Cellular transformation by altered expression of ana adapter protein Gab1

经致癌剂处理的叙利亚仓鼠胚胎(SHE)细胞培养的体外转化系统代表了在体内正常细胞向肿瘤细胞的肿瘤进展过程中发生的多步骤遗传和非遗传变化。我们首先研究了适配蛋白GAB1在SHE细胞肿瘤进展中的作用。在肿瘤进展过程中，SHE细胞表现出一种新的87 kDa形式的GAB1表达增加，而原始100 kDa GAB1的表达减少。编码87 kDa GAB1的互补DNA预测了一种形式的GAB1缺少氨基末端103氨基酸(GAB1^&lt；^Δ1-103&gt；)，这对应于Pleckstrin同源(PH)结构域的大部分丢失。此外，在SHE细胞中转染和表达GAB1-Δ1-103-GT；而不是GAB1，可促进其在软琼脂中形成依赖于表皮生长因子的集落。因此，接头蛋白表达的改变可能与人类癌症和一些慢性炎症性疾病有关。滑膜…类风湿关节炎(RA)患者的成纤维细胞样细胞(SFL)大量表达血小板衍生生长因子(PDGF)受体，PDGF刺激可促进RA-SFL细胞的贴壁依赖性和非贴壁性生长。因此，我们接下来研究了PDGF受体信号转导中适配蛋白在RA-SFL细胞瘤样增殖中的作用。GAB1在RA-SFL细胞中表达，并在PDGF刺激下迅速酪氨酸磷酸化。治疗慢性粒细胞白血病的关键药物甲磺酸伊马替尼抑制PDGF受体酪氨酸激酶的激活，从而抑制这些适配蛋白依赖于PDGF的酪氨酸磷酸化。此外，甲磺酸伊马替尼可阻断PDGF刺激的RA-SFL细胞的贴壁依赖性和非依赖性增殖。这些结果表明，许多接头蛋白参与了类风湿滑膜细胞的生长因子信号转导，抑制这些分子可能对部分恶性肿瘤或慢性炎症性疾病的治疗有效。较少

An in vitro transformation system of carcinogen-treated Syrian hamster embryo (SHE) cell cultures represents multistep genetic and non-genetic changes that develop during the neoplastic progression of normal cells to tumor cells in vivo. We first examined the role of the adaptor protein Gab1 in the neoplastic progression of SHE cells. During the neoplastic progression, SHE cells showed increasing expression of a novel 87-kDa form of Gab1 with diminishing expression of the original 100-kDa Gab1. Complementary DNA encoding the 87-kDa Gab1 predicts a form of Gab1 lacking the ammo-terminal 103 ammo acids (Gab1^<^Δ1-103>), which corresponds to loss of most of the pleckstrin homology (PH) domain. Moreover, transfection and expression of Gab1^<^Δ1-103>, but not Gab1, in SHE cells enhanced their epidermal growth factor (EGF) -dependent colony formation in soft agar. Thus, an altered expression of adaptor proteins may be involved in human cancers and some chronic inflammatory diseases. Synovial … More fibroblast-like (SFL) cells from patients with rheumatoid arthritis (RA) abundantly express receptors for platelet-derived growth factor (PDGF), and stimulation with PDGF enhances both the anchorage-dependent and -independent growth of RA-SFL cells. Therefore, we next examined the roles of adapter proteins in PDGF receptor signaling in tumor-like proliferation of RA-SFL cells. Gab1 was expressed in RA-SFL cells, and was rapidly tyrosine-phosphorylated after PDGF stimulation. The inhibition of PDGF receptor tyrosine kinase activation by imatinib mesylate, a key drug in the treatment of chronic myeloid leukemia, suppressed the PDGF-dependent tyrosine phosphorylation of these adapter proteins. Moreover, imatinib mesylate abolished both the anchorage-dependent and -independent proliferation of RA-SFL cells induced by PDGF stimulation. These results suggest that many adapter proteins are involved in the growth factor signaling of rheumatoid synovial cells and that the inhibition of those molecules may be effective for the treatment of a part of malignancies or chronic inflammatory diseases. Less