Inflammatory cytokines has been of great interest in the field of colorectal cancer (CRC) tumor immunology in recent years. As an anti-inflammatory interleukin (IL), IL-38 may contribute to the early diagnosis of CRC and improve the prognosis of CRC patients. This study was designed to investigate the role of circulating IL-38 and the regulatory mechanism of IL-38 in CRC. Expression of IL-38 were detected by ELISA and immunohistochemical staining. The influence of IL-38 on CRC were evaluated by Western blot and cell biology assays after CRC cells were treated by rhIL-38 or LM22B-10. We also verified the anti-tumor activity of IL-38 in transgenic mouse model. The expression of IL-38 was found to be correlated with progression of CRC. IL-38 inhibits CRC metastasis, proliferation and facilitates apoptosis through suppressing the activation of extracellular signal-regulated kinases (ERK) signaling pathway inducing the decrease of downstream genes, which were partially abrogated by ERK activator LM22B-10 in vitro. We also found that IL-38 overexpression inhibits tumorigenesis in vivo. Our findings indicate that IL-38 may serve as a serum prediction marker to identify the prognosis of CRC patients. IL-38 may inhibit the progression of CRC by negatively regulation on ERK signaling pathway.
Keywords: ERK signaling pathway; apoptosis; colorectal cancer; interleukin-38; metastasis; proliferation.