Lahm H, Amstad P, Yilmaz A, Borbenyi Z, Wyniger J, Fischer J R, Suardet L, Givel J C, Odartchenko N
Swiss Institute for Experimental Cancer Research, Department of Cellular Biology, Epalinges, Switzerland.
Cell Growth Differ. 1995 Sep;6(9):1111-8.
Stem cell factor (SCF) is a cytokine which plays an important role in the development of precursor cells. We have investigated the expression of SCF and its receptor, the c-kit proto-oncogene, in human colorectal carcinoma cell lines. Using reverse transcription-PCR, we confirmed the expression of c-kit in two lines (LS174T and LS1034) and of SCF in 9 of 11 cell lines tested. In a Northern blot, a single transcript of 6.6 kb was detected for SCF mRNA. In addition, two lines (LS174T and HT29) synthesized SCF protein, as detected by Western blot analysis. SCF stimulated proliferation and colony formation of LS174T in a dose-dependent manner up to 160%. A half-maximal effect was obtained with about 5.5 ng/ml of SCF under both growth conditions. LS174T cells expressed the M(r) 145,000 c-kit protein on the cell surface and a neutralizing anti-c-kit mAb inhibited colony formation of LS174T by 40%. Interleukin 4 (IL-4) completely inhibited SCF-induced proliferation of LS174T cells. Interestingly, IL-4 induced an almost complete down-regulation of both c-kit and SCF expression in LS174T. Our findings suggest that in LS174T cells, an SCF-mediated autocrine loop is functional and that IL-4 down-regulates the expression of both the receptor and the ligand of this circuit.
干细胞因子（SCF）是一种在祖细胞发育中起重要作用的细胞因子。我们研究了SCF及其受体c-kit原癌基因在人结肠癌细胞系中的表达。利用逆转录-聚合酶链反应（RT-PCR），我们证实了在两个细胞系（LS174T和LS1034）中c-kit的表达，以及在11个测试细胞系中的9个中SCF的表达。在Northern印迹法中，检测到SCF mRNA有一条6.6 kb的单一转录本。此外，通过蛋白质印迹分析检测到两个细胞系（LS174T和HT29）合成了SCF蛋白。SCF以剂量依赖的方式刺激LS174T的增殖和集落形成，最高可达160%。在两种生长条件下，约5.5 ng/ml的SCF可获得半数最大效应。LS174T细胞在细胞表面表达分子量为145,000的c-kit蛋白，一种中和性抗c-kit单克隆抗体可抑制LS174T的集落形成达40%。白细胞介素4（IL-4）完全抑制SCF诱导的LS174T细胞增殖。有趣的是，IL-4几乎完全下调了LS174T中c-kit和SCF的表达。我们的研究结果表明，在LS174T细胞中，一个SCF介导的自分泌环是有功能的，并且IL-4下调了该信号通路中受体和配体的表达。
