Knockdown of SOD1 sensitizes the CD34+ CML cells to imatinib therapy.

Leukemia stem cell is thought to be one of the leading causes of imatinib resistance and the resultant relapse of chronic myelogenous leukemia (CML). Eradicating the leukemia stem cells holds the promise of CML treatment. In this study, we found that the CD34+ subpopulation in the CML cell line K562 had a higher expression of SOD1 than that in the CD34 negative cells. Knockdown of SOD1 in CD34+ cells had no significant effects on cell survival and growth, while it sensitized the CD34+ cells to imatinib therapy. N-acetyl-L cysteine (NAC) blocked the pro-apoptotic effects of SOD1 knockdown, suggesting the antioxidant effects of SOD1 was essential for the resistance of CD34+ cells to imatinib therapy. In summary, our results suggest that antagonizing the enhanced endogenous antioxidant activity in leukemia stem cells sheds lights on CML therapy.