WDR4调控慢性髓细胞白血病细胞生长和伊马替尼反应的研究

Objective: Chronic myelogenous leukemia (CML) is a hematological malignancy, which originates from hematopoietic stem cells acquiring BCR/ABL oncoprotein. Tyrosine kinase inhibitors (TKIs) have witnessed great progress of the disease treatment. However, TKI resistance and disease recurrence remain significant challenges for some CML patients. WDR4, as an important component of RNA 7-methylguanosine (m7G) methyltransferase is implicated in the development and progression of various cancers. Nevertheless, the function and mechanism of WDR4 in CML have not been reported. Therefore, the present study aims to investigate the role of WDR4 in the growth and imatinib methylate (IM) response of CML cells. Methods:(1) CD34+ stem/progenitor cells were isolated from CML patient samples and normal bone marrow samples, and then the expression of WDR4 mRNA was detected by RT-qPCR. (2) Following overexpression or silencing of WDR4 through lentiviral transduction in CML cells, the m7G modification abundance, cell growth, colony-forming cell (CFC) production, and IM sensitivity were evaluated. (3) The effect of WDR4 overexpression or silencing on the overall translation level of cells was evaluated through puromycin incorporation experiments. (4) The effect of WDR4 silencing on BCR/ABL and c-MYC was detected by Western blot, and rescue experiment was performed by overexpressing c-MYC. Results:(1) RT-qPCR showed that the expression of WDR4 in CML CD34+ cells was significantly higher than NBM CD34+ cells. (2) Overexpression of WDR4 enhanced RNA m7G modification in both K562 and BaF3-BCR/ABL cells, which significantly promoted cell proliferation and CFC, and conferred these cells IM resistance. WDR4 silencing experiments obtained opposite results. (3)The results of the puromycin incorporation experiment showed that overexpressing WDR4 significantly increased protein translation, while WDR4 silencing significantly reduced protein translation.(4) Following IM treatment in K562 and BaF3-BCR/ABL cells, WDR4 showed a dose-dependent decrease. WDR4 silencing did not affect the phosphorylation of CRKL, while triggered a decrease of c-MYC protein expression withnot affecting its mRNA expression. c-MYC overexpression significantly reversed cell growth inhibition and IM sensitization induced by WDR4 silencing. Conclusion: WDR4, a key component of m7G methyltransferase, is highly expressed in CML and modulates the growth of CML cells and their response to imatinib.