Posted by rob on June 24, 2010 under Uncategorized | 
Variant Isoforms of BCR-ABL1 in Chronic Myelogenous Leukemia Reflect Alternative Splicing of ABL1 in Normal Tissue – Letter.
Mol Cancer Ther. 2010 Jun 22;
Authors: Khorashad JS, Milojkovic D, Reid AG
Routine sequencing of the BCR-ABL kinase domain for the identification of resistance-associated point mutations is now a critical aspect of the management of chronic myeloid leukemia patients showing suboptimal response to imatinib. The recent correspondence between Lee and Santamaria (1-3) regarding the expression of an aberrant isoform of BCR-ABL1 in chronic myelogenous leukemia (CML) and the observation that the same insertion variant occurs in normal individuals (2) is therefore timely and relevant. In our experience and that of other groups, alternative splicing of BCR-ABL1 is not restricted to the BCR-ABL1(ins35) transcript reported by Lee et al. (1), but includes a variety of other isoforms (4, 5). The most common aberrant transcript we have observed harbored a deletion of exon 7 of ABL1 [ABL1(del7); identified in 82 of 236 (34%) CML patients]. Less common recurrent variations include complete or partial deletion of one or more ABL1 exons between 4 and 9, sometimes accompanied by partial insertion of intronic sequences. Although Lee and others have proposed a role for some of these splice variants in modulating BCR-ABL1 activity (1, 2), we found no correlation between the presence of a variant transcript and clinical features or likelihood of treatment response in patients with CML. Using the common exon 7 deletion as a model, we screened for the presence of similar alternative splicing of native ABL1 in normal individuals by reverse transcription-PCR and Scorpions-based allele-specific oligonucleotide PCR. Importantly, an ABL1(del7) transcript was detected in 4 of 17 normal cDNA samples. These observations argue against the notion that excision of exon 7 of ABL1 by alternative splicing is exclusively associated with CML and contradict the proposal of tyrosine kinase inhibitor therapy as a causative factor. Based on predictive analysis of protein structure, loss of exon 7 would confer no obvious novel function to the ABL1 molecule. Similarly, Sherbenou et al. (5) showed that BCR-ABL1 mutants lacking all or part of ABL1 exon 4 were catalytically inactive and did not interfere with the oncogenic activity of native BCR-ABL1. The expression of nonfunctional splice variants is not without precedent. Data generated by the ENCODE project indicate that many genes undergo a low level of alternative splicing, with little evidence to suggest that the alternative isoforms have a role as functional proteins (6). In the context of the clinical management of CML, it is therefore plausible that at least a proportion of the aberrantly spliced BCR-ABL1 transcripts are epiphenomena with no significant impact on disease course. The suggestions that expression of the BCR-ABL1(ins35) isoform increases relative to native BCR-ABL1 with prolonged exposure to imatinib and that the transcript is associated with resistance (1) are intriguing. However, such observations should be viewed with caution pending systematic validation using serial samples from imatinib-treated patients with a range of treatment responses and a sensitive means of quantifying relative expression of normal and aberrant transcripts. Disclosure of Potential Conflicts of Interest No potential conflicts of interest were disclosed.
PMID: 20571070 [PubMed - as supplied by publisher]
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Targeting Activating Transcription Factor 3 by Galectin-9 Induces Apoptosis and Overcomes Various Types of Treatment Resistance in Chronic Myelogenous Leukemia.
Mol Cancer Res. 2010 Jun 22;
Authors: Kuroda J, Yamamoto M, Nagoshi H, Kobayashi T, Sasaki N, Shimura Y, Horiike S, Kimura S, Yamauchi A, Hirashima M, Taniwaki M
Tyrosine kinase inhibitors (TKI) against Bcr-Abl are the first-line therapeutics for chronic myelogenous leukemia (CML). However, the resistance to Bcr-Abl TKIs is induced in leukemic cells not only by loss of sensitivity to TKIs through Bcr-Abl-related molecular mechanisms but also by loss of addiction to Bcr-Abl TK activity by acquiring Bcr-Abl-unrelated additional oncogenic mutations. Therefore, the identification of an additional therapeutic target has been anticipated for achievement of a complete cure and to overcome resistance to treatment. We here showed that modified human Galectin-9 (hGal9), a lectin that show specific affinity for beta-galactosides, inhibits the proliferation of five CML-derived cell lines by inducing apoptosis at their IC(50)s from 17.5 to 164.9 nmol/L. Our study revealed that activating transcription factor 3 (ATF3), a member of the ATF/cAMP-responsive element binding protein family transcription factors, is the critical mediator for cell killing by hGal9, and that Noxa is one of the downstream effector molecules of ATF3. Bim, on the other hand, the BH3-only protein essential for apoptosis by Bcr-Abl TKIs, was not associated with hGal9-induced cell death. ATF3-mediated cell death by hGal9 was not hampered by the absence of p53, the presence of mutant Abl(T315I), or by P-glycoprotein overexpression. In addition, hGal9 showed the additive growth-inhibitory effect with imatinib on CML cell lines. Collectively, hGal9 is a candidate agent that may overcome various kinds of resistance to treatment for CML and may suggest that ATF3 may be a new target molecule for the development of new treatment modalities that can overcome resistance to currently available chemotherapeutics. Mol Cancer Res; 8(7); OF1-8. (c)2010 AACR.
PMID: 20571063 [PubMed - as supplied by publisher]
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The viscoelastic properties of microvilli are dependent upon the cell surface molecule.
Biochem Biophys Res Commun. 2010 Jun 3;
Authors: Python JL, Wilson KO, Snook JH, Guo B, Guilford WH
We studied at nanometer resolution the viscoelastic properties of microvilli and tethers pulled from myelogenous cells via P-selectin glycoprotein ligand 1 (PSGL-1) and found that in contrast to pure membrane tethers, the viscoelastic properties of microvillus deformations are dependent upon the cell-surface molecule through which load is applied. A laser trap and polymer bead coated with anti-PSGL-1 (KPL-1) were used to apply step loads to microvilli. The lengthening of the microvillus in response to the induced step loads was fitted with a viscoelastic model. The quasi-steady state force on the microvillus at any given length was approximately four-fold lower in cells treated with cytochalasin D or when pulled with concanavalin A-coated rather than KPL-1-coated beads. These data suggest that associations between PSGL-1 and the underlying actin cytoskeleton significantly affect the early stages of leukocyte deformation under flow.
PMID: 20570653 [PubMed - as supplied by publisher]
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P02-185 – Healthy siblings of children with cancer: the forgotten givers.
Eur Psychiatry. 2010;25S1:809
Authors: Karampela K, Hatira P, Damigos D
OBJECTIVES: To understand how healthy siblings visualize and represent health and disease as conditions affecting them and others in their family. Furthermore, to evaluate the emotional settings following health and disease for healthy siblings, the reasons lead to illness and what could be done to avoid that path. Additionally, this study aims to investigate the parameters that interfere with the physical and emotional living of healthy siblings and finally to access their subjective knowledge on disease and in particular, cancer. METHODS: Fourteen healthy children, aged between 7 and 14, siblings to children diagnosed and receiving treatment for leukemia (acute lymphoblastic & myelogenous leukemia), nephroblastoma (Wilms’ tumor), lymphoma, rhabdomyosarcoma, where evaluated according to the Hatira’s Projective Technique. RESULTS: Analyzing the interviews lead tomicron different kind of responses; some positive but mainly negative ones. The negative reactions addressed emotional instability, rejection, separation, siblings’ rivalry, the medical treatment itself and the fear of death, while positive reactions concerned self-awareness, sensitization, earlier maturing and increased family coherence after the crisis. CONCLUSION: The physical relationship between siblings is a special kind of human relationship that can outrun time and crises, even outgrowing in some cases the relationship between parents and their children. On the other hand, it is simultaneously a very fragile and vulnerable relationship, since traumatic experiences such as those arising from childhood cancer interfere with the mental and emotional growing of the healthy brother or sister, causing confusion to the body, mind and soul.
PMID: 20569906 [PubMed - as supplied by publisher]
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Two Novel Monoclonal Antibodies Against Human CD133-2: Distinct Epitopes and Agonist Activity to Enhance Growth of CD133 Expression Cells In Vitro.
Hybridoma (Larchmt). 2010 Jun;29(3):241-9
Authors: Wang J, Li F, Zhang G, Chen Y, Hu Y, Chen X, Lu B, Zhang X
Human AC133 antigen, also called CD133, is a unique transmembrane glycoprotein encoded by the PROM1 gene. It was initially suggested as a cell surface marker for hematopoietic stem/progenitor cells and has also been identified recently as a cancer stem cell marker in brain, colorectal, and prostate cancers. AC133 has two isoforms, one is AC133-1 and the other is AC133-2. Whether the two isoforms are functionally redundant or serve distinct functions remains unclear. In order to further explore the physiological and pathological functions of CD133-2, we generated two mouse antihuman CD133-2 monoclonal antibodies (clones 6B3 and 9G4). Then, we carefully characterized the biological functions of these monoclonal antibodies (MAbs) and showed that 6B3 and 9G4 bound to two epitopes of CD133, which are different from that recognized by the commercially available anti-CD133 MAb (AC141). These two MAbs could be used in cell immunostaining, Western blot, and immunohistochemical staining. We have further shown that MAb 6B3 enhances the growth of human myelogenous leukemic cell line U937 and human colon adenocarcinoma cell line SW480, suggesting a functional role of CD133 in these cells. Taken together as a useful tool, these two antibodies might be of great value for further exploration of the expression and function of CD133.
PMID: 20569000 [PubMed - in process]
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