Ochratoxin A (OTA), a mycotoxin produced by different Aspergillus and Penicillium species, is a ubiquitous contaminant of food, which has both nephrotoxic and carcinogenic potential. The underlying changes of gene expression responsible for nephrotoxicity and cancerogenity of OTA are still unknown. Therefore, the effect of nanomolar OTA concentrations on gene expression was analyzed in human kidney proximal tubule cells (RPTEC) in primary culture. Cells were incubated with 10 nM OTA for 14 days, RNA was isolated and the effect of OTA was examined using different pathway specific RT² Profiler PCR Arrays. The PCR array data indicate that prolonged OTA exposure influences Wnt-signaling by altering the expression of genes involved in this pathway (up-regulation: APC, WISP1, WT1; down-regulation: TCF7). Wnt-signaling is known to be essential in embryogenesis and also kidney development. A disruption of this pathway can trigger cancerogenesis. Furthermore, OTA increases the expression of genes that are involved in inflammatory processes (TNF-a, COX2 and NFkB) and thus cause fibrotic changes in renal tissue. In summary, a long-term exposure of human primary kidney cells with an OTA concentration detectable in human renal tissue changes the expression of genes that are involved in both Wnt-signaling and inflammation. These findings allow a new perspective on how OTA leads to kidney damage. (This work was supported by the Deutsche Forschungsgemeinschaft; GE 905/12-2)