miR-4284 as a novel epigenetic mechanism triggered by immunogenic cancer cell death

LAMBERTI MJ; RAVO M; MONTICO B; IORIO R; GIURATO G; NIGRO A; TARALLO R; WEISZ A; STEFFAN A; STELLATO C; CASOLARO V; FAE D; DAL COL J

Congreso; World Immune Regulation Meeting XV; 2021

Immunogenic cell death (ICD) in cancer is a functionally unique regulated form of stress-mediated cell death that activates innate and adaptive immune system response against tumor cells. ICD is characterized by the sequential release and/or exposure of certain damage-associated molecular patterns by dying cells. MicroRNAs (miRNAs) play critical roles in the regulation of both cell death and immune-associated mechanisms in cancer, while evidence of their potential involvement in ICD is limited. Therefore, we explored the participation of miRNAs in well-established models of ICD induced in vitro in aggressive B cell lymphoma (Mino) and breast cancer (MDA-MB-231) cell lines by the combination of retinoic acid (RA) and interferon-alpha (IFN-a) or by doxorubicin. Small non-coding RNA sequencing was performed in untreated, treated, and gamma-irradiated (necrotic) cells. Analysis of expression profiles identified 16 miRNAs differentially expressed in cells subjected to ICD relative to viable and gamma-irradiated/necrotic cells. Among them, RT-qPCR-based validation showed that miR-4284 was upregulated by both ICD inducers in either breast or lymphoma cancer cells. To elucidate the role of miR-4284 in ICD, we compared the RNA profiles of RA/IFNa-treated lymphoma exposed or not to anti-miR-4284. Canonical pathway enrichment analysis identified miR-4284-dependent downregulation of biological significance in the ?Antigen Presentation Pathway?. The predicted miR-4284 targets involved in this pathway were MCH-II-associated genes, whose transcription and surface expression were suppressed by RA/IFNa treatment. In silico analysis of RNA-sequencing data of B-cell lymphoma and paired normal tissues demonstrated that those MHC-II transcripts were remarkably lower in tumor samples. Overall, our data suggest a protumor role of miR-4284 in ICD-subjected lymphoma cells, putatively linked to inhibition of MHC-II-dependent antigen presentation pathways, which could ultimately suppress tumor recognition by the immune system.