P1210: targeting ptgds as a novel therapeutic approach in peripheral t cell lymphoma through regulating iron metabolism

Topic: 20. Lymphoma Biology & Translational Research Background: Ferroptosis, characterized by reactive oxygen species (ROS) accumulation and lipid peroxidation, is a kind of specialized cell death dependent on iron metabolism. Accumulating evidence indicates that ferroptosis is involved in the development of several tumors, and targeting ferroptosis holds great potential for tumor therapy. Aims: Herein, we aim to investigate the regulatory networks of ferroptosis and its molecular mechanisms in peripheral T cell lymphoma (PTCL). Methods: Archived, paraffin-embedded samples extracted from 112 de novo PTCL patients and 38 reactive hyperplasia cases were collected with informed consents. Empty lentiviral vectors (sh-Control) or those coding for sh-PTGDS were stably transfected into PTCL cell lines. Tandem mass tag (TMT)-mass spectrometry and RNA-sequencing (RNA-seq) were performed. Xenograft models were established and ARRIE guidelines were strictly adhered to for all experiments. Results: We firstly explored the expression level and biological function of PTGDS in PTCL. IHC staining showed higher expression levels of PTGDS in PTCL tissues than those in control tissues (Fig. 1A). Survival analysis revealed that the positive expression of PTGDS was closely associated with worse prognosis in PTCL patients (Fig. 1B). Functional enrichment analysis based on RNA-seq indicated that PTGDS was closely associated with tumor biology in PTCL cells, including cell death, cell apoptosis, cell cycle, cell aging, autophagy and so on. PTGDS specific inhibitor AT56 could significantly inhibit the proliferation of PTCL cells, in a dose- and time-dependent manner (Fig. 1C). Moreover, tumors with PTGDS-repression displayed suppressed bioluminescence and growth (Fig. 1D) in vivo. Analysis based on TMT-mass spectrometry found that AT56 treatment could significantly regulate the expression level of ferroptosis-related molecules (Fig. 1E) in PTCL cells. Further in-vivo experiments observed that AT56 treatment enhanced the antitumor effects of ferroptosis inducer sorafenib in PTCL mice model (Fig. 1F). Moreover, it’s found that AT56 significantly promoted erastin/sorafenib-induced accumulation of lipid ROS (Fig. 1G), a classic biomarker of ferroptosis, indicating the involvement of PTGDS in ferroptosis process in PTCL. Ferroptosis process was mainly dominated by ROS production, iron accumulation and lipid peroxidation. Our experiments found that deferoxamine (DFO), an iron chelator, could rescue the inhibitory role of AT56 on cell proliferation in PTCL (Fig. 1H), indicating the regulatory role of PTGDS in iron metabolism. Mechanically, structure analysis of differentially expressed molecules in TMT-mass spectrometry identified HMOX1, a regulator of heme catabolism, as PTGDS interactive protein. Furthermore, Co-IP and confocal immunofluorescence assays verified the co-localization and interaction of PTGDS and HMOX1 protein in PTCL cells (Fig. 1I-J). Summary/Conclusion: Taken together, our investigations firstly identified the high expression of PTGDS and its prognostic significance in PTCL patients. In-vitro and in-vivo investigation revealed that targeting PTGDS might act as a novel therapeutic approach in PTCL patients through regulating HMOX1-mediated iron metabolism.Keywords: Iron metabolism, Prognosis, Targeted therapy, T cell lymphoma