Abstract 4777: Exploring ferroptosis pathway for the development of therapeutic strategy in liposarcoma
Authors: Yen Chueh-Chuan , Chen San-Chi , Chen Chih-Hsueh , Wang Jir-You , Chen Chao-Ming , Wu Po-Kuei , Yang Muh-Hwa 
Published: April 2023

Abstract
Background: Liposarcoma (LPS) is one of the most common soft tissue sarcoma (STS) subtypes. Both well-differentiated LPS (WDLPS) and dedifferentiated LPS (DDLPS) have 12q13-15 amplification. Mouse double minute 2 homolog (MDM2) is one of the most important oncogenes within this region. Ferroptosis is a unique type of necrotic cell death featured accumulation of lipid-based reactive oxygen species (ROS) derived from the oxidative modification of phospholipid membranes. Cysteine metabolism is the critical part of ferroptosis regulation. Cystine-glutamate antiporter (system xc-; xCT), encoded by two subcomponents, the solute carrier family 7 member 11 (SLC7A11) and SLC3A2, is responsible for cystine supply from extra-cellular environment. Imported cystine is then reduced to cysteine, a key component of tripeptide glutathione (GSH). Glutathione peroxidase 4 (GPX4) requires GSH to repair lipid peroxidation and prevent ferroptosis. Inactivation of GPX4, either through cystine deprivation due to xCT inhibitor erastin, or by GPX4 inhibitor Ras-selective lethal small molecule 3 (RSL3), will lead to accumulation of lipid-based ROS, and eventually ferroptosis cell death. The tumor suppressor p53 (TP53) could suppress the expression of SLC7A11 and induce ferroptosis. TP53 could also indirectly suppress 3-hydroxy-3-methyl-glutaryl (HMG)-coenzyme A (CoA) reductase (HMGCR) activity, a key pathway for generation of biomolecules with anti-ferroptosis property. MDM2, the key oncogene in DDLPS, and homolog MDM4 could facilitate ferroptotic death in TP53-dependent or -independent mechanisms.
Methods: We explored public domain database to identify possible aberrations of ferroptosis-related genes in DDLPS. We then examined the sensitivity of DDLPS cell lines to possible ferroptosis-inducing agents. Furthermore, we used nutlin-3, a MDM2 inhibitor, to modulate the MDM2 expression in DDLPS cell line, and explored the potential synergistic effect of nutlin-3 with ferroptosis-inducing agents. Finally, we used immunoblotting study to reveal the potential mechanism responsible to possible synergistic effect.
Results: Expression level of GPX4 is significantly lower in DDLPS than adipose tissue and WDLPS, and DPP4 was general higher in LPS than adipose tissue. HMGCR, SLC7A11 and SLC3A2 were mostly up-regulated in LPS in comparison with benign counterpart. Both DDLPS cell lines showed sensitivity to erastin and RSL3. In addition, nutlin-3 could exert synergistic ferroptosis-inducing effect and cytotoxicity with erastin and RSL3 in sequential manner. Furthermore, nultin-3 treatment could upregulate SLC3A2 with altered cystine/glutamate exchange in DDLPS cell lines, indicating possible mechanism responsible for nultin-3 resistance and the synergistic effect of nultin-3 with erastin or RSL3.
Conclusion: Our study showed that modulation of ferroptosis is a potential treatment strategy in DDLPS.
Citation Format: Chueh-Chuan Yen, San-Chi Chen, Chih-Hsueh Chen, Jir-You Wang, Chao-Ming Chen, Po-Kuei Wu, Muh-Hwa Yang. Exploring ferroptosis pathway for the development of therapeutic strategy in liposarcoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4777.