TGF-beta in Mammary Development and Tumorigenesis

描述（由申请人提供）：基质-上皮相互作用在乳腺发育和肿瘤发生中的重要性已经得到证实。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tgf - β家族成员，在基质和上皮中均有表达。我们之前已经证明，在乳腺基质中，使用金属硫蛋白（MT）启动子表达显性阴性II型tgf - β受体构建体（DNIIR）会导致侧分支增加。目前的证据表明，DNIIR仅引起tgf - β信号的部分阻断。为了在乳腺基质细胞中完全敲除II型tgf - β受体基因（Tgfbr2），我们将FSP1-Cre小鼠与Tgfbr2（floxE2/floxE2）小鼠杂交。FSP1（成纤维细胞特异性蛋白- i）在间质成纤维细胞中表达。如初步研究所示，这些小鼠的表型不同于MT-DNIIR小鼠中基质细胞中tgf - β信号的部分消除。完全敲除基质细胞中的Tgfbr2后，乳腺脂肪细胞减少，基质细胞明显增多，导管分支减少，上皮细胞发育不全。具有FSP1-Cre和杂合的Tgfbr2 [Tgfbr2(floxE2/wt)]使其在基质细胞中单倍缺乏Tgfbr2的动物具有正常的乳腺发育，但在哺乳后退化缺陷。因此，我们有一个独特的模型来研究基质细胞中tgf - β信号在乳腺发育和肿瘤发生中的作用。基于这些信息，我们提出了以下假设：(1)基质中tgf - β信号对乳腺的正常发育至关重要，并在癌细胞的侵袭和转移潜能中发挥作用。(2)基质单倍体Tgfbr2不足导致泌乳后不完全消退，改变共表达癌基因诱导的乳腺肿瘤的侵袭和转移能力。为了验证这些假设，提出了具体的目标：1。FSP1-Cre:Tgfbr2（floxE2/floxE2）小鼠Cre表达模式、重组及表型表征2. 间质中Tgfbr2单倍不足小鼠，FSP1-Cre:Tgfbr2（floxE2/wt）小鼠的Cre表达模式、重组和表型表征。3. Tgfbr2阴性基质细胞的鉴定及其对癌细胞侵袭转移的影响。

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.