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STAT5 activation by BCR-Abl contributes to transformation of K562 leukemia cells
R P de Groot1, J A Raaijmakers, J W Lammers
1Department of Pulmonary Diseases, University Hospital Utrecht, Utrecht, The Netherlands. R.deGroot.hli.azu.nl
Abstract:
Signal transducers and activators of transcription (STATs) belong to a family of transcription factors that were originally identified as mediators of cytokine-induced gene expression. Recent evidence, however, has shown that certain members of the STAT family, including STAT3, are also involved in cellular transformation. Here we show that STAT5 also plays a role in cellular transformation by the BCR-Abl oncogene. In BCR-Abl transformed K562 cells, STAT5A and 5B are constitutively phosphorylated on tyrosine and are transcriptionally active. Moreover, expression of a dominant negative form of STAT5 shows that active STAT5 is necessary for the growth in soft agar of these cells. These results show that besides STAT3, STAT5 can also be involved in cellular transformation.
Insights
Signal transducers and activators of transcription (STATs) are key in gene expression. New findings show STAT5, like STAT3, actively contributes to cellular transformation, particularly in BCR-Abl oncogene-driven cancers.
Area of Science:
- Molecular Biology
- Oncology
- Cellular Biology
Background:
- Signal transducers and activators of transcription (STATs) are transcription factors primarily known for mediating cytokine signaling.
- Emerging research indicates roles for STAT family members, such as STAT3, in cellular transformation.
- The specific involvement of STAT5 in oncogene-induced cellular transformation requires further elucidation.
Purpose of the Study:
- To investigate the role of STAT5 in cellular transformation mediated by the BCR-Abl oncogene.
- To determine if STAT5 is transcriptionally active in BCR-Abl transformed cells.
- To assess the necessity of active STAT5 for the transformation phenotype.
Main Methods:
- Analysis of STAT5 phosphorylation and transcriptional activity in BCR-Abl transformed K562 cells.
- Utilizing a dominant-negative STAT5 construct to inhibit STAT5 activity.
- Assessing cell transformation through soft agar growth assays.
Main Results:
- STAT5A and STAT5B were found to be constitutively phosphorylated on tyrosine and transcriptionally active in BCR-Abl transformed K562 cells.
- Inhibition of STAT5 activity using a dominant-negative form impaired the ability of these cells to grow in soft agar.
- These findings demonstrate that active STAT5 is essential for BCR-Abl-mediated cellular transformation.
Conclusions:
- STAT5 plays a significant role in cellular transformation, extending beyond its known function in cytokine signaling.
- STAT5, in addition to STAT3, is implicated as a key mediator in BCR-Abl oncogene-driven cellular transformation.
- These findings highlight STAT5 as a potential therapeutic target in relevant cancers.