Leptin and its receptors have been shown to be expressed in several tissues, suggesting that this protein might be effective not only at the CNS level but also peripherally. We have previously reported that leptin and its long form receptor are expressed in the mouse mammary epithelial cell line HC11. In this study, we report a specific relationship among leptin, prolactin (PRL), interleukin-6 (IL-6), and tumor necrosis-alpha (TNF-alpha) in the modulation of the suppressor of cytokine signaling 1 (SOCS-1). Furthermore, we show that leptin and PRL are able to effectively enhance SOCS-1 gene expression in the HC11 cell line. Finally, high concentrations of leptin (100 nM) and/or PRL significantly (p<0.05) reduce the inhibitory effect of IL-6 (10 and 100 ng/ml) and TNF-alpha (10 and 100 ng/ml) on beta-casein gene expression in HC11 cells transfected with pbetacCAT, a chimeric rat-beta casein gene promoter-cloramphenicol acetyl transferase (CAT) gene construct. These results provide evidence that leptin may be an important mediator in regulating mammary gland growth and development and that this role may be related to the immune factors that are involved in inflammation.
Copyright 2004 Elsevier B.V.