NPM1突变基因通过MMPs参与调控白血病细胞体外侵袭

Nucleophosmin Gene Mutations Involved in Leukemic Cell Invasion through MMPs

核仁磷蛋白基因(nucleophosmin,NPM1)突变是目前急性髓系白血病(AML)中突变率最高的基因改变,在白血病的发生发展过程中发挥重要的调控作用。为探讨NPM1突变参与调控白血病髓外浸润的分子机制,将表达质粒pEGFPC1-NPM1-mA转染THP-1细胞系,筛选稳定表达NPM1突变蛋白的白血病细胞株(THP-1-mA)。利用RT-PCR及Western blot分析了THP-1-mA细胞与亲代细胞间MMP-2、MMP-9、TIMP-1、TIMP-2表达水平的差异。结果显示,具有体外高侵袭能力的THP-1-mA组细胞MMP-2的mRNA水平和蛋白水平均明显高于两对照组,而MMP-9 mRNA表达水平虽有所增高,但蛋白表达水平却明显降低。同时,与空载体转染组和未处理组细胞相比,THP-1-mA组细胞TIMP-2的mRNA水平和蛋白水平表达显著降低,差异具有统计学意义;TIMP-1表达水平无明显改变。提示MMP-2及其抑制剂TIMP-2在NPM1突变参与调控的白血病细胞髓外浸润中可能发挥重要作用。

Nucleophosmin （NPM1） mutations have been recently identified as the most frequent genetic alterations in acute myeloid leukemia and played an important role in leukemogenesis. To explore the possible molecular mechanisms of NPM1 mutations in leukemic cell invasion in vitro, the pEGFPC1-NPM 1-mA plasmid vector with NPM1 mutation A （NPMI-mA） was transfected into THP-1 cells, and the leukemic cells with stably expressed NPMI-mA protein （THP-I-mA） were established. The expression of MMP-2, MMP-9, TIMP-1 and TIMP-2 was assayed by RT-PCR and Western blot. Compared with the control groups, there was a higher expression of MMP-2 in THP-I-mA group, but a lower expression of MMP-9. At the same time, in THP-l-mA group, the levels of TIMP-2 mRNA and protein were significantly decreased, while the expression of TIMP-I mRNA and protein was similar to the cells in the control groups. So our findings suggest that MMP-2 and its inhibitor TIMP-2 may play a key role in extramedullary infiltration of leukemic cells with NPMI mutations.