Abstract 1184P
Background
Receptor-Interacting Serin/Threonin-Protein Kinase 3 (RIPK3) mediates necroptosis, a programmed form of cell death, which elicits the release of intracellular contents (DAMPs) and cytokines. These substances attract and activate anti-tumoral immune cells, rendering necroptosis highly immunogenic. In lung adenocarcinomas (LUAD), RIPK3 is a tumor suppressive aberrational target, which has been shown to induce immune suppression in the tumor microenvironment.
Methods
To investigate RIPK3 in human LUAD, we took advantage of The Cancer Genome Atlas program (TCGA) and primary samples. We further studied RIPK3 in a LUAD mouse model, carrying Kras G12D oncogene as well as Cas9 (both under a floxed stop codon) and floxed p53 tumor suppressor. Tumor induction was obtained through Cre recombination, which induced Cas9 and Kras G12D activation as well as p53 deletion. Together with Cre we delivered single guide RNA for Cas9 activity directed against Ripk3 (sgRipk3) or the negative control LacZ (sgLacZ).
Results
Expression of RIPK3 was decreased in human LUAD tumors compared to paired healthy tissue, both at mRNA and protein levels. Moreover, RIPK3 expression was further decreased in advanced stage tumors. Leveraging the Danaher scores, as an index of immune infiltration, we identified that high RIPK3 expression correlates with an overall enrichment of tumor infiltrating leukocytes, such as T-cells, B-cells, macrophages, and dendritic cells. In LUAD mice exposed to sgRipk3, the Cre-recombination did not show a full penetrance, therefore eliciting Ripk3 proficient and deficient lesions within the same animal. Interestingly, the tumor area of Ripk3 deficient lesions was significantly higher than Ripk3 proficient lesions. Analysis of the sgLacZ group revealed an heterogenous Ripk3 expression profile in tumors, where more advanced and bigger tumors showed weaker expression of Ripk3, suggesting that tumors actively evade Ripk3 expression.
Conclusions
Taken together our data clearly point to RIPK3 as a tumor suppressor in LUAD. This effect may be driven by the inhibition of necroptotic cell death, which in turn alters immune cell recruitment.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Deutsche Forschungsgemeinschaft (DFG).
Disclosure
N. McGranahan: Financial Interests, Personal and Institutional, Stocks/Shares, received consultancy fees: Achilles Therapeutics. P.J. Jost: Financial Interests, Personal and Institutional, Advisory Role, Received Honoraria, Research Funding: AbbVie; Financial Interests, Personal and Institutional, Advisory Role, received honoraria, travel/accomodation: Bayer; Financial Interests, Personal and Institutional, Advisory Role, received honoraria, research funding, and/or travel/accommodation expenses: Boehringer Ingelheim; Financial Interests, Personal and Institutional, Advisory Role, received honoraria, research funding, and/or travel/accommodation expenses: Novartis; Financial Interests, Personal and Institutional, Advisory Role, received honoraria, travel/accommodation: Pfizer; Financial Interests, Personal and Institutional, Advisory Role, received honoraria, travel/accommodation: Servier; Financial Interests, Personal and Institutional, Advisory Role, received honoraria, research funding, and/or travel/accommodation expenses: Roche; Financial Interests, Personal and Institutional, Advisory Role, received honoraria, research funding, and/or travel/accommodation expenses: BMS/Celgene. All other authors have declared no conflicts of interest.