Extracellular Granzyme A Promotes Colorectal Cancer Development by Enhancing Gut Inflammation

If not properly regulated, the inflammatory immune response can promote carcinogenesis, as evident in colorectal cancer (CRC). Aiming to gain mechanistic insight into the link between inflammation and CRC, we perform transcriptomics analysis of human CRC, identifying a strong correlation between expression of the serine protease granzyme A (GzmA) and inflammation. In a dextran sodium sulfate and azoxymethane (DSS/AOM) mouse model, deficiency and pharmacological inhibition of extracellular GzmA both attenuate gut inflammation and prevent CRC development, including the initial steps of cell transformation and epithelial-to-mesenchymal transition. Mechanistically, extracellular GzmA induces NF-κB-dependent IL-6 production in macrophages, which in turn promotes STAT3 activation in cultured CRC cells. Accordingly, colon tissues from DSS/AOM-treated, GzmA-deficient animals present reduced levels of pSTAT3. By identifying GzmA as a proinflammatory protease that promotes CRC development, these findings provide information on mechanisms that link immune cell infiltration to cancer progression and present GzmA as a therapeutic target for CRC. [Display omitted] •GZMA mRNA expression correlates with inflammation in human CRC patients•GzmA deficiency reduces gut inflammation and colorectal cancer development•Therapeutic GzmA inhibition in WT mice reduces colorectal cancer development•GzmA induces IL-6 production in macrophages activating pSTAT3 in colon cancer cells Santiago et al. show that extracellular granzyme A (GzmA) contributes to gut inflammation and colorectal cancer (CRC) development by promoting IL-6 production in macrophages. Therapeutic inhibition of GzmA attenuates inflammation and CRC development, suggesting that GzmA could be useful to treat gut inflammation and prevent CRC.