PTGDS PROMOTES TUMORIGENESIS OF PERIPHERAL T CELL LYMPHOMA THROUGH REGULATING IRON METABOLISM

Abstract

Introduction: Accumulating evidence indicates that ferroptosis, an iron-dependent cell death, is involved in the development of tumors, and targeting ferroptosis offers great potential in tumor therapy. However, the regulatory networks of ferroptosis in peripheral T cell lymphoma (PTCL) remain unclear. Methods: Paraffin-embedded tissues of 112 PTCL patients and 38 reactive hyperplasia cases were collected with informed consents. Lentiviral vectors were stably transfected into PTCL cell lines. Tandem mass tag (TMT)-mass spectrometry and RNA-sequencing (RNA-seq) were performed for downstream analysis. Co-IP and confocal immunofluorescence were performed to verify protein–protein interaction. Xenograft models were established using SCID Beige mice. Results: Firstly, both mRNA and protein levels of PTGDS were found to be higher in PTCL cells and patients’ tissue (Figure 1A–C). Survival analysis revealed that the positive expression of PTGDS was closely associated with worse prognosis in PTCL patients (Figure 1D). PTGDS overexpression could significantly promote the proliferation of PTCL cells while PTGDS knockdown inhibited it in vitro and in vivo (Figure 2A,B). Besides, PTCL cells with PTGDS knockdown displayed a higher apoptosis rate (Figure 2C). PTGDS specific inhibitor AT56 could significantly inhibit the proliferation of PTCL cells, in a dose- and time-dependent manner (Figure 2D). Moreover, AT56 treatment induced the cell cycle arrest at G0/G1 phase in PTCL cells (Figure 2E). Analysis based on TMT-mass spectrometry found that AT56 treatment significantly regulated the expression of ferroptosis-related molecules (Figure 3A) in PTCL cells. The anti-tumor effects of sorafenib and erastin, classic ferroptosis inducers, was significantly enhanced by AT56 treatment, and Fer-1, ferroptosis inhibitor, rescued the inhibitory role of AT56 on cell proliferation (Figure 3B,C). Moreover, AT56 promoted erastin/sorafenib-induced accumulation of lipid ROS (Figure 3D), a classic biomarker of ferroptosis. Further in-vivo experiments observed that AT56 treatment enhanced the anti-tumor effects of sorafenib (Figure 3E). Mechanically, structure analysis of differentially expressed molecules in TMT-mass spectrometry identified HMOX1, a regulator of heme catabolism, as PTGDS interactive protein. Co-IP and confocal immunofluorescence assays verified their co-localization and interaction in PTCL cells (Figure 4A,B). Moreover, AT56 treatment increased the level of intracellular iron, and HMOX1 knockdown could rescue it (Figure 4C). Keywords: aggressive T-cell non-Hodgkin lymphoma, diagnostic and prognostic biomarkers, molecular targeted therapies The research was funded by: National Natural Science Foundation (No. 82270200, No. 82170189, No. 82070203, No. 81800194, No. 81770210); Key Research and Development Program of Shandong Province (No. 2018CXGC1213); China Postdoctoral Science Foundation (No. 2021T1404223); Translational Research Grant of NCRCH (No. 2021WWB02, No. 2020ZKMB01); Shandong Provincial Natural Science Foundation (ZR2021YQ51); Taishan Scholars Program of Shandong Province; Shandong Provincial Engineering Research Center of Lymphoma; Academic Promotion Programme of Shandong First Medical University (No. 2019QL018). No conflicts of interests pertinent to the abstract.