AIM:Many growth factors,such as epidermal growth factor(EGF),are associated with the carcinogenesis.EGF plays itsrole in the proliferation of hepatoma ceils through bindingwith EGF receptor(EGFR)and a series of signal transduction.But the postreceptor pathway is still not clear.In the presentexperiment,we studied the effect of tyrosine kinase,proteinkinase C,Na~+/H~+ exchange,calmodulin and voltage-dependent Ca~(2+)channel on EGF-induced hepatoma cellproliferation.METHODS:Hepatoma cell line SMMC7721 was cultured inRPMI1640 serum-free medium.In order to study the effectof thyrosine kinase,protein kinase C,Na~+/H~+ exchange,calmodulin and voltage-dependent Ca~(2+)channel on humanheptoma cell proliferation induced by epidermal growth factor(EGF),DNA synthesis rate of hepatoma cells was measuredby the method of ~3H-TdR incorporation.RESULTS:EGF(10~(-9)M)stimulated the proliferation of heptomacells significantly(~3H-TdR incorporation was 1 880±281 cpm/well,P<0.05),and this effect was significantly inhibited bytyrosine kinase inhibitor genistein(~3H-TdR incorporation was808±209 cpm/well,P<0.001).Calmodulin inhibitor W-7,proteinkinase C inhibitor H-7 and Na~+/H~+ exchange inhibitor amilorideindividually had significant inhibiting effect on EGF-inducedproliferation of hepatoma cells(~3H-TdR incorporation was978±87.3 cpm/well,1 241±147 cpm/well,1 380±189 cpm/well,respectivly,P<0.001,P<0.01,P<0.05),but they allhad no effect on the basal level proliferation of culturedhepatoma cells(~3H-TdR incorporation was 1 284±260 cpm/well,1 179±150 cpm/well,1 392±152 cpm/well,respectivly,~3H-TdR incorporation of the control was 1 353±175 cpm/well,P>0.05).Voltage-dependent Ca~(2+)channel inhibitorverapamil had no inhibition on EGF-induced proliferation ofhepatoma cells(~3H-TdR incorporation was 1 637±133 cpm/well,P>0.05),it also had no effect on the basal levelproliferation of cultured hepatoma cells(~3H-TdR incorporationwas 1 196±112 cpm/well,P>0.05).CONCLUSION:Our data suggest that tyrosine kinase,Ca~(2+)-calmodulin-dependent pathway,protein kinase C and Na~+/ H~+ exchange play a critical role in EGF-induced proliferationof hepatoma cells and that the effect of EGF is independentof voltage-dependent Ca~(2+)channel. AIM: Many growth factors, such as epidermal growth factor (EGF), are associated with the carcinogenesis. EGF plays its blood in the proliferation of hepatoma ceils through binding with EGF receptor (EGFR) and a series of signal transduction. But the postreceptor pathway is still not clear.In the presentexperiment, we studied the effect of tyrosine kinase, proteinkinase C, Na ~ + / H ~ + exchange, calmodulin and voltage-dependent Ca 2+ channel on EGF-induced hepatoma cellproliferation.METHODS: Hepatoma cell line SMMC7721 was cultured in RPMI1640 serum-free medium. In order to study the effect of thyrosine kinase, protein kinase C, Na ~ + / H ~ + exchange, calmodulin and voltage-dependent Ca 2+ channel on humanheptoma cell proliferation induced by epidermal growth factor (EGF), DNA synthesis rate of hepatoma cells was measured by the method of ~ 3H-TdR incorporation. RESULTS: EGF (10-9 (-9) M) stimulated the proliferation of heptomacells significantly 880 ± 281 cpm / well, P <0.05), and this effect was signi ficantly inhibited by tyrosine kinase inhibitor genistein (~ 3H-TdR incorporation was808 ± 209 cpm / well, P <0.001) .Calmodulin inhibitor W-7, proteinkinase C inhibitor H-7 and Na ~ + / H ~ + exchange inhibitor amilorideindivntly had only significant effect on EGF-inducedproliferation of hepatoma cells (~ 3H-TdR incorporation was978 ± 87.3 cpm / well, 1 241 ± 147 cpm / well, 1 380 ± 189 cpm / well, respectivly, P <0.001, P <0.01, P <0.05 ), but they allhad no effect on the basal level proliferation of cultured hepatoma cells (~ 3H-TdR incorporation was 1 284 ± 260 cpm / well, 1 179 ± 150 cpm / well, 1 392 ± 152 cpm / well, respectivly, ~ 3H -TdR incorporation of the control was 1 353 ± 175 cpm / well, P> 0.05) .Voltage-dependent Ca 2+ channel inhibitor of pamil had no inhibition on EGF-induced proliferation of hepatoma cells (~ 3H-TdR incorporation was 1 637 ± 133 cpm / well, P> 0.05), it also had no effect on the basal level protolution of cultured hepatoma cells (~ 3H-TdR incorporation was 1 196 ± 112 cpm / well, P> 0.05) that tyrosine kinase, Ca ~ (2 +) - calmodulin-dependent pathway, protein kinase C and Na ~ + / H ~ + exchange play a critical role in EGF-induced proliferation of hepatoma cells and that the effect of EGF is independent of voltage-dependent Ca ~ (2+) channel.