脐带间充质干细胞增强伊马替尼诱导慢性粒细胞白血病细胞的凋亡

Umbilical cord mesenchymal stem cells enhance imatinib-induced apoptosis in chronic myeloid leukemia

背景:伊马替尼对慢性粒细胞白血病疗效显著,但仍有部分患者对其敏感性较低。人间充质干细胞影响多种血液系统肿瘤的凋亡,但人脐带间充质干细胞是否影响伊马替尼诱导的慢性粒细胞白血病细胞的凋亡的相关研究未见报道。目的:研究人脐带间充质干细胞与伊马替尼联合应用对慢性粒细胞白血病细胞K562细胞凋亡的影响并探讨作用机制。方法:K562细胞与人脐带间充质干细胞和/或伊马替尼共培养。(1)分离培养人脐带间充质干细胞并鉴定;(2)应用流式细胞仪Annexin V-FITC/PI双标法检测细胞凋亡率;(3)Western blot检测凋亡信号通路相关蛋白Bax,Bcl-2,caspase-9,caspase-3,PARP在K562细胞的表达;(4)应用泛caspase抑制剂Z-VAD-FMK抑制caspase信号通路活性,检测caspase凋亡信号通路在人脐带间充质干细胞联合伊马替尼诱导K562细胞凋亡中的作用。结果与结论:(1)体外细胞凋亡实验证实:当人脐带间充质干细胞联合伊马替尼时,K562细胞凋亡率显著增加;(2)Western blot实验证明,当人脐带间充质干细胞联合伊马替尼时,促凋亡蛋白Bax表达升高,抑凋亡蛋白Bcl-2表达降低,caspase凋亡信号通路相关蛋白剪切体形式cleaved-caspase3、cleaved-caspase9及cleaved-PARP均表达升高;(3)泛caspase抑制剂Z-VAD-FMK显著抑制人脐带间充质干细胞和伊马替尼联合应用实验组中K562细胞的凋亡;(4)结果表明,人脐带间充质干细胞联合伊马替尼可促进慢性粒细胞白血病细胞的凋亡,其作用机制是通过激活caspase凋亡信号通路实现的。

BACKGROUND:Imatinib has a significant pro-apoptosis effect on chronic myelogenous leukemia(CML),but there are still some patients being resistant to it.Human umbilical cord mesenchymal stem cells(hUC-MSCs)affect the apoptosis of a variety of hematologic malignancies.However,the impacts of hUC-MSCs on the apoptosis of CML cells induced by imatinib remain unclear.OBJECTIVE:To investigate whether hUC-MSCs have an influence on the apoptosis of K562cells induced by imatinib and to reveal the possible underlying mechanism.METHODS:K562cells were cultured with hUC-MSCs or/and imatinib.Cellular apoptosis was measured with Annexin-V and PI staining by flow cytometry analysis.The protein expressions of Bax,Bcl-2,caspase-3,caspase-9and cleaved-PARP in K562cells were detected by western blot assay.Pan-caspase inhibitor Z-VAD-FMK was used to block apoptosis in each group,and during this process the effect of caspase apoptosis signaling pathway was detected.RESULTS AND CONCLUSION:The apoptosis of K562cells was enhanced,when imatinib was combined with hUC-MSCs.Western blot analysis showed that the expression of pro-apoptotic protein Bax was enhenced and the expression of anti-apoptotic protein Bcl-2was suppressed.Furthermore,the cleaved forms of caspase-9,caspase-3and PARP in K562cell were higher in the hUC-MSCs+imatinib group than in the imatinib group.The apoptosis of K562cells induced by the hUC-MSCs combined with imatinib was significantly inhibited by Z-VAD-FMK.In conclusion,these findings indicate that hUC-MSCs can enhance imatinib-induced apoptosis of K562cells by activating caspase apoptosis signaling pathway.