OVER-EXPRESSION AND AMPLIFICATION OF THE CDC2 GENE IN LEUKEMIA-CELLS

The expression and structure of the cdc2 gene, one of the master regul ators of the eukaryotic cell cycle, were investigated in fresh leukaem ic cells from 51 cases of various types of leukaemia. Cdc2 mRNA transc ripts were detectable in approximately 40% (21/51) of cases by Norther n blotting. Over-expression of cdc2 mRNA as compared to normal bone ma rrow cells was noted in 10/21 cases with detectable cdc2 mRNA transcri pts. Amplification of the cdc2 gene was found in three cases. Cdc2 mRN A was over-expressed in these three cases, suggesting that gene amplif ication is a direct cause of mRNA over-expression in a subset of cases . Cell proliferative capacity was well correlated with the amount of c dc2 mRNA transcripts, i.e. H-3-thymidine incorporation was highest in cases with cdc2 mRNA over-expression and was significantly higher in c dc2-positive cases than in cdc2-negative cases. These results suggest that over-expression of CDC2, which is due to the gene amplification i n some cases, might play a role in altered growth of leukaemid cells.