神经母细胞瘤中Gαi-Gab1信号复合物的表达及生物学功能研究

In neuroblastoma (NB), anaplastic lymphoma kinase (ALK) and other receptor tyrosine kinases (RTKs) are often over-expressed and/or constitutively-activated to promote tumor progression. Our preliminary studies have identified two important adaptor proteins for RTK: namely inhibitory heterotrimeric G proteins α subunit (Gαi proteins) and Grb2-associated binder 1 (Gab1). We found that Gαi proteins form a complex with Gab1, and were over-expressed in human NB tissues. Meanwhile, this complex appeared important for ALK- and other RTKs (EGFR, VEGFR and Trk-B)-induced activation of downstream signals including PI3K-Akt-mTOR, and Erk-mitogen-activated protein kinase (MAPK) pathways. SiRNA-mediated silencing or genetic knockout of Gαi or Gab1 significantly inhibited Akt/mTOR and Erk activation by the above RTK ligands. We propose here that Gαi-Gab1 adaptor complex associates with multiple RTKs to mediate downstream signal transduction, and eventually promotes NB progression. We are set to test the role the Gαi-Gab1 adaptor complex in mediating ALK and other RTKs’ signaling and NB progression both in vitro and in vivo, and to study the underlying mechanisms. We will also test the expression of Gαi-Gab1 complex in human NB tissues, and analyze its relationship with NB clinical indexes and patients’ prognosis. We suggest that Gαi-Gab1 signaling complex might be the “common adaptor” to mediate signaling transduction for NB-associated RTKs, and is important for NB cancerous behaviors.

变性淋巴瘤激酶（ALK）等多个受体酪氨酸激酶（RTKs）在神经母细胞瘤（NB）中过度表达及异常活化，促进NB发生发展和化疗抵抗。我们预实验结果证实了ALK及其他多个RTKs信号通路中2个重要接头蛋白：Gαi（G蛋白抑制性α亚单位）和Gab1；两者在人NB组织中高表达，耦联形成信号复合物，并关联多个RTKs。基因敲除或siRNA沉默Gαi/Gab1阻断ALK、EGFR、VEGFR及TrkB诱导的PI3K-Akt-mTOR和Erk的活化。本项目中，申请者将系统观察该信号复合物在人NB组织中的表达水平，分析其与NB病理分类、分级、患者预后等临床指标相关性。重点阐明Gαi-Gab1介导ALK等RTK信号转导的机制。并利用多种方法，体内、外系统研究Gαi-Gab1信号复合物在NB恶性生物学行为中的作用。拟证实Gαi-Gab1是ALK及多个RTKs的通用接头蛋白，负责信号传递并调控NB恶性生物学行为。

变性淋巴瘤激酶（ALK）等多个受体酪氨酸激酶（RTKs）在神经母细胞瘤（NB）中过度表达及异常活化，促进NB发生发展和化疗抵抗。实验结果证实ALK及其他多个RTKs信号通路中2个重要接头蛋白：Gαi（G蛋白抑制性α亚单位）和Gab1；两者在人NB组织中高表达，耦联形成信号复合物，并关联多个RTKs。基因敲除或siRNA沉默Gαi/Gab1阻断ALK、EGFR、VEGFR及TrkB诱导的PI3K-Akt-mTOR和Erk的活化。本课题系统观察了该信号复合物在人NB组织中的表达水平，分析其与NB病理分类、分级、患者预后等临床指标相关性。阐明了Gαi-Gab1介导ALK等RTK信号转导的机制。利用多种方法，体内、外系统研究Gαi-Gab1信号复合物在NB恶性生物学行为中的作用。证实Gαi-Gab1是ALK及多个RTK的通用接头蛋白，负责信号传递并调控NB恶性生物学行为。