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,Massimo Libra,Saverio Candido,Vivian Ruvolo,James A Mccubrey,Luca M Neri,Peter Ruvolo,Steve L Abrams,Lucio Cocco,Alberto M Martelli,Stefano Ratti

doi:10.18632/oncotarget.22956

Abstract

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.

Highlights

The PI3K/PTEN/AKT/mTORC1/GSK-3, RAS/ RAF/MEK1/ERK, and TP53 pathways are critical in many biological processes including cancer progression and drug resistance
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 doxorubicin-sensitivities of the FL5.12, FL/ Doxo, FL/Doxo + TP53(DN) and FL/Doxo + MEK1(CA) cells are presented in Figure 1, Panel B

Summary

Introduction

The PI3K/PTEN/AKT/mTORC1/GSK-3, RAS/ RAF/MEK1/ERK, and TP53 pathways are critical in many biological processes including cancer progression and drug resistance. These pathways exert pivotal roles in cell growth, death and senescence. The biological and biochemical effects of the Raf/MEK1/ERK, PI3K/ PTEN/AKT/mTORC1/GSK-3 and TP53 pathways have been recently reviewed [1,2,3,4,5,6,7]. These signaling cascades are important in cardiovascular diseases, diabetes, metabolism, neurological diseases, obesity and other maladies [8,9,10]. It is noted that GSK-3 can function as a tumor suppressor or an oncogene which might be due to the cell type or biological situation [1,2,3,4,5,6]

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