Dependence of Cisplatin-Induced Cell Death In Vitro and In Vivo on Cyclin-Dependent Kinase 2

Abstract

Cisplatin is one of the most effective chemotherapeutics, but its usefulness is limited by its toxicity to normal tissues, including cells of the kidney proximal tubule. The purpose of these studies was to determine the mechanism of cisplatin cytotoxicity. It was shown in vivo that cisplatin administration induces upregulation of the gene for the p21 cyclin-dependent kinase (cdk) inhibitor in kidney cells. This protein is a positive effector on the fate of cisplatin-exposed renal tubule cells in vivo and in vitro; adenoviral transduction of p21 completely protected proximal tubule cells from cisplatin toxicity. Herein is reported that cdk2 inhibitory drugs protect kidney cells in vivo and in vitro, that transduction of kidney cells in vitro with dominant-negative cdk2 also protected, and that cdk2 knockout cells were resistant to cisplatin. The cdk2 knockout cells regained cisplatin sensitivity after transduction with wild-type cdk2. It is concluded that cisplatin cytotoxicity depends on cdk2 activation and that the mechanism of p21 protection is by direct inhibition of cdk2. This demonstrated the involvement of a protein that previously was associated with cell-cycle progression with pathways of apoptosis. It also was demonstrated that this pathway of cisplatin-induced cell death can be interceded in vivo to prevent nephrotoxicity.J Am Soc Nephrol 17: 2434 -2442 , 2006 . doi: 10.1681 C isplatin is one of the most effective chemotherapeutic agents against testicular and bladder tumors, head and neck, ovarian, breast, and lung cancers, and refractory non-Hodgkin's lymphomas (1,2). The major adverse effect of cisplatin use is nephrotoxicity, in which kidney proximal tubule cells are especially sensitive (3). It is likely that its anticancer activity depends on formation of DNA intrastrand cross-links (4). Several distinct mechanisms have been proposed for cisplatin cytotoxicity in renal tubule cells, including direct DNA damage (5), caspase activation (6), mitochondrial dysfunction (7), formation of reactive oxygen species (8), effects on the endoplasmic reticulum (9), and activation of TNF-␣ apoptotic pathways (10). However, it is unclear whether cisplatin nephrotoxicity depends on any of these pathways or these apoptotic cascades merely amplify more proximal initiated cell death signals.We have shown in vivo that kidney cells entered the cell cycle after cisplatin administration and that the gene for the p21Cip1/WAF1 cell-cycle inhibitor was induced simultaneously (11). The p21 protein interacts with several members of the cell cycle to regulate cell-cycle progression (12-14), and its induction is a positive effector on the fate of renal tubule cells both in vivo and in vitro (15,16). In addition, we recently reported that cells cultured from mouse proximal tubules were completely protected from cisplatin cytotoxicity by adenoviral transduction of human p21 (17). The activity of cyclin-dependent kinase 2 (cdk2), a serine/threonine kinase whose main function is the phosphorylation of substrates necessary for cel...

HIF Activation Protects From Acute Kidney Injury

“…27 Recently, inhibition of the cyclin-dependent kinase-2 (cdk-2) has been identified to be protective in cisplatin-induced cellular injury. 28,29 In MEFs, hypoxia significantly reduced proliferation, decreased cdk-2 activity, and increased p21 expression in an HIF-1␣-dependent manner. 30 Therefore, it could be argued that the protective effects of preconditional HIF activation in cisplatin-induced renal injury described here may also be mediated by the cessation of cell growth.…”

Targeting Endogenous Repair Pathways after AKI

“…Previous studies suggest that expression of the Cdk inhibitor p21 ameliorates the injury 34 and that overexpression of p21 or the use of other Cdk inhibitors can protect against cisplatin and ischemic cell death. 35,36 Therefore, transient expression of Cdk2 or Cdk4/6 inhibitors represents a novel strategy to improve renal repair and could provide protection against early tubular cell death but still allow for normal repopulation of injured tubules to undergo subsequent proliferation.…”

Mechanisms of Renal Apoptosis in Health and Disease

“…94 Cdk2 and E2F1 also participate in cisplatin-induced tubular cell death. 95,96 TARGETING APOPTOSIS Survival factors and anticytokine strategies prevent apoptosis in vivo. 21,26,[31][32][33][34][35]46 Proof-of-concept studies have also involved genetic manipulation, small interference RNA, or oligodeoxyribonucleotide targeting of different intracellular molecules.…”