Effects of SHIP Over Expression On the Invasion and Migration of K562 Cells and Its Mechanism.

The phosphatidylinositol-3 kinase (PI3K) pathway plays a central role in regulating numerous biologic processes, including survival, adhesion, migration, metabolic activity, proliferation, differentiation, and end cell activation through the generation of the potent second messenger PI-3,4,5-trisphosphate (PI-3,4,5-P(3)). The SH2 domain-containing inositol polyphosphate 5-phosphatase (SHIP) is known to play an important role in the negative regulation by PI3K-dependent signaling cascades activated by several tyrosine-kinase coupled cytokine receptors. SHIP knockout mice display myeloproliferation and hyper-responsiveness to growth factor stimulation and have short life span with myeloid cell infiltration into vital organs. We have proved SHIP inhibits growth of leukemia cells, and it may have an important role in apoptosis of leukemia cells. However, to date the role of anti-migrated effect of SHIP and its mechanism is unclear.

Based on the results of our previous studies, with different human leukemia cell lines K562 as study samples, including K562 transfected with wtSHIP (Group A), K562 transfected with muSHIP^C1076T (Group B) and K562 transfected with empty vector (Group C); Expression of SHIP at mRNA and protein level was detected by real-time PCR and Western blot, respectively; By Transwell chamber assay was used to count the numbers of Group A and Group B cells that penetrated the matrigel to the back of PVPF membrane after transfection; Primary migration associated factor FAK, p-FAK and NFκB were screened by Western blot. The expression of MMP-2 and MMP-9 was examined by zymography.

Compared with Group C and Group B, the migration of Group A cells was decreased (32±6 vs 78±13 and 83±16)(P<0.01); Over expression of wild-type SHIP does not affect the MMP2 secretion in K562, but site-directed mutant in C terminus of SHIP can significantly block MMP-9 secretion in K562 cells, By Western blot analysis, the expression of p-FAK and NFκB protein in Group A cells were down-regulated to 44% and 63% of the Group C, respectively.

The results confirmed SHIP as a negative regulator for cell migration and invasion in bcr/abl transformed cells through decreasing the MMP-9 expression, which may be induced by reduced phopha-FAK and NFαB expression, and implied that it may function through its PXXP domain.

No relevant conflicts of interest to declare.