ErbB receptor signaling via small G-proteins in breast cancer

乳腺癌中通过小 G 蛋白进行的 ErbB 受体信号传导

• 批准号: 8468659
• 负责人: MARCELO G. KAZANIETZ
• 金额: $ 35.16万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-15 至 2015-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8468659
• 关键词: Actins; Address; Affect; Anchorage-Independent Growth; Animal Model; Biological Assay; Breast Cancer Cell; Breast Cancer Model; Breast Carcinoma; CXCR4 gene; Cancer cell line; Cell model; Cell physiology; Cells; Cytoskeleton; Disease; Disease Progression; Dissociation; Down-Regulation; ERBB2 gene; Epidermal Growth Factor; Epidermal Growth Factor Receptor; ErbB4 gene; Estrogen Antagonists; Etiology; Family; Fluorescence Resonance Energy Transfer; G Protein-Coupled Receptor Signaling; G-Protein-Coupled Receptors; GTPase-Activating Proteins; Gene Amplification; Gene Mutation; Goals; Guanine Nucleotide Exchange Factors; Guanosine Triphosphate; Guanosine Triphosphate Phosphohydrolases; Heregulin; Human; Isoenzymes; Lead; Ligands; Malignant Neoplasms; Mammary Neoplasms; Mammary gland; Mediating; Mediator of activation protein; Membrane; Modeling; Molecular; Monomeric GTP-Binding Proteins; Mus; Mutate; Neoplasm Metastasis; Normal Cell; Nude Mice; PTEN gene; Pathway interactions; Pertussis Toxin; Phosphatidylinositols; Play; Properdin; Property; Protein Tyrosine Kinase; Proteins; RNA Interference; Receptor Protein-Tyrosine Kinases; Receptor Signaling; Relative (related person); Resistance; Role; Signal Transduction; Stimulation of Cell Proliferation; Testing; Therapeutic; Tissue Banking; Tissue Banks; Toxin; Transactivation; Tumorigenicity; Up-Regulation; base; cell motility; chemokine; inhibitor/antagonist; malignant breast neoplasm; member; migration; mouse model; neutrophil; novel; outcome forecast; overexpression; prevent; prognostic; public health relevance; receptor; receptor coupling; response; rho; rho GTPase-activating protein; tripolyphosphate; tumor; tumor progression; tumorigenesis; tumorigenic; wortmannin

DESCRIPTION (provided by applicant): The human epidermal growth factor (EGF) family of tyrosine kinase receptors consists of ErbB1 (EGFR), ErbB2 (Neu), ErbB3, and ErbB4, and plays key roles in cancer progression. Dysregulation of ErbB signaling due to hyperactivation of receptors (such as mutated EGFR or ErbB2 overexpression), overexpression of ligands (such as TGF-? or heregulins), or augmented downstream signaling (such as enhanced PI3K signaling) plays a major role in the etiology of breast cancer. We found that ligand stimulation of ErbB1 and ErbB3 receptors leads to a strong activation of the small GTPase Rac1 to promote mitogenesis and motility. The search for Rac-GEFs that mediate Rac1 activation by ErbB ligands in breast cancer cells revealed a prominent role for phosphatidylinositol-3,4,5-triphosphate-dependent Rac exchanger-1 (P-Rex1), a Rac-GEF originally identified in neutrophils but not studied in any cancer so far. Strikingly, P-Rex1 is highly expressed in most breast cancer cell lines as well as in tumors. P-Rex1 is a PI3K- and G??-dependent Rac-GEF, and coincidentally, ErbB receptor-mediated activation of Rac1 is inhibited by Pertusis toxin, which prevents G23 subunit release from heterotrimeric Gi proteins, by the PI3K inhibitor wortmannin, and by inhibition/depletion of PI3K?, a class Ib PI3K that is activated by G?? subunits. Moreover, ErbB3-induced activation of Rac1 is dependent on the transactivation of CXCR4, a Gi-coupled receptor widely implicated in breast cancer progression, and Rac1 activation by direct stimulation of CXCR4 with the chemokine SDF-11 also depends on P-Rex1. Therefore, P-Rex1 is a common mediator of Rac activation by ErbB receptors and GPCRs in breast cancer cells. In Specific Aim 1 we will investigate whether ligand stimulation of ErbB receptors can promote the activation of P-Rex1 in breast cancer cells, and assess the functional consequences for such activation, including actin cytoskeleton reorganization, migration, and proliferation. Translocation studies as well as FRET approaches will be used to address the relative contribution of discrete PI3K isozymes and the CXCR4-G?? pathway to P-Rex1 and Rac1 activation. In Specific Aim 2 we will determine whether RNAi depletion of P-Rex1 affects tumorigenicity and metastatic dissemination of breast cancer cells driven by overexpression of an ErbB3 ligand. We will also assess the involvement of P-Rex1 in anti-estrogen resistance. In Specific Aim 3 we will determine if Rac signaling via P-Rex1 contributes to ErbB2-driven tumorigenesis and metastasis, and whether this is mediated by the CXCR4-G??-PI3K? pathway. We will generate mammary-specific mouse models for P-Rex1 overexpression and determine whether it can lead to tumor formation or cooperate with ErbB2 overexpression. In Specific Aim 4 the goal is to determine whether P-Rex1 is a hallmark of human breast cancer, and P-Rex1 expression in human tumors correlates with signaling parameters. The identification of P-Rex1 as an effector of ErbB receptors may have major relevance for understanding the molecular basis and etiology of breast cancer as well as significant prognostic and therapeutic implications.

描述（由申请人提供）：酪氨酸激酶受体的人表皮生长因子（EGF）家族由ErbB 1（EGFR）、ErbB 2（Neu）、ErbB 3和ErbB 4组成，在癌症进展中起关键作用。由于受体过度活化（如突变的EGFR或ErbB 2过表达）、配体过表达（如TGF-？或调蛋白）或增强的下游信号传导（例如增强的PI 3 K信号传导）在乳腺癌的病因中发挥着重要作用。我们发现，ErbB 1和ErbB 3受体的配体刺激导致小GTTR Rac 1的强烈激活，以促进有丝分裂和运动。在乳腺癌细胞中通过ErbB配体介导Rac 1活化的Rac-GEF的研究揭示了磷脂酰肌醇-3，4，5-三磷酸依赖性Rac交换器-1（P-Rex 1）的突出作用，这是一种最初在中性粒细胞中鉴定的Rac-GEF，但迄今为止尚未在任何癌症中进行研究。引人注目的是，P-Rex 1在大多数乳腺癌细胞系以及肿瘤中高度表达。P-Rex 1是PI 3 K-和G？？-依赖Rac-GEF，并且巧合的是，ErbB受体介导的Rac 1的活化被百日咳毒素抑制，百日咳毒素阻止G23亚基从异源三聚体Gi蛋白释放，被PI 3 K抑制剂渥曼青霉素抑制，并且被PI 3 K？的抑制/消耗抑制，一种由G激活的Ib类PI 3 K？？亚单位。此外，ErbB 3诱导的Rac 1激活依赖于CXCR 4的反式激活，CXCR 4是一种广泛参与乳腺癌进展的Gi偶联受体，而趋化因子SDF-11直接刺激CXCR 4激活Rac 1也依赖于P-Rex 1。因此，P-Rex 1是乳腺癌细胞中ErbB受体和GPCR激活Rac的共同介质。在具体目标1中，我们将研究ErbB受体的配体刺激是否可以促进乳腺癌细胞中P-Rex 1的激活，并评估这种激活的功能后果，包括肌动蛋白细胞骨架重组，迁移和增殖。易位研究以及FRET方法将被用来解决离散PI 3 K同工酶和CXCR 4-G？？P-Rex 1和Rac 1激活的途径。在特定目标2中，我们将确定P-Rex 1的RNAi缺失是否影响由ErbB 3配体过表达驱动的乳腺癌细胞的致瘤性和转移性扩散。我们还将评估P-Rex 1参与抗雌激素抵抗。在具体目标3中，我们将确定Rac信号通过P-Rex 1是否有助于ErbB 2驱动的肿瘤发生和转移，以及这是否由CXCR 4-G？PI3K？通路我们将建立P-Rex 1过表达的乳腺特异性小鼠模型，并确定它是否会导致肿瘤形成或与ErbB 2过表达合作。在特定目标4中，目标是确定P-Rex 1是否是人类乳腺癌的标志，以及P-Rex 1在人类肿瘤中的表达与信号参数相关。P-Rex 1作为ErbB受体的效应子的鉴定对于理解乳腺癌的分子基础和病因学以及显著的预后和治疗意义可能具有重要意义。