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Interferon affects nuclear proteins in cells of clinically sensitive chronic myelogenous leukemia patients
O M Howard1, M Talpaz, H Kantarjian
1Department of Hematology, University of Texas M.D. Anderson Cancer Center, Houston, TX.
Abstract:
Cytoplasmic protein extracts from chronic myelogenous leukemia (CML) cells contained an activity that altered the electrophoretic mobility of complexes formed between nuclear proteins and the transcriptional enhancers of interferon (IFN)-inducible genes. Exposure of CML cells to IFN-alpha diminished the effect of the CML cytoplasmic proteins on these nuclear protein-DNA complexes. The presence of clinical responsiveness to IFN-alpha correlated with the sensitivity to the IFN-induced change in the electrophoretic mobility of nuclear protein-DNA complexes. These data suggest that the action of IFN-alpha in CML may be linked to a pathway that can result in posttranslational modification of nuclear proteins.
Insights
Cytoplasmic proteins in chronic myelogenous leukemia (CML) alter gene activity. Interferon-alpha (IFN-alpha) treatment reduces this effect, suggesting a link between IFN-alpha
Area of Science:
- Molecular Biology
- Oncology
- Virology
Background:
- Chronic myelogenous leukemia (CML) is a myeloproliferative neoplasm characterized by the Philadelphia chromosome.
- Interferon-alpha (IFN-alpha) is a cytokine used in CML treatment, but its precise mechanism of action remains incompletely understood.
- Transcriptional enhancers regulate gene expression, and their interaction with nuclear proteins is crucial for cellular function.
Purpose of the Study:
- To investigate the role of cytoplasmic factors in CML cells concerning the regulation of interferon-inducible genes.
- To explore the interaction between CML cytoplasmic proteins, nuclear proteins, and DNA complexes involved in gene transcription.
- To determine if IFN-alpha modulates the activity of these cytoplasmic factors and if this correlates with clinical response.
Main Methods:
- Preparation of cytoplasmic protein extracts from CML cells.
- Electrophoretic mobility shift assays (EMSA) to analyze protein-DNA complex formation and alterations.
- Treatment of CML cells with IFN-alpha and assessment of its effect on cytoplasmic protein activity.
Main Results:
- Cytoplasmic extracts from CML cells exhibited an activity that modified the electrophoretic mobility of nuclear protein-DNA complexes binding to interferon-inducible gene enhancers.
- Exposure of CML cells to IFN-alpha significantly diminished the influence of these CML cytoplasmic proteins on the nuclear protein-DNA complexes.
- Clinical responsiveness to IFN-alpha in CML patients correlated with the sensitivity of these nuclear protein-DNA complexes to IFN-alpha-induced mobility changes.
Conclusions:
- The findings suggest that IFN-alpha's therapeutic effect in CML may involve a pathway impacting posttranslational modifications of nuclear proteins.
- Cytoplasmic factors in CML cells play a role in regulating the transcriptional machinery of interferon-inducible genes.
- The modulation of nuclear protein-DNA complex dynamics by IFN-alpha is a potential biomarker for treatment response in CML.