The Effort And The Molecular Mechanisms Of NPM1 Mutations In Leukemia Cells Invasion In Vitro

Nucleophosmin (NPM1) mutations have been recently identified as the most frequent genetic alteration in acute myeloid leukemia and are related with leukemogenesis. NPM1 mutations are involved in leukemogenesis by promoting cell proliferation, inhibiting cell apoptosis and suppressing cell differentiation. However, the effort of the NPM1 mutations on leukemia cell invasion has not been fully understood. To explore the role of NPM1 mutations in cell invasion, the pEGFPC1-NPM1-mA plasmid vector with NPM1 mutation A (NPM1-mA) was transfected into NIH3T3 cells, and the leukemic cells with stably expressed NPM1-mA protein were established. The cell migration assays and invasion assays were performed. In addition, the expression of MMP-2 and MMP-9 were assayed by quantitative real-time PCR and western blot. Our findings suggested that the migration and invasion of NIH3T3 cells were significantly enhanced after treated by NPM1-mA (p<0.01). Furthermore, there was a higher expression of MMP-9, but a lower expression of MMP-2 in NPM1 mA group. These results demonstrate that NPM1 mutations may promote cell invasion by enhancing the expression of MMP-9 in vitro, which should provide a better foundation for studying the effort of NPM1 mutations on leukemia cell invasion in vitro.NPM1 mutations play an important role in leukemogenesis. We have found that NPM1 mutations could involve in cell invasion by regulating the expression of MMPs. In order to explore the role of NPM1 mutations in leukemia cell invasion in vitro, the pEGFPC1-NPM1-mA plasmid vector with NPM1 mutation A (NPM1-mA) was transfected into THP-1 cells, and the leukemic cells with stably expressed NPM1-mA protein (THP-1-mA) were established. Transwell migration assays, matrigel invasion assays and cell adhesion assay were performed. In addition, the expression of MMP-2/9 and TIMP-1/2 were assayed by quantitative real-time PCR and western blot. The protein phosphorylation levels of MEK and ERK were evaluated by western blot. Our findings suggested that the invasion of THP-1 cells were significantly enhanced after treated by NPM1-mA (p<0.01). Furthermore, there were a higher expression of MMP-2, a lower expression of MMP-9 and an increased MEK and ERK protein phosphorylation levels in THP-1-mA group. These results demonstrate that NPM1 mutations may promote leukemia cell invasion by enhancing the expression of MMP-2 in vitro, and the Ras/MEK/ERK(MAPK)singnaling pathway may involve in the regulation of leukemia cell invasion.