Regulation of hTERT by BCR-ABL at multiple levels in K562 cells

BMC Cancer

Research Article

Baojie Li¹  Yong Zhang²  Wee Joo Chng³  Wei Han Tan⁴  Juin Hsien Chai⁴  Xueying Wang⁵ 

[1] Bio-X Center, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai, P.R. China;Department of Biochemistry, Yong Loo Lin School of Medicine, Cancer Science Institute of Singapore (CSI), National University of Singapore, Singapore, Singapore;Department of Biochemistry, Yong Loo Lin School of Medicine, Cancer Science Institute of Singapore (CSI), National University of Singapore, Singapore, Singapore;Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore;Department of Haematology-Oncology, National University Cancer Institute of Singapore, National University Health System, Singapore, Singapore;Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, 117597, Singapore, Singapore;Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, 117597, Singapore, Singapore;Department of Biochemistry, Yong Loo Lin School of Medicine, Cancer Science Institute of Singapore (CSI), National University of Singapore, Singapore, Singapore;

关键词: Chronic Myeloid Leukemia;    K562 Cell;    HL60 Cell;    Telomere Length;    Jurkat Cell;   

DOI  :  10.1186/1471-2407-11-512

 received in 2011-07-19, accepted in 2011-12-09,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundThe cytogenetic characteristic of Chronic Myeloid Leukemia (CML) is the formation of the Philadelphia chromosome gene product, BCR-ABL. Given that BCR-ABL is the specific target of Gleevec in CML treatment, we investigated the regulation of the catalytic component of telomerase, hTERT, by BCR-ABL at multiple levels in K562 cells.MethodsMolecular techniques such as over expression, knockdown, real-time PCR, immunoprecipitation, western blotting, reporter assay, confocal microscopy, telomerase assays and microarray were used to suggest that hTERT expression and activity is modulated by BCR-ABL at multiple levels.ResultsOur results suggest that BCR-ABL plays an important role in regulating hTERT in K562 (BCR-ABL positive human leukemia) cells. When Gleevec inhibited the tyrosine kinase activity of BCR-ABL, phosphorylation of hTERT was downregulated, therefore suggesting a positive correlation between BCR-ABL and hTERT. Gleevec treatment inhibited hTERT at mRNA level and significantly reduced telomerase activity (TA) in K562 cells, but not in HL60 or Jurkat cells (BCR-ABL negative cells). We also demonstrated that the transcription factor STAT5a plays a critical role in hTERT gene regulation in K562 cells. Knockdown of STAT5a, but not STAT5b, resulted in a marked downregulation of hTERT mRNA level, TA and hTERT protein level in K562 cells. Furthermore, translocation of hTERT from nucleoli to nucleoplasm was observed in K562 cells induced by Gleevec.ConclusionsOur data reveal that BCR-ABL can regulate TA at multiple levels, including transcription, post-translational level, and proper localization. Thus, suppression of cell growth and induction of apoptosis by Gleevec treatment may be partially due to TA inhibition. Additionally, we have identified STAT5a as critical mediator of the hTERT gene expression in BCR-ABL positive CML cells, suggesting that targeting STAT5a may be a promising therapeutic strategy for BCR-ABL positive CML patients.

【 授权许可】

Unknown   
© Chai et al; licensee BioMed Central Ltd. 2011. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.