Forkhead box Q1: A key player in the pathogenesis of tumors (Review).

As a member of the Forkhead box protein family, Forkhead box Q1 (FOXQ1) is a transcription factor that functions to regulate cell differentiation. Recently, an increasing number of studies have demonstrated that FOXQ1 is significantly associated with the pathogenesis of tumors. This review aims to predominantly discuss the relationship between FOXQ1 and various types of tumor. The FOXQ1 gene is located at human chromosome 6p25.3 and encodes a functional 403 amino acid protein, which has many physiological functions, including promoting epithelial differentiation, inhibiting smooth muscle differentiation, activating T cells and autoimmunity, and controlling mucin gene expression and granule content in stomach surface mucous cells. There are several modes of regulation of FOXQ1 expression that have been demonstrated in normal and tumor cells, such as microRNA and the Wnt signaling pathway. The activation of FOXQ1 affects downstream genes promoting the initiation, proliferation and invasion, in addition to the metastasis of tumor cells. Amongst these, the regulation of invasion and metastasis by FOXQ1 is the most extensively studied. The detailed mechanism involves angiogenesis, tumor re-initiation, alterations in the tumor microenvironment and epithelial-mesenchymal transition. In a number of studies, the expression of FOXQ1 has been reported to be upregulated in breast, colorectal, pancreatic, bladder and ovarian cancer, and glioma, amongst other tumor types. Together, these studies contribute to cancer diagnostics, prognostics and therapeutics. In conclusion, the application prospect of FOXQ1 in tumors is hopeful.