Effective targeting of chronic Myeloid Leukemia stem cells using a combination of Arsenic Trioxide and Interferon Alpha

Abstract

Background and Objectives: Chronic myeloid leukemia (CML) is a clonal myeloproliferative stem cell disorder that results from a reciprocal translocation between chromosomes 9 and 22 coding for a constitutively active tyrosine kinase (BCR-ABL). Nowadays treatment involves the utilization of tyrosine kinase inhibitors (TKIs) that have succeeded in prolonging the life of CML patients without offering a cure.Arsenic trioxide, an ancient remedy, has recently gained attention in the treatment of hematologic disorders including acute promyelocytic leukemia (APL). Interferon alpha was formerly used to treat CML patients prior to the development of TKIs and was shown to induce hematologic and cytogenetic remission. Both arsenic and interferon have been shown separately to be effective against CML cells in culture and in vivo. The aim of or study is to demonstrate the anti-leukemic effect of the combination of arsenic and interferon on CML cell lines AR230 and K562 and their imatinib-resistant counterpart (AR230-R and K562-R).Design and Methods: Cells were treated with arsenic, interferon or their combination. Cell viability was determined using Trypan blue exclusion assay. The effect on cell growth was determined by MTT assay. Cell cycle analysis was performed by propidium iodide staining, and apoptosis was determined by measurement of pre-G0-G1 DNA content, PARP cleavage and using Rhodamine 123 staining to show decreased mitochondrial membrane potential. Finally, the effect of treatment on the level and activity of BCR-ABL was evaluated by western blot.Results: Combined arsenic and Interferon treatment resulted in inhibition of proliferation, increase cell death and activation of apoptosis as evidenced by PARP cleavage and decrease in mitochondrial membrane potential. No significant change in cell cycle distribution was noted with arsenic-interferon combination. No significant inhibition, neither of the levels nor of the activity, of BCR-ABL was noted.Discussion and Conclusion: The combination of arsenic and interferon was