The SH2 domain containing inositol 5'-phosphatase (SHIP) was initially described as a 145 kD protein phosphorylated on tyrosines upon growth factor and cytokine stimulation. SHIP is predominately expressed in hematopoietic cells, and is a crucial negative regulator in the development of hematopoietic cells. To evaluate the role of the SHIP gene in human leukemogenesis, expression and mutation of SHIP gene in bone marrow and/or peripheral blood from 32 patients with acute myeloid leukemia (AML), 9 patients with acute lymphoblastic leukemia (ALL), as well as human hematopoietic cell lines were analyzed by reverse transcription-polymerase chain reaction (RT-PCR), single strand conformational polymorphism (SSCP) and sequencing. The RT-PCR showed that all samples expressed SHIP gene. Mutations of SHIP gene were detected in 7 out of 32 AML patients (22%) and one out of 9 ALL patients (12%). Interestingly, two missense mutations that had been observed in one AML patient at diagnosis disappeared after complete remission (CR). In addition, Akt phosphorylation was prolonged and increased following IL-3 stimulation in this patient sample. In conclusion, data of this study demonstrate the mutation of the SHIP gene in acute leukemia for the first time and suggest a possible role of the mutation of this gene in the development of acute leukemia. SHIP serves as a tumor suppressor by negatively regulating the PI3K/Akt signaling pathway in hematopoietic cells.
Cell Line ; Humans ; Leukemia, Myeloid, Acute ; genetics ; Mutation ; PTEN Phosphohydrolase ; Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases ; Phosphoric Monoester Hydrolases ; genetics ; physiology ; Phosphorylation ; Polymorphism, Genetic ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; genetics ; Protein-Serine-Threonine Kinases ; metabolism ; Proto-Oncogene Proteins ; metabolism ; Proto-Oncogene Proteins c-akt ; Tumor Suppressor Proteins ; physiology

The hematopoietic cell phosphatase (HCP or SHP-1), the SH2 domain contain protein tyrosine phosphatase, is a crucial negative regulator in the process of hematopoietic cell development, proliferation and receptor-mediated mitogenic signaling pathways, and its mutation is responsible for the over-expansion and inappropriate activation of myelomonocytic population in motheaten mice. The aim of the study was to evaluate the role of the HCP gene in leukemogenesis. Bone marrow and/or peripheral blood from 32 acute myeloid leukemia (AML) patients, 9 acute lymphocytic leukemia (ALL) patients, 8 leukemia cell lines and 50 normal controls were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) based on single strand conformation polymorphism (SSCP) and sequencing. RT-PCR showed that all samples expressed HCP gene, only one missense mutation at codon 225 (AAC to AGC, Asn to Ser) within N-terminal SH2 domain was found in an ALL patient. In addition, four polymorphic base substitutions were detected in codon 69, 85, 86 and 266, respectively. In conclusion, mutation of HCP gene is an infrequent genetic aberration which may only play a role in pathogenesis of a small part of leukemia, however, its significance needs to be further clarified.
Acute Disease ; Cell Line, Tumor ; Humans ; Intracellular Signaling Peptides and Proteins ; Leukemia ; enzymology ; genetics ; Mutation ; Polymorphism, Single-Stranded Conformational ; Protein Tyrosine Phosphatase, Non-Receptor Type 6 ; Protein Tyrosine Phosphatases ; genetics

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