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Background and Objective: The hemopoietic-restricted Src homology 2-containing inositol 5'-phosphatase (SHIP) acts as a negative regulator for the proliferation and survival of hematopoietic cells by hydrolysing the phosphoinositide 3-kinase (PI3K)-generated second messenger, PtdIns(3,4,5)-P3 (PI-3,4,5-P3) to PtdIns(3,4)-P2 (PI-3,4-P2). This study was to investigate the biological function of SHIP gene in pathogenesis of leukemia cells by lentiviral vector-mediated SHIP transfection., Methods: Ectopic SHIP gene was transfected into leukemia K562 cells by the mediation of lentiviral vector. The mRNA level of SHIP was detected by fluorescent quantitative reverse transcription-polymerase chain reaction (FQ-PCR). The expression of SHIP, Akt, and phosphorylated Akt (p-Akt) was detected by Western blot. The proliferation and morphology of K562 cells before and after SHIP gene transfection were compared., Results: The proliferation of K562 cells was inhibited after transfection: the proliferation inhibition rate was increased from (9.9+/-1.5)% on Day 3 to (40.6+/-2.3)% on Day 5. K562 cells were SHIP-negative but expressed high level of p-Akt which was down-regulated from 0.533 to 0.245 (P<0.01) after SHIP transfection. Apoptotic characteristics were showed in K562 cells after SHIP transfection. The early apoptosis rate was significantly higher in K562-wtSHIP-FIV-G cells than in K562-FIV-G cells and untransfected K562 cells [(38.3+/-4.3)% vs. (8.2+/-0.9)% and (7.7+/-0.8)%, P<0.05]., Conclusions: SHIP gene can inhibit cell proliferation and promote cell apoptosis via inactivating PI3K/Akt pathway. Loss of SHIP might activate PI3K/Akt pathway and promote the proliferation of K562 cells.

Background and Objective: Inducing gene demethylation may be a mechanism of arsenic trioxide (As(2)O(3)) in treating hematologic cancers. This study was to investigate the effect of As(2)O(3) on demethylation of SH2-containing phosphatase-1 (SHP-1) in human lymphoma cell line T2 and on the proliferation of T2 cells., Methods: T2 cells were treated with As(2)O(3) and 5-aza-2'-deoxyoytidine (5-AC) alone or in combination. The methylation of SHP-1 in T2 cells was detected by methylation-specific polymerase chain reaction (MSP). The mRNA and protein expression of SHP-1 were determined by fluorescence quantitative-polymerase chain reaction (FQ-PCR) and Western blot. The expression of p-c-kit was detected by Western blot. Cell proliferation was detected by MTT assay. Cell apoptosis was detected by flow cytometry., Results: As(2)O(3) led to progressive demethylation and re-expression of SHP-1 in T2 cells, as well as down-regulation of phosphorylated c-kit. As(2)O(3) inhibited the proliferation and promoted the apoptosis of T2 cells, and its effects were enhanced along with the increase of concentration and treatment time (p<0.05). The proliferation inhibition rates were significantly lower in As(2)O(3) (2.5 micromol/L) group than in combination (2.5 micromol/L As(2)O(3) plus 2 micromol/L 5-AC) group (9.8% vs. 11.0%on Day 1, 20.3% vs. 36.7% on Day 2, 47.5% vs. 61.0% on Day 3, p<0.05). The apoptosis rates were significantly higher in combination group than in As(2)O(3) group (17.3% vs. 6.1% on Day 1, 37.9% vs. 26.5% on Day 2, 67.9% vs. 50.9% on Day 3, p<0.05)., Conclusions: As(2)O(3) could cause demethylation and re-expression of SHP-1 in T2 cells, and may inhibit proliferation and induce apoptosis of T2 cells via suppressing activation of c-kit receptor and its signal transduction.