Caracterização molecular e funcional de ANKHD1 na hematopoese normal e neoplasica / Molecular and functional characterization of ANKHD1 in normal and neoplastic hematopoiesis

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The identification and the structural and functional characterization of genes differentially expressed between tumors and normal tissues are fundamental steps towards the understanding of the neoplastic process and the development of new anti-cancer strategies. The Ankyrin Repeat Single KH Domain containing 1 (ANKHD1) was first described in humans in a prostate carcinoma cell line LNCaP, in 2003; however, the expression pattern and function of ANKHD1 have not yet been described. ANKHD1 is an orthologous protein of the Drosophila melanogaster, MASK (Multiple Ankyrin repeat and single KH domain), where it was first identified using a genetic screen designed to discover proteins that interact with the protein tyrosine phosphatase Corkscrew (CSW), which is a homolog to the SH2-containing protein tyrosine phosphatase (SHP2) in humans. SHP2 is a cytoplasmic protein-tyrosine phosphatase, coded by the PTPN11 gene and plays an important role in the development of normal hematopoiese and leukemogenesis. The aim of the present study was to characterize the gene expression pattern of ANKHD1 in normal and leukemic hematopoietic cells and to determine their function in cellular process.This study has demonstrated that the ANKHD1 gene is located on chromosome 5, this gene has several possible variant transcripts generated by splicing alternative mechanisms and encodes proteins with domains of ankyrin repeats. The promoter region of this gene has several regulatory elements such as the transcription factor GATA-1 binding sites and rich sequences in dinucleotide CG, CpG islands.The expression of the ANKHD1 gene and some of the gene´s variants in normal tissues and neoplastic cell lines was detected in different intensities. The increase in the expression of this gene was demonstrated using cellular differentiation and proliferation models. However, during the process of apoptosis, a decrease in the expression of ANKHD1 transcripts variants was observed. In the cells of patients with myelodysplastic syndrome (MDS), a low expression of ANKHD1 was observed. During erythroid differentiation of CD34+ cells obtained from the bone marrow of these patients, no increase in the expression of ANKHD1 gene and transcription factor GATA-1 was observed, as expected. The mononuclear cells of MDS patients were treated with decitabine, a demethylation agent, and showed an increase in the ANKHD1 gene expression compared to untreated cells. The same was observed in CD34+ cells treated during erythroid differentiation. However in cells of acute myeloid leukemia (AML) or Multiple Myeloma (MM) patients, characterized by proliferation and resistance mechanisms of apoptosis, the high expression of gene transcripts ANKHD1 and its variants was demonstrated. The association of SHP2 with ANKHD1 was identified by Western Blot in RPMI 8226 MM cell line. A decrease in the ANKHD1 gene expression in these cells when the process of apoptosis was induced by dexamethasone was observed. In conclusion, this study identified ANKHD1 and some of gene´s transcripts variants as a new gene with a variable expression profile in normal and neoplastic hematopoietic cells. The study has also demonstrated the involvement of the ANKHD1 in basic cellular processes, which maintain homeostasis and the association of ANKHD1 with SHP2 in multiple myeloma. ANKHD1 may be involved with the abnormal phenotype of tumor cells through a possible role in the apoptosis pathway. The findings herein described suggest that ANKHD1 could be a molecular target for neoplasic disease therapy and could guide further studies towards a better elucidation of the specific functions of ANKHD1 in normal and neoplasic hematopoietic cells.

ASSUNTO(S)

hematopoese expressão genica cytoskeletal proteins hematopoiesis neoplasms proteinas citoesqueleto tumores gene expression

ACESSO AO ARTIGO

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