Bacterial lipopolysaccharide induces transforming growth factor β and hepatocyte growth factor through toll-like receptor 2 in cultured human colon cancer cells

This study examined, in human cancer cell lines, the pattern of cytokine production stimulated by lipopolysaccharide (LPS), a major component of the outer surface of Gram-negative bacteria, and characterized the expression pattern of CD14, cell surface LPS receptor antigen, and toll-like receptors (TLRs), which appear to be key regulators of the innate immune response system. Two colon cancer cell lines (DLD and LoVo), a hepatocellular carcinoma cell line and a myelomonocytic cell line were incubated with LPS for 0-72 h, and transforming growth factor (TGF) beta1 and beta2, hepatocyte growth factor (HGF) and interleukins 6, 8 and 15 were assayed. The only changes induced by incubation with LPS were significant increases in TGF beta1 production at 12 h, and in HGF production at 72 h, in LPS-stimulated DLD cells, and significant increases in TGF beta2 production after 12 h and in HGF after 72 h in LoVo cells. Using reverse transcriptase-polymerase chain reaction analysis, expression of CD14 and TLR-2 mRNA was detected in DLD and LoVo cells, and expression of TLR-4 mRNA was detected in PLC/PRF/S and KG-1 cells. These results suggest that LPS induces TGF beta and HGF production mediated by CD14/TLR-2 in cultured human colon cancer cell lines.