Transcriptomic analysis of the anti-tumor effects of leflunomide in prolactinoma

Leflunomide's anti-tumor effects have been investigated in various types of tumors; however, its impact on pituitary adenoma, particularly prolactinoma, is unclear. Hence, the current study evaluates the effects of leflunomide on prolactinoma cells in vitro and in vivo and elucidates the potential underlying mechanism(s). Cell Counting Kit-8 results revealed that leflunomide inhibits the proliferation of rat pituitary tumor cell lines (GH3 and MMQ) in a concentration-dependent manner in vitro. However, combination therapy of cabergoline and leflunomide exerted stronger inhibitory effects than cabergoline in MMQ cells in vitro and in vivo. Transcriptomics and gene ontology (GO) analyses identified genes significantly enriched in apoptotic processes and programmed cell death. Protein-Protein Interaction (PPI) networks defined the roles of hub genes (Mdm2, Cdkn1a, Plk2, and Ccng1) in leflunomide-induced cell death. GO and pathway enrichment analyses showed that the combination drug-specific differentially expressed genes were associated with inhibiting protein translation, but were active in gene expression processes. Hence, the anti-proliferative effects of leflunomide on prolactinoma cell lines may be mediated through programmed cell death pathways. Importantly, combining cabergoline with leflunomide effectively enhances the toxic effect of cabergoline, suggesting a potential therapeutic role for leflunomide in drug-resistant prolactinoma.