BCR-ABL fusion oncogene originates from the reciprocal translocation of chromosome 9 and 22 t(9;22) (q34;q11). It translates a chimeric protein, p210, characterized by constitutive activation of its tyrosine kinase, w...BCR-ABL fusion oncogene originates from the reciprocal translocation of chromosome 9 and 22 t(9;22) (q34;q11). It translates a chimeric protein, p210, characterized by constitutive activation of its tyrosine kinase, which triggers leukemogenic pathways resulting in onset of chronic myeloid leukemia (CML). In CML, the classic fusion is b2a2 or b3a2 fusing exon 13 (b2) or exon 14 (b3) of BCR to exon 2 (a2) of ABL. The type of bcr/abl transcripts may be associated with different prognosis and hence useful in therapeutic plan. This study was conducted to calculate the frequency of these splice variants as the frequencies of different fusion oncogenes associated with leukaemia can vary in different geographical regions due to interplay of genetic variation in different ethnic populations, diverse environmental factors and living style. A very sensitive nested RT-PCR was established to detect BCR-ABL splice variants in CML. Sensitivity of RT-PCR assay was of the order of 10–6. Thirty CML patients were subjected to BCR-ABL analysis. Out of 30 Pakistani patients, 19 (64%) expressed b3a2 while 11 (36%) expressed b2a2 transcript. This shows that BCR-ABL splice variants differ in their frequencies which may have an effect on biology and implications for prognosis and management of BCR-ABL positive Leukemias.展开更多
Clinical trials have demonstrated that some patients with chronic myeloid leukemia(CML)treated for several years with tyrosine kinase inhibitors(TKIs)who have maintained a molecular response can successfully discontin...Clinical trials have demonstrated that some patients with chronic myeloid leukemia(CML)treated for several years with tyrosine kinase inhibitors(TKIs)who have maintained a molecular response can successfully discontinue treatment without relapsing.Treatment free remission(TFR)can be reached by approximately 50%of patients who discontinue.Despite having similar levels of deep molecular response and an identical duration of treatment,the factors that influence the successful discontinuation of CML patients remain to be determined.In this review we will explore the factors identified to date that can help predict whether a patient will successfully achieve TFR.We will also discuss the need for the identification of predictive biomarkers associated with a high probability of achieving TFR for the future personalized identification of patients who are suitable for the discontinuation of TKI treatment.展开更多
Background This study was designed to quantitatively measure WT-1 expression levels in patients with chronic myelogenous leukemia (CML) and acute lymphoblastic leukemia (ALL) during follow-up and to clarify the value...Background This study was designed to quantitatively measure WT-1 expression levels in patients with chronic myelogenous leukemia (CML) and acute lymphoblastic leukemia (ALL) during follow-up and to clarify the value of WT-1 as a molecular marker in minimal residual disease monitoring.Methods The TaqMan quantitative real-time RT-PCR method was established by using cloned WT-1 cDNA or synthesized oligonucleotides resembling WT-1 cDNA fragments in limit dilution as template until a stable and reliable standard curve was obtained. In a 25-month follow-up, the transcriptional levels of WT-1, Bcr-Abl, and Abl gene, were quantitatively measured in bone marrow cells from 25 CML or acute lymphoblastic leukemia (ALL) patients with the Ph chromosome. In addition, the expression of these genes in 40 samples of normal peripheral blood was also examined using the same method. The ratios of WT-1/Abl and Bcr-Abl/Abl were both plotted, and the two expression patterns were compared as well as their clinical significance.Results The levels of WT-1 expression in normal peripheral blood were detectable. In CML and Ph positive ALL patients, WT-1 expression levels changed in parallel with the Bcr-Abl expression pattern as the disease progressed or responded to effective treatment.Conclusion WT-1 expression provides a novel molecular marker in addition to Bcr-Abl for monitoring minimal residual disease (MRD) and targeting therapy in Ph chromosome-positive leukemia patients.展开更多
Objective: To investigate the in vitro cleavage ability and effects on apoptosis and cell growth of the bcr-abl fusion gene specific multi-unit ribozymes. Methods: Three fusion point specific ribozymes were designed ...Objective: To investigate the in vitro cleavage ability and effects on apoptosis and cell growth of the bcr-abl fusion gene specific multi-unit ribozymes. Methods: Three fusion point specific ribozymes were designed and the multi-unit ribozymes?in vitro transcription vector and retroviral vector were constructed. The in vitro cleavage ability was tested. The retroviral vector was transfected into K562 cell and the effects on proliferation, apoptosis, cell cycle and cell structure were observed. Results: Multi-unit ribozymes had in vitro cleavage efficiency of 70.8%, which was more efficient than single-unit and double-unit ribozymes. Transfection of the retroviral vector of the ribozyme into K562 cells, induced inhibition of cell growth and apoptosis. The incorporation rate of DNA in ribozymes transfected K562 cells was greatly decreased along with time passed, with an inhibition rate of more than 50% after 96 h of transfection. Under FCM, 18.4% of the cells underwent apoptosis 72 h after transfection and more cells were blocked in G phase, with the ratio in S phase greatly decreased (41.9%). Under electron microscope, compaction of nuclear chromatin and apoptosis bodies were observed. Conclusion: Multi-unit ribozymes specific to bcr-abl fusion gene can be used to treat CML and to purge bone marrow for self-grafting.展开更多
Objective: To survey the role of protein tyrosine kinases (PTKs) in the pathogenesis of several hematopoietic malignancies. Methods: By reviewing the published laboratory and clinical studies on PTK-related oncoprotei...Objective: To survey the role of protein tyrosine kinases (PTKs) in the pathogenesis of several hematopoietic malignancies. Methods: By reviewing the published laboratory and clinical studies on PTK-related oncoproteins and their causative role in some leukemias and lymphomas. Results: Protein tyrosine kinases are key participants in signal transduction pathways that regulate cellular growth, activation and differentiations. Aberrant PTK activity resulting from gene mutation (often accompanying chromosome translocation) plays an etiologic role in several clonal hematopoietic malignancies. For example, the PTK product of the BCR-ABL fusion gene resulting from the t (9; 22) translocation exhibits several fold higher tyrosine kinase activity than the product of the ABL gene. Evidence suggests that the BCR-ABL oncoprotein alone is sufficient to case chronic myelogenous leukemia (CML) and other Ph positive acute leukemia. PTK over-activity resulting from chromosomal translocations creating TEL-ABL, TEL-JAK2 and TEL-PDGFRβ fusion proteins plays an important role in the pathogenesis of other types of leukemia. Another example occurs in anaplastic large cell lymphoma (ALCL). Experimental and clinical evidences indicate that translocations involving ALK gene on chromosome 2p23, most commonly resulting in an NPM-ALK fusion oncogene, result in constitutive activation of ALK and cause ALCL. This group of lymphomas is now named ALK positive lymphoma or ALKoma. Conclusion: Genetic lesions creating aberrant fusion proteins that result in excessive PTK activity are increasingly being recognized as central to the pathogenesis of hemotopoietic malignancies. These chimeric PTK molecules represent attractive disease-specific targets against which new classes therapeutic agents are being developed.展开更多
文摘BCR-ABL fusion oncogene originates from the reciprocal translocation of chromosome 9 and 22 t(9;22) (q34;q11). It translates a chimeric protein, p210, characterized by constitutive activation of its tyrosine kinase, which triggers leukemogenic pathways resulting in onset of chronic myeloid leukemia (CML). In CML, the classic fusion is b2a2 or b3a2 fusing exon 13 (b2) or exon 14 (b3) of BCR to exon 2 (a2) of ABL. The type of bcr/abl transcripts may be associated with different prognosis and hence useful in therapeutic plan. This study was conducted to calculate the frequency of these splice variants as the frequencies of different fusion oncogenes associated with leukaemia can vary in different geographical regions due to interplay of genetic variation in different ethnic populations, diverse environmental factors and living style. A very sensitive nested RT-PCR was established to detect BCR-ABL splice variants in CML. Sensitivity of RT-PCR assay was of the order of 10–6. Thirty CML patients were subjected to BCR-ABL analysis. Out of 30 Pakistani patients, 19 (64%) expressed b3a2 while 11 (36%) expressed b2a2 transcript. This shows that BCR-ABL splice variants differ in their frequencies which may have an effect on biology and implications for prognosis and management of BCR-ABL positive Leukemias.
文摘Clinical trials have demonstrated that some patients with chronic myeloid leukemia(CML)treated for several years with tyrosine kinase inhibitors(TKIs)who have maintained a molecular response can successfully discontinue treatment without relapsing.Treatment free remission(TFR)can be reached by approximately 50%of patients who discontinue.Despite having similar levels of deep molecular response and an identical duration of treatment,the factors that influence the successful discontinuation of CML patients remain to be determined.In this review we will explore the factors identified to date that can help predict whether a patient will successfully achieve TFR.We will also discuss the need for the identification of predictive biomarkers associated with a high probability of achieving TFR for the future personalized identification of patients who are suitable for the discontinuation of TKI treatment.
文摘Background This study was designed to quantitatively measure WT-1 expression levels in patients with chronic myelogenous leukemia (CML) and acute lymphoblastic leukemia (ALL) during follow-up and to clarify the value of WT-1 as a molecular marker in minimal residual disease monitoring.Methods The TaqMan quantitative real-time RT-PCR method was established by using cloned WT-1 cDNA or synthesized oligonucleotides resembling WT-1 cDNA fragments in limit dilution as template until a stable and reliable standard curve was obtained. In a 25-month follow-up, the transcriptional levels of WT-1, Bcr-Abl, and Abl gene, were quantitatively measured in bone marrow cells from 25 CML or acute lymphoblastic leukemia (ALL) patients with the Ph chromosome. In addition, the expression of these genes in 40 samples of normal peripheral blood was also examined using the same method. The ratios of WT-1/Abl and Bcr-Abl/Abl were both plotted, and the two expression patterns were compared as well as their clinical significance.Results The levels of WT-1 expression in normal peripheral blood were detectable. In CML and Ph positive ALL patients, WT-1 expression levels changed in parallel with the Bcr-Abl expression pattern as the disease progressed or responded to effective treatment.Conclusion WT-1 expression provides a novel molecular marker in addition to Bcr-Abl for monitoring minimal residual disease (MRD) and targeting therapy in Ph chromosome-positive leukemia patients.
基金National Natural Science Foundation of China (No. 39670330).
文摘Objective: To investigate the in vitro cleavage ability and effects on apoptosis and cell growth of the bcr-abl fusion gene specific multi-unit ribozymes. Methods: Three fusion point specific ribozymes were designed and the multi-unit ribozymes?in vitro transcription vector and retroviral vector were constructed. The in vitro cleavage ability was tested. The retroviral vector was transfected into K562 cell and the effects on proliferation, apoptosis, cell cycle and cell structure were observed. Results: Multi-unit ribozymes had in vitro cleavage efficiency of 70.8%, which was more efficient than single-unit and double-unit ribozymes. Transfection of the retroviral vector of the ribozyme into K562 cells, induced inhibition of cell growth and apoptosis. The incorporation rate of DNA in ribozymes transfected K562 cells was greatly decreased along with time passed, with an inhibition rate of more than 50% after 96 h of transfection. Under FCM, 18.4% of the cells underwent apoptosis 72 h after transfection and more cells were blocked in G phase, with the ratio in S phase greatly decreased (41.9%). Under electron microscope, compaction of nuclear chromatin and apoptosis bodies were observed. Conclusion: Multi-unit ribozymes specific to bcr-abl fusion gene can be used to treat CML and to purge bone marrow for self-grafting.
基金This work was partially supported by a grant from World Health Organization Fellowship (XS) (WPRO AWARD No. 0008/99).
文摘Objective: To survey the role of protein tyrosine kinases (PTKs) in the pathogenesis of several hematopoietic malignancies. Methods: By reviewing the published laboratory and clinical studies on PTK-related oncoproteins and their causative role in some leukemias and lymphomas. Results: Protein tyrosine kinases are key participants in signal transduction pathways that regulate cellular growth, activation and differentiations. Aberrant PTK activity resulting from gene mutation (often accompanying chromosome translocation) plays an etiologic role in several clonal hematopoietic malignancies. For example, the PTK product of the BCR-ABL fusion gene resulting from the t (9; 22) translocation exhibits several fold higher tyrosine kinase activity than the product of the ABL gene. Evidence suggests that the BCR-ABL oncoprotein alone is sufficient to case chronic myelogenous leukemia (CML) and other Ph positive acute leukemia. PTK over-activity resulting from chromosomal translocations creating TEL-ABL, TEL-JAK2 and TEL-PDGFRβ fusion proteins plays an important role in the pathogenesis of other types of leukemia. Another example occurs in anaplastic large cell lymphoma (ALCL). Experimental and clinical evidences indicate that translocations involving ALK gene on chromosome 2p23, most commonly resulting in an NPM-ALK fusion oncogene, result in constitutive activation of ALK and cause ALCL. This group of lymphomas is now named ALK positive lymphoma or ALKoma. Conclusion: Genetic lesions creating aberrant fusion proteins that result in excessive PTK activity are increasingly being recognized as central to the pathogenesis of hemotopoietic malignancies. These chimeric PTK molecules represent attractive disease-specific targets against which new classes therapeutic agents are being developed.
