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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.

肿瘤转移是导致人类乳腺癌死亡的主要原因。此前的研究表明，乳腺癌的转移是由肿瘤细胞和间质细胞之间的旁分泌信号驱动的，促进继发部位的侵袭、渗入、渗出和肿瘤生长。这种旁分泌信号依赖于基质产生的生长因子、细胞因子和趋化因子的相互作用细胞和肿瘤细胞，其中许多通过G蛋白偶联受体(GPCRs)传递信号。我们现在向大家介绍大量的初步数据表明，PI3Kβ的gpr信号对肿瘤细胞的侵袭至关重要，渗入和渗出。重要的是，pI3Kβ的gpcr信号丢失具有更严重的表型对肿瘤体内渗出和渗出的影响大于对激酶活性的丧失，提示对肿瘤的抑制 P110β-Gβγ结合可能为乳腺癌的预防提供另一种治疗途径转移。本研究采用体外和体外两种方法研究了PI3Kβ在乳腺癌转移中的作用。活体接近了。第一个目标包括评估PI3Kβ在糖尿病形成中的作用的机制研究。侵袭性，允许肿瘤细胞侵入周围组织。我们将重点介绍两种型号的p110β 在失足动物成熟中的作用：(A)作为PI[3，4，5]P3的局部来源，其代谢到PI[3，4]P2新兵以及(B)作为整合素信号的调节者，这对内翻足的成熟和基质金属蛋白酶的分泌。AIM 2研究了p110β如何整合来自 GPCRs、RTK和RAC1，并研究RAC1信号转导PI3Kβ在乳腺癌转移中的作用。在……里面特别是，我们发现p110βγ中G-β结合位点的突变对Rac1GTP结合没有影响。在体外激活p110β，但通过在细胞中结构性激活β来阻断PI3K Rac1的激活。同样，阻断p85调节亚基与酪氨酸磷酸化蛋白结合的抑制剂也会抑制 CA-RAC激活PI3Kβ。我们将探索两个假设来解释这些数据：第一，RAC绑定到细胞中的PI3Kβ需要将PI3Kβ靶向到膜上，第二，通过Gβ或Gβγ激活PI3K DNA 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的结合作用在乳腺癌转移中采用体外和体内异种移植模型。最后，我们将研究PI3Kβ的作用在乳腺癌转移中使用已建立的遗传小鼠模型MMTV-PYMT，该模型开发了乳腺上皮性肿瘤具有较高的透明度和完整的免疫系统。我们将穿越PYMT小鼠在表达p110β的gpR-解偶联突变体的敲入小鼠中，明确确定 PI3Kβ的GPCR信号在肿瘤进展和转移中的作用总之，这些研究将导致重要的对PI3Kβ基本生物学的新认识，以及这种复杂的信号酶在乳腺癌中的作用转移。