ABSTRACT: The nephrotoxic ifosfamide-metabolite chloroacetaldehyde (CAA) induces changes in intracellular Ca2+-concentration of human RPTEC. This effect is due to a PKA-dependent inhibition of Na+/Ca2+ exchange (Benesic, A., Schwerdt, G. at. al. (2005) Kidney Int 68, 2029-2041). Thus, possible effects of CAA-exposure on cAMP and Ca2+ regulated genes as well the Ca2+/NFAT pathway were investigated by cDNA-microarray analysis. Both microarrays (cAMP/Ca2+ and Ca2+(NFAT) were performed twice. After 24 h CAA exposure a marked downregulation of c-fos and junB was observed in all arrays performed. In the cAMP/Ca2+-arrays downregulation of FOS, ADRB1, INHBA, CDK5, IL2, PLN, SRF, GCG, SGK, JUNB, BDNF, S100A6, CCNA1, MIF, HK2, SST and EGR2 by CAA was observed in two independent experiments. From the AP-1 family expression of junD and fosB were not altered. Overexpression by CAA of CREB and DDIT3 were only observed in one of two experiments. JUND, FOSB, FOSL1, CREM and CREBBP expression was not influenced in reproducible manner, as well as all members of the NFAT-family. In the Ca2+/NFAT-Arrays, PPP3CB, VAV3, NFATC1, IL8, IL6, FASLG, IL3, IFNB1, FOS, BCL2, EGR3, CD3G, HRAS, EP300, IL4, CALM3, RELA, EGR2, NPPB, IFNG, NFATC4, KPNA5, CAMK2BNFKB2 , VEGF, IL8RA, IL2,GATA4, MEF2A, PTPRC, ICOS, NFKBIE, CDKN1A, CSNK2B, ACTB, MEF2B and JUNB mRNA´s were repeatedly reduced by CAA exposure. The only gene with upregulation in both experiments was found to be IFN-alpha. Thus CAA exposure for 24 h leads to a downregulation of of the AP-1 members JUNB and FOS, whereas there is small positive effect on CREB mRNA. CAA reproducibly lowers the expression of IL-2, 3, 4, 6 and 8, whereas the levels of TNFalpha and TGFbeta1 and 3 mRNA were not altered. IFN-alpha mRNA levels were reproducibly increased (>2-fold). In conclusion, CAA seems to interact with Ca2+ and cAMP signalling pathways, with a strong impact on AP-1 proteins and inflammatory signalling. Keywords: stress response to toxic agent
