Regulation of the multidrug resistance transporter P-glycoprotein in multicellular prostate tumor spheroids by hyperthermia and reactive oxygen species.
Hyperthermia is an important component of many cancer treatment protocols. In our study the regulation of the multidrug resistance (MDR) transporter P-glycoprotein by hyperthermia was studied in multicellular prostate tumor spheroids. Hyperthermia treatment of small (50-100 microm) tumor spheroids significantly increased P-glycoprotein and mdr-1 mRNA expression with a maximum effect at 42 degrees C, whereas only moderate elevation of P-glycoprotein was found in large (350-450 microm) tumor spheroids. Hyperthermia caused an elevation of intracellular reactive oxygen species (ROS). Inhibition of ROS generation with NADPH-oxidase inhibitors diphenylen iodonium (DPI) and 4-(2-aminoethyl)benzenesulfonyl fluoride (AEBSF) abolished P-glycoprotein expression but did not affect its transcript levels following heat treatment. This indicates that P-glycoprotein levels are controlled by regulating its translation rate or stability. Hyperthermia incubation resulted in a differential activation of p38 mitogen-activated protein kinase (MAPK), extracellular regulated kinase 1,2 (ERK1,2), and c-jun N-terminal kinase (JNK) immediately, 4 hr and 24 hr after treatment. Furthermore, upregulation of hypoxia-inducible factor 1alpha (HIF-1alpha) was observed. Elevation of HIF-1alpha and P-glycoprotein expression following hyperthermia treatment were abolished upon coadministration of the p38 inhibitor SB203580. In contrast the JNK inhibitor SP600125 and the ERK1,2 inhibitor UO126 resulted in increase of HIF-1alpha and P-glycoprotein in the control as well as the hyperthermia-treated samples, indicating negative regulation of intrinsic HIF-1alpha and P-glycoprotein expression by ERK1,2 and JNK signaling cascades. In summary our data demonstrate that hyperthermia-induced upregulation of P-glycoprotein and HIF-1alpha is mediated by activation of p38, whereas ERK1,2 and JNK are involved in repression of P-glycoprotein and HIF-1alpha under control conditions.
Wartenberg
Maria
M
Institute of Neurophysiology, University of Cologne, Cologne, Germany.
Gronczynska
Sabina
S
Bekhite
Mohamed M
MM
Saric
Tomo
T
Niedermeier
Wilhelm
W
Hescheler
Jürgen
J
Sauer
Heinrich
H
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis*; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000494:pharmacology; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D006979:Hyperthermia, Induced; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008297:Male; D048052:Mitogen-Activated Protein Kinase 3 / Q000494:pharmacology; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000473:pathology*; D012333:RNA, Messenger / Q000096:biosynthesis; D017382:Reactive Oxygen Species; D018874:Spheroids, Cellular; D014157:Transcription Factors / Q000096:biosynthesis* / Q000494:pharmacology; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000494:pharmacology
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D004268:DNA-Binding Proteins; C497442:HIF1A protein, human; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009687:Nuclear Proteins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D014157:Transcription Factors; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases