RIPK3 activation induces TRIM28 derepression in cancer cells and enhances the anti-tumor microenvironment

• Main Authors: Han-Hee Park, Hwa-Ryeon Kim, Sang-Yeong Park, Sung-Min Hwang, Sun Mi Hong, Sangwook Park, Ho Chul Kang, Michael J. Morgan, Jong-Ho Cha, Dakeun Lee, Jae-Seok Roe, You-Sun Kim
• Format: Article
• Language: English
• Published: BMC 2021-08-01
• Series: Molecular Cancer
• Subjects: RIPK3; TRIM28; NF-κB; Transcriptional regulator; Chromatin; Immunostimulatory cytokines
• Online Access: https://doi.org/10.1186/s12943-021-01399-3

Abstract Background Necroptosis is emerging as a new target for cancer immunotherapy as it is now recognized as a form of cell death that increases tumor immunogenicity, which would be especially helpful in treating immune-desert tumors. De novo synthesis of inflammatory proteins during necroptosis appears especially important in facilitating increased anti-tumor immune responses. While late-stage transcription mediated by NF-κB during cell death is believed to play a role in this process, it is otherwise unclear what cell signaling events initiate this transactivation of inflammatory genes. Methods We employed tandem-affinity purification linked to mass spectrometry (TAP-MS), in combination with the analysis of RNA-sequencing (RNA-Seq) datasets to identify the Tripartite Motif Protein 28 (TRIM28) as a candidate co-repressor. Comprehensive biochemical and molecular biology techniques were used to characterize the role of TRIM28 in RIPK3 activation-induced transcriptional and immunomodulatory events. The cell composition estimation module was used to evaluate the correlation between RIPK3/TRIM28 levels and CD8+ T cells or dendritic cells (DC) in all TCGA tumors. Results We identified TRIM28 as a co-repressor that regulates transcriptional activity during necroptosis. Activated RIPK3 phosphorylates TRIM28 on serine 473, inhibiting its chromatin binding activity, thereby contributing to the transactivation of NF-κB and other transcription factors, such as SOX9. This leads to elevated cytokine expression, which then potentiates immunoregulatory processes, such as DC maturation. The expression of RIPK3 has a significant positive association with the tumor-infiltrating immune cells populations in various tumor type, thereby activating anti-cancer responses. Conclusion Our data suggest that RIPK3 activation-dependent derepression of TRIM28 in cancer cells leads to increased immunostimulatory cytokine production in the tumor microenvironment, which then contributes to robust cytotoxic anti-tumor immunity.