Involvement of leptin and interleukin-1 signaling in mammary cancer progression

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DESCRIPTION (provided by applicant): Notice Number:NOT-OD_09-058 Notice Title: NIH Announces the Availability of Recovery Act Funds for Competitive Revision Applications. Specific cross-talk between leptin and IL-1 signaling found in endometrial and breast cancer (BC) cells could be involved in their pro-angiogenic effects. It is hypothesized that the leptin-induced effects on breast cancer could occur upon leptin signaling the activation of MAPK and NFkB and, an increased expression of VEGF/VEGFR2, which may be linked to, or regulated, in part by IL-1 signaling. To test this hypothesis three Aims involving in vitro investigations in mouse (4T1, EMT6 and MMT) and human BC cells (MCF-7 and MDA-MB231) will be developed. In Aim 1, leptin's regulatory mechanisms involved in IL-1 system expression (ligand, receptor and antagonist) will be investigated in mouse and human BC cells. To determine mechanisms of leptin-transcriptional regulation of IL-1 and IL-1R promoter-luciferase reporters (intact and site-directed mutagenesis for different transcription factors) will be used. ER expression and activation status relationships to leptin- IL-1 crosstalk will be analyzed in mouse and human BC cells. In Aim 2, leptin regulation of IL-1 signaling intermediaries (i.e., MyD88, IRAK1, IRAK4 and TRAF6) and relationships between leptin-mediated activation of MAPK and MAP3 kinases (TAK1 and MEKK1) and JNK and P38 kinases related to IL-1 signaling will be investigated. Different vectors and ChIP assays will be used to study gene regulation of MyD88. ChIP assays and co-immunoprecipitation tests will be used to identify specific binding of leptin-activated transcription factors to MyD88 gene and to determine the extent of MyD88 homodimerization. Aim 3 will investigate the molecular mechanism(s) involved in the leptin regulation of VEGF and VEGFR2 in breast cancer cells. While retaining the other binding regions for transcription factors, a series of VEGF promoter-reporter constructs with major cis-acting elements individually deleted will be used. To investigate the mechanisms of leptin regulation of VEGR2 luciferase constructs containing full-length of VEGFR2 promoter and truncated versions for AP2, NFkB binding deletions will be used. Data from these investigations will provide strong scientific basis to understand leptin-IL-1 crosstalk and to assess whether disruption of leptin-signaling could serve as a novel method for prevention/treatment of BC. PUBLIC HEALTH RELEVANCE: Results from these investigations would allow us to be a step closer to the potential translational use of inhibitoes [sic] of leptin signaling (PEG-LPrA) for prevention and/or treatment of BC that is highly important for obese and post-menopausal women. PEG-LPrA could be a useful biological agent or adjuvant to improve the efficacy of preventive/therapeutic regimens for BC.