Integrin-Mediated Regulation of TGF-Beta Signaling and Tumorigenesis

描述(申请人提供)：乳腺癌是美国女性癌症死亡的第二大原因。侵袭和转移是乳腺癌最致命的特征，也是乳腺癌相关死亡的主要原因。转化生长因子-？通常通过阻止乳腺上皮细胞(MEC)增殖或通过诱导MEC凋亡来抑制乳腺癌的发展。乳腺肿瘤的发生抵消了转化生长因子-β的抑瘤活性，从而使转化生长因子-β成为可能。刺激乳腺癌的侵袭和转移。对于恶性微血管内皮细胞如何克服转化生长因子-β的细胞抑制作用，以及转化生长因子-β是如何发挥作用的，我们的认识存在着根本的空白。刺激乳腺肿瘤的发展和进展。这些知识空白阻碍了科学和医学开发有效地拮抗转化生长因子？？的致癌活性的疗法。在乳腺癌的发生和发展中起重要作用。我们最近建立了V？3整合素和Src作为转化生长因子刺激的MAP激酶激活、细胞侵袭和上皮向间充质转化(EMT)的基本介体。基于这些和其他的初步发现，我们假设在乳腺癌发生过程中整合素βV？3和src的异常激活促进了转化生长因子-β的致癌作用。其诱导乳腺癌细胞EMT、侵袭和转移的机制是：(1)诱导整合素β-V？3的形成：转化生长因子-β？受体复合体；(Ii)刺激转化生长因子-βI型(T？R-I)和2型(T？R-II)受体的酪氨酸磷酸化；(3)协调形成Shc：Grb2：GAB1/2复合体，放大转化生长因子-β激活的MAP激酶。由此推论，灭活av？3整合素和Src功能将阻止转化生长因子β由抑制者转化为乳腺癌生长和侵袭的促进者，从而减轻转化生长因子β刺激的乳腺癌的发生和发展。假设将通过三个具体的目标来解决。具体目标1将确定介导av？3整合素：T？R-II复合体形成的3整合素和T？R-II决定因素，缺乏这些功能的突变体将被用来确定av？3整合素：T？R-II复合体在正常和恶性MEC中介导转化生长因子-β介导的致癌信号中的作用。特异性目标2将确定T？R-I和T？R-II中被Src磷酸化的Tyr残基，缺乏这些功能的突变体将被用来确定这些反应对正常和恶性MEC中转化生长因子-β功能的影响。具体目的3将确定阻断av？3整合素和Src功能在阻止转化生长因子-β刺激小鼠乳腺癌细胞生长、侵袭、血管生成和转移方面的有效性。这些研究将提供关于转化生长因子β如何促进乳腺癌侵袭和转移的有价值的信息，更重要的是，关于如何通过开发和使用av？3整合素和Src拮抗剂来靶向转化生长因子β的致癌活性来控制这些致命过程。此外，我们的发现的应用将使科学和医学有朝一日能够改善转移性乳腺癌患者的预后和治疗。

DESCRIPTION (provided by applicant): Breast cancer is the second leading cause of cancer death in women in the United States. Invasion and metastasis are the most lethal characteristics of breast cancer and the leading cause of breast cancer-related death. TGF-? normally inhibits breast cancer development by preventing mammary epithelial cell (MEC) proliferation, or by inducing MEC apoptosis. Mammary tumorigenesis counteracts the tumor suppressing activities of TGF-?, thus enabling TGF-? to stimulate breast cancer invasion and metastasis. Fundamental gaps exist in our knowledge of how malignant MECs overcome the cytostatic actions of TGF-?, and of how TGF-? stimulates the development and progression of mammary tumors. These knowledge gaps have prevented science and medicine from developing treatments effective in antagonizing the oncogenic activities of TGF-? in developing and progressing breast cancers. We recently established ?v?3 integrin and Src as essential mediators of TGF-?-stimulated MAP kinase activation, cell invasion, and epithelial-to-mesenchymal transition (EMT) in normal and malignant MECs. Based on these and other preliminary findings, we hypothesize that aberrant activation of ?v?3 integrin and Src in developing breast cancers promotes the oncogenic function of TGF-? and its induction of breast cancer cell EMT, invasion, and metastasis by (i) inducing formation of ?v?3 integrin:TGF-? receptor complexes; (ii) stimulating Tyr phosphorylation of the TGF-¿ type I (T¿R-I) and type II (T¿R-II) receptors; and (iii) coordinating the formation Shc:Grb2:Gab1/2 complexes that amplify activation of MAP kinases by TGF-¿. A corollary states that inactivating av¿3 integrin and Src function will prevent the conversion of TGF-¿ from a suppressor to a promoter of breast cancer growth and invasion, thereby alleviating breast cancer development and progression stimulated by TGF-¿. Theses hypotheses will be addressed by three specific aims. Specific Aim 1 will identify the ¿3 integrin and T¿R-II determinants that mediate av¿3 integrin:T¿R-II complex formation and mutants lacking these functions will be used to establish the role of av¿3 integrin:T¿R-II complexes in mediating oncogenic signaling by TGF-¿ in normal and malignant MECs. Specific Aim 2 will identify the Tyr residues in T¿R-I and T¿R-II that are phosphorylated by Src and mutants lacking these functions will be used to determine the impact of these reactions on TGF-¿ function in normal and malignant MECs. Specific Aim 3 will determine the effectiveness of interdicting av¿3 integrin and Src function in preventing TGF-¿ stimulation of breast cancer cell growth, invasion, angiogenesis, and metastasis in mice. These studies will provide valuable information on how TGF-¿ promotes breast cancer invasion and metastasis, and more importantly, on how to control these deadly processes by targeting the oncogenic activities of TGF-¿ through the development and use of av¿3 integrin and Src antagonists. Moreover, application of our findings will enable science and medicine to, one day, improve the prognosis and treatment of patients with metastatic breast cancer.