Deregulation of apoptotic volume decrease and ionic movements in multidrug-resistant tumor cells: role of chloride channels

• Published in: American Journal of Physiology: Cell Physiology 2010-01, Vol.298 (1), p.C14-C25
• Main Authors: Poulsen, K. A, Andersen, E. C, Hansen, C. F, Klausen, T. K, Hougaard, C, Lambert, I. H, Hoffmann, E. K
• Format: Article
• Language: English
• Subjects: Animals; Apoptosis; Apoptosis - physiology; ATP-Binding Cassette, Sub-Family B, Member 1 - genetics; Carrier Proteins - genetics; Cell Cycle; Cell Size; Cells; Chloride Channels - physiology; Chlorine; Cisplatin - therapeutic use; Drug resistance; Drug Resistance, Multiple - physiology; Drug Resistance, Neoplasm; Homeostasis - physiology; Humans; Ions; Neoplasms - drug therapy; Reaction kinetics; Tumors
• ISSN: 0363-6143; 1522-1563
• DOI: 10.1152/ajpcell.00654.2008

1 Department of Biology, University of Copenhagen, Copenhagen; and 2 Neurosearch, Ballerup, Denmark Submitted 22 December 2008 ; accepted in final form 18 October 2009 Changes in cell volume and ion gradients across the plasma membrane play a pivotal role in the initiation of apoptosis. Here we explore the kinetics of apoptotic volume decrease (AVD) and ion content dynamics in wild-type (WT) and multidrug-resistant (MDR) Ehrlich ascites tumor cells (EATC). In WT EATC, induction of apoptosis with cisplatin (5 µM) leads to three distinctive AVD stages: an early AVD 1 (4–12 h), associated with a 30% cell water loss; a transition stage AVD T ( 12 to 32 h), where cell volume is partly recovered; and a secondary AVD 2 (past 32 h), where cell volume was further reduced. AVD 1 and AVD 2 were coupled to net loss of Cl – , K + , Na + , and amino acids (ninhydrin-positive substances), whereas during AVD T , Na + and Cl – were accumulated. MDR EATC was resistant to cisplatin, showing increased viability and less caspase 3 activation. Compared with WT EATC, MDR EATC underwent a less pronounced AVD 1, an augmented AVD T , and a delay in induction of AVD 2 . Changes in AVD were associated with inhibition of Cl – loss during AVD 1 , augmented NaCl uptake during AVD T , and a delay of Cl – loss during AVD 2 . Application of the anion channel inhibitor NS3728 inhibited AVD and completely abolished the differences in AVD, ionic movements, and caspase 3 activation between WT and MDR EATC. Finally, the maximal capacity of volume-regulated anion channel was found to be strongly repressed in MDR EATC. Together, these data suggest that impairment of AVD, primarily via modulation of NaCl movements, contribute to protection against apoptosis in MDR EATC. caspase 3; volume-regulated anion channel; cisplatin; cell volume Address for reprint requests and other correspondence: K. A. Poulsen, Section of Cell- and Developmental Biology, Dept. of Biology, The August Krogh Bldg., Univ. of Copenhagen, 13 Universitetsparken, DK-2100, Copenhagen Ø (e-mail: kapoulsen{at}bio.ku.dk ).