The antiretroviral agent saquinavir enhances hTERT expression and telomerase activity in human T leukaemia cells in vitro

Journal of Experimental & Clinical Cancer Research

Ornella Franzese²  Enzo Bonmassar¹  Loredana Guglielmi³  Laura Bonmassar⁴  Angelo Aquino²  Alessandro Comandini²  Riccardo Adamo² 

[1] Institute of Translational Pharmacology (IFT) National Council of Research Rome, Via Fosso del Cavaliere 100, Rome, Italy;Department of Systems Medicine, Pharmacology Section, University of Rome Tor Vergata, Rome, Italy;CNR-Cellular Biology and Neurobiology Institute, Via del Fosso di Fiorano 64, 00143, Rome, Italy;Laboratory of Molecular Oncology, Istituto Dermopatico dell’Immacolata-IRCSS, Via dei Monti di Creta 104, 00167, Rome, Italy

关键词: c-Myc;    Saquinavir;    hTERT;    Telomerase;    Leukaemia;   

Others  :  824951
DOI  :  10.1186/1756-9966-32-38

 received in 2013-04-30, accepted in 2013-05-17,  发布年份 2013

【 摘 要 】

Background

Saquinavir, a protease inhibitor utilized in HIV infection, shows antitumor activity in various experimental models. In previous studies performed in our laboratory the drug was found to induce a substantial increase of telomerase activity in normal peripheral blood mononuclear cells. Aim of the present investigation was to test whether saquinavir was able to increase telomerase activity and the expression of the catalytic subunit of telomerase, hTERT, in human malignant hematopoietic cells.

Methods

Human Jurkat CD4⁺ T cell leukaemia cell line was used throughout the present study. The antiproliferative effect of saquinavir was tested by the MTT assay. Telomerase activity was determined according to the telomeric repeat amplification protocol. The expression of hTERT mRNA was semi-quantitative evaluated by RT-PCR amplification and quantitative Real Time PCR. The binding of the transcription factor c-Myc to its specific E-Box DNA binding-site of hTERT promoter was analyzed by Electophoretic Mobility Shift Assay (EMSA). The amount of c-Myc in cytoplasm and nucleus of leukemia cells was determined by Western Blot analysis, and c-Myc down-regulation was obtained by siRNA transfection.

Results

Saquinavir produced a substantial increase of telomerase activity in Jurkat cells in vitro without increasing but rather reducing target cell proliferation rate. Telomerase up-regulation appeared to be the result of enhanced expression of hTERT. Saquinavir-mediated up-regulation of hTERT gene was the result of the increased binding of proteins to the E-Box sequence of the promoter. Moreover, saquinavir amplified the expression of c-Myc especially in the nuclear cell fraction. The direct influence of saquinavir on this transcription factor was also demonstrated by the antagonistic effect of the drug on siRNA induced c-Myc suppression. Since c-Myc is the main responsible for hTERT transcription, these findings suggest that the main mechanism underlying saquinavir-induced telomerase activation is mediated by c-Myc up-regulation.

Conclusions

Saquinavir augments hTERT expression while inhibiting leukemic cell growth. Experimental evidences show that this effect is mediated by saquinavir-influenced increase of c-Myc levels. This could have relevance in terms of enhanced hTERT-dependent tumor cell immunogenicity and suggests new paharmacological approaches interfering with c-Myc dependent pathways.

【 授权许可】

   
2013 Adamo et al.; licensee BioMed Central Ltd.

【 图 表 】

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