Integration of miRNA:mRNA co-expression revealed crucial mechanisms modulated in immunogenic cancer cell death

LAMBERTI MJ; MONTICO B; RAVO M; GIURATO G; NIGRO A; STEFFAN A; WEISZ A; RUMIE VITTAR NB; CASOLARO V; DAL COL J

Congreso; 28th Congress of European Association for Cancer Research; 2022

Introduction: 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 aimed to explore the participation of miRNAs and their putative targets in the context of ICD.Methods: B cell lymphoma (Mino) and breast cancer (MDA-MB-231) cell lines were exposed to two different ICD inducers: RA/IFNα and doxorubicin, and to non-ICD inducer: gamma irradiation. Then, miRNA and mRNA profiles were studied by next-generation sequencing. miRNA predicted targets were analyzed by real-time PCR and flow cytometry. Results: Co-expression analysis identified 16 miRNAs differentially modulated in cells subjected to ICD. Integrated miRNA-mRNA functional analysis revealed candidate miRNAs, mRNAs, and modulated pathways associated with Immune System Process (GO Term). In this sense, ICD induced a distinctive transcriptional signature hallmarked by regulation of antigen presentation, a crucial step for a proper immune system antitumor response activation. Interestingly, the major histocompatibility complex class I (MHC-I) pathway was upregulated whereas class II (MHC-II) was downregulated. Analysis of MHC-II associated transcripts and HLA-DR surface expression validated the inhibition of this pathway by ICD on lymphoma cells. miR-4284 and miR-212-3p were the strongest miRNAs upregulated by ICD associated with this event. It is well known that MHC-II expression on tumor cells facilitates the recruitment of CD4+ T cells. However, the interaction between tumor MHC-II and the inhibitory coreceptor LAG-3 on tumor-associated lymphocytes could provide an immunosuppressive signal that directly represses effector cytotoxic activity. In this context, MHC-II downregulation by ICD could enhance antitumor immunity.Conclusion: We found that the miRNA profile was significantly altered during ICD. Several miRNAs are predicted to be involved in the regulation of Class I and II MHC pathway, whose implication in ICD was demonstrated herein for the first time, which could eventually modulate tumor recognition and attack by the immune system.