Gene Expression in Lipopolysaccharide-treated Human Monocytes Following Interaction with Hepatic Cancer Cells

Abstract

Background/aim: Monocytes migrate into the tissue where they differentiate into various types of macrophages with tissue-specific characteristics. When human monocytes are co-cultured with colon cancer cells they exhibit increased mRNA expression of angiogenesis- and signaling pathway-related genes; however, this increase is suppressed by pretreatment with low-dose lipopolysaccharide (LPS). Thus, LPS-treated human monocytes may be useful in suppressing tumor invasion and proliferation in colon cancer. However, it is suggested that the characteristics of tumor-associated macrophages may differ depending on the type of cancer. The function of human tumor-associated macrophages in hepatic cancer remains unclear. In this study, we investigated mRNA expression of various genes in LPS-treated human monocytes following interaction with hepatic cancer cells.

Materials and methods: The human monocyte cell line THP-1 was treated with LPS and subsequently co-cultured with the human hepatic cancer cell line HepG2. mRNA expression of various factors were then analyzed using quantitative real-time polymerase chain reaction (PCR) and DNA microarray.

Results: The mRNA expressions of monocyte chemotactic protein-1, vascular endothelial growth factor-A, tumor necrosis factor-α, interleukin (IL)-1β, IL-8, nuclear factor-κB, RelB, signal transducer and activator of transcription 3, IL-10 and transforming growth factor-β in THP-1 cells following interaction with HepG2 cells, were suppressed by pretreatment with LPS.

Conclusion: LPS-treated human monocytes may be useful in suppressing tumor invasion and proliferation of hepatic cancer, as well as colon cancer. The co-culture system of monocytes and cancer cells may be beneficial for evaluating antitumor effects in LPS-treated monocytes.

Keywords: Monocyte; co-culture; hepatic cancer cell; lipopolysaccharide.