Comparative cytotoxicity of selected cyanotoxins on Human Embryonic Kidney (HEK-293) and Human Kidney Adenocarcinoma (ACHN) Cells

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INTRODUCTION AND OBJECTIVES: Freshwater resources are now threatened by the presence and increase of toxic cyanobacterial blooms all over the world. This is typically a direct result of anthropogenic pollution of water bodies, such as partially treated nutrient-rich effluents and the leaching of fertilizers and animal wastes. Approximately 75% of water samples containing cyanobacteria consists cyanobacterial secondary metabolites which can produce toxic effects to livestock, . wildlife and human. There is a wide spectrum of cyanotoxins, predominantly causing neurotoxic, hepatotoxic and dermatotoxic effects on contaminated individuals. In diverse aquatic systems, cyclic peptide toxins microcystins (MCs) and nodularin are the most abundant and most noxious cyanotoxins present causing highest impact on hepatocytes. Though these toxins are reputed as potent hepatotoxins, recent evidence suggests that these peptides could cause kidney injuries. Present study was carried out to evaluate cytotoxic effects of some selected MCs (MC-LR, MC-RR, MC-LF and MCLW) and Nodularin on human embryonic kidney cells (HEK-293) and METHOD: Human kidney adenocarcinoma cells (ACHN). HEK-293 and ACHN cells were treated with different concentrations of MC-LR, MC-RR, MC-LF, MC-LW and Nodularin (1.0-200 pM) for 24 h and cytotoxicity was evaluated by Sulphorhodamine B (SRB) assay. RESULTS: A significant cytotoxicity was induced in both types of cells by the toxins tested. All the toxins had a significantly higher cytotoxicity on normal kidney cells than on the kidney adenocarcinoma cells. Furthermore, MC-LR had the lowest IC50 values (16.57±0.035 for HEK-293 and 62.36±0.037 for ACHN cells) while MC-LW had the highest IC50 values (1158.16±9.025 for HEK-293 and 1589.78±3.206 for ACHN cells). CONCLUSION: Overall findings of the present study demonstrate that cyanotoxins could cause cytotoxic effects on kidney cells. MC-LR was the most toxic while MC-LW was least toxic cyanotoxin on both cell types tested. MC-RR, MC-LF and Nodularin had moderate cytotoxicity on human renal cells. Key words: Microcystins, Nodularin, ACHN cells, HEK293 cells, cytotoxicity This work was financially supported by National Research Council of Sri Lanka Grant 11-034. 1 Department of Zoology, Faculty of Applied sciences, University of Sri Jayewardenepura, Gangodawila, Nugegoda, Sri Lanka.2 Institute of Biochemistry, Molecular Biology and Biotechnology, University of Colombo, 90, Cumaratunga Munidasa Mawatha, Colombo 03, Sri Lanka.