Involvement of Leptin and Interleukin-1 Signaling in Mammary Cancer Progression

描述(由申请人提供)：尽管越来越多的证据表明瘦素水平、肥胖、绝经后和乳腺癌发病率之间存在正相关关系，但我们目前对这些关系所涉及的机制的了解仍然不完整。我们的初步数据显示，特定的瘦素诱导的信号通路参与了乳腺肿瘤(MT)同基因免疫活性小鼠模型中血管生成和有丝分裂相关因子水平的增加。我们创新的瘦素多肽受体拮抗剂(LPrA)在体外和体内抑制瘦素信号，显著减少MT的建立和生长，同时降低VEGF/VEGFR2的水平。在子宫内膜癌细胞和乳腺癌细胞中发现的瘦素和IL-1信号之间的特定串扰可能与它们的促血管生成和抗凋亡作用有关。 推测瘦素可能通过激活Akt1/NFkB和上调VEGF/VEGFR2和bcl2的表达来发挥瘦素对乳腺癌的作用，这可能与IL-1信号转导有关或部分受IL-1信号调节。为了验证这一假说，我们将使用四种体内外模型：(1)将小鼠乳腺癌细胞移植到同基因免疫活性小鼠体内；(2)将(对雌二醇有反应和无反应的)人乳腺癌细胞植入免疫低下小鼠体内；(3)用致癌剂(DMBA)处理人乳腺癌细胞；(4)用DMBA-MT诱导大鼠乳腺癌细胞死亡。在这些啮齿动物模型中，瘦素水平在MT的建立/进展中的影响将被仔细研究。为了确定特定的瘦素诱导的信号通路的影响，将使用激酶抑制剂、siRNAs、聚乙二醇化的LPrAs(半衰期，55H)。荧光素酶-血管内皮生长因子启动子(鼠和人)和几个转录因子-记者将被用来研究瘦素在鼠和人乳腺癌细胞中的靶点。IL-1ra对IL-1信号的抑制作用将有助于确定瘦素/IL-1信号串扰对MT的影响。这项研究将扩大我们对瘦素/IL-1信号在MT中作用的有限了解，并可能为针对乳腺癌的新治疗策略产生必要的数据，特别是对绝经后和肥胖女性。在这种情况下，抑制瘦素信号可能是一种预防或辅助措施。

DESCRIPTION (provided by applicant): Despite accumulating evidence suggesting a positive correlation between leptin levels, obesity, post-menopause and breast cancer incidence, our current knowledge on the mechanisms involved in these relationships is still incomplete. Our preliminary data show that specific leptin-induced signaling pathways are involved in the increased levels of factors related to angiogenesis and mitosis in syngeneic immuno-competent mouse models of mammary tumors (MT). The inhibition of leptin signaling in vitro and in vivo by our innovative leptin peptide receptor antagonists (LPrA) significantly reduced establishment and growth of MT and simultaneously decreased the levels of VEGF/VEGFR2. Specific cross-talk between leptin and IL-1 signaling found in endometrial and mammary cancer cells could be involved in their pro-angiogenic and anti-apoptotic effects. It is hypothesized that the leptin-induced effects on mammary cancer could occur upon leptin signaling the activation of Akt1/NFkB and an increased expression of VEGF/VEGFR2 and bcl-2, which may be linked to, or regulated, in part by IL-1 signaling. To test this hypothesis four models will be used in vitro and in vivo: (1) mouse mammary cancer cells implanted in syngeneic immuno-competent mice; (2) human breast cancer cells (responsive and irresponsive to estradiol) implanted in immuno-compromised mice; (3) human mammary epithelial cells treated with a carcinogenic agent (DMBA); (4) DMBA-MT induced in rats. The impact of leptin levels in establishment/ progression of MT in these rodent models will carefully be examined. To determine the effects of specific leptin-induced signaling pathways, kinase inhibitors, siRNAs, PEGylated-LPrAs (half-lives, 55h) will be used. Luciferase-VEGF promoter (mouse and human) and several transcription factor-reporters will be used to investigate leptin's targets in mouse and human mammary cancer cells. IL-1Ra inhibition of IL-1 signaling will serve to determine the impact of leptin/IL-1 signaling crosstalk on MT. This research would expand our limited knowledge on leptin/IL-1 signaling roles in MT and could generate essential data for new therapeutic strategies to target breast cancer, particularly for post-menopausal and obese women. Inhibition of leptin signaling in such instances might serve as a preventative or adjuvant measure.