力达霉素对碱性成纤维细胞生长因子诱导的肿瘤细胞PKC活性的抑制

目的研究和探讨力达霉素对碱性成纤维细胞生长因子(bFGF)诱导的癌细胞中信号转导的抑制作用。方法MTT法检测LDM和阿霉素(ADR)对3种人癌细胞系的增殖抑制作用。受体结合实验检测LDM对bFGF与其受体结合的作用。Western blotting检测bFGF受体复合物的形成，流式细胞测定细胞内Ca²⁺的流动，免疫印迹法测定bFGF所诱导的3种PKC亚型的活性。结果MTT法实验结果，LDM在体外对3种人癌细胞均显示出强烈的增殖抑制作用。按IC₅₀值进行比较表明，LDM的活性比ADR强1 000倍以上。LDM抑制［¹²⁵I］-bFGF对大鼠肺细胞膜受体的IC₅₀为2.0×10^-4 nmol·L^-1。LDM能阻碍bFGF与其受体复合物的形成，LDM (10 nmol·L^-1)预孵育2 h可阻止bFGF诱导的细胞内Ca²⁺效应。免疫印迹法证明，LDM可抑制bFGF诱导的癌细胞的3种PKC亚型的活性。结论力达霉素抗肿瘤作用的机制之一可能是通过阻断bFGF受体的信号转导途径。

Lidamycin inhibits the cancer cell PKC activity induced by basic fibroblast growth factor

AIM: To study the mechanism of inhibition of basic fibroblast growth factor (bFGF) related signal transduction by lidamycin in cancer cells. METHODS: MTT assay was used to determine the growth inhibitory effect of lidamycin (LDM) and adriamycin (ADR) in several cancer cell lines. The inhibition of bFGF bound to its receptor by LDM was measured with 125I]-bFGF binding assay. Intracellular Ca2+ stimulated by bFGF was measured by Fura-3. The formation of bFGF-receptor immune complex and the inhibitory effect of LDM on the activity of PKC isoenzymes induced by bFGF in cancer cells were identified by Western blotting analysis. RESULTS: LDM displayed extremely potent growth inhibitory effect on several cancer cell lines in a dose-dependent manner. A comparison of the IC50 values showed that the effect of LDM was 1000-fold more potent than that of ADR. LDM blocked the specific binding of 125I]-bFGF to rat lung membranes with an IC50 value of 2.0 x 10(-4) nmol x L(-1). As detected by anti-FGFR specific antibody, LDM inhibited the formation of bFGF-receptor immune complex. bFGF induced cytosolic Ca2+ response was obstructed by pretreatment with 10 nmol x L(-1) LDM. Immunoblotting demonstrated that LDM inhibited the activity of PKC isoenzymes in cancer cells stimulated with bFGF. CONCLUSION: The blocking of bFGF receptors in the signal transduction pathway may be involved in the effect of LDM on cancer cells.