Aberrant activation of hedgehog signaling promotes cell proliferation via the transcriptional activation of forkhead Box M1 in colorectal cancer cells

Abstract

BackgroundRecent evidence suggests that the aberrant activation of Hedgehog (Hh) signaling by Gli transcription factors is characteristic of a variety of aggressive human carcinomas, including colorectal cancer (CRC). Forkhead box M1 (FoxM1) controls the expression of a number of cell cycle regulatory proteins, and FoxM1 expression is elevated in a broad range of human malignancies, which suggests that it plays a crucial role in tumorigenesis. However, the mechanisms underlying FoxM1 expression are not fully understood. Here, we aim to further investigate the molecular mechanism by which Gli1 regulates FoxM1 in CRC.MethodsWestern blotting and immunohistochemistry (IHC) were used to evaluate FoxM1 and Gli1 protein expression, respectively, in CRC tissues and matched adjacent normal mucosa. BrdU (5-bromo-2′-deoxyuridine) and clone formation assays were used to clarify the influence of FoxM1 on CRC cell growth and proliferation. Chromatin immunoprecipitation (ChIP) and luciferase experiments were performed to explore the potential mechanisms by which Gli1 regulates FoxM1. Additionally, the protein and mRNA expression levels of Gli1 and FoxM1 in six CRC cell lines were measured using Western blotting and real-time PCR. Finally, the effect of Hh signaling on the expression of FoxM1 was studied in cell biology experiments, and the effects of Hh signaling activation and FoxM1 inhibition on the distribution of CRC cells among cell cycle phases was assessed by flow cytometry.ResultsGli1 and FoxM1 were abnormally elevated in human CRC tissues compared with matched adjacent normal mucosa samples, and FoxM1 is a downstream target gene of the transcription factor Gli1 in CRC and promoted CRC cell growth and proliferation. Moreover, the aberrant activation of Hh signaling promoted CRC cell proliferation by directly binding to the promoter of FoxM1 and transactivating the activity of FoxM1 in CRC cells.ConclusionThe dysregulation of the Hh-Gli1-FoxM1 axis is essential for the proliferation and growth of human CRC cells and offers a potent target for therapeutic intervention in CRC.Electronic supplementary materialThe online version of this article (doi:10.1186/s13046-017-0491-7) contains supplementary material, which is available to authorized users.

Akt/FoxM1 signaling pathway-mediated upregulation of MYBL2 promotes progression of human glioma

“…FoxM1 is a member of the Forkhead box (Fox) transcription factor family, which has been shown to be over-expressed in various cancers and studies have shown that alterations in FoxM1 signaling were associated with carcinogenesis. FoxM1 is substantially elevated in several aggressive human carcinomas and can contribute to oncogenesis in many tissue types, including breast [ 12 ], hepatocellular [ 13 ], prostate [ 14 ], lung [ 15 ], and colorectal cancers [ 16 ]. Aberrant FoxM1expression was found to be a common molecular alteration in malignant glioma [ 17 ].…”

Regulation of the master regulator FOXM1 in cancer

“…More than 75% of these binding sites act as cis-activation elements, but they do not all function through the same basic mechanisms. For example, glioma-associated oncogene homolog 1 (Gli1), CCCTC-binding factor (CTCF), cAMP responsive element-binding protein (CREB), signal transducer and activator of transcription 3 (STAT3), and E2F interact directly with their binding sites and upregulate FOXM1 expression [ 9 , 30 – 34 ]. In human colorectal cancer (CRC), Gli1 regulates FOXM1 by directly binding to its promoter at BS4 (GCCCACCCA), which contributes to the proliferation of CRC cells [ 9 ].…”

“…For example, glioma-associated oncogene homolog 1 (Gli1), CCCTC-binding factor (CTCF), cAMP responsive element-binding protein (CREB), signal transducer and activator of transcription 3 (STAT3), and E2F interact directly with their binding sites and upregulate FOXM1 expression [ 9 , 30 – 34 ]. In human colorectal cancer (CRC), Gli1 regulates FOXM1 by directly binding to its promoter at BS4 (GCCCACCCA), which contributes to the proliferation of CRC cells [ 9 ]. The DNA-binding protein, CTCF, may regulate the motility and invasiveness of primary hepatocellular carcinoma (HCC) cells via interaction with the CTCF-binding site(s) located in the proximal promoter of FOXM1 [ 30 ].…”

“…For example, it has been demonstrated that Gli1 regulates FOXM1 in murine stem cells [ 8 ]. In human basal cell carcinomas and colorectal cancer cells, FOXM1 is also a direct target of Gli1 [ 9 , 10 ]. This may be due to the evolutionary conservation between the DNA binding domain of both human and murine FOXM1, suggesting the FOXM1 of the two species may share target genes.…”

Overview of the oncogenic signaling pathways in colorectal cancer: Mechanistic insights

“…Aberrantly active Hh signaling promoted proliferation of CRC cells by directly binding to the promoter of FoxM1 and increasing its transactivational activity [93]. FoxM1 inhibition dramatically reduced colony formation and growth rate of HCT116 cells [93]. Three-dimensional organoid culture models were prepared from tissues of colorectal cancer patients.…”