Although leukaemic subtypes with poor prognosis have a decreased tendency to undergo apoptosis, gene-expression-profiling studies have identified few differentially expressed apoptosis genes. William Evans, Rob Pieters and colleagues therefore analysed the expression of 70 key apoptosis genes in leukaemic cells taken from 190 children with acute lymphoblastic leukaemia (ALL).
The authors found differences between the expression profiles of ALL subtypes: 44 genes were differentially expressed in T-lineage versus B-lineage ALL, 22 genes differed in hyperdiploid versus non-hyperdiploid B-lineage ALL, 16 genes differed in TEL–AML1+ versus TEL–AML1− B-lineage ALL, and 13 genes differed in E2A-rearranged versus E2A-germline B-lineage ALL. Next, they looked at the differences in expression of apoptotic genes between drug-sensitive and -resistant patients in the B-lineage ALL group. Although no probe sets were associated with resistance to vincristine or daunorubicin, MCL1 and DAPK1 were associated with prednisolone resistance, and BCL2L13, HRK and TNF were associated with resistance to L-asparaginase.
