Abstract: AimTo study the mechanism of inhibition of basic fibroblast growth factor (bFGF) related signal transduction by lidamycin in cancer cells. MethodsMTT 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. ResultsLDM 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 1 000-fold more potent than that of ADR. LDM blocked the specific binding of ［¹²⁵I］-bFGF to rat lung membranes with an IC₅₀ value of 2.0×10^-4 nmol·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·L^-1 LDM. Immunoblotting demonstrated that LDM inhibited the activity of PKC isoenzymes in cancer cells stimulated with bFGF. ConclusionThe blocking of bFGF receptors in the signal transduction pathway may be involved in the effect of LDM on cancer cells.