OBJECTIVETo explore the effect of mutation in PxxP domain of SHIP on migration and invasion of leukemia cells and its mechanism.

METHODSThe lentiviral vector mediated wild type SHIP (wtSHIP) and mutant SHIP (muSHIP) plasmids were transfected into K562 cells through gene transfection techniques. Expression of SHIP at mRNA and protein level was detected by real-time PCR and Western blot, respectively. Transwell assay was used to analyze the difference between the migration and invasion ability of the K562/wtSHIP and the K562/muSHIP cells after transfection. Primary migration associated factor FAK, MMP and NF-κB were assayed by Western blot.

RESULTSAfter transfection, the SHIP expression in transfected K562 cells were significantly increased. Compared with the migration ability of K562/wtSHIP\[(15.8 ± 1.4)%\], that of K562/muSHIP cells \[(54.3 ± 2.4)% \] increased greatly and almost at the same level of that of K562/pFIV\[(50.3 ± 3.8)%\] (P < 0.01). The invasion assay also showed that K562/wtSHIP\[(32 ± 6)/HP\] has a lower invasion ability than that of the K562/muSHIP group \[(83 ± 16)/HP\] and K562/pFIV group \[(78 ± 13)/HP\] (P < 0.01). Western blot analysis showed that the expression of p-FAK and NF-κB was up-regulated in K562/muSHIP group compared to that of the K562/wtSHIP group.

CONCLUSIONSThe results confirmed that mutation in PxxP domain of SHIP gene played an important role in negative regulating function of SHIP gene. The mutation affects the cell migration and invasion ability through increase in MMP-9 expression, FAK phosphorylation and NF-κB activation. It suggested that the mutation of PxxP domain in SHIP gene might be pathogenic, and be one of the reasons for SHIP abnormality in leukemia.

Cell Movement ; Genetic Vectors ; Humans ; Inositol Polyphosphate 5-Phosphatases ; K562 Cells ; Leukemia ; pathology ; Mutation ; Phosphoric Monoester Hydrolases ; genetics ; Plasmids

This study was aimed to investigate the effects of bortezomib combined with 5-azacytidine on the apoptosis of K562 cells and expressiom of SHIP mRNA. The K562 cells were cultured and treated with different concentrations of bortezomib, 5-azacytidine or their combination for 24 hours. Then, the expression of SHIP mRNA was detected by RT-PCR,the cell proliferation was analyzed by using MTT assay and flow cytometry. The results showed that 5-20 nmol/L bortezomib could effectively inhibit the proliferation of K562 and this inhibitory effect gradually enhanced along with the increase of bortezomib concentration, the group of bortezomib combined with 5-azacytidine showed more inhibitory effect on K562 cells than that of bortezomib or 5-azacytidine alone.The bortezomib could promote the apoptosis of K562 cells in a dose-dependent manner,and this apoptotic effect was higher in group of bortezomib combined with 5-azacytidine than that in group of bortezomib or 5-azacytidine alone.Bortezomib could down-regulated the expression of SHIP mRNA in a dose-dependent manner,and this down-requlated effect was higher in group of bortezomib combined with 5-azacytidine than that in group of bortezomib or 5-azacytidine alone.It is concluded that bortezomib and 5-azacytidine can induce apoptosis by inhibiting the expression of SHIP mRNA in K562 cells.The combination of bortezomib with 5-azacytidine displays a synergetic effect.
Apoptosis ; drug effects ; Azacitidine ; pharmacology ; Boronic Acids ; pharmacology ; Bortezomib ; Cell Proliferation ; Humans ; Inositol Polyphosphate 5-Phosphatases ; K562 Cells ; Phosphoric Monoester Hydrolases ; genetics ; Pyrazines ; pharmacology ; RNA, Messenger ; biosynthesis

OBJECTIVETo investigate the effect of SHIP gene mutation on the cell cycle and its related gene expression in K562 cells.

METHODSThe recombined green fluorescent protein (GFP) containing FIV-SHIP gene was transfected into K562 cells. The transfection efficiency and cell cycle of K562/SHIP were assessed by flow cytometry (FCM). The proliferation of K562 cells was detected by MTT assay, the mRNA levels of SHIP by real-time fluorescent relative-quantification reverse transcriptional PCR (FQ-PCR), and the protein levels of SHIP, Cyclin D1, p21(WAF1/CIPI) and p27(KIP1) by Western blot.

RESULTSWild type SHIP inhibited K562 cell proliferation and caused a G(0)/G(1) arrest \[(34.2 +/- 7.8)% vs (0.7 +/- 8.3)% (P < 0.01)\]; while the point mutation of SHIP gene did not show such effect. Western blot results showed that the Akt phosphorylation and cyclin D1 expression was significantly decreased (P < 0.01), and the expression of p27(KIP1) and p21(WAF1/CIPI) increased. Site-directed mutation of SHIP gene SH2 domain (TTC-->CTC, Phe-->Leu) did not influence the Akt phosphorylation and cyclins (P > 0.05).

CONCLUSION(1) wtSHIP gene can down-regulate Akt phosphorylation and result in inhibition of cyclin D1 expression, up-regulating p27(KIP1) and p21(WAF1/CIPI) expression, finally leading to the reduction of K562 cell proliferation, and inducing G(0)/G(1) phase arrest. (2) SHIP gene suppresses the proliferation of K562, being dependent on its intact structure and function.

Cell Cycle Proteins ; metabolism ; Humans ; Inositol Polyphosphate 5-Phosphatases ; K562 Cells ; Mutation ; Phosphoric Monoester Hydrolases ; genetics ; Phosphorylation ; Proto-Oncogene Proteins c-akt ; metabolism ; Transfection

This study was aimed to investigate the effects of proteasome inhibitor bortezomib on proliferation, apoptosis and the SHIP expression of K562 cells. K562 cells were treated with bortezomib of different concentrations. Cell proliferation was analyzed by MTT assay, cell apoptosis was detected by flow cytometry and SHIP mRNA expression was assayed by RT-PCR.The results showed that after being treated with 10, 20, 50 and 100 nmol/L bortezomib for 24 h, the inhibitory rates of K562 cells were (5.76 ± 1.47)%, (10.55 ± 1.59)%, (17.14 ± 2.05)% and (27.69 ± 3.57)% respectively, and were higher than that in control (1.30 ± 0.10); when K562 cells were treated with 20 nmol/L bortezomib for 24, 48 and 72 h, the inhibitory rates of cell proliferation were (10.55 ± 1.59)%, (16.33 ± 2.53)% and (19.78 ± 1.56)% respectively, there was statistic difference of cell proliferation rate between 24 h group and 48 h group (P < 0.05). After being treated with 10,20,50,100 nmol/L bortezomib for 24 h, the apoptotic rates of K562 cells were (12.7 ± 0.6)%, (26.9 ± 0.9)%, (32.6 ± 1.2)% and (72.5 ± 1.5)% respectively,and all higher than that in control (1.0 ± 0.5)% (P < 0.05). According to results of RT-PCR detection, the expression level of SHIP mRNA was obviously up-regulated after treatment with bortezomib, and showed statistical difference in comparison with control. It is concluded that bortezomib inhibits proliferation of K562 cells in time and concentration-dependent manner and induces apoptosis through up-regulation of SHIP gene.
Antineoplastic Agents ; pharmacology ; Apoptosis ; drug effects ; Boronic Acids ; pharmacology ; Bortezomib ; Cell Proliferation ; drug effects ; Humans ; Inositol Polyphosphate 5-Phosphatases ; K562 Cells ; Phosphoric Monoester Hydrolases ; genetics ; metabolism ; Proteasome Inhibitors ; pharmacology ; Pyrazines ; pharmacology

The src homology 2 (SH2)-domain containing inositol-5-phosphatase (SHIP) is another recently identified lipid phosphatase after phosphatase and tensin homology deleted on chromosome ten gene (PTEN). It plays an important role in negatively regulating the proliferation of hematopoietic cells. The relationship between SHIP and the inhibition of tumor proliferation is rarely reported. The purpose of this study is to evaluate the apoptosis induced by SHIP gene in K562 cell line and to explore the involved signaling pathway. The K562 cells were transfected with human SHIP gene by using the lentiviral vector containing SHIP, and the transfection was verified by fluorescent quantitative PCR (FQ-PCR) and Western blot. Then the effects of SHIP protein expression on cell growth and apoptosis were measured. The levels of p-Akt, bcl-2 family, caspase and the activity of NFkappaB were assayed by Western blot and ELISA, respectively. The results are as follows: (1) Human leukemia cell line K562 was SHIP-negative; (2) Transfection with SHIP gene led to the re-expression of SHIP mRNA and protein in K562, as shown by FQ-PCR and Western blot; (3) The expression of SHIP protein inhibited cell growth and significantly increased apoptosis in K562 cells; (4) Compared to that in control group, the expression level of p-Akt-308 and p-Akt-473 in SHIP-expressing cell group decreased significantly (P<0.01); SHIP activated caspase-9, caspase-3, up-regulated protein levels of bad, p27, down-regulated expression of bcl-xL, while it had no effect on the expression of bcl-2 and bax. Furthermore, the inhibition of NF-kappaB was achieved along with the inactivation of Akt. These data suggest that SHIP gene has potential abilities to inhibit K562 leukemic cell proliferation and induce its apoptosis via inactivating PI3K/Akt pathway. The loss of SHIP might be the explanation of aberrant high-level p-Akt in human leukemia. It may be at least one of the mechanisms by which the loss of SHIP expression contributes to leukemia progression.
Apoptosis ; Apoptosis Regulatory Proteins ; metabolism ; Cell Proliferation ; Down-Regulation ; Genetic Vectors ; Humans ; Inositol Polyphosphate 5-Phosphatases ; K562 Cells ; NF-kappa B ; metabolism ; Phosphatidylinositol 3-Kinases ; metabolism ; Phosphoric Monoester Hydrolases ; genetics ; Proto-Oncogene Proteins c-akt ; metabolism ; Signal Transduction ; Transfection

OBJECTIVEThe SH2 domain containing inositol 5'-phosphatase (SHIP) is predominately expressed in hematopoietic cells, and is a crucial negative regulator in the development of hematopoietic cells. This paper is to evaluate the role of the SHIP gene in human leukemogenesis.

METHODSExpression of SHIP gene in bone marrow and/or peripheral blood from 32 patients with acute myeloid leukemia (AML), 9 with acute lymphoblastic leukemia (ALL), as well as human hematopoietic cell lines was analyzed by reverse transcription-polymerase chain reaction (RT-PCR), single strand conformational polymorphism (SSCP) and DNA sequencing.

RESULTSRT-PCR showed that all samples expressed SHIP gene. Mutations of SHIP gene were detected in 7 (22%) of 32 AML patients and one (12%) of 9 ALL patients. Interestingly, two missense mutations that had been observed in a AML patient at diagnosis disappeared after complete remission (CR). In addition, in vitro Akt phosphorylation was prolonged and increased following IL-3 stimulation of this patient's cells.

CONCLUSIONOur data demonstrate for the first time the mutation of SHIP gene in acute leukemia and suggest a possible role of the mutation of this gene in the development of acute leukemia. SHIP may serve as a tumor suppressor by negatively regulating the PI3K/Akt signaling pathway in hematopoietic cells.

Blotting, Western ; Cell Line, Tumor ; DNA Mutational Analysis ; HL-60 Cells ; Humans ; Inositol Polyphosphate 5-Phosphatases ; Interleukin-3 ; pharmacology ; K562 Cells ; Leukemia, Myeloid, Acute ; genetics ; metabolism ; Mutation ; Oncogene Protein v-akt ; metabolism ; Phosphoric Monoester Hydrolases ; genetics ; metabolism ; Phosphorylation ; drug effects ; Polymorphism, Single-Stranded Conformational ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; U937 Cells