Hashimoto K, Tsujimura T, Moriyama Y, Yamatodani A, Kimura M, Tohya K, Morimoto M, Kitayama H, Kanakura Y, Kitamura Y
Department of Pathology, Faculty of Medicine, Osaka University, Suita, Japan.
Am J Pathol. 1996 Jan;148(1):189-200.
Two mutations of c-kit receptor tyrosine kinase (KIT), valine-559 to glycine (G559) and aspartic acid-814 to valine (V814), resulted in its constitutive activation. To examine the transforming and differentiation-inducing potential of the mutant KIT, we used the murine interleukin-3-dependent IC-2 mast cell line as a transfectant. The IC-2 cells contained few basophilic granules and did not express KIT on the surface. The KITG559 or KITV814 gene was introduced into IC-2 cells using a retroviral vector. KITG559 and KITV814 expressed in IC-2 cells were constitutively phosphorylated on tyrosine and demonstrated kinase activity in the absence of stem cell factor, which is a ligand for KIT. IC-2 cells expressing either KITG559 or KITV814 (IC-2G559 or IC-2V814 cells) showed factor-independent growth in suspension culture and produced tumors in nude athymic mice. In addition, IC-2G559 and IC-2V814 cells showed a more mature phenotype compared with the phenotype of the original IC-2 cells, especially after transplantation into nude mice. The number of basophilic granules and the content of histamine increased remarkably. KITG559 and KITV814 also influenced the transcriptional phenotype of mouse mast cell proteases (MMCP) in IC-2 cells. The expression of MMCP-2, MMCP-4, and MMCP-6 was much greater in IC-2G559 and IC-2V814 cells than in the original IC-2 cells. The results indicated that constitutively activated KIT had not only oncogenic activity but also differentiation-inducing activity in mast cells.
c-kit受体酪氨酸激酶（KIT）的两种突变，缬氨酸559突变为甘氨酸（G559）和天冬氨酸814突变为缬氨酸（V814），导致其组成性激活。为了检测突变型KIT的转化和诱导分化潜能，我们使用了依赖小鼠白细胞介素-3的IC-2肥大细胞系作为转染细胞。IC-2细胞含有的嗜碱性颗粒很少，且表面不表达KIT。使用逆转录病毒载体将KITG559或KITV814基因导入IC-2细胞。在IC-2细胞中表达的KITG559和KITV814在酪氨酸上组成性磷酸化，并且在没有作为KIT配体的干细胞因子的情况下表现出激酶活性。表达KITG559或KITV814的IC-2细胞（IC-2G559或IC-2V814细胞）在悬浮培养中表现出不依赖因子的生长，并在无胸腺裸鼠中产生肿瘤。此外，与原始IC-2细胞的表型相比，IC-2G559和IC-2V814细胞表现出更成熟的表型，尤其是在移植到裸鼠体内后。嗜碱性颗粒的数量和组胺的含量显著增加。KITG559和KITV814也影响IC-2细胞中小鼠肥大细胞蛋白酶（MMCP）的转录表型。MMCP-2、MMCP-4和MMCP-6在IC-2G559和IC-2V814细胞中的表达比在原始IC-2细胞中高得多。结果表明，组成性激活的KIT在肥大细胞中不仅具有致癌活性，还具有诱导分化活性。
