Inactivation/deficiency of DHODH induces cell cycle arrest and programed cell death in melanoma

Abstract

Malignant melanoma (MM) is one of the most malignant tumors and has a very poor prognosis. However, there are no effective drugs to treat this disease. As a kind of iron flavin dependent enzyme, dihydroorotate dehydrogenase (DHODH, EC 1.3.3.1) is the fourth and a key enzyme in the de novo biosynthesis of pyrimidines. Herein, we found that DHODH inactivation/deficiency inhibited melanoma cell proliferation, induced cell cycle arrest at S phase and lead to autophagy in human melanoma cells. Meanwhile, leflunomide treatment induced cell apoptosis and deficiency of DHODH sensitized cells to drug-induced apoptosis in BCL-2 deficient melanoma cells, while not in BCL-2 abundant melanoma cells. Then we found that BCL-2 could rescue apoptosis induced by DHODH inactivation/deficiency. Moreover, BCL-2 also showed to promote cell cycle arrest and to inhibit autophagy induced by leflunomide. To explore the mechanisms underlying autophagy induced by DHODH inhibition, we found that AMPK-Ulk1 axis was activated in this process. Besides, JNK was phosphorylated and activated to phosphorylate BCL-2, which abrogated the interaction between BCL-2 and Beclin1 and then abolished autophagy. Our findings provided evidences for the potential of DHODH used as a drug target for melanoma treatment.

Replication and ribosomal stress induced by targeting pyrimidine synthesis and cellular checkpoints suppress p53-deficient tumors

“…The lack of balanced dNTP pool can induce delay of replication fork progression and DNA replication as well as inhibition of RNA synthesis and proper assembly of ribosome 35,36 . In accordance with previous reports 5,7,37,38 , we have observed cell cycle arrest in the early S phase after inhibition of DHODH activity by leflunomide, a clinically used agent in patients with rheumatoid arthritis and multiple sclerosis 39,40 . Surprisingly, we did not observe an increase in DNA damage, unlike reported previously 41 .…”

“…DHODH catalyzes conversion of DHO to orotate, a precursor of uridine monophosphate (UMP) 4 that can yield all other pyrimidines. Since constant replenishment of the pyrimidine pool from glutamine via UMP is required for replication of nuclear DNA and cell growth, dysfunction of DHODH may result in genomic instability 5 , replication stress 6 , and cell cycle arrest 7 . This is particularly relevant for rapidly proliferating cancer cells that are not able to efficiently replenish their pyrimidine pool by salvage pathways and are therefore 'addicted' to DHODH-dependent synthesis of pyrimidines.…”

Cross-Cancer Pleiotropic Associations with Lung Cancer Risk in African Americans

“…DHODH has also been investigated for a role in cancer, including melanoma (58) and acute myeloid leukemia (59), and decreased expression of DHODH was associated with breast cancer risk (60). Several other studies have examined the utility of DHODH inhibitors in cancer by inducing cell-cycle arrest and apoptosis in cancer cells (59,(61)(62)(63)(64)(65)(66). Although DHODH has not been previously associated with lung cancer risk, the abundance of biological evidence for its pleiotropic role in cancer gives credibility to the association.…”

Cross-cancer pleiotropic associations with lung cancer risk in African Americans

“…Several other studies have examined the utility of DHODH inhibitors in cancer by inducing cell cycle arrest and apoptosis in cancer cells (59,(61)(62)(63)(64)(65)(66). While DHODH has not been previously associated with lung cancer risk, the abundance of biological evidence for its pleiotropic role in cancer gives credibility to the association.…”