Hath1, Down-Regulated in Colon Adenocarcinomas, Inhibits Proliferation and Tumorigenesis of Colon Cancer Cells

Abstract

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 D1 and p27 kip1 . Hath1 expression also was up-regulated on inhibition of the Wnt 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.

Atoh1, an Essential Transcription Factor in Neurogenesis and Intestinal and Inner Ear Development: Function, Regulation, and Context Dependency

“…In other tissues, Atoh1 acts not as an oncogene, but as a tumor suppressor gene in adenomatous polyposis carcinoma (APC), Atoh1 is downregulated (Leow et al 2004;Bossuyt et al 2009b). Whereas in neural development Atoh1 makes cells receptive to signals promoting proliferation, in gut development and homeostasis, Atoh1 represses proliferation.…”

Achaete-scute like 2 (ascl2) is a target of Wnt signalling and is upregulated in intestinal neoplasia

“…Several strategies were chosen to repress Wnt signalling in colorectal cancer cells, with the hypothesis that this would influence ascl2 expression. The expression of ascl2 was decreased by approximately 40% in HT29 cells stably expressing either APC2 (a negative regulator of b-catenin) or LEF1 DN (a negative regulator of the b-catenin-TCF/LEF transcriptional activating complex), compared to cells transfected with the empty vector ( Figure 5) (Leow et al, 2004). Both APC2 and LEF1 DN stably transfected cell lines showed evidence for a decrease in b-catenin-TCF/LEF activity by the TOPflash assay, compared to cells transfected with the empty vector (Leow et al, 2004).…”

“…The expression of ascl2 was decreased by approximately 40% in HT29 cells stably expressing either APC2 (a negative regulator of b-catenin) or LEF1 DN (a negative regulator of the b-catenin-TCF/LEF transcriptional activating complex), compared to cells transfected with the empty vector ( Figure 5) (Leow et al, 2004). Both APC2 and LEF1 DN stably transfected cell lines showed evidence for a decrease in b-catenin-TCF/LEF activity by the TOPflash assay, compared to cells transfected with the empty vector (Leow et al, 2004). Short-interfering RNA (siRNA) against b-catenin was also employed in seven colorectal cancer cell lines, showing evidence for a Achaete-scute like 2 in intestinal neoplasia AM Jubb et al decrease in ascl2 mRNA expression compared to controls ( Figure 6).…”

“…Stably expressing HT29 cell clones were generated by C Leow (Genentech) as described elsewhere (Leow et al, 2004). Cells were harvested for RNA and analysed by QRT-PCR as described above.…”

“…Cells were harvested for RNA and analysed by QRT-PCR as described above. Inhibition of b-catenin-TCF/LEF target binding was confirmed by a TOPflash luciferase assay described elsewhere (Leow et al, 2004).…”