Cis-platin is an effective anti-neoplastic agent, but it is also highly nephrotoxic. Here, we clearly identify the human organic cation transporter 2 (hOCT2) as the critical transporter for cis-platin nephrotoxicity in isolated human proximal tubules and offer a potential mechanism for reducing nephrotoxicity in clinical practice. Interaction of cis-platin with hOCT2 in kidney or hOCT1 in liver was investigated with the fluorescent cation 4-[4-(dimethyl-amino)styril]-methylpyridinium in stably transfected HEK293 cells and for the first time in tissues physiologically expressing these transporters, human proximal tubules, and human hepatocyte couplets. Cis-platin (100 micromol/L) inhibited transport via hOCT2-HEK293 but not hOCT1-HEK293. In human proximal tubules cis-platin competed with basolateral organic cation transport, whereas it had no effect in tubules from a diabetic kidney or in hepatocytes. In hOCT2-HEK293 cells treated for 15 hours, incubation with cis-platin induced apoptosis, which was completely suppressed by contemporaneous incubation with the hOCT2 substrate cimetidine (100 micromol/L). These findings demonstrate that uptake of cis-platin is mediated by hOCT2 in renal proximal tubules, explaining its organ-specific toxicity. A combination of cis-platin with other substrates that compete for hOCT2 offers an effective option to decrease nephrotoxicity in the clinical setting.

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Tumor cells chronically exposed to cisplatin (cDDP) acquire cDDP resistance that impacts tumor therapy. To elucidate the mechanism of acquired cDDP resistance (ACR), we compared HeLa cells that gained ACR upon chronic cDDP treatment with the parental strain. We show that ACR is due to a lower level of induced apoptosis. Further, upon cDDP treatment, the levels of Fas, Bax and Bid remained unchanged, whereas Bcl-2 and p-Bad were reduced at late times (120 hr

Pediatric aspects are nowadays integrated early in the development process of a new drug. The stronger enforcement to obtain pediatric information by the regulatory agencies in recent years resulted in an increased number of trials in children. Specific guidelines and requirements from, in particular, the European Medicines Agency (EMA) and the Food and Drug Administration (FDA) form the regulatory framework. This review summarizes the regulatory requirements and strategies for pediatric drug development from an industry perspective. It covers pediatric study planning and conduct, considerations for first dose in children, appropriate sampling strategies, and different methods for data generation and analysis to generate knowledge about the pharmacokinetics (PK) and pharmacodynamics (PD) of a drug in children. The role of Modeling and Simulation (M&S) in pediatrics is highlighted—including the regulatory basis—and examples of the use of M&S are illustrated to support pediatric drug development.

Raf kinase plays a central role in oncogenic signaling and acts as a downstream effector of Ras in the extracellular signal-regulated (ERK) kinase pathway. BAY 43-9006 (BAY) is a novel signal transduction inhibitor that prevents tumor cell proliferation and angiogenesis through blockade of the Raf/MEK/ERK pathway at the level of Raf kinase and the receptor tyrosine kinases vascular endothelial growth factor receptor-2 and platelet-derived growth factor receptor-beta. The present study evaluates the effects of combining BAY and platinum derivatives on human colorectal cancer cells using different incubation protocols. Our data show that the combination of oxaliplatin or cisplatin with BAY results in marked antagonism irrespective of the used application schedule. Furthermore, BAY abrogates the cisplatin-induced G2 arrest as well as the G1 arrest induced by oxaliplatin. BAY alone arrests cancer cells in their current cell cycle phase and affects cell cycle regulative genes. Specifically, BAY reduced the protein expression of p21Cip1 as well as cyclin D1, and inhibits the expression of cdc2 (cdk1). Utilizing atom absorption spectrometry, BAY significantly reduced cellular uptake of platinum compounds and thereby the generation of DNA adducts. Taken together, co-incubation with BAY results in reduced cellular uptake of platinum compounds and consecutively reduced generation of DNA adducts, and eventually decreased cellular cytotoxicity in human colorectal cancer cells. Our results indicate that the Raf kinase inhibitor BAY 43-9006 might also directly or indirectly interact with platinum transporter proteins in vitro.