Development of Resistance to Endoplasmic Reticulum Stress-Inducing Agents in Mouse Leukemic L1210 Cells.

Martin Cagala,Mario Seres,Albert Breier,Lucia Pavlikova,Zdena Sulova,Karolina Kadlecikova

doi:10.3390/molecules25112517

Abstract

Four new variants of L1210 cells resistant to endoplasmic reticulum (ER) stressors, tunicamycin (STun), thapsigargin (SThap), bortezomib (SBor), and MG-132 (SMG-132), were developed via an 18-month periodic cultivation in culture medium with a gradual increase in substance concentration. Multidrug resistance was generated for STun (to tunicamycin, bortezomib and MG-132), SThap (to tunicamycin, thapsigargin and MG-132), SBor (to bortezomib and MG-132), and SMG-132 (to bortezomib and MG-132). These cells were compared to the original L1210 cells and another two variants, which expressed P-gp due to induction with vincristine or transfection with the gene encoding P-gp, in terms of the following properties: sensitivity to either vincristine or the ER stressors listed above, proliferative activity, expression of resistance markers and proteins involved in the ER stress response, and proteasome activity. The resistance of the new cell variants to ER stressors was accompanied by a decreased proliferation rate and increased proteasome activity. The most consistent change in protein expression was the elevation of GRP78/BiP at the mRNA and protein levels in all resistant variants of L1210 cells. In conclusion, the mechanisms of resistance to these stressors have certain common features, but there are also specific differences.

Highlights

Multidrug resistance (MDR) represents a real obstacle in the effective chemotherapy of leukemia patients; understanding the mechanisms of its development and finding molecular markers with sufficient predictive properties represent important goals [1,2]
We studied the response of S cells to persistent stress caused by culturing at stepwise increasing concentrations of tunicamycin, thapsigargin, bortezomib and MG-132
S cells were exposed to endoplasmic reticulum (ER) stressors during repeated passages over one and a half years in culture medium with a gradually increasing concentration of one of the four stressors: Tun, Thap, Bor and MG-132

Summary

Introduction

Multidrug resistance (MDR) represents a real obstacle in the effective chemotherapy of leukemia patients; understanding the mechanisms of its development and finding molecular markers with sufficient predictive properties represent important goals [1,2]. There are several well-defined molecular mechanisms that confer cells with loss of sensitivity to anticancer drugs, of which the following are prevalent: i. Elevation of cell drug efflux caused by upregulation of the expression/activity of plasma membrane efflux pumps, members of the ABC (ATP-binding cassette) gene family [3,4]; iii. Alteration in activity/expression of enzymes involved in DNA repair mechanisms [7]; and v. The most often observed molecular causes of MDR are overexpression of P-glycoprotein (ABCB1, a member of the ABC transporter gene family), a drug efflux pump in the plasma membrane that ensures the effective expulsion of P-gp substrates from the inner space of cells (reviewed in [3]).

Methods

Results

Discussion

Conclusion