Expression of Protooncogene c-kit and Its Ligand Stem Cell Factor (SCF) in Gastric Carcinoma Cell Lines

We examined 13 human gastric carcinoma celllines for the expression of both c-kit and stem cellfactor (SCF). Expression of mRNAs was detected by bothNorthern blot analysis and reversetranscriptase-polymerase chain reaction (RT-PCR), and expression oftranslated proteins was detected by western blotting.Using RT-PCR we confirmed the expression of c-kit infive (ECC12, TMK1, MKN7, GCIY, and HGC27) cell lines. Northern blot analysis showed coexpression ofboth c-kit and SCF in ECC12 and expression of SCF infive other (MKN74, MKN1 OKAJIMA, KATOIII, and TMK1) celllines. SCF stimulated both tyrosine phosphorylation of c-kit and growth of ECC12, whereas it didnot stimulate those of GCIY. The sizes of c-kittranscript and protein in GCIY were slightly smallerthan those of the reported ones, suggesting the presence of a biologically inactive truncated form ofc-kit in GCIY. The present study suggests that c-kit/SCFsystem might play an important role in thecarcinogenesis and tumor growth of ECC12 and that thetruncated form of c-kit in GCIY might not be associatedwith malignant transformation.