Zushi S, Shinomura Y, Kiyohara T, Miyazaki Y, Tsutsui S, Sugimachi M, Higashimoto Y, Kanayama S, Matsuzawa Y
Second Department of Internal Medicine, Osaka University Medical School, Suita, Japan.
Int J Cancer. 1997 Dec 10;73(6):917-23. doi: 10.1002/(sici)1097-0215(19971210)73:6<917::aid-ijc26>3.0.co;2-#.
The ras mutation is a common and critical step in carcinogenesis. Autocrine growth factors are also known to play an important role in cancer cell growth and transformation. However, the contribution of autocrine growth factors in regulation of proliferation and apoptosis of activated ras-stimulated intestinal epithelium is not fully understood. Therefore, we constructed activated ras-transfected intestinal epithelial cell clones (IEC-ras) to examine the role of epidermal growth factor (EGF)-related peptides in the behavior of IEC-ras. Overexpression of EGF family growth factors (transforming growth factor alpha, heparin-binding EGF-like growth factor, amphiregulin and betacellulin) and stronger phosphorylation of the EGF receptor was observed in IEC-ras compared with control cells. IEC-ras proliferated more rapidly than control cells, and a specific EGF receptor kinase inhibitor, AG 1478, abolished the increased proliferation of IEC-ras. Heparitinase and chlorate also prevented increased proliferation of IEC-ras. Additionally, IEC-ras expressed more bcl-2 and was more resistant to apoptosis induction by UV radiation and mitomycin C. AG 1478 suppressed bcl-2 expression and inhibited resistance to apoptosis of IEC-ras. Heparitinase and chlorate had effects similar to those of AG 1478. Our data indicate that heparin-binding EGF family growth factors play an important role in both increased proliferation and resistance to apoptosis of ras-stimulated intestinal epithelial cells.
Ras突变是致癌过程中常见且关键的一步。自分泌生长因子在癌细胞生长和转化中也起着重要作用。然而，自分泌生长因子在活化的Ras刺激的肠上皮细胞增殖和凋亡调节中的作用尚未完全明确。因此，我们构建了转染活化Ras的肠上皮细胞克隆（IEC-Ras），以研究表皮生长因子（EGF）相关肽在IEC-Ras细胞行为中的作用。与对照细胞相比，在IEC-Ras细胞中观察到EGF家族生长因子（转化生长因子α、肝素结合表皮生长因子样生长因子、双调蛋白和β细胞素）的过表达以及更强的EGF受体磷酸化。IEC-Ras细胞比对照细胞增殖更快，一种特异性的EGF受体激酶抑制剂AG 1478可消除IEC-Ras细胞增殖的增加。肝素酶和氯酸盐也可阻止IEC-Ras细胞增殖增加。此外，IEC-Ras细胞表达更多的bcl-2，对紫外线辐射和丝裂霉素C诱导的凋亡更具抗性。AG 1478可抑制bcl-2表达并抑制IEC-Ras细胞的抗凋亡能力。肝素酶和氯酸盐具有与AG 1478类似的作用。我们的数据表明，肝素结合EGF家族生长因子在Ras刺激的肠上皮细胞增殖增加和抗凋亡中均起重要作用。
