Microarray analysis of Leflunomide-induced limb malformations in CD-1 mice

The immuno-suppressant Leflunomide, a potent inhibitor of dihydroorotate dehydrogenase (DHODH) and tyrosine kinases, is teratogenic in laboratory animals. To better understand its teratogenic mechanism, pregnant mice (CD-1) received a single dose of 70mg/kg Leflunomide, or vehicle control, by gastric intubation on gestation day 10. Gene expression was evaluated in the pooled fore- and hindlimb buds of embryos 4 and 24h post-treatment. The down-regulation of cholesterol biosynthesis-related genes was observed but could not be correlated with teratogenicity, since Leflunomide did not alter cholesterol concentration in limb bud. Leflunomide inhibited the mitosis of limb mesenchymal cells, which may be linked to DHODH inhibition as well as a potential effect on tyrosine kinases that mediate cytokine and growth factor signaling and that may be responsible for the Leflunomide's teratogenicity.