and corticotrophic cell proliferation. RG-13022, an EGF receptor inhibitor, inhibited the cell proliferation induced by EGF or OE(2), showing that the EGF receptor was involved in the growth response in mammotrophs and corticotrophs. Treatment with antisense TGF-alpha oligodeoxynucleotide (ODN) inhibited the cell proliferation induced by OE(2), but treatment with antisense EGF ODN did not. RT-PCR analysis revealed that OE(2) stimulated TGF-alpha mRNA and EGF receptor mRNA expression. These results indicate that TGF-alpha mediates the stimulatory effect of oestrogen on the pituitary cell proliferation in a paracrine or autocrine manner, and that EGF receptor expression is stimulated by oestrogen.
 ...
PMID:Transforming growth factor-alpha stimulates proliferation of mammotrophs and corticotrophs in the mouse pituitary. 1081 Mar 13

Estrogen rapidly activates the mitogen-activated protein kinases, Erk-1 and Erk-2, via an as yet unknown mechanism. Here, evidence is provided that estrogen-induced Erk-1/-2 activation occurs independently of known estrogen receptors, but requires the expression of the G protein-coupled receptor homolog, GPR30. We show that 17beta-estradiol activates Erk-1/-2 not only in MCF-7 cells, which express both estrogen receptor alpha (ER alpha) and ER beta, but also in SKBR3 breast cancer cells, which fail to express either receptor. Immunoblot analysis using GPR30 peptide antibodies showed that this estrogen response was associated with the presence of GPR30 protein in these cells. MDA-MB-231 breast cancer cells (ER alpha-, ER beta+) are GPR30 deficient and insensitive to Erk-1/-2 activation by 17beta-estradiol. Transfection of MDA-MB-231 cells with a GPR30 complementary DNA resulted in overexpression of GPR30 protein and conversion to an estrogen-responsive phenotype. In addition, GPR30-dependent Erk-1/-2 activation was triggered by ER antagonists, including ICI 182,780, yet not by 17alpha-estradiol or progesterone. Consistent with acting through a G protein-coupled receptor, estradiol signaling to Erk-1/-2 occurred via a Gbetagamma-dependent, pertussis toxin-sensitive pathway that required Src-related tyrosine kinase activity and tyrosine phosphorylation of tyrosine 317 of the Shc adapter protein. Reinforcing this idea, estradiol signaling to Erk-1/-2 was dependent upon trans-activation of the epidermal growth factor (EGF) receptor via release of heparan-bound EGF (HB-EGF). Estradiol signaling to Erk-1/-2 could be blocked by: 1) inhibiting EGF-receptor tyrosine kinase activity, 2) neutralizing HB-EGF with antibodies, or 3) down-modulating HB-EGF from the cell surface with the diphtheria toxin mutant, CRM-197. Our data imply that ER-negative breast tumors that continue to express GPR30 may use estrogen to drive growth factor-dependent cellular responses.
 ...
PMID:Estrogen-induced activation of Erk-1 and Erk-2 requires the G protein-coupled receptor homolog, GPR30, and occurs via trans-activation of the epidermal growth factor receptor through release of HB-EGF. 1104 79

Uterine leiomyomas develop during the reproductive years and regress after menopause, indicating ovarian steroid-dependent growth potential. Although the clinical and biochemical observations have traditionally supported an important role for estrogen in the promotion of leiomyoma growth, there is also increasing evidence to suggest the involvement of progesterone in the pathogenesis of leiomyoma. In this review, much attention has been paid to characterizing the molecular mechanisms of sex steroidal regulation of leiomyoma growth and apoptosis by evaluating the effects of sex steroids on the expression of growth factors and apoptosis-related factors. The effects of GnRH agonist on the expression of these factors in leiomyoma are also described. 17beta-Estradiol up-regulates epidermal growth factor (EGF) receptor, but down-regulates p53 protein in leiomyoma cells, whereas progesterone augments EGF and Bcl-2 protein, but inhibits insulin-like growth factor (IGF-I) and tumour necrosis factor (TNFalpha). Since it is now evident that EGF and IGF-I act as local factors which stimulate leiomyoma growth, these findings suggest that progesterone may have dual actions, stimulatory and inhibitory, on leiomyoma cell growth and survival, depending on the local growth factor conditions around each leiomyoma. This may explain why the size of uterine leiomyomas during the use of levonorgestrel-releasing intrauterine system (LNG-IUS) increases in some but decreases in other instances. This may also explain why the size of leiomyomas during pregnancy does not increase despite the overwhelming increase in circulating concentrations of sex steroid hormones. Moreover, there is further evidence to suggest that the interactions between estrogen receptors and progesterone receptors may be involved in the modulation of gene transcription activity in leiomyoma. This review demonstrates that leiomyoma growth is integrally regulated by the complex cross-talk between sex steroid hormones and growth factors.
 ...
PMID:Sex steroidal regulation of uterine leiomyoma growth and apoptosis. 1514 Aug 68

This study questioned whether the mechanisms of resistance to antiestrogens differ when acquired under premenopausal (Pre-M) vs. postmenopausal (PM) conditions and whether structurally diverse antiestrogens induce adaptation of differing signaling pathways. To address this issue, we conducted systematic studies under Pre-M vs. PM culture conditions with long-term exposure to different antiestrogens and examined the resultant "specific biologic signatures" of the various resistant cells. Estradiol stimulated growth and inhibited apoptosis of "pre-menopausal" antiestrogen-resistant cells but exerted opposite effects on their "post-menopausal" counterparts. Under Pre-M conditions, tamoxifen (TAM)-resistant cells exhibited a marked translocation of estrogen receptor alpha from the nucleus into the cytoplasm, whereas this occurred to a lesser extent under PM conditions. MCF-7 cells exposed to PM but not Pre-M conditions exhibited up-regulation of basal epidermal growth factor (EGF) receptor (EGFR) levels, an effect exaggerated in cells exposed to 4-hydroxytamoxifen. Differing effects occurred in response to structurally divergent antiestrogens. Long-term treatment with both 4-hydroxytamoxifen and ICI182,780 increased EGFR levels, but this was not seen in response to TAM. Surprisingly, EGF administration slightly increased cell number in TAM-resistant cells, whereas only increasing cell weight and decreasing cell number in EGFR overexpressing-resistant cells. To assess potential differences among various parental cell lines, we induced resistance in cell lines obtained from other laboratories and confirmed the results from our own parental cells with minor differences. Together, these data demonstrate that culture of breast cancer cells under Pre-M and PM conditions and structurally diverse antiestrogens results in adaptive responses with differing biological signatures.
 ...
PMID:Mechanisms of resistance to structurally diverse antiestrogens differ under premenopausal and postmenopausal conditions: evidence from in vitro breast cancer cell models. 1917 45