Human primary renal cells as a model for toxicity assessment of chemo-therapeutic drugs Weiwei Li * , Marilyn Lam, David Choy, Andrew Birkeland 1 , Mark E. Sullivan, Joseph M. Post Department of Pharmacology, Berlex Biosciences, Richmond, CA 94804, United States Available online 10 November 2005 Abstract Chemo-therapeutic drugs act on cancerous and normal cells non-selectively and often cause organ impairments during treatment. Improving safety or reducing toxicity becomes an important challenge for developing better anticancer drugs. In the present study, effects of selected anticancer drugs (camptothecin, doxorubicin, colchicine, paclitaxel, cisplatin, and carboplatin) on cell viability and prolifer- ation was investigated. The anti-proliferative activity of each drug on cancer cells (human hepatoma HepG2) and human primary renal proximal tubule cells (hRPTECs and LLC-PK1) was determined with the [ 3 H]thymidine incorporation assay. Results indicated all six drugs blocked cell proliferation in cancer and normal cells. When the anti-proliferation potency was ranked in hRPTECs based on EC50 values, camptothecin is the most potent, followed by doxorubicin, paclitaxel, colchicine, cisplatin and carboplatin. Cytotoxicity of drugs to hRPTECs was assessed with the ATP bioluminescence assay. Doxorubicin and cisplatin were known to induce nephrotoxicity in vivo and they were indeed cytotoxic to hRPTECs in our study with EC50 values at 11.2 and 39.6 lM. All other drugs are not cytotoxic in the concentrations tested. These drugs typically displayed separation of EC50s between potency (anti-proliferation) and cytotoxicity. The dose separation provides a concentration range for each drug to act on cell proliferation without induction of significant cytotox- icity. Our results suggest that hRPTEC system can serve as an in vitro model for assessing potential nephrotoxicity of chemo-therapeutic drugs. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Cytotoxicity; Anti-proliferation; Renal toxicity; Human primary renal proximal tubule epithelial cells 1. Introduction Chemotherapy has been an important approach to the treatment of human cancers. Many chemo-therapeutic agents exert anti-tumor effect by directly interacting with DNA or by disrupting cell division processes. These drugs were developed to inhibit cell division because tumor cells proliferate faster than normal cells. Ideally chemo-thera- peutics should target only neoplastic cells and decrease tumor burden by inducing cytotostatic or cytotoxic effect. In reality, due to lack of specificity, adverse effect on nor- mal cells and organs are common for most chemo-thera- peutic drugs. These side effects include nephrotoxicity, hematotoxicity, neurotoxicity and impairment of other functions (Kintzel, 2001; Viale et al., 2003; Cavaletti et al., 1995). In vitro toxicology analysis using cell cultures has been developed into an important alternative for early toxicity assessment. Nevertheless, cultured cell lines are often altered in many aspects comparing with their tissues of origin. The sensitivity to chemical agents in these cells may not represent the sensitivity of the original normal tis- sues. Several recent studies reported the successful use of human primary cells as models for toxicity analysis and provide a more promising alternative to the animal models 0887-2333/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.tiv.2005.09.016 Abbreviations: DMSO, Dimethyl sulfoxide; PAP, 4-aminophenol; h- RPTEC, Human renal proximal tubule epithelial cells. * Corresponding author. Tel.: +1 510 669 4831; fax: +1 510 669 4247. E-mail address: wei-wei_li@berlex.com (W. Li). 1 Current address: Department of Molecular and Cell Biology, Univer- sity of California at Berkeley, Berkeley, CA, United States. www.elsevier.com/locate/toxinvit Toxicology in Vitro 20 (2006) 669–676