ABSTRACT
Background: Chronic myeloid leukemia (CML) is a hematological disorder caused by fusion of BCR and ABL genes. BCR-ABL dependent and independent pathways play equally important role in CML. TGFß-Smad pathway, an important BCR -ABL independent pathway, has scarce data in CML. Present study investigate the association between TGFß-Smad pathway and CML. Materials and Methods: Sixty-four CML patients and age matched healthy controls (n=63) were enrolled in this study. Patients were segregated into responder and resistant groups depending on their response to Imatinib mesylate (IM). TGFß1 serum levels were evaluated by ELISA and transcript levels of TGFß1 receptors, SMAD4 and SMAD7 were evaluated by Real-Time PCR. Sequencing of exons and exon-intron boundaries of study genes was performed using Next Generation Sequencing (NGS) in 20 CML patients. Statistical analysis was performed using SPSS version 16.0. Results:TGFß1 serum levels were significantly elevated (p = 0.02) and TGFßR2 and SMAD4 were significantly down-regulated (p = 0.012 and p = 0.043 respectively) in the patients. c.69A>G in TGFß1, c.1024+24G>A in TGFßR1 and g.46474746C>T in SMAD7 were the most important genetic variants observed with their presence in 10/20, 8/20 and 7/20 patients respectively. In addition, TGFßR1 transcript levels were reduced in CML patients with c.69A>G mutation. None of the genes differed significantly in terms of expression or genetic variants between responder and resistant patient groups. Conclusion: Our findings demonstrate the role of differential expression and genetic variants of TGFß-Smad pathway in CML. Decreased TGFßR2 and SMAD4 levels observed in the present study may be responsible for reduced tumor suppressive effects of this pathway in CML.
