Abstract
Leflunomide, an anti-inflammatory agent, has been shown to be effective in multiple myeloma (MM) treatment; however, the mechanism of this phenomenon has not been fully elucidated. The aim of the study was to assess the role of mitochondria and dihydroorotate dehydrogenase (DHODH) inhibition in the cytotoxicity of leflunomide in relation to the MM cell line RPMI 8226. The cytotoxic effect of teriflunomide—an active metabolite of leflunomide—was determined using MTT assay, apoptosis detection, and cell cycle analysis. To evaluate DHODH-dependent toxicity, the cultures treated with teriflunomide were supplemented with uridine. Additionally, the level of cellular thiols as oxidative stress symptom was measured as well as mitochondrial membrane potential and protein tyrosine kinases (PTK) activity. The localization of the compound in cell compartments was examined using HPLC method. Teriflunomide cytotoxicity was not abolished in uridine presence. Observed apoptosis occurred in a mitochondria-independent manner, there was also no decrease in cellular thiols level. Teriflunomide arrested cell cycle in the G2/M phase which is not typical for DHODH deficiency. PTK activity was decreased only at the highest drug concentration. Interestingly, teriflunomide was not detected in the mitochondria. The aforementioned results indicate DHODH- and mitochondria-independent mechanism of leflunomide toxicity against RPMI 8226 cell line.
Highlights
Leflunomide is metabolized to one major metabolite A771726, which is responsible for its activity in vivo, and many other minor metabolites (Figure 1) [3]
Leflunomide has been shown to be effective in studies, the exact mechanism of its cytotoxic activity in MM has not been fully elucidated and the role of dihydroorotate dehydrogenase (DHODH) inhibition remains uncertain
Cytotoxicity was evaluated by the MTT assay were shriveled as compared to control cells, and contained cytoplasmic blebbing
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Leflunomide is anti-inflammatory and immunomodulatory drug which was approved for treatment of autoimmune diseases. It is used to reduce the symptoms of rheumatoid arthritis and psoriatic arthritis [1,2]. It is well absorbed after oral administration and it is almost completely converted during the first pass. Leflunomide is metabolized to one major metabolite A771726 (teriflunomide), which is responsible for its activity in vivo, and many other minor metabolites (Figure 1) [3]
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