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

生长因子可以增强肿瘤细胞的恶性潜能。为了研究表皮生长因子（EGF）对人口腔鳞状细胞癌侵袭和转移的影响，我们利用从Ca9-22细胞系获得的EGF敏感的S-1克隆细胞系，检测了egp诱导的细胞间信号转导。经EGF处理的S-1细胞受到一些阻断化学物质的影响，并通过吞噬动力学径迹法检测随机运动的调节。当细胞用erb抑素类似物处理时；抑制酪氨酸磷酸化，或抑制磷脂酰肌醇转化，EGF增强的运动完全被抑制。当使用phorbol 12-肉豆蔻酸13-乙酸酯（PMA）刺激蛋白激酶C（PKC）时，在没有EGF的情况下，运动性的增强与EGF刺激时相似。Calphostin C是PKC激活的抑制剂，完全消除了egf诱导的运动增强。用激光共聚焦显微镜检查PKC的细胞间定位，发现EGF刺激后PKC表达增强，PKC向膜区转导。这些结果提示，EGF受体自磷酸化引起的磷脂酶C-v （PLC）的激活可能在EGF诱导细胞运动的信号转导中起重要作用。为了研究生长因子与肿瘤进展的关系，我们事先从雌性SHR大鼠乳腺癌细胞系中建立了弱恶性细胞系ER-1。我们发现24小时暴露于ER-1 celisto EGF诱导的恶性特性是可逆的，但暴露1个月后，这些变化是不可逆的。长期EGE刺激后，ER-I细胞DNA指纹图谱出现异常条带。这些结果表明，长期EF刺激可以影响ER-I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.