α2β1 Integrin Regulates Lineage Commitment in Multipotent Human Colorectal Cancer Cells*

Huijun Ying,Susan C. Kirkland

doi:10.1074/jbc.m802932200

Abstract

The human colorectal epithelium is maintained by multipotent stem cells that give rise to absorptive, mucous, and endocrine lineages. Recent evidence suggests that human colorectal cancers are likewise maintained by a minority population of so-called cancer stem cells. We have previously established a human colorectal cancer cell line with multipotent characteristics (HRA-19) and developed a serum-free medium that induces endocrine, mucous and absorptive lineage commitment by HRA-19 cells in vitro. In this study, we investigate the role of the β1 integrin family of cell surface extracellular matrix receptors in multilineage differentiation by these multipotent human colorectal cancer cells. We show that endocrine and mucous lineage commitment is blocked in the presence of function-blocking antibodies to β1 integrin. Function-blocking antibodies to α2 integrin also blocked both HRA-19 endocrine lineage commitment and enterocytic differentiation by Caco-2 human colon cancer cells; both effects being abrogated by the MEK inhibitor, PD98059, suggesting a role for ERK signaling in α2-mediated regulation of colorectal cancer cell differentiation. To further explore the role of α2 integrin in multilineage differentiation, we established multipotent cells expressing high levels of wild-type α2 integrin or a non-signaling chimeric α2 integrin. Overexpression of wild-type α2 integrin in HRA-19 cells significantly enhanced endocrine and mucous lineage commitment, while cells expressing the non-signaling chimeric α2 integrin had negligible ability for either endocrine or mucous lineage commitment. This study indicates that the collagen receptor α2β1 integrin is a regulator of cell fate in human multipotent colorectal cancer cells.

Highlights

Ulator of normal stem cell renewal, is commonly present in colorectal cancer as the result of well described mutations in Wnt signaling components[3]
Elevated ␤1 integrin expression is a hallmark of skin [16], prostate [17], and neural stem cells [18]; and ␤1 integrins regulate epidermal [19], neural [20], and embryonic [21] stem cell fate. ␤1 integrins are candidate intestinal stem cell regulators as they are highly expressed in the stem cell region, and epithelial cells with high ␤1 expression show enhanced clonogenicity in vitro [22]
This study investigates the role of cell surface ␣␤1 integrin matrix receptors in lineage commitment in these multipotent human colon cancer cells in vitro

Summary

Introduction

Ulator of normal stem cell renewal, is commonly present in colorectal cancer as the result of well described mutations in Wnt signaling components[3]. Free medium to induce endocrine lineage commitment in the presence of a ␤1 antibody (JB1A), which blocks cell adhesion [26] and signaling [34]. These results indicate a role for the ␤1 integrins in regulating endocrine and mucous lineage commitment in HRA-19 cells.

Results

Conclusion