Protective effect of roscovitine on renal ischemia–reperfusion injury

Evaluating the Effects of CDK Inhibitors in Ischemia-Reperfusion Injury Models

CDK inhibitors have been used to induce protection in various experimental models. Kidney ischemia-reperfusion (I/R) is a form of acute kidney injury resulting in a cascade of cellular events prompting rapid cellular damage and suppression of kidney function. I/R injury, an inevitable impairment during renal transplant surgery, remains one of the major causes of acute kidney injury and represents the most prominent factor leading to delayed graft function after transplantation. Understanding the molecular events responsible for tubule damage and recovery would help to develop new strategies for organ preservation. This chapter describes procedures to study the effect of CDK inhibitors in the cellular I/R model developed from an epithelial cell line deriving from pig kidney proximal tubule cells (LLC-PK1). We briefly describe methods for determining the protective effect of CDK inhibitors such as activation of caspase 3/7, western blot analysis, gene silencing, and immunoprecipitation.

Roscovitine in cancer and other diseases

Roscovitine [CY-202, (R)-Roscovitine, Seliciclib] is a small molecule that inhibits cyclin-dependent kinases (CDKs) through direct competition at the ATP-binding site. It is a broad-range purine inhibitor, which inhibits CDK1, CDK2, CDK5 and CDK7, but is a poor inhibitor for CDK4 and CDK6. Roscovitine is widely used as a biological tool in cell cycle, cancer, apoptosis and neurobiology studies. Moreover, it is currently evaluated as a potential drug to treat cancers, neurodegenerative diseases, inflammation, viral infections, polycystic kidney disease and glomerulonephritis. This review focuses on the use of roscovitine in the disease model as well as clinical model research.

Discovery and development of Seliciclib. How systems biology approaches can lead to better drug performance

Seliciclib (R-Roscovitine) was identified as an inhibitor of CDKs and has undergone drug development and clinical testing as an anticancer agent. In this review, the authors describe the discovery of Seliciclib and give a brief summary of the biology of the CDKs Seliciclib inhibits. An overview of the published in vitro and in vivo work supporting the development as an anti-cancer agent, from in vitro experiments to animal model studies ending with a summary of the clinical trial results and trials underway is presented. In addition some potential non-oncology applications are explored and the potential mode of action of Seliciclib in these areas is described. Finally the authors argue that optimisation of the therapeutic effects of kinase inhibitors such as Seliciclib could be enhanced using a systems biology approach involving mathematical modelling of the molecular pathways regulating cell growth and division.

Role of CDK5/cyclin complexes in ischemia-induced death and survival of renal tubular cells

Ischemia reperfusion processes induce damage in renal tubules and compromise the viability of kidney transplants. Understanding the molecular events responsible for tubule damage and recovery would help to develop new strategies for organ preservation. CDK5 has been traditionally considered a neuronal kinase with dual roles in cell death and survival. Here, we demonstrate that CDK5 and their regulators p35/p25 and cyclin I are also expressed in renal tubular cells. We show that treatment with CDK inhibitors promotes the formation of pro-survival CDK5/cyclin I complexes and enhances cell survival upon an ischemia reperfusion pro-apoptotic insult. These findings support the benefit of treating with CDK inhibitors for renal preservation, assisting renal tubule protection.

Twice switched at birth: cell cycle-independent roles of the "neuron-specific" cyclin-dependent kinase 5 (Cdk5) in non-neuronal cells

Cdk5 (cyclin-dependent kinase 5 or initially NCLK for neuronal CDC2-like kinase) was switched twice at its birth nearly twenty years ago: first it was thought to be cyclin-dependent, second it was assumed to be primarily of importance in neuronal cells-both turned out not to be the case. In this review we want to discuss issues of pharmacological inhibition, to highlight the versatile roles, and to summarize the growing evidence for the functional importance of Cdk5 in non-neuronal tissues, such as blood cells, tumor cells, epithelial cells, the vascular endothelium, testis, adipose and endocrine tissues. The organizing principles we follow are apoptosis/cell death, migration/motility, aspects of inflammation, and, finally, secretion/metabolism.

Hyperbaric oxygenation attenuates renal ischemia-reperfusion injury in rats

BACKGROUND

Oxygen-derived free radicals play an important role in ischemia-reperfusion injury (IR). Hyperbaric oxygenation (HO) decreases free radical production. The aim of this study was to determine the effect of HO treatment on renal ischemia-reperfusion injury in rats.

METHODS

Rats were divided into four groups. All groups underwent right nephrectomy. Group I served as the control group; group II had left renal ischemia-reperfusion; group III was pretreated with HO; and group IV, ischemia-reperfusion and HO pretreatment. Tissue malondialdehyde (MDA) and glutathione (GSH) levels were measured, and histopathologic damage scored.

RESULTS

HO pretreatment significantly decreased tissue MDA levels and histopathologic scores among rats with IR. There was an increased GSH in HO-pretreated rats with IR; however, the difference was not significant.

CONCLUSION

HO prior to ischemia displayed a beneficial effect on renal IR by reducing oxygen radical peroxidation of lipid membranes.

Evaluation of Liver Damage After Application of TVE in the Rat Model

INTRODUCTION

The aim of this study was to investigate the effects of total vascular exclusion (TVE) on the liver during the early period of reperfusion.

MATERIALS AND METHODS

Forty Wistar-Albino rats were divided into four groups. Portal pedicle clamping (groups 1 and 2) or TVE (groups 3 and 4) were applied for 10 minutes. Samples were collected at the time of clamp release (groups 1 and 3) and at 30 minutes of reperfusion (groups 2 and 4). We examined oxidative injury to and histopathology of the liver.

RESULTS

Oxidative stress was more prominent with TVE application. Significant alterations were shown in hepatic superoxide dismutase, catalase, glutathione, and glutathione S-transferase levels. The levels of malondialdehyde and myeloperoxidase were not altered significantly.

CONCLUSION

Inflow-outflow occlusion of the liver causes more oxidative stress compared with inflow occlusion.

Analysis of roscovitine using novel high performance liquid chromatography and UV-detection method: pharmacokinetics of roscovitine in rat

Roscovitine (2-(R)-(1-ethyl-2-hydroxyethylamino)-6-benzylamino-9-isopropylpurine, is a potent and selective inhibitor of cyclin-dependent kinases (CDKs). It inhibits cdc2, cdk2, cdk5 and erk 1 and 2 by competing for the ATP binding domain of the kinases. It inhibits cell proliferation; induces DNA fragmentation and causes cell cycle arrest in S phase. Its stability and toxicity are not fully known. A liquid chromatography method was developed to measure roscovitine in human and rat plasma. The lower limit of quantitation (LLOQ) was 100ng/ml; the intra- and inter-day precision was below 10% at all control levels. Likewise, the accuracy between and within days was lower than 6% at all levels. The drug was stable at room temperature. Twenty-four hours at room temperature has result in a decrease of only 9% of the drug. The recovery of roscovitine from plasma was 84% at 750ng/ml. The present method was used to study the pharmacokinetics of the drug in a rat model. The present investigation, to the authors' knowledge, is the first analytical method reported and the first pharmacokinetics investigation of roscovitine in rat. Roscovitine was administered as a bolus injection (25mg/kg body weight). The pharmacokinetic analysis showed that roscovitine is fitted to a two-compartment open-mode with a biphasic elimination half-life (6 and 26min, respectively). The distribution volume was determined to 3.5l/kg and the clearance (Cl) was 29.5ml/min.

Antiapoptotic and protective effects of roscovitine on ischemia-reperfusion injury of the rat liver

OBJECTIVE

This study was designed to investigate the role of apoptosis on liver IR injury and to determine the effects of roscovitine on this process.

MATERIALS AND METHODS

Rat livers pretreated with roscovitine received 60 min right lobe ischemia followed by 4 h (n=8) and 24 h (n=8) reperfusion. Tissue injury was evaluated by serum alanine aminotransferase, aspartate aminotransferase, tissue malondialdehyde, myeloperoxidase measurements and histological examination. Dead (apoptotic and necrotic) hepatocytes were determined by trypan blue dye and apoptosis was evaluated with M30 monoclonal antibody.

RESULTS

Administration of roscovitine significantly decreased both apoptotic and dead hepatocyte counts compared to controls (P<0.01). Liver transaminase levels were decreased significantly in the roscovitine-pretreated groups (P<0.05). In the groups evaluated 24 h after reperfusion, MPO levels (P<0.02) and leukocyte infiltration on histologic sections were decreased significantly in the roscovitine-administered group compared to its control.

CONCLUSIONS

This study indicates that hepatocyte apoptosis may play a role in the development of IR injury of the liver. Administration of roscovitine may be beneficial in preventing this injury.