Eftect of Lewis lung cancer on mouse intestinal stem cells and their microenvironment

Abstract

Objective To investigate the changes in intestinal stem cells (ISCs) and their microenvironment in a mouse model bearing Lewis lung cancer (LLC). Methods We compared the tumorigenicity of LLC cells in mice following subcutaneous transplantation and tail vein injection of the cells. HE staining, immunostaining and qPCR were used to analyze how LLC affected the intestinal morphology, cell proliferation dynamics, ISCs and their niche-related genes, intestinal epithelial cell tight junctions, and the expression of inflammatory cytokines.We also evaluated the effect of LLC conditioned medium (LLC-CM) onthe proliferation of cultured IEC-6 cells using EdU staining, and observed the growth of intestinal enteroids co- cultured with LLC cells or in the presence of LLC-CM. Results Tail vein injection more efficiently induced the formation of LLC in mice than subcutaneous transplantation of LLC cells.The mice bearing LLC exhibited significantly increased length of the mucosal villi and depth of the crypts (P < 0.01), and had more BrdU- positive cells and a higher level of Ki67 mRNA expression in the intestines as compared with the control mice (P < 0.05).LLC-CM obviously promoted the incorporation of EdU in IEC-6 cells.The tumor-bearing mice showed significantly decreased expression of ISC markers and microenvironment-related genes (including Lgr5, Olfm4, Axin2, and Wnt3) in the intestines (P < 0.05), where the staining signals of ZO-1 and the mRNA expression of TJP1 and OCLN was significantly decreased and the mRNA levels of IL-1β and TNF-α were markedly increased (P < 0.05).Both LLC and LLC-CM significantly inhibited the growth of cultured mouse intestinal organoids Conclusion LLC disrupts the ISCs and their niche in mice, which provides new evidence of the interaction between lung cancer and the gastrointestinal tract.

Keywords

• lewis lung cancer
• intestinal stem cells
• microenvironment
• tumor