Search

Abstract Rare cases of CML present with monocytosis as well as morphologic dysplasia and harbor p210BCR‐ABL1. Cytogenetic and molecular studies must be performed to confirm the diagnosis of this kind of CML.

Rare cases of CML present with monocytosis as well as morphologic dysplasia and harbor p210BCR‐ABL1. Cytogenetic and molecular studies must be performed to confirm the diagnosis of this kind of CML. [ABSTRACT FROM AUTHOR]

Numerous acquired molecular and cytogenetic abnormalities are strongly associated with hematological malignancies. The breakpoint cluster region-ABL proto-oncogene 1 (BCR-ABL) rearrangement leads to a p210 chimeric protein in typical chronic myeloid leukemia (CML), whereas 17-25% of patients with acute lymphocytic leukemia and 0.9-3% patients with de novo acute myeloid leukemia (AML) carry a p190BCR-ABL fusion protein. Cases of patients with AML/CML carrying two specific primary molecular changes, BCR-ABL and core binding factor-β-myosin heavy chain 11 (CBFβ-MYH11) fusion genes have been rarely reported. The present study aimed to understand the nature and mechanism of this particular type of leukemia through case reports and literature review. A total of four patients who were diagnosed as AML/CML with BCR-ABL and CBFβ-MYH11 fusion genes in the First Affiliated Hospital of Soochow University (Suzhou, China) between January 2004 and December 2012 were examined. Morphological analysis of bone marrow cells, flow cytometry, quantitative polymerase chain reaction of p210BCR-ABL and CBFβ-MYH11 transcripts as well as cytogenetic and fluorescence in situ hybridization analyses were performed. A total of 4 patients who exhibited fusion of p210BCR-ABL and CBFβ-MYH11 were identified. A single patient (case 1) was first diagnosed CML-acute phase (AP), which progressed rapidly to CML-blast crisis (BC), and three patients (cases 2, 3 and 4) were diagnosed with AML with bone marrow eosinophilia at first presentation with no evidence of previous onset of CML. All cases achieved remission following conventional chemotherapy/hematological stem cell transplantation combined with the inhibitor of tyrosine kinase (TKI) maintenance therapy. The patients with CML carrying and expressing BCR-ABL and CBFβ-MYH11 fusion genes appeared more likely to rapidly progress to AP or BC. Therefore, the product of the CBFβ-MYH11 fusion gene may serve an important role in the transformation of CML. The co-expression of p210BCR-ABL and CBFβ-MYH11 fusion genes in myeloid leukemia may be a molecular event occurring not only during the development of CML, but also in AML. [ABSTRACT FROM AUTHOR]

Chronic myeloid leukemia (CML) is a lethal hematological disorder caused by the p210Bcr−Abl oncogene. Previous studies have suggested that p210Bcr−Abl transformation contributes to homing and retention defects, typical of immature myeloid cells in CML, by attenuating chemotactic response to stromal-derived factor-1α (SDF-1α). As Rho family GTPases are key regulators of the cytoskeleton and have been previously found to interact with p210Bcr−Abl, this study aimed to determine whether p210Bcr−Abl signaling affects SDF-1α chemotaxis through Rho GTPase signaling. We found that SDF-1α stimulated Cdc42 GTPase activation in myeloid progenitor 32D, but not in p210Bcr−Abl-transformed (32Dp210) cells. In fact, the basal level of active Cdc42 was elevated in 32Dp210 cells and mononuclear cells isolated from bone marrow of CML patients. Inhibition of p210Bcr−Abl kinase activity decreased basal Cdc42 activity and restored SDF-1α-induced Cdc42 and migration responses. Transduction of active Tat-Cdc42V12 abolished this reconstituted chemotactic response. As Cdc42 is particularly important in cytoskeletal remodeling and directional sensing, these results suggest that sustained activation of Cdc42 GTPase through p210Bcr−Abl tyrosine kinase signaling in CML cells contributes to defects in SDF-1α-chemotactic response due to desensitization of the actin polarization signal required for directional migration. [ABSTRACT FROM AUTHOR]

We analysed the subcellular distribution of p210BCR-ABL protein using a junction-specific anti-BCR-ABL monoclonal antibody and confocal laser scanning microscopy (CLSM). Our studies have shown that p210BCR-ABL is arranged in discrete foci in the cytoplasm of cell lines and primary CD34+ cells but not mononuclear cells suggesting the foci may be a feature of immature chronic myeloid leukaemia cells. We have devised a strategy to score the foci and found the mean number of foci varies between the cell types. The number of foci per cell is directly related to the level of p210BCR-ABL expression. CLSM was also used to analyse the distribution and colocalization of CT10 regulator-like (CRKL) p210BCR-ABL. CRKL-p210BCR-ABL foci were completely or partially associated, touching or separate in different regions of the same cell. We also analysed the distribution of phosphorylated CRKL (pCRKL) with p210BCR-ABL and unexpectedly found only a small proportion of pCRKL in complex with p210BCR-ABL. The foci distribution and high levels of uncomplexed p210BCR-ABL, pCRKL and CRKL protein suggested the possibility of a dynamic equilibrium. Imatinib promoted nuclear transport of p210BCR-ABL-positive foci. It also disrupted complex formation between p210BCR-ABL and casitas B-cell lymphoma and CRKL but not between p210BCR-ABL and GRB2. Our observations of the CRKL and p210BCR-ABL complex may be important for understanding the function of CRKL.Leukemia (2008) 22, 559–571; doi:10.1038/sj.leu.2405057; published online 6 December 2007 [ABSTRACT FROM AUTHOR]

Trichosanthin (TCS), an active component extracted from the root tubers of traditional Chinese medical herb Tian-Hua-Fen of the Cucurbitaceae family, has long been used for medical purpose in China; there is increasing interest in developing TCS as cancer therapeutic agents. The present study was to investigate the growth arrest of K562 cells and its molecular mechanisms, which the drugs induced by TCS and the possible functional interaction of TCS with imatinib (STI571) to K562 cells. Trypan blue exclusive staining was used to access the cell growth inhibition; western blot was used to evaluate the p210Bcr-Abl, phosphorylated tyrosine kinase (PTK), and some signaling molecules involving in cell proliferation and apoptosis in K562 cells. TCS and imatinib inhibited K562 cells at a time- and dose-dependent manners, respectively; TCS down-regulated p210Bcr-Abl at a time- and dose-dependent manners; TCS synergistically enhanced imatinib-induced K562 cell growth arrest and down-regulation of p210Bcr-Abl, PTK activities, procaspase-3, Hsp90,NF-κB and PKC. The results suggest that TCS not only by itself involves but also synergizes activities of imatinib to induce K562 cell growth arrest, down-regulation of p210Bcr-Abl and its downstream signals and to stimulate the effect of the tyrosine kinase inhibition. [ABSTRACT FROM AUTHOR]

Centrosomes play fundamental roles in mitotic spindle organization, chromosome segregation and maintenance of genetic stability. Recently, we have shown that centrosome aberrations occur early in chronic myeloid leukemia (CML) and are induced by imatinib in normal fibroblasts in vitro. To investigate the influence of BCR-ABL on centrosomes, we performed long-term in vitro experiments employing the conditionally p210BCR-ABL-expressing (tetracycline-inducible promoter) human monocytic cell line U937p210BCR-ABL/c6 as a model of CML chronic phase. Centrosome hypertrophy was detectable after 4 weeks of transgene expression onset, increasing up to a rate of 25.7% aberrant cells within 13 weeks of propagation. This concurred with clonal expansion of aneuploid cells displaying a hyperdiploid phenotype with 57 chromosomes. Partial reversibility of centrosome aberrations (26–8%) was achieved under prolonged propagation (14 weeks) after abortion of induction and bcr-abl silencing using small interfering RNA. Therapeutic doses of imatinib did not revert the aberrant phenotype, but counteracted the observed reverting effect of bcr-abl gene expression switch off. Suggesting a mechanistic model that features distinct abl-related tyrosine kinase activity levels as essential determinants of centrosomal integrity, this is the first report mechanistically linking p210BCR-ABL oncoprotein activity to centrosomal hypertrophy.Leukemia (2007) 21, 1971–1976; doi:10.1038/sj.leu.2404834; published online 28 June 2007 [ABSTRACT FROM AUTHOR]

Abstract: A series of novel, sterically hindered lipophilic analogs of AG 957 was designed and synthesized as potential protein tyrosine kinase (PTK) inhibitors. The in vitro activity, in vivo anti-leukemia activity, and pharmacology of these PTK inhibitors were studied. Some aspects of the structure–activity relationship associated with the carboxylic acid, phenol ring, and linker modifications are discussed. We have demonstrated that the 1,4-hydroquinone moiety is essential for activity and that sterically hindered esters contribute to enhanced in vivo efficacy. Adaphostin (NSC 680410) has emerged as the improved compound with the maximum in vivo anti-leukemia hollow fiber activity, concordant with the original lead compound AG 957. Currently, adaphostin is undergoing preclinical toxicology studies. [Copyright &y& Elsevier]

Chronic myeloid leukemia (CML) is believed to be caused by the tyrosine kinase p210BCR-ABL, which exhibits growth-promoting and anti-apoptotic activities. However, mechanisms that allow cell differentiation in CML still remain elusive. Here we established tetracycline (Tet)-regulatable p210BCR-ABL-expressing murine 32D myeloid progenitor (32D/TetOff-p210) cells to explore p210BCR-ABL-induced cell death and differentiation. Tet-regulatable overexpression of p210BCR-ABL induced cell death due to the activation of both caspase-1 and caspase-3, coincident with the differentiation from myeloid progenitors into CD11b + Ly6C + Ly6G + cells with segmented nuclei, exemplified as granulocytic myeloid-derived suppressor cells (G-MDSC), and the ability to secrete IL-1β, TNF-α, and S100A8/A9 into the culture supernatant. Treatment with imatinib almost completely abrogated all these phenotypes. Moreover, overexpression of a sensor of activated caspase-1 based on fluorescence resonance energy transfer (FRET) probe enabled us to detect activation of caspase-1 in a human CML cell line, K562. Furthermore, increased numbers of splenic G-MDSC associated with enhancement of S100A8/A9 production were observed in transgenic mice expressing p210BCR-ABL compared with that in wild-type mice. We also propose the novel mode of cell death in this 32D/TetOff-p210 system termed as myeloptosis., Competing Interests: CONFLICTS OF INTEREST All authors declare no conflicts of interest.

Numerous acquired molecular and cytogenetic abnormalities are strongly associated with hematological malignancies. The breakpoint cluster region-ABL proto-oncogene 1 ( BCR-ABL ) rearrangement leads to a p210 chimeric protein in typical chronic myeloid leukemia (CML), whereas 17-25% of patients with acute lymphocytic leukemia and 0.9-3% patients with de novo acute myeloid leukemia (AML) carry a p190 BCR-ABL fusion protein. Cases of patients with AML/CML carrying two specific primary molecular changes, BCR-ABL and core binding factor-β-myosin heavy chain 11 ( CBFβ-MYH11 ) fusion genes have been rarely reported. The present study aimed to understand the nature and mechanism of this particular type of leukemia through case reports and literature review. A total of four patients who were diagnosed as AML/CML with BCR-ABL and CBFβ-MYH11 fusion genes in the First Affiliated Hospital of Soochow University (Suzhou, China) between January 2004 and December 2012 were examined. Morphological analysis of bone marrow cells, flow cytometry, quantitative polymerase chain reaction of p 210BCR-ABL and CBFβ-MYH11 transcripts as well as cytogenetic and fluorescence in situ hybridization analyses were performed. A total of 4 patients who exhibited fusion of p 210BCR-ABL and CBFβ-MYH11 were identified. A single patient (case 1) was first diagnosed CML-acute phase (AP), which progressed rapidly to CML-blast crisis (BC), and three patients (cases 2, 3 and 4) were diagnosed with AML with bone marrow eosinophilia at first presentation with no evidence of previous onset of CML. All cases achieved remission following conventional chemotherapy/hematological stem cell transplantation combined with the inhibitor of tyrosine kinase (TKI) maintenance therapy. The patients with CML carrying and expressing BCR-ABL and CBFβ-MYH11 fusion genes appeared more likely to rapidly progress to AP or BC. Therefore, the product of the CBFβ-MYH11 fusion gene may serve an important role in the transformation of CML. The co-expression of p 210BCR-ABL and CBFβ-MYH11 fusion genes in myeloid leukemia may be a molecular event occurring not only during the development of CML, but also in AML.