TGF-beta in Mammary Development and Tumorigenesis

描述（由申请方提供）：基质-上皮相互作用在乳腺发育和肿瘤发生中的重要性已得到充分证实。这些相互作用可能涉及多种生长因子的自分泌和旁分泌作用，包括在基质和上皮中表达的TGF-β家族成员。我们先前已经证明，使用金属硫蛋白（MT）启动子在乳腺基质中表达显性阴性II型TGF-β受体构建体（DNIIR）导致侧向分支增加。目前的证据表明，DNIIR仅导致TGF-β信号传导的部分阻断。为了完成乳腺基质细胞中II型TGF-β受体基因（Tgfbr 2）的完全敲除，我们将FSP 1-Cre小鼠与Tgfbr 2（Tgfbr 2/Tgfbr 2）小鼠杂交。FSP 1（成纤维细胞特异性蛋白-I）在基质成纤维细胞中表达。如初步研究所示，这些小鼠具有与MT-DNIIR小鼠中基质细胞中TGF-β信号传导部分消除所观察到的表型不同的表型。随着基质细胞中Tgfbr 2的完全敲除，乳腺脂肪细胞丢失，基质细胞明显增多，导管分支减少，上皮细胞发育不良。具有FSP 1-Cre和杂合floxed Tgfbr 2 [Tgfbr 2（E2/wt）]的动物使其在基质细胞中的Tgfbr 2单倍不足，具有正常的乳腺发育，但在泌乳后退化不良。因此，我们有一个独特的模型来研究TGF-β信号在乳腺发育和肿瘤发生的基质细胞中的作用。基于这些信息，我们提出了以下假设：（1）间质中的TGF-β信号传导对于乳腺的正常发育是必不可少的，并且在癌细胞的侵袭和转移潜力中起作用。(2)Tgfbr 2的间质单倍不足导致哺乳后的不完全消退，并改变了共表达癌基因诱导的乳腺肿瘤的侵袭和转移能力。本研究的具体目的是：1. FSP 1-Cre：Tgfbr 2（FSP 2/FSP 2）小鼠Cre表达模式、重组和表型的表征。2.间质中Tgfbr 2单倍不足的小鼠的Cre表达模式、重组和表型的表征，FSP 1-Cre：Tgfbr 2（FSP 2/wt）小鼠。3. Tgfbr 2缺失基质细胞的表征及其对癌细胞侵袭和转移的影响的测定。

DESCRIPTION (provided by applicant): The importance of stromal-epithelial interactions in mammary gland development and tumorigenesis is well established. These interactions likely involve autocrine and paracrine action of multiple growth factors, including members of the TGF-beta family, which are expressed in both stroma and epithelium. We have previously demonstrated that expression of a dominant-negative type II TGF-beta receptor construct (DNIIR) in mammary stroma using a metallothionein (MT) promoter results in increased lateral branching. Current evidence indicates that DNIIR causes only partial blockage of TGF-beta signaling. To accomplish complete knock-out of the type II TGF-beta receptor gene (Tgfbr2) in mammary stromal cells we have crossed FSP1-Cre mice with the Tgfbr2(floxE2/floxE2) mice. FSP1 (fibroblast-specific protein-I) is expressed in stromal fibroblasts. As shown under Preliminary Studies, these mice have a phenotype different from that observed with partial abrogation of TGF-beta signaling in stromal cells in the MT-DNIIR mice. With complete knock-out of Tgfbr2 in stromal cells there was loss of mammary fat cells with a markedly hypercellular stroma and decreased ductal branching with hypoplastic epithelial cells. Animals with FSP1-Cre and heterozygous floxed Tgfbr2 [Tgfbr2(floxE2/wt)] making them haploinsufficient for Tgfbr2 in stromal cells have normal mammary gland development, but defective regression following lactation. Thus, we have a unique model for studying the role of TGF-beta signaling in stromal cells on mammary gland development and tumorigenesis. Based on this information, we have formulated the following hypotheses: (1) TGF-beta signaling in stroma is essential for normal development of the mammary gland and plays a role in the invasive and metastatic potential of carcinoma cells. (2) Stromal haploinsufficiency of Tgfbr2 leads to incomplete regression following lactation and alters the invasion and metastatic capabilities of mammary tumors induced by coexpressed oncogenes. The Specific Aims are proposed to test these hypotheses are: 1. Characterization of Cre expression pattern, recombination and phenotype of FSP1-Cre:Tgfbr2(floxE2/floxE2) mice. 2. Characterization of Cre expression pattern, recombination and phenotype of mice haploinsufficient for Tgfbr2 in stroma, FSP1-Cre:Tgfbr2(floxE2/wt) mice. 3. Characterization of Tgfbr2 null stromal cells and determination of their effect on invasion and metastasis of carcinoma cells.