Abstract
Interleukin-33 (IL-33), a damage-associated molecular pattern molecule, is a cytokine within the IL-1 interleukin family that binds to the plasma membrane receptor suppression of tumorigenicity 2 on numerous cell types. IL-33 has been extensively studied in its role in autoimmune diseases, host responses to pathogens and allergens, and has been associated with tumorigenic effects in cancer research. The present study was performed to investigate the effects of IL-33 on colon cancer cells, based off the previous data that have demonstrated an anti-tumor effect of IL-33 on pancreatic cancer cells. The effects of IL-33 on proliferation, cell survival and apoptosis on human HCT-116 colon cancer cells were examined using clonogenic survival assays, proliferation and caspase-3 activity kits, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining and immunocytochemistry. It was determined that the HCT-116 cells demonstrated an notable decrease in optical density value upon incubation with IL-33, along with a decrease in the number of colonies, compared with the controls. It was further determined that the anti-proliferative effect of IL-33 on HCT-116 cells was associated with downregulation of the pro-proliferative molecules cyclin B, cyclin D and cyclin dependent kinase 2. An apoptosis-inducing effect of IL-33 on HCT-116 cells was associated with downregulation of the anti-apoptotic molecules Flice-like inhibitory protein and B-cell lymphoma 2. Taken together, the results indicated that IL-33 inhibits the growth of colon cancer by suppressing cellular proliferation, whilst simultaneously promoting apoptosis.