Hath1, down-regulated in colon adenocarcinomas, inhibits proliferation and tumorigenesis of colon cancer cells

A striking feature of colon tumors is the significant reduction of goblet cells. Although targeted deletion of Math1 in mice leads to a loss of intestinal secretory cells, including goblet cells, the role of Hath1 in colon tumorigenesis remains unknown. Here we report that Hath1, the human ortholog of Math1, was dramatically down-regulated in colon tumor samples and colon cancer cell lines. Overexpression of Hath1 in HT29, an aggressive colon cancer cell line, resulted in a significant inhibition on cell proliferation, anchorage-independent growth in soft agar and, more importantly, growth of human colon cancer cell xenografts in athymic nude mice. Such inhibition was accompanied by altered expression of a goblet cell differentiation marker, MUC2, and cell cycle regulators cyclin 131 and p27(kip1). Hath1 expression also was up-regulated on inhibition of the Writ pathway, which has been well implicated in colon tumorigenesis. Hence, this study suggests that Hath1 may be a novel factor downstream of the Wnt pathway capable of suppressing anchorage-independent growth of colon cancer cell lines. More importantly, this study is the first to establish a link between down-regulation of Hath1 expression and colon tumorigenesis.