Expression of SOCS3 mRNA in bone marrow cells from CML patients associated with cytogenetic response to IFN-α

Previously, we have demonstrated that constitutive expression of suppressor of cytokine signaling-3 (SOCS3) affects the sensitivity of chronic myelogenous leukemia (CML) cell lines to interferon-α (IFN-α). In the present study, we analyzed the expression of SOCS3 mRNA in bone marrow cells from patients with CML at diagnosis, with the aid of real-time polymerase chain reaction. SOCS3 mRNA expression in bone marrow cells from CML patients who responded well to IFN-α therapy was significantly lower than that in cells from healthy volunteers and patients who were resistant to IFN-α therapy. Methylation of SOCS3 promoter was absent in bone marrow cells from all CML patients examined. These results indicate that the expression of SOCS3 mRNA is inversely associated with the sensitivity to IFN-α both in vitro and in vivo and that differences in SOCS3 mRNA expression are not due to the methylation status of SOCS3 promoters.