This first collaborative study has established a process for prospective data collection and future multinational collaborative research in the Middle East. Despite the limitations of an incomplete population-based study, it provides the first comprehensive baseline data on clinical characteristics, laboratory evaluation, induction outcome, and toxicity. Further work is planned to uncover possible biologic differences of ALL in the region and to improve diagnosis and management.
Recent molecular investigations have demonstrated over-expression of a large number of tumor associated antigens (TAAs) in a variety of malignancies. Over-expression of ROR1 gene, a member of the receptor tyrosine kinase family, has recently been reported in B-cell chronic lymphocytic leukemia. Wilms' tumor gene 1 (WT1) has long been known as a universal TAA expressed in a variety of solid and hematopoietic malignancies. In the present study, the expression profile of ROR1 and WT1 was investigated in different immunophenotypic subsets of B-cell acute lymphoblastic leukemia (B-ALL) patients. RT-PCR method was used to determine the ROR1 and WT1 genes expression in bone marrow (BM) and peripheral blood (PB) samples from 51 newly diagnosed Iranian B-ALL patients. Isolated tumor cells from all patients were immunophenotyped by flow cytometry. Based on immunophenotypic results, our B-ALL patients were classified in four differentiation subsets; Pro-B (n = 7), Pre-B I (n = 29), Pre-B II (n = 13) and Immature/mature B-ALL (n = 2). Although ROR1 was over-expressed in more mature subsets (16.7%, 42.9%, 45.5% and 100%, respectively), WT1 was more represented in immature subsets of B-ALL patients (57.1%, 64.3%, 38.5% and 0%, respectively). Comparison of the frequency of ROR1 and WT1 positive samples at each immunophenotypic subtype revealed statistically significant difference only in Pre B I subtype (p = 0.02). Our results suggest that expression of ROR1 and WT1 in B-ALL is associated with the differentiation stage of the leukemic cells.
Receptor tyrosine kinases (RTKs) are a group of enzymes involved in a variety of physiological and pathological processes. The human Ror1 is a member of the RTK family with unknown ligand and biological function. Overexpression of Ror1 has recently been reported in B-cell chronic lymphocytic leukemia. The aim of this study was to explore the expression profile of Ror1 in acute lymphoblastic leukemia (ALL) cells. Therefore, leukemic cells were isolated from the bone marrow and/or peripheral blood (PB) of 57 ALL patients. Immunophenotyping was performed by flow cytometry and mRNA expression was detected by RT-PCR. Overexpression of Ror1 mRNA was detected in 23 of 57 (40%) ALL patients. A similar expression pattern was observed in ALL cell lines, with 4 of 12 (33%) being positive. Stimulation of normal PB mononuclear cells with pokeweed mitogen and phorbol myristate acetate induced substantially higher Ror1 mRNA expression compared to unstimulated cultured cells. There has been neither a significant association between Ror1 expression and the immunophenotypic profile of the leukemic cells, nor with other clinical or hematological features of the patients. In conclusion, our findings propose Ror1 as a new tumor-associated antigen and a potential tool for targeted immunotherapy and monitoring of minimal residual disease in ALL.
Acute promyelocytic leukemia (APL) is characterized by specific t(15;17), distinct morphologic picture, and clinical coagulopathy that contribute to the morbidity and mortality of the disease. This study aims to investigate the effects of antitelomerase compound BIBR1532 on APL cells (NB4). BIBR 1532 exerts a direct short-term growth suppressive effect in a concentration-dependent manner probably through downregulation of c-Myc and hTERT expression. Our results also suggest that induction of p21 and subsequent disturbance of Bax/Bcl-2 balanced ratio as well as decreased telomerase activity may be rational mechanisms for the potent/direct short-term cytotoxicity of high doses of BIBR1532 against NB4 cells.
Efforts have been undertaken to find an alternative approach to packed red cell transfusion (PRCT) in major beta-thalassemia. Augmentation of fetal hemoglobin (HbF) by hydroxyurea (HU) has been reported to be less effective in this condition as compared to sickle cell anemia due to molecular heterogeneity of the former disease. HU efficacy and its relation to Xmn1 polymorphism and IVSII-1 mutation was evaluated in major beta-thalassemics. Forty-five patients, M/F ratio 0.8, aged 6-33 years, received oral HU, 20 mg/kg per day, 4 days per week and daily1 mg folic acid. Thirty-six patients were PRCT dependent (group A) and nine independent (group B). The aim was to stabilize or increase pre-PRCT Hb over 10.0+/-0.5 g/dl and to reduce the need or cease the PRCT in group A and to increase Hb level and curb the ineffective erythropoesis, e.g., splenomegaly, facial bone deformity, in group B. HU was administered for at least 6 months (mean: 9 months) and discontinued in case of response failure. Screening for Xmn1 polymorphism and IVSII-1 mutation was carried out in most patients. In group A, 25 patients have become PRCT independent for a period of 2.5-7.3 years (mean: 4 years). The mean Hb, pre-HU 10.0 and post-HU 10.7 g/dl (range: 8.8-13.7 g/dl), mean serum ferritin pre- and post-HU was1877 and 525 ng/ml. The PRCT requirement was reduced in one patient, and ten patients did not respond. In group B HU has been given over 3.3 years (range: 2.8-4.8 years), Hb increased from 9.3 to 10.4/dl, and there was no tangible progression of ineffective erythropoesis. Responders in both groups expressed more comfort with this regimen. Xmn1 and IVSII-1 (homo- and/or heterozygosis) are relevant markers in most responding patients. Molecular determination of genetic markers in early childhood will help to identify candidates for pharmacological HbF switching by HU.
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