Celastrol induces proteasomal degradation of FANCD2 to sensitize lung cancer cells to DNA crosslinking agents.
Bottom Line: In the present study, we aimed to identify FANCD2-targeting agents, and found that the natural compound celastrol induced degradation of FANCD2 through the ubiquitin-proteasome pathway.We demonstrated that celastrol downregulated the basal and DNA damaging agent-induced monoubiquitination of FANCD2, followed by proteolytic degradation of the substrate.Furthermore, celastrol treatment abrogated the G2 checkpoint induced by IR, and enhanced the ICL agent-induced DNA damage and inhibitory effects on lung cancer cells through depletion of FANCD2.
Affiliation: Division of Molecular Carcinogenesis and Targeted Therapy for Cancer, State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.Show MeSH
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Mentions: We examined the effect of celastrol on monoubiquitinated FANCD2 in NSCLC cells, and found that compared to the unmodified FANCD2, the monoubiquitinated FANCD2 was decreased more rapidly upon celastrol treatment at 5 μM for 1–4 h (Fig.3a), suggesting that celastrol decreased monoubiquitination of FANCD2 and then reduced protein stability. Furthermore, while cisplatin, HU, MMC and IR induced monoubiquitination of FANCD2 in A549 cells, celastrol treatment (at 5 μM for 4 h) markedly attenuated this effect (Fig.3b). By immunofluorescence assay, we observed that cisplatin induced marked increase in FANCD2 in the nucleus (Fig.3c), suggesting formation of nuclear foci in A549 cells. This phenomenon was attenuated by celastrol (Fig.3c).
Affiliation: Division of Molecular Carcinogenesis and Targeted Therapy for Cancer, State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.