Major contribution of the multidrug transporter P-glycoprotein to reduced susceptibility of poly(ADP-ribose) polymerase-1 knock-out cells to doxorubicin action
✍ Scribed by Józefa Węsierska-Gądek
- Book ID
- 102875820
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 572 KB
- Volume
- 95
- Category
- Article
- ISSN
- 0730-2312
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✦ Synopsis
Abstract
Inactivation of poly(ADP‐ribose) polymerase‐1 (PARP‐1) has been shown to potentiate the cytotoxicity of distinct DNA targeting agents including topoisomerase I inhibitors. On the other hand, the PARP‐1 deficient cells exhibited resistance to conventional inhibitors of topoisomerase II such as etoposide or doxorubicin (DOX). Recently, we observed the extreme sensitivity of PARP‐1 knock‐out (KO) cells to C‐1305, a new biologically active triazoloacridone compound. C‐1305 permanently arrested the cells in G~2~‐phase of the cell‐cycle. These observations prompted us to investigate more thoroughly the susceptibility of PARP‐1 KO cells to DOX and to examine the effect of DOX on the progression of cell‐cycle. We determined the uptake of DOX and P‐glycoprotein (P‐gp) expression in mouse cells and compared it with that in human myeloma 8226/Dox40 cells overexpressing P‐gp. Exposure of mouse cells to DOX revealed a reduced drug uptake in cells lacking PARP‐1. However, combined treatment with verapamil, a potent MDR modulator increased the DOX accumulation. Detailed immunoblotting experiments revealed an approximately threefold higher P‐gp level in PARP‐1 KO cells as compared with normal counterparts. Interestingly, DOX induced in normal fibroblasts very rapidly G~2~ arrest whereas in PARP‐1 KO cells it blocked primarily the transition between S and G~2~ resulting in the increase of cells remaining in S‐phase. This coincided with the lack of the site‐specific phosphorylation of CDK2. Simultaneous inhibition of P‐gp in cells lacking PARP‐1 resulted in an accumulation of cells in G~2~. Exposure of mouse cells to high DOX dose activated significantly caspase‐3/7 in PARP‐1 KO cells. © 2005 Wiley‐Liss, Inc.