Notch pathway is involved in the suppression of colorectal cancer by embryonic stem cell microenvironment

Objectives: Recently, embryonic microenvironment is being known for its non-permissive property for tumor growth. However, the regulatory mechanism to maintain the balance between differentiation and tumorigenicity of cancer cell in microenvironment is not well understood. Materials and Methods: qRT-PCR was performed to detect the levels of gene expression in HT29, LoVo and Caco-2 colorectal cancer cells, and Western blot was used to measure the protein levels. Cell migration and apoptosis were measured by Transwell and flow cytometry assays. Cancer cell markers were detected using immunohistochemical staining. In vivo tumor formation assay was conducted by subcutaneous injection of embryonic microenvironment-treated cancer cells. Results: Colorectal cancer cell lines were treated with human embryonic stem cell conditioned culture and then collected for in vivo tumor formation assay and in vitro assays assessing the aggressive properties. We found exposure of cancer cells in human ES cultures resulted in inhibition of growth, migration of tumor cells. Moreover, we found that manipulation of Notch pathway in the ES cells microenvironment could influence the stemness of tumor. We specifically discovered that some factor in the embryonic microenvironment could suppress Notch1 pathway in the cancer cells, leading to a reduction in tumorigenesis and invasiveness. Conclusions: This study may provide another evidence to understand the crosstalk between tumor cells and embryonic environment and may offer new therapeutic strategies to inhibit colorectal cancer progression.