The Role of PI3K Beta in Breast Cancer Metastasis

PI3K Beta 在乳腺癌转移中的作用

基本信息

批准号：
9894513
负责人：
ANNE R BRESNICK
金额：
$ 6.79万
依托单位：
ALBERT EINSTEIN COLLEGE OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-08-01 至 2020-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9894513
关键词：
1-Phosphatidylinositol 3-Kinase Binding Binding Sites Biology Breast Cancer Prevention Breast cancer metastasis Cell Proliferation Cell Survival Cells Complex Data Drug Targeting Enzymes Epithelial Extravasation G Protein-Coupled Receptor Signaling G-Protein-Coupled Receptors Genetic Growth Factor Human Immune system In Vitro Integrins Invaded Knock-in Mouse Malignant Neoplasms Mammary gland Matrix Metalloproteinases Mediating Membrane Metabolism Modeling Mouse Mammary Tumor Virus Mus Mutation Neoplasm Metastasis Normal Cell Paracrine Communication Penetrance Pharmaceutical Preparations Phenotype Phosphotransferases Play Prevention approach Production Proteins Role Signal Transduction Site Source Stromal Cells Stromal Neoplasm Testing Therapeutic Tissues Tumor Cell Invasion Tyrosine Work Xenograft Model cancer cell chemokine cytokine design human disease in vivo inhibitor/antagonist insight malignant breast neoplasm mortality mouse model mutant neoplastic cell novel recruit tumor tumor growth tumor progression

项目摘要

Tumor metastasis is the major cause of mortality in human breast cancer. Previous studies have shown that breast cancer metastasis is driven by paracrine signaling between tumor cells and stromal cells, which promotes invasion, intravasation, extravasation and tumor growth at secondary sites. This paracrine signaling is dependent on the reciprocal production of growth factors, cytokines and chemokines produced by stromal cells and tumor cells, many of which signal via G-protein-coupled receptors (GPCRs). We now present extensive preliminary data showing that GPCR signaling to PI3Kβ is critical for tumor cell invasion, intravasation and extravasation. Importantly, loss of GPCR signaling to PI3Kβ has a more severe phenotype on tumor intravasation and extravasation in vivo than loss of kinase activity, suggesting that inhibition of p110β-Gβγ binding might provide an alternative therapeutic approach for the prevention of breast cancer metastasis. This proposal examines the role of PI3Kβ in breast cancer metastasis, using both in vitro and in vivo approaches. The first aim comprises mechanistic studies to evaluate the role of PI3Kβ in the formation of invadopodia, which allow tumor cells to invade into surrounding tissue. We will focus on two models of p110β function in invadopodia maturation: (a) as a local source of PI[3,4,5]P3, whose metabolism to PI[3,4]P2 recruits the critical invadopodia protein Tks5; and (b) as a regulator of integrin signaling, which is important for invadopodia maturation and MMP secretion. Aim 2 examines how p110β integrates upstream signals from GPCRs, RTKs and Rac1, and examines the role of Rac1 signaling to PI3Kβ in breast cancer metastasis. In particular, we find that mutation of the Gβγ binding site in p110β has no effect on Rac1GTP binding and activation of p110β in vitro, but blocks PI3Kβ activation by constitutively active Rac1 in cells. Similarly, inhibitors that block the binding of the p85 regulatory subunit to tyrosine-phosphorylated proteins also inhibit PI3Kβ activation by CA-Rac. We will explore two hypotheses to explain these data: first, that Rac binding to PI3Kβ in cells requires the targeting of PI3Kβ to the membrane, and second, that activation of PI3Kβ by Gβγ or SH2-mediated interactions sensitizes PI3Kβ to Rac. We will also directly test the role of Rac binding to p110β in breast cancer metastasis using in vitro and in vivo xenograft models. Finally, we will study the role of PI3Kβ in breast cancer metastasis using an established genetic mouse model, MMTV-PyMT, which develops mammary epithelial tumors with high penetrance and has an intact immune system. We will cross PyMT mice to a knock-in mouse expressing the GPCR-uncoupled mutant of p110β, to definitively establish the role of GPCR signaling to PI3Kβ in tumor progression and metastasis. Altogether, these studies will lead to important new insights into the basic biology of PI3Kβ, and the role of this complex signaling enzyme in breast cancer metastasis.

以往的研究表明，肿瘤转移是人类乳腺癌死亡的主要原因。乳腺癌转移是由肿瘤细胞和基质细胞之间的旁分泌信号驱动的，这种旁分泌信号促进继发部位的侵袭、内渗、外渗和肿瘤生长。取决于基质产生的生长因子、细胞因子和趋化因子的相互产生细胞和肿瘤细胞，其中许多通过 G 蛋白偶联受体 (GPCR) 发出信号。大量初步数据表明，GPCR 信号传导至 PI3Kβ 对于肿瘤细胞侵袭至关重要，重要的是，PI3Kβ 的 GPCR 信号丢失具有更严重的表型。体内肿瘤内渗出和外渗的影响大于激酶活性的丧失，表明抑制 p110β-Gβγ 结合可能为预防乳腺癌提供另一种治疗方法该提案利用体外和体内研究研究了 PI3Kβ 在乳腺癌转移中的作用。第一个目标包括评估 PI3Kβ 在形成中的作用的机制研究。侵袭伪足，允许肿瘤细胞侵入周围组织，我们将重点关注 p110β 的两种模型。在侵袭伪足成熟中的功能：(a) 作为 PI[3,4,5]P3 的局部来源，其代谢为 PI[3,4]P2 关键的侵袭伪足蛋白 Tks5；以及 (b) 作为整合素信号传导的调节剂，这对于侵袭伪足成熟和 MMP 分泌。目标 2 检查 p110β 如何整合上游信号。 GPCR、RTK 和 Rac1，并检查 Rac1 信号传导至 PI3Kβ 在乳腺癌转移中的作用。特别是，我们发现 p110β 中 Gβγ 结合位点的突变对 Rac1GTP 结合没有影响，并且体外激活 p110β，但通过细胞中持续活跃的 Rac1 阻断 PI3Kβ 激活。阻断 p85 调节亚基与酪氨酸磷酸化结合的抑制剂也会抑制蛋白质 CA-Rac 激活 PI3Kβ 我们将探讨两个假设来解释这些数据：首先，Rac 与细胞中的 PI3Kβ 需要将 PI3Kβ 靶向细胞膜，其次，Gβγ 或 Gβγ 激活 PI3Kβ SH2 介导的相互作用使 PI3Kβ 对 Rac 敏感。我们还将直接测试 Rac 与 p110β 结合的作用。最后，我们将研究 PI3Kβ 在乳腺癌转移中的作用。使用已建立的遗传小鼠模型 MMTV-PyMT 来治疗乳腺癌转移，该模型开发我们将与 PyMT 小鼠进行杂交。到表达 GPCR 解偶联 p110β 突变体的敲入小鼠中，以明确确定总而言之，这些研究将在肿瘤进展和转移中发挥重要作用。对 PI3Kβ 基础生物学以及这种复杂信号酶在乳腺癌中的作用的新见解转移。