THE EFFECT OF VITAMIN E AS DIFFERENTIATION-LIKE FACTOR IN CML BLAST CRISIS K562 CELLS.

Shvachko L. P.*

ABSTRACT

Background: Chronic myelogenous leukemia (CML) is a clonal hematopoietic stem cell disorder associated with the activity of BCR-ABL fusion oncogene that arises from the reciprocal translocation t(9;22)(q34;q11). The molecular events underlying the transition from the chronic phase to the blast crisis are still poorly understood. The transcription factor C/EBP-alpha (CCAAT/enhancer-binding protein α) implicated as an inhibitor of cell proliferation and a master regulator of hematopoietc stem cell (HSC) myelopoiesis plays a critical role in granulocytic differentiation. The progression of CML to blast crisis is correlated with down-modulation of myeloid C/EBP-alpha transcription factor. Therefore, C/EBP-alpha may be considered as a putative target in differentiation therapies in myeloid leukemias as CML and AML. The aim of the study was to assess the potential of vitamin E as the possible inducer of C/EBP-alpha expression in BCR-ABL-positive chronic myelogenous blast crisis (BC-CML) K562 leukemic cells. Methods: RNA extracted from CML blast crisis K562 leukemic cells was converted to cDNA and real-time RT-PCR was performed using SYBR Green protocol with primers to C/EBP alpha and G-CSFR genes. Samples were cycled using the standard SYBR Green protocol on Q5 Bio-Rad StepOne qPCR instrument and analyzed using the comparative cycle threshold (CT) method to obtain relative mRNA expression. To analyze the modulation of expression of C/EBP alpha and G-CSFR, CML cells were incubated with 100 μM vitamin E. Results: We have not found detectable expression of C/EBP-alpha in CML blast crisis K562 cells. Upon 48-h culture with vitamin E at a dose of 100 μM, K562 cells expressed both C/EBP-alpha and G-CSFR (granulocyte colony-stimulate factor receptor) gene expression. Conclusion: Vitamin E restored the expression of C/EBP-alpha mRNA in CML blast crisis K562 cells. In this setting, G-CSFR expression in vitamin E treated K562 cells seems to point out to the activation to granulocytic differentiation. It should be further elucidated whether such effects of vitamin E on C/EBP-alpha transcription factor are direct or mediated through generation of indirectly due to antioxidant properties of vitamin E.

Keywords: C/EBP alpha and G-CSFR, CML cells.