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Query: UNIPROT:P04626 (erbB-2)
 5,251 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We examined the mechanism through which leptin increases Na(+), K(+)-ATPase activity in the rat kidney. Leptin was infused under anaesthesia into the abdominal aorta proximally to the renal arteries and then Na(+), K(+)-ATPase activity was measured in the renal cortex and medulla. Leptin (1mug/kgmin) increased Na(+), K(+)-ATPase activity after 3h of infusion, which was accompanied by the increase in urinary H(2)O(2) excretion and phosphorylation level of extracellular signal regulated kinase (ERK). The effect of leptin on ERK and Na(+), K(+)-ATPase was abolished by catalase, specific inhibitors of epidermal growth factor (EGF) receptor, AG1478 and PD158780, as well as by ERK inhibitor, PD98059, and was mimicked by both exogenous H(2)O(2) and EGF. The effect of leptin was also prevented by the inhibitor of Src tyrosine kinase, PP2. Leptin and H(2)O(2) increased Src phosphorylation at Tyr(418). We conclude that leptin-induced stimulation of renal Na(+), K(+)-ATPase involves H(2)O(2) generation, Src kinase, transactivation of the EGF receptor, and stimulation of ERK.
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PMID:H2O2 and Src-dependent transactivation of the EGF receptor mediates the stimulatory effect of leptin on renal ERK and Na+, K+-ATPase. 1697 40

We examined the role of epidermal growth factor (EGF) receptor in the pathogenesis of leptin-induced hypertension in the rat. Leptin, administered in increasing doses (0.1-0.5 mg/kg/day) for 10 days, increased phosphorylation levels of non-receptor tyrosine kinase, c-Src, EGF receptor and extracellular signal-regulated kinases (ERK) in aorta and kidney, which was accompanied by the increase in plasma concentration and urinary excretion of isoprostanes and H2O2. Blood pressure and renal Na+,K+-ATPase activity were higher, whereas urinary sodium excretion was lower in animals receiving leptin. The effects of leptin on renal Na+,K+-ATPase, natriuresis and blood pressure were abolished by NADPH oxidase inhibitor, apocynin, Src kinase inhibitor, PP2, EGF receptor inhibitor, AG1478, protein farnesyltransferase inhibitor, manumycin A, and ERK inhibitor, PD98059. In contrast, inhibitors of insulin-like growth factor-1 and platelet-derived growth factor receptors, AG1024 and AG1295, respectively, only slightly reduced ERK phosphorylation and had no effect on blood pressure in rats receiving leptin. These data indicate that: (1) experimental hyperleptinemia is associated with oxidative stress and c-Src-dependent transactivation of the EGF receptor, which stimulates ERK in vascular wall and the kidney, (2) overactivity of EGF receptor-ERK pathway contributes to leptin-induced hypertension by stimulating renal Na+,K+-ATPase and reducing sodium excretion, (3) inhibitors of c-Src, EGF receptor and ERK may be considered as a novel therapy for hypertension associated with hyperleptinemia, e.g. in patients with obesity and metabolic syndrome.
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PMID:Transactivation of epidermal growth factor receptor in vascular and renal systems in rats with experimental hyperleptinemia: role in leptin-induced hypertension. 1828 56

Leptin is an adipocyte-derived protein and plays an important role in the control of body weight by acting as a neurohormone regulating energy balance and food intake in the hypothalamus. The high serum leptin levels and the overexpression of leptin receptors have been documented in breast cancer patients, but the levels never checked preoperatively. In the present study, the relationship between preoperative serum leptin levels of the breast cancer patients and the healthy controls were evaluated. The serum leptin levels in 30 breast cancer patients were compared to 30 healthy female volunteers. In addition, the association of serum leptin levels and the various well-known risk factors were studied. Serum leptin levels of patients with breast cancer (28.55 + 19.7 ng/ml) were tended to be higher than those of controls (26.43 + 19.4 ng/ml), but it did not reach statistical difference (P = 0.712). There was significant correlation between the expression of ER, PR, and serum leptin levels (P = 0.018 and 0.037, respectively), but not with the HER-2/neu receptor expression (P = 0.067). Also association was not found between the tumor size, lymph node involvement, and the levels of serum leptin (P = 0.235, 0.34, and 0.86, respectively). The serum leptin level was also found to be similar in premenopausal (24.85 +/- 18.14 ng/ml) and postmenopausal (30.49 +/- 17.19 ng/ml) patients (P = 0.235). The preoperative serum leptin levels in breast cancer patients were similar to healthy controls. In subset analysis, the significant correlation between the leptin level and hormonal status was noted, but association with HER-2/neu was not detected. These findings should be confirmed with larger studies.
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PMID:Preoperative serum leptin levels in patients with breast cancer. 1941 73