cDNA microarray study to identify expression changes relevant for apoptosis in K562 cells co-treated with amifostine and imatinib.
PURPOSE: Chronic myeloid leukemia is a clonal myeloproliferative disorder characterized by the presence of the fusion gene BCR/ABL. We had previously demonstrated an increased proapoptotic effect of imatinib (STI571) in combination with amifostine (AMI) in K562 cell line. In this study, we used genomic scale gene expression profiling to monitor changes at transcriptional level in K562 cells during the treatment with AMI + STI571. MATERIALS AND METHODS: cRNA from Control and treated K562 cells were mixed in equal amounts and incubated with a microarray slide for hybridization. RNA from six independent paired experiments was subjected to transcriptional profiling. With the aim to automate the process of biological theme determination, selected genes were further analyzed by EASE. Validation of the expression was carried out by quantitative real-time PCR and western blotting. RESULTS: As expected, a small percentage of genes accounts for the effects of the combined drug treatment. We identified 61 sequences corresponding to known genes; 17 of the 61 genes were up regulated, such as RHO6, PPP2R5E, PPM1E and BTF that appear to reflect favorable events for apoptosis induction. Between down regulated genes, API5, TUBB2 and TLK1 are also of considerable interest. CONCLUSION: We identified a transcriptional repressor of survival genes, known as BTF, which triggers a proapoptotic signal, potentially helpful to overcome the resistance to STI571. This finding could be particularly useful to design novel therapeutic strategies for leukemia patients. This study demonstrates the importance of in vitro testing of a novel drug combination most likely to predict its potential usefulness for in vivo application.