The Pro-Tumor Biological Function of IL-36α Plays an Important Role in the Tumor Microenvironment of HCC

IL-36 antagonism blunts the proliferation and migration of oral squamous cell carcinoma cells

IL-36 is known to mediate inflammation and fibrosis. Nevertheless, IL-36 signalling axis has also been implicated in cancer, although understanding of exact contribution of IL-36 to cancer progression is very limited, partly due to existence of multiple IL-36 ligands with agonistic and antagonistic function. Here we explored the role of IL-36 in oral squamous cell carcinoma (OSCC). Firstly, we analyzed expression of IL-36 ligands and receptor and found that the expression of IL-36γ was significantly higher in head and neck cancer (HNSCC) than that of normal tissues, and that the high expression of IL-36γ predicted poor clinical outcomes. Secondly, we investigated the direct effect of IL-36γ on OSCC cells and found that IL-36γ stimulated proliferation of OSCC cells with high expression of IL-36R expression. Interestingly, IL-36γ also promoted migration of OSCC cells with low to high IL-36R expression. Critically, both proliferation and migration of OSCC cells induced by IL-36γ were abrogated by anti-IL-36R mAb. Fittingly, RNA sequence analysis revealed that IL-36γ regulated genes involved in cell cycle and cell division. In summary, our results showed that IL-36γ can be a tumor-promoting factor, and targeting of IL-36R signalling may be a beneficial targeted therapy for patients with abnormal IL-36 signalling.

The role of IL-36 and 37 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has garnered considerable attention due to its morbidity and mortality. Although the precise mechanisms underlying HCC tumorigenesis remain to be elucidated, evidence suggests that host immunity plays a pivotal role in its development. IL-36 and IL-37 are important immunoregulatory cytokines classified as pro-inflammatory and anti-inflammatory respectively. In the context of HCC, the downregulation of intrahepatic IL-36 is inversely correlated with cirrhosis, but positively correlated with 5-year survival rates, suggesting that IL-36 offers protection during HCC development. However, IL-36 may lose its hepatoprotective effects as the disease progresses to HCC in the context of dysregulated immunity in cirrhotic patients. Substantially increased circulating IL-36 in HCC patients is likely a systemic response to HCC stimulation, but is insufficient to suppress progression towards HCC. Intrahepatic IL-37 is suppressed in HCC patients, consistent with the inverse correlation between intrahepatic IL-37 and the level of AFP in HCC patients, suggesting IL-37 exerts hepatoprotection. There is no significant difference in IL-37 among differentiations of HCC or with respect to clinical BCLC stages or cirrhosis status in HCC patients. However, IL-37 protection is demonstrated in an IL-37 transfected HCC animal model, showing significantly reduced tumour size. IL-36/37 may inhibit HCC by enhancing M1 tumour-associated macrophages while not affecting M2 macrophages. The interplay between IL-36 (pro-inflammatory) and IL-37 (anti-inflammatory) is emerging as a crucial factor in host protection against the development of HCC. Further research is needed to investigate the complex mechanisms involved and the therapeutic potential of targeting these cytokines in HCC management.