NFS1, together with FXN, protects cells from ferroptosis and DNA damage in diffuse large B-cell lymphoma

Abstract

Diffuse large B cell lymphoma (DLBCL) is a common hematologic malignancy. NFS1 cysteine desulfurase, as a rate-limiting enzyme in the iron-sulfur cluster (ISC) biogenesis, has been reported to be associated with tumor progression. However, the role of NFS1 in DLBCL remains elusive. Here, we showed an upregulation of NFS1 in DLBCL tumor tissues. Knockdown of NFS1 decreased the cell viability and enhanced LDH levels in DLBCL cells. Animal experiments further indicated that downregulation of NFS1 suppresses tumor growth in vivo. NFS1 knockdown increased the lipid reactive oxygen species (ROS) level in cells, and this promotional effect was reversed by ferroptosis inhibitors, but not influenced by other types of cell death inhibitors. This result suggested that NFS1 depletion-impaired cell viability is associated with ferroptosis. Silenced NFS1 aggravated ferroptosis inducers caused cell viability inhibition, lactate dehydrogenase (LDH), and lipid ROS levels enhancement, while the addition of ferroptosis inhibitors abated these trends. Moreover, catalytic residue mutation of NFS1 did not affect its protein expression but decreased the cell viability, which was promoted by NFS1 upregulation, indicating that the protective effect of NFS1 in DLBCL cells was related to its catalytic activity. Further results showed that frataxin (FXN), the upstream activator of NFS1, reduced the cell viability in NFS1 upregulated cells. Consistent with NFS1, FXN silencing aggravated erastin-induced cell viability inhibition and LDH level enhancement. Silencing NFS1 or FXN inhibited the level of iron ions storage-related proteins but promoted the level of transport-related proteins. In addition, silenced NFS1 or FXN displayed an inhibition effect on protein expression of DNA polymerases, but a promotion trend in the phosphorylation of DNA damage markers. In conclusion, we demonstrated that ISC-related proteins NFS1 and FXN protect DLBCL cells from ferroptosis and DNA damage, thus exhibiting an essential role in DLBCL progression.