OBJECTIVETo investigate the adaptor protein CRKL phosphorylation level (p-CRKL) and its significance in chronic myeloid leukemia (CML) treated with imatinib.

METHODSABL kinase domain was amplified by nested RT-PCR, domain point mutations analysis by direct sequencing, BCR-ABL mRNA level by real time-PCR, and p-CRKL level by flow cytometry in 52 bone marrow samples from 35 CML patients, and the relationship of p-CRKL level with ABL kinase domain mutation and with BCR-ABL mRNA level was analyzed.

RESULTSIn the 15 imatinib-resistant patients, ABL domain point mutations were detected in 6 with 4 types of nucleotide substitutions: T315I (n = 3), Y253H (n = 1), E255K and F317L. The incidence of mutations in disease chronic phase (CP), accelerated phase (AP) and blast phase (BP) was 25.00%, 40.00% and 30.00%, respectively. The BCR-ABL mRNA level in newly diagnosed CML was higher than that in imatinib-responded patients (P = 0.01); and so did in imatinib-resistant patients than in imatinib-effective patients (P = 0.03). The level of BCR-ABL mRNA was not significantly different between newly diagnosed CML and imatinib-resistant patients. p-CRKL%, MFI showed a high degree of phosphorylation in newly diagnosed CML and imatinib-resistant patients (P = 5.130; P = 3.178). The level of p-CRKL % and MFI in newly diagnosed group was higher than that in imatinib responded group (P = 0.000; P = 0.01) and also higher in imatinib-effective group than in imatinib-resistant group (P = 0.000; P = 0.02). There was a positive correlation between the level of BCR-ABL expression and p-CRKL% (and the MFI of p-CRKL) (P < 0.05).

CONCLUSIONIt seems that p-CRKL detection might be helpful in predicting imatinib treatment outcomes.