Study of the effects of epidermal growth factor on genomic instability and malignant phenotype of oral squamous cell carcinoma cells

生长因子可增强肿瘤细胞的恶性潜能。为研究表皮生长因子（EGF）对人口腔鳞癌侵袭和转移的影响，我们从人口腔鳞癌细胞系Ca 9 -22中分离出一株EGF敏感的S-1细胞系，用细胞内信号转导的方法研究EGF诱导的运动性。EGF处理的S-1细胞被某些阻断剂所影响，用吞噬动力追踪法检测细胞随机运动的调节作用，当细胞被抑制酪氨酸磷酸化的erbstatin类似物或抑制磷脂酰肌醇转换的psi-tectorigenin处理时，EGF增强的运动被完全抑制。当使用佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA）刺激蛋白激酶C（PKC）时，在没有EGF的情况下运动性增强，类似于EGF刺激。钙磷蛋白C，PKC激活的抑制剂，完全消除EGF诱导的运动增强。用激光共聚焦显微镜观察PKC在细胞内的定位，发现EGF刺激后，PKC表达增强，并向膜区转导。为探讨生长因子与肿瘤发生发展的关系，我们从雌性SHR大鼠乳腺癌细胞系ER-1中建立了一株弱恶性细胞系ER-1。我们发现，24小时暴露的ER-1细胞表皮生长因子诱导的恶性性质是可逆的，但在1个月的暴露后，这些变化是不可逆的。在DNA指纹图谱中，EGE长期刺激后ER-1细胞出现异常条带。这些结果表明，长期EF刺激可以影响ER-1细胞的基因组不稳定性。

Growth factors can enhance the malignant potential of tumor cells. To study the effects of epidermal growth factor(EGF) on invasion and metastasis of human oral squamous cell carcinoma, we examined the intercellular signal transduction of EGP-induced motility using an EGF sensitive S-1 clone cell line, obtained from Ca9-22 cell line. EGF -treatde S-1 cells were affected some blocking chemicals, and moduration of random motility was examined by phagokinetic track assay.When the cells were treated with erbstatin analog; to inhibit tyrosine phosphorylation, or psi-tectorigenin to inhibit phosphatidyl-inositol turnover the motility enhanced by EGF was completely inhibited. When phorbol 12-myristate 13-acetate(PMA) was used, to stimulate protein kinase C(PKC), motility in the absence of EGF was enhanced similar to that of EGF stimulation. Calphostin C, an inhibitor of PKC activation, completely eliminated the EGF-induced enhancement of motility. Examination of the intercellularlocalization of PKC with a confocal laser microscope showed enhanced expression of PKC and transduction of PKC to membrane area after EGF stimulation. These results suggest that activation of phospholipase C-v (PLC) caused by auto-phosphorylation of EGF receptor might play an important role in the signal transduction of EGF induced cell motility.To examine the relationship between growth factor and tumor progression, we pleviously established a weakly malignant cell line, ER-1, from rat mammary carcinoma cell line in female SHR rat. We found that a 24-hour exposure of ER-1 celisto EGF induced malignant properties that were reversible but that, after a 1-month exposure, these changes were irreversible. In DNA fingerprinting as abnormal bands were observed in ER-I cells after long-term EGE stimulation. These results suggest that long-term EF stimulation can affect the genomic instability of ER-I cells.