Research Papers:

Drug-resistance in doxorubicin-resistant FL5.12 hematopoietic cells: elevated MDR1, drug efflux and side-population positive and decreased BCL2-family member expression

Linda S. Steelman, Steve L. Abrams, Peter Ruvolo, Vivian Ruvolo, Lucio Cocco, Stefano Ratti, Alberto M. Martelli, Luca M. Neri, Saverio Candido, Massimo Libra and James A. McCubrey _

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Oncotarget. 2017; 8:113013-113033. https://doi.org/10.18632/oncotarget.22956

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Linda S. Steelman1, Steve L. Abrams1, Peter Ruvolo2,3, Vivian Ruvolo2,3, Lucio Cocco4, Stefano Ratti4, Alberto M. Martelli4, Luca M. Neri5, Saverio Candido6, Massimo Libra6 and James A. McCubrey1

1Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University, Greenville, SC, USA

2Section of Signal Transduction and Apoptosis, Hormel Institute, University of Minnesota, Austin, TX, USA

3Current/Present address: Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, USA

4Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy

5Department of Morphology, Surgery and Experimental Medicine, University of Ferrara, Ferrara, Italy

6Department of Biomedical and Biotechnological Sciences – Oncological, Clinical and General Pathology Section, University of Catania, Catania, Italy

Correspondence to:

James A. McCubrey, email: [email protected]

Keywords: drug transporters; bcl-2; MEK1; p53; cancer stem cells

Received: October 16, 2017    Accepted: November 20, 2017    Published: December 06, 2017


Chemotherapeutic drug treatment can result in the emergence of drug-resistant cells. By culturing an interleukin-3 (IL-3)-dependent cell line, FL5.12 cells in the presence of the chemotherapeutic drug doxorubicin, we isolated FL/Doxo cells which are multi-drug resistant. Increased levels of drug efflux were detected in FL/Doxo cells which could be inhibited by the MDR1 inhibitor verapamil but not by the MRP1 inhibitor MK571. The effects of TP53 and MEK1 were examined by infection of FL/Doxo cells with retroviruses encoding either a dominant negative TP-53 gene (FL/Doxo+ TP53 (DN) or a constitutively-activated MEK-1 gene (FL/Doxo + MEK1 (CA). Elevated MDR1 but not MRP1 mRNA transcripts were detected by quantitative RT-PCR in the drug-resistant cells while transcripts encoding anti-apoptotic genes such as: BCL2, BCLXL and MCL1 were observed at higher levels in the drug-sensitive FL5.12 cells. The percentage of cells that were side-population positive was increased in the drug-resistant cells compared to the parental line. Drug-resistance and side-positive population cells have been associated with cancer stem cells (CSC). Our studies suggest mechanisms which could allow the targeting of these molecules to prevent drug-resistance.

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