Homoharringtonine contributes to imatinib sensitivity in chronic myeloid leukemia cell lines / 中国肿瘤临床

ABSTRACT

Objective: To investigate the mechanism responsible for homoharringtonine (HHT), which contributes to imatinib (IM) sensitivity in the chronic myeloid leukemia (CML) cell line. Methods:We established cell lines from a patient with CML at the time of first diagnosis and relapse phase, and designated the cell lines as NPHA1 and NPHA2, respectively. Stable underexpressed EphB4 cells (NPHA2-EphB4-sh) were obtained. Leukemia cell lines were incubated with HHT. The activated signal proteins in cells were tested by Western blot. Results:EphB4 was overexpressed in IM-resistant NPHA2 compared with the NPHA1 cell line. However, the expression of EphB4 mRNA and protein were significantly decreased in knockdown NPHA2-EphB4-sh cells compared with the NPHA2 and NPHA1 (P<0.001) cell lines. NPHA2-EphB4-sh cells were sensitive to IM (IC50:0.93 mg/L), and NPHA2 showed IM re-sistance (IC50 : 5.45 mg/L) (P<0.001). However, co-stimulation with HHT+IM decreased IC50 of NPHA2 cells to 1.17 mg/L (P<0.001). Meanwhile, phospho-Rac1/cdc42 was significantly increased in NPHA2 cells compared with NPHA2-EphB4-sh (P<0.001). HHT blocked the expression of EphB4/RhoA. Conclusion: The overexpression of EphB4 contributed to IM resistance in CML line cells. EphB4/RhoA may be a new marker of IM resistance. HHT with IM yielded more treatment advantages than IM alone by blocking EphB4/RhoA pathways.