Forkhead Box Q1 (FOXQ1) is a member of the forkhead transcription factor family, and it has recently been proposed to participate in gastric acid secretion and mucin gene expression in mice. However, the role of FOXQ1 in humans and especially in cancer cells remains unknown.

We found that FOXQ1 mRNA is overexpressed in clinical specimens of colorectal cancer (28-fold / colonic mucosa). A microarray analysis revealed that the knockdown of FOXQ1 using siRNA resulted in a decrease in p21CIP1/WAF1 expression, and a reporter assay and ChIP assay showed that p21CIP1/WAF1 was one of target genes of FOXQ1. Stable FOXQ1-overexpressing cells (H1299/FOXQ1) exhibited elevated levels of p21CIP1/WAF1 expression and inhibition of apoptosis induced by doxorubicin or camptothecin. Although cellular proliferation was decreased in H1299/FOXQ1 cells in vitro, H1299/FOXQ1 cells significantly increased tumorigenicity (EGFP: 2/15, FOXQ1: 7/15) and enhanced tumor growth (437 ± 301 vs. 1735 ± 769 mm3, p<0.001) in vivo. Meanwhile, stable p21CIP1/WAF1 knockdown of H1299/FOXQ1 cells increased tumor growth, suggesting that FOXQ1 promotes tumor growth independent of p21CIP1/WAF1. Microarray analysis of H1299/EGFP and H1299/FOXQ1 revealed that FOXQ1-overexpression upregulated several genes that have positive roles for tumor growth including VEGFA, WNT3A, RSPO2 and BCL11A. CD31 and TUNEL staining of the tumor specimens showed that FOXQ1-overexpression mediated the angiogenic and anti-apoptotic effect in vivo.

In conclusion, FOXQ1 is overexpressed in colorectal cancer and enhances tumorigenicity and tumor growth presumably through its angiogenic and anti-apoptotic effects. Our findings demonstrate that FOXQ1 is a new member of the cancer-related FOX family.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3893.