DIFFERENTIAL EXPRESSION OF CELL-PROLIFERATION REGULATORY PROTEINS IN B-LINEAGE AND T-LINEAGE ACUTE LYMPHOBLASTIC LEUKEMIAS

In order to better understand the molecular background of differences between the clinical picture of T- and B-lineage ALLs, we studied the expression of several proteins involved in the regulation of cell prol iferation in bone marrow blast cells from 30 cases of previously untre ated acute lymphoblastic leukaemia (ALL): 14 cases were T- and 16 B-ce ll lineage ALCs, We studied several cyclin-dependent kinases (cdk1, cd k2, cdk4, cdk6) and cyclins (cyclin A, cyclin B1, cyclin D3 and cyclin E). We also studied proliferating cell nuclear antigen (PCNA) and Bcl -2 expression, the Latter protein known to be involved in the prolonge d survival of B-lineage ALL blasts. Proteins obtained from cell lysate s were resolved on polyacrylamide gel followed by immunodetection and densitometry of specific bands. Expression of cdk1 and PCNA, markers o f proliferative activity, was significantly higher in T- than in B-lin eage ALL, Cdk6, which was highly correlated to PCNA, was also higher i n T-cell ALL. In contrast, B-lineage ALL displayed a higher expression of anti-apoptotic protein Bcl-2. We hypothesize that those particular ities may reflect differential roles of cell multiplication and apopto sis in the neoplastic proliferation of B- and T-lineage ALL.