erastin and Osteosarcoma

Osteosarcoma (OS) is a highly fatal bone tumor characterized by high degree of malignancy and early lung metastasis. Traditional chemotherapy fails in improving the efficacy and survival rate of patients with OS. Butyrate (NaBu) has been reported as a new antitumor drug for inhibiting proliferation and inducing apoptosis in various cancer cells. However, the effect of NaBu on the ferroptosis of OS is still unknown. This study aimed to investigate whether NaBu promotes erastin-induced ferroptosis in OS cells and to uncover the underlying mechanism. Here, we found that NaBu significantly enhanced erastin-induced ferroptosis in vitro and in vivo. Compared with the group that erastin used alonely, pre-treating with NaBu exacerbated erastin-meditated GSH depletion, lipid peroxidation, and mitochondrial morphologic changes in OS cells. In a subcutaneous OS model, NaBu combined with erastin significantly reduced tumor growth and increased the levels of 4-HNE. Mechanistically, NaBu downregulated SLC7A11 transcription via regulating ATF3 expression. Overexpression of ATF3 facilitated erastin to induce ferroptosis, while ATF3 knockdown attenuated NaBu-induced ferroptosis sensitivity. In conclusion, our findings revealed a previously unidentified role of NaBu in erastin-induced ferroptosis by regulating SLC7A11, suggesting that NaBu may be a potential therapeutic agent for OS treatment.

Topics: Activating Transcription Factor 3; Amino Acid Transport System y+; Bone Neoplasms; Butyrates; Ferroptosis; Humans; Osteosarcoma

Lipid metabolism is the key to ferroptosis susceptibility. However, little is known about the underlying mechanisms in osteosarcoma cells. Functional restriction of bromodomain-containing protein 4 (BRD4) reduced the susceptibility to erastin-induced ferroptosis of osteosarcoma cells both in vitro and in vivo. Mechanically, BRD4 controls the splicing efficiency of the RNA precursor (pre-mACSL3) of ACSL3 (ACSL3) by recruiting serinerich/threonine protein kinase 2 (SRPK2) to assemble the splicing catalytic platform. Moreover, the AMP-binding domain of ACSL3 significantly influences arachidonic acid synthesis and thus determines the susceptibility to erastin-induced ferroptosis. Overall, we found a BRD4-mediated pre-mACSL3 splicing influences erastin-induced ferroptosis by affecting arachidonic acid synthesis in osteosarcoma cells. Data in this study fills some of the gap in understanding the post-transcriptional regulatory mechanisms of ACSL3 and provides new insights into the mechanisms of lipid metabolism regulation and its effect on susceptibility to ferroptosis in osteosarcoma cells.

Topics: Arachidonic Acid; Cell Cycle Proteins; Ferroptosis; Humans; Nuclear Proteins; Osteosarcoma; Protein Kinases; Protein Serine-Threonine Kinases; RNA Precursors; RNA-Binding Proteins; Serine-Arginine Splicing Factors; Transcription Factors

Recent studies have indicated that promoting ferroptosis is a promising approach to attenuate drug resistance of cancer cells. Hence, this study aimed to induce ferroptosis in osteosarcoma cells, thereby increasing the sensitivity to cisplatin. Osteosarcoma cells MG63 and Saos-2 were incubated with increasing doses of cisplatin to generate cisplatin-resistant strains, MG63/DDP and Saos-2/DDP. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry assays were performed to evaluate cell proliferation and cell death, respectively. Malondialdehyde (MDA), reactive oxygen species (ROS), and lipid oxidation in cells were measured to evaluate the degree of cell ferroptosis. MG63/DDP and Saos-2/DDP cells showed increased viability and decreased death rate compared with MG63 and Saos-2 cells, respectively, upon cisplatin treatment. Western blotting analysis indicated that protein levels of p-STAT3 (Ser727), nuclear factor erythroid 2-related factor 2 (Nrf2), and glutathione peroxidase 4 (GPx4) in drug-resistant strains increased significantly in response to cisplatin. Co-treatment with cisplatin and agonists of ferroptosis, Erastin, and RSL3, remarkably increased MDA, ROS, lipid oxidation, and sensitivity to cisplatin, in MG63/DDP and Saos-2/DDP cells. Similar results were observed by co-treatment of cells with cisplatin and a STAT3 inhibitor. The reduction of protein levels of p-STAT3 (Ser727), Nrf2, and GPx4 in MG63/DDP and Saos-2/DDP cells resulted in increased ferroptosis and sensitivity to cisplatin. These results indicate that cisplatin-resistant osteosarcoma cells inhibited ferroptosis after exposure to low doses of cisplatin. However, ferroptosis agonists and STAT3 inhibitor reactivated ferroptosis in the cells and consequently increased sensitivity to cisplatin. This study demonstrates a new approach to attenuate resistance of osteosarcoma to cisplatin in vitro .

Topics: Bone Neoplasms; Cell Line, Tumor; Cisplatin; Drug Resistance, Neoplasm; Ferroptosis; Humans; NF-E2-Related Factor 2; Osteosarcoma; Phospholipid Hydroperoxide Glutathione Peroxidase; Piperazines; STAT3 Transcription Factor