MyD88 Regulates LPS-induced NF-ĸB/MAPK Cytokines and Promotes Inflammation and Malignancy in Colorectal Cancer Cells

Abstract

Background/aim: Inflammation may play a role in cancer initiation and progression. The molecular mechanisms by which inflammation causes colorectal cancer, remains unclear. The present study investigated a signaling pathway that affects inflammation in colorectal cancer.

Materials and methods: SW480 cells, HCT116 cells, and cells with knockdown of myeloid differentiation 88 (MyD88), and forced expression of MyD88 were treated with lipopolysaccharide (LPS; 1 μg/ml). Inflammation-related mRNA expression was analyzed by the quantitative reverse transcription polymerase chain reaction and inflammatory cytokines were detected by western blotting. The enzyme-linked immunosorbent assay (ELISA) was used to quantify inflammation-related cytokines in colorectal cancer cells. Cancer cell properties were evaluated using the wound-healing assay, transwell migration assay, transwell invasion assay, colony-formation assay, and CCK-8 assay.

Results: LPS up-regulated mRNA and protein levels of inflammatory factors in colorectal cancer cells. Knockdown of MyD88 inhibited LPS-induced mRNA expression and inflammatory protein expression in colorectal cancer cells. Similarly, silencing of MyD88 expression suppressed LPS-induced changes in the biological behavior of colorectal cancer cells. Silencing of MyD88 expression down-regulated expression of proteins of the LPS/nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-ĸB)/mitogen-activated protein kinase (MAPK) signaling pathway. Restoration of the expression of MyD88 reversed the effects in LPS-treated HCT116 cells.

Conclusion: MyD88-regulated LPS/NF-ĸB/MAPK signaling pathway affects the inflammatory and biological behavior of LPS-induced colorectal cancer cells.

Keywords: LPS; MyD88; NF-ĸB/MAPK; colorectal cancer; inflammatory.