Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0006142 (breast cancer)
 160,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of prolactin (PRL) and N-(2-mercaptopropionyl)-glycine (MPG) on the growth of MCF-7 human breast cancer cells, and the influence of MPG on PRL-induced MCF- 7 cell proliferation, when added simultaneously to the culture medium, were examined. Prolactin at concentrations of 200 ng/ml - 350 ng/ml enhanced the growth of MCF-7 cells, while at lower and higher concentrations its action was diminished. MPG alone at concentrations above 2 mM caused a decrease in cell proliferation. When PRL and MPG were added simultaneously to the culture medium, an inhibitory effect on PRL-induced MCF-7 cell proliferation was observed, at concentrations of MPG lower than 2 mM.
 ...
PMID:Effects of sulfhydryl compounds on cancer cell lines: I: N-(2-mercaptopropionyl)-glycine exerts antiproliferating effects and antagonizes the stimulating effect of prolactin on MCF-7 human breast cancer cells. 1743 84

Prolactin is associated with an increased risk of postmenopausal breast cancer; however, few modifiable factors are known to reduce prolactin concentrations. Therefore, we examined the effect of a 12-month moderate-intensity exercise intervention on serum prolactin concentrations as a secondary end point (primary end points were estrogens and androgens). We randomly assigned 173 postmenopausal women who were sedentary, overweight (body mass index >24 kg/m(2), body fat >33%), ages 50 to 75 years, and not using hormone therapy to an exercise intervention or stretching control group. The intervention was facility- and home-based (45 min, 5 days/wk moderate-intensity sports/recreational exercise). One hundred and seventy (98%) women completed the study. Prolactin concentrations were similar at baseline (P = 0.25, geometric mean exercisers = 6.9 and controls = 7.5 ng/mL). Overall, the intervention was not associated with changes in prolactin concentrations between exercisers and controls at 3 months (P = 0.46) or 12 months (P = 0.29). The intervention effect did not vary by baseline age, body mass index, parity, or change in percent body fat during the intervention. Among exercisers, there was a significant difference in prolactin concentrations by change in fitness (VO(2)max) between baseline and 12 months. Exercisers whose VO(2)max changed by <5% had a 5% increase in prolactin concentrations, whereas those who increased their VO(2)max by 5% to 15% and >15% had a 11% (P = 0.03) and 7% (P = 0.01) decrease in prolactin concentrations, respectively. Although the exercise intervention had little effect on prolactin concentrations overall, increasing physical fitness was associated with reduced prolactin concentrations among postmenopausal women.
 ...
PMID:Effect of a 12-month randomized clinical trial of exercise on serum prolactin concentrations in postmenopausal women. 1750 12

Prolactin (PRL) receptors (PRLRs) have been considered selective activators of Janus tyrosine kinase (Jak)2 but not Jak1, Jak3, or Tyk2. We now report marked PRL-induced tyrosine phosphorylation of Jak1, in addition to Jak2, in a series of human breast cancer cell lines, including T47D, MCF7, and SKBR3. In contrast, PRL did not activate Jak1 in immortalized, noncancerous breast epithelial lines HC11, MCF10A, ME16C, and HBL-100, or in CWR22Rv1 prostate cancer cells or MDA-MB-231 breast cancer cells. However, introduction of exogenous PRLR into MCF10A, ME16C, or MDA-MB-231 cells reconstituted both PRL-Jak1 and PRL-Jak2 signals. In vitro kinase assays verified that PRL stimulated enzymatic activity of Jak1 in T47D cells, and PRL activated Jak1 and Jak2 with indistinguishable time and dose kinetics. Relative Jak2 deficiency did not cause PRLR activation of Jak1, because overexpression of Jak2 did not interfere with PRL activation of Jak1. Instead, PRL activated Jak1 through a Jak2-dependent mechanism, based on disruption of PRL activation of Jak1 after Jak2 suppression by 1) lentiviral delivery of Jak2 short hairpin RNA, 2) adenoviral delivery of dominant-negative Jak2, and 3) AG490 pharmacological inhibition. Finally, suppression of Jak1 by lentiviral delivery of Jak1 short hairpin RNA blocked PRL activation of ERK and signal transducer and activator of transcription (Stat)3 and suppressed PRL activation of Jak2, Stat5a, Stat5b, and Akt, as well as tyrosine phosphorylation of PRLR. The data suggest that PRL activation of Jak1 represents a novel, Jak2-dependent mechanism that may serve as a regulatory switch leading to PRL activation of ERK and Stat3 pathways, while also serving to enhance PRL-induced Stat5a/b and Akt signaling.
 ...
PMID:Coactivation of janus tyrosine kinase (Jak)1 positively modulates prolactin-Jak2 signaling in breast cancer: recruitment of ERK and signal transducer and activator of transcription (Stat)3 and enhancement of Akt and Stat5a/b pathways. 1755 Sep 76

High prolactin levels have been associated with increased breast cancer risk. Prolactin is essential for breast-feeding. Prolactin is lowered primarily by the first full-term pregnancy and not by subsequent pregnancies. The protection from breast cancer conferred by a long breast-feeding duration (>1 year) seems to be much greater for women with BRCA1 mutations (45%) than for women in the general population (4%). One study reported poor milk production to be more common in BRCA1 carriers (75%) than in non-carriers (36%). We aimed to explore the relationships between prolactin levels, breast-feeding duration, milk production and BRCA carrier status in young healthy women from high-risk breast cancer families. Questionnaires including information on reproductive factors and lifestyle were completed by 269 healthy women, aged 40 years or younger. Body measurements and plasma prolactin levels were obtained during cycle days 5-10 and 18-23. Prolactin was higher in nulliparous than in parous women (P < 0.0001). In parous women, post-lactational prolactin levels in both cycle phases were significantly negatively associated with breast-feeding duration of the first child (P < or = 0.009), but not with additional breast-feeding of subsequent children (P > or = 0.12). Prolactin was higher in women who reported insufficient versus sufficient milk production (P < or = 0.01). Neither BRCA1/2 carrier status nor increasing parity was significantly associated with prolactin, breast-feeding duration of the first child or milk production. In conclusion, post-lactational prolactin levels were determined by breast-feeding duration of the first child and not simply by the first full-term pregnancy. Since prolactin modifies the risk for breast cancer, adequate counseling in favor of breast-feeding is essential.
 ...
PMID:Prolactin levels, breast-feeding and milk production in a cohort of young healthy women from high-risk breast cancer families: implications for breast cancer risk. 1827 92

The formation of new blood vessels has become a major focus of mammary gland research stimulated by the therapeutic opportunities of controlling angiogenesis in breast cancer. Normal growth and involution of the mammary gland are profoundly affected by the expansion and regression of blood vessels, whereas dysregulation of angiogenesis is characteristic of breast cancer growth and metastasis. Prolactin stimulates the growth and differentiation of the mammary gland under normal conditions, but its role in breast cancer is controversial. Its action is complicated by the fact that prolactin itself is angiogenic, but proteases cleave prolactin to generate vasoinhibins, a family of peptides that act on endothelial cells to suppress angiogenesis and vasodilation and to promote apoptosis-mediated vascular regression. This review summarizes our current knowledge about the vascular effects of prolactin and the generation and action of vasoinhibins, and discusses their possible contribution to the regulation of blood vessels in the normal and malignant mammary gland.
 ...
PMID:Role of prolactin and vasoinhibins in the regulation of vascular function in mammary gland. 1820 88

Transgenic models to explore the role of prolactin and its interactions with other factors in mammary oncogenesis have begun to reveal the dynamic contributions of prolactin to the development and progression of this disease. Targeting prolactin to mammary epithelial cells mimics the local production of this hormone that is prominent in women, and permits studies in the absence of effects on the ovarian steroid milieu. These models have demonstrated that local production of prolactin is sufficient to induce mammary tumors after a long latency. Prolactin also can potentiate actions of other oncogenic stimuli, decreasing tumor latency and increasing incidence in several models. Augmented proliferation, without alteration of apoptosis, is a consistent feature. Pathways in addition to the well-characterized Jak2-Stat5 pathway, including ERK1/2 and Akt1/2, are implicated in these actions. These studies have also revealed a complex relationship with estrogen; while prolactin increases ERalpha expression, it does not require estrogenic ligand for lesion development, and indeed, in combination with the EGFR ligand, TGFalpha, prolactin can contribute to estrogen insensitivity. These studies highlight the utility of these models to decipher the interplay between prolactin and other oncogenic factors in breast cancer, with implications for preventative and therapeutic strategies.
 ...
PMID:Transgenic models to study actions of prolactin in mammary neoplasia. 1821 62

Mammary morphogenesis is orchestrated with other reproductive events by pituitary-driven changes to the systemic hormone environment, initiating the formation of a mammary ductal network during puberty and the addition of secretory alveoli during pregnancy. Prolactin is the major driver of development during pregnancy via regulation of ovarian progesterone production (in many species) and direct effects on mammary epithelial cells (in all species). Together these hormones regulate two aspects of development that are the subject of intense interest: (1) a genomic regulatory network that integrates many additional spatial and temporal cues to control gene expression and (2), the activity of a stem and progenitor cell hierarchy. Amalgamation of these two aspects will increase our understanding of cell proliferation and differentiation within the mammary gland, with clear application to our attempts to control breast cancer. Here we focus on providing an over-view of prolactin action during development of the model murine mammary gland.
 ...
PMID:Prolactin regulation of mammary gland development. 1821 64

Prolactin receptors (PRLr) expressed in a majority of breast cancer are activated by prolactin and growth hormone. The PRLr is commonly stabilized in human breast cancer due to decreased phosphorylation of residue Ser(349), which, when phosphorylated, recruits the beta Trcp E3 ubiquitin ligase and facilitates PRLr degradation. Here, we show that constitutive oncogenic signaling downstream of ErbB2 and Ras stabilizes PRLr via inhibitory phosphorylation of glycogen synthase kinase-3beta (GSK3 beta) on Ser(9). Importantly, inactivation of GSK3 beta correlates with elevated levels of PRLr protein in clinical human breast cancer specimens. Additional studies using pharmacologic, biochemical, and genetic approaches reveal that GSK3 beta is a bona fide PRLr kinase that phosphorylates PRLr on Ser(349) and is required for the recognition of PRLr by beta Trcp, as well as for PRLr ubiquitination and degradation.
 ...
PMID:Oncogene-mediated inhibition of glycogen synthase kinase 3 beta impairs degradation of prolactin receptor. 1831 98

Hyperprolactinaemia may be associated with hidden longer-term consequences, such as osteoporosis, bone fractures, pituitary tumours and breast cancer. Prolactin data from clinical trials is not always reported in a categorical manner and does not always allow the risk of hyperprolactinaemia to be evaluated for specific patient cohorts. Patients participating in a physical health management programme in the UK for severe mental illness patients--the Well-being Support Programme--had prolactin measurements made regardless of symptoms. Prolactin data from the complete cohort of 178 patients receiving antipsychotics in Leeds and London are reported. Hyperprolactinaemia was measured in 33.1% but more commonly in females than males (47.3% and 17.6%) and was associated with all antipsychotics except clozapine. The highest prevalence rates were found in amisulpride (n=20) 89%, risperidone long-acting intramuscular injection (LAIM) 67% (n=6) and risperidone (n=30) 55% used as antipsychotic monotherapy. Clinically Significant hyperprolactinaemia (>1000 mIU/L approximately 47 ng/ml) was measured in 15.8% of patients, predominantly in females. Levels >2000 mIU/L approximately 95 ng/ml in 6.2% of the complete cohort. Clinicians may wish to add prolactin measurement to the routine laboratory parameters currently measured for some antipsychotics and should be advised of the potential longer-term consequences of hidden hyperprolactinaemia.
 ...
PMID:Categorical prevalence and severity of hyperprolactinaemia in two UK cohorts of patients with severe mental illness during treatment with antipsychotics. 1847 21

Prolactin (PRL) is a pleiotrophic hormone that contributes to the growth of normal and malignant breast tissues. PRL signals through its receptor (PRLr), a transmembrane receptor that belongs to the cytokine receptor family. The mechanism of how the PRL:PRLr interaction triggers activation of signaling networks remains enigmatic. This review examines the effect of ligand binding on PRLr and the processes that initiate receptor-associated signaling. Evidence for PRLr predimerization in the absence of ligand and the actions of the prolyl isomerase cyclophilin A in ligand-induced activation of PRLr-associated Jak2 kinase are discussed. These studies reveal that ligand-induced conformational change of the PRLr complex is necessary for its function and open avenues for therapies to inhibit PRLr action in breast cancer.
 ...
PMID:New mechanisms for PRLr action in breast cancer. 1953 62


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>