2305

FOXM1

FoxM1 is known to play important role in the development and progression of many malignancies including pancreatic cancer. Studies have shown that the acquisition of epithelial-to-mesenchymal transition (EMT) phenotype and induction of cancer stem cell (CSC) or cancer stem-like cell phenotypes are highly inter-related, and contributes to drug resistance, tumor recurrence, and metastasis. The molecular mechanism(s) by which FoxM1 contributes to the acquisition of EMT phenotype and induction of CSC self-renewal capacity is poorly understood. Therefore, we established FoxM1 over-expressing pancreatic cancer (AsPC-1) cells, which showed increased cell growth, clonogenicity, and cell migration. Moreover, over-expression of FoxM1 led to the acquisition of EMT phenotype by activation of mesenchymal cell markers, ZEB1, ZEB2, Snail2, E-cadherin, and vimentin, which is consistent with increased sphere-forming (pancreatospheres) capacity and expression of CSC surface markers (CD44 and EpCAM). We also found that over-expression of FoxM1 led to decreased expression of miRNAs (let-7a, let-7b, let-7c, miR-200b, and miR-200c); however, re-expression of miR-200b inhibited the expression of ZEB1, ZEB2, vimentin as well as FoxM1, and induced the expression of E-cadherin, leading to the reversal of EMT phenotype. Finally, we found that genistein, a natural chemo-preventive agent, inhibited cell growth, clonogenicity, cell migration and invasion, EMT phenotype, and formation of pancreatospheres consistent with reduced expression of CD44 and EpCAM. These results suggest, for the first time, that FoxM1 over-expression is responsible for the acquisition of EMT and CSC phenotype, which is in part mediated through the regulation of miR-200b and these processes, could be easily attenuated by genistein.CI - Copyright (c) 2011 Wiley-Liss, Inc.

FOXM1, a member of the Forkhead transcriptional family, plays an important role in the EMT process, and transforming growth factor-beta1 (TGF-beta1) has been identified as the most potent factor that can independently induce EMT in various types of cancer cells. Here we examine the important role of FOXM1 in TGF-beta1-induced EMT and investigate the mechanism underlying the relationship between TGF-beta1 and FOXM1. Lentivirus-mediated transfection was used to stably upregulate the expression of FOXM1, and a small interfering RNA (siRNA) was introduced to silence the expression of FOXM1. Transwell and wound-healing assays were then performed to assess the invasion and motility potential of non-small cell lung cancer (NSCLC) cells. The NSCLC cell lines exhibited EMT characteristics, including an elongated fibroblastoid shape, induced expression of EMT marker proteins, and increased migratory and invasive potential after induction with TGF-beta1. The overexpression of FOXM1 enhanced TGF-beta1-induced EMT in NSCLC cells. Knockdown of FOXM1 reversed TGF-beta1-induced EMT in NSCLC cell lines but had no effect on the phosphorylation level of ERK. Additionally, U0126, an ERK signaling inhibitor, exerted a reversible effect on TGF-beta1-induced EMT and inhibited FOXM1 expression. FOXM1 regulated by the ERK pathway can mediate TGF-beta1-induced EMT in NSCLC and is a potential target for the treatment of NSCLC.

High expression levels of the forkhead box M1 (FoxM1) transcription factor are associated with metastasis and poor prognosis of malignancies. However, little is known concerning its function in nasopharyngeal carcinoma (NPC). The present study aimed to investigate the impact of FoxM1 inhibition on the migration and invasion of NPC cells and the potential mechanisms. The effects of FoxM1 inhibitor treatment and FoxM1 silencing on the proliferation, migration and invasion of NPC CNE-1 and CNE-2 cells were examined by CCK-8, Transwell migration/invasion and colony formation assays. The effects of stable FoxM1 silencing on the growth and lung metastasis of implanted NPC were evaluated. The relative levels of FoxM1, zinc finger E-box binding homeobox 2 (ZEB2), Snail2 and E-cadherin in the different groups of NPC cells and tumors were determined by quantitative real-time PCR, western blotting and immunohistochemical assays. Treatment with thiostrepton, FoxM1 inhibitor, significantly reduced the survival of NPC cells. Treatment with thiostrepton and/or knockdown of FoxM1 inhibited the anchorage-independent proliferation, migration and invasion of NPC cells. Inhibition of FoxM1 also increased the relative levels of E-cadherin, but reduced ZEB2 and Snail2 expression in NPC cells. Stable FoxM1 silencing inhibited the growth and lung metastasis of implanted NPC in vivo, which was associated with increased levels of E-cadherin, but decreased ZEB2 and Snail2 expression in the NPC tumors. In conclusion, our data clearly indicate that knockdown of FoxM1 inhibited the growth and metastasis of human NPC by modulating epithelial-to-mesenchymal transition (EMT), and FoxM1 may be a potential target for the intervention of NPC.

BACKGROUND: The Forkhead box M1 (FOXM1) is an oncogenic transcription factor and plays a significant role in cell EMT, proliferation, metastasis in a multitude of human solid tumors including colorectal cancer (CRC). However, the underlying molecular mechanisms by which FoxM1 contributes to epithelial-to-mesenchymal (EMT) and metastasis have not been fully elucidated in CRC. METHODS: In our study, we investigated FOXM1 protein expression in 87 CRC tissue specimens, invasive lymph nodes and adjacent paired normal colorectal tissues by immunohistochemical analysis. Then we transfected FOXM1 specific shRNA into SW620 cells to examine effect of FOXM1 on proliferation, colony formation, migration and invasion in vitro. Western blotting and real-time PCR were used to detect the protein and mRNA expression of FOXM1 and EMT-related markers. RESULTS: FOXM1 was overexpressed in CRC tissues, invasive lymph nodes and CRC cell lines. FoxM1 overexpression was significantly associated with lymph node metastasis (P < 0.001), and tumor recurrence (P < 0.001). Moreover, downregulation of FOXM1 in SW620 cells by shRNA approach inhibited cell growth, clonogenicity, migration and invasion in vitro. In addition, decreased FOXM1 expression in SW620 cells reversed the acquisition of EMT phenotype by up-regulating E-cadherin, as well as reduction Vimentin and Snail expressions at protein and mRNA levels. CONCLUSIONS: FOXM1 may regulate CRC cells metastasis through EMT program and FOXM1 may be a potential target for treatment of CRC.

MicroRNAs (miRNAs), endogenous noncoding small RNAs, have been reported to play crucial roles in epithelial-mesenchymal transition (EMT) in cancers. Deregulation of microRNA-204 (miR-204) has been documented in many cancers, but its role in the development of esophageal cancer (EC) has not been studied. Here, we reported the role of miR-204 in invasion and EMT in EC. We identified an inverse correlation between miR-204 expression level and the invasion and EMT phenotype of EC cells, and up-regulation of miR-204 inhibited invasion and EMT phenotype of EC cells. Furthermore, we showed that forkhead box protein M1 (FOXM1) was a direct target gene of miR-204, and miR-204 regulated invasion and EMT in EC by acting directly on the 3'UTR of FOXM1 mRNA and suppressing its protein expression. We also explored the anti-tumor effect of miR-204, and found that overexpression of miR-204 suppressed the growth of esophageal tumors in vivo. These findings suggest that miR-204 might be a suppressor of invasion and EMT in EC, which offers a novel potential therapeutic target for EC.

Colorectal cancer(CRC) is one of the most commonly diagnosed cancers in human beings and metastasis is the main death reason. Recently, Gli1 has been reported to be a key regulator of various cancer biologies and genes expressions. However, the detailed molecular mechanism of Gli1 in CRC metastasis remains largely unknown. In this study, we aimed to investigate the role of Gli1 in CRC metastasis. We used qRT-PCR, Immunohistochemistry and Western blot to test the expression levels of Gli1, Foxm1 and other target genes in the tissues and cells; Lentivirus stable transfection to change the expression levels of Gli1 and Foxm1; Wound-healing, cell invasion, migration assays and tail vein metastatic assay to test the role of Gli1 in CRC metastasis in vitro and vivo. We demonstrated that Gli1 was significantly overexpressed in colorectal cancer tissues and cells. Foxm1 level had a positive correlation with Gli1. Furthermore, we found that Gli1 promotes colorectal cancer cells metastasis in a Foxm1-dependent manner by activating EMT and PI3K-AKT signaling. Thus, we proved that Gli1 plays important role in CRC metastasis and provided a new visual field on the therapy of CRC metastasis.

Gastric cancer (GC) is the most common epithelial malignancy worldwide. Basic transcription factor 3 (BTF3) plays a crucial role in the regulation of various biological processes. We designed experiments to investigate the molecular mechanism underlying the role of BTF3 in GC cell proliferation and metastasis. We confirmed that BTF3 expression was decreased in GC tissues and several GC cell lines. Lentivirus-mediated downregulation of BTF3 reduced cell proliferation, induced S and G2/M cell cycle arrest, and increased apoptosis. Knockdown of BTF3 significantly reduced the expression of Forkhead box M1 (FOXM1). Upregulation of FOXM1 significantly inhibited the decrease in cell proliferation due to BTF3 silencing, S and G2/M cell cycle arrest, and increase in apoptosis. Knockdown of BTF3 decreased Ki-67 and PCNA expression, whereas it increased p27 expression, which was inhibited by upregulation of FOXM1. Knockdown of BTF3 significantly decreased the ability to invade and migrate. Moreover, knockdown of BTF3 increased E-cadherin expression, whereas it decreased N-cadherin and ZEB2 expression, indicating a decrease in epithelial-mesenchymal transition (EMT). Phosphorylation of Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) was significantly inhibited by knockdown of BTF3. IL-6-stimulated phosphorylation of STAT3 and JAK2 markedly suppressed inhibition of EMT due to BTF3 silencing. Silencing of BTF3 decreased tumor volume and weight and reduced peritoneal nodules in implanted tumors. Our findings provide a novel understanding of the mechanism of GC and highlight the important role of BTF3/FOXM1 in tumor growth and BTF3/JAK2/STAT3 in EMT and metastasis.

In the present study, we investigated the functional role of microRNA (miR)-630 in epithelial-to-mesenchymal transition (EMT) of gastric cancer (GC) cells, as well as the regulatory mechanism. Cells of human GC cell line SGC 7901 were transfected with miR-630 mimic or miR-630 inhibitor. The transfection efficiency was confirmed by qRT-PCR. Cell migration and invasion were determined by Transwell assay. Protein expression of E-cadherin, vimentin, and Forkhead box protein M1 (FoxM1) was tested by Western blot. Moreover, the expression of FoxM1 was elevated or suppressed, and then the effects of miR-630 abnormal expression on EMT and properties of migration and invasion were examined again, as well as protein expression of Ras/phosphoinositide 3-kinase (PI3K)/AKT related factors. The results showed that (i) the EMT and properties of migration and invasion were statistically decreased by overexpression of miR-630 compared to the control group but markedly increased by suppression of miR-630. However, (ii) abnormal expression of FoxM1 reversed these effects in GC cells. Moreover, (iii) expression of GTP-Rac1, p-PI3K, and p-AKT was decreased by miR-630 overexpression but increased by FoxM1 overexpression. (iv) The decreased levels of GTP-Rac1, p-PI3K, and p-AKT induced by miR-630 overexpression were dramatically elevated by simultaneous overexpression of FoxM1. In conclusion, our results suggest that miR-630 might be a tumor suppressor in GC cells. MiR-630 suppresses EMT by regulating FoxM1 in GC cells, supposedly via inactivation of the Ras/PI3K/AKT pathway.

Forkhead box protein M1 (FoxM1) has been associated with cancer progression and metastasis. However, the function of FoxM1 in tongue squamous cell carcinoma (TSCC) remains largely unknown. The purpose of this study was to determine the role of FoxM1 in regulation of epithelial-mesenchymal transition (EMT) and migration of TSCC cells. We found that FoxM1 induced EMT and increased invasion/migration capacity in SCC9 and SCC25 cells. FoxM1 stimulation increased c-Met, pAKT, and vimentin levels but decreased E-cadherin level. Chromatin immunoprecipitation assay established that FoxM1 is bound to the promoter of c-Met to activate its transcription. In turn, c-Met promoted the expression of FoxM1 and pAKT. Blocking AKT signaling attenuated the invasion and migration of SCC9 and SCC25 cells stimulated by FoxM1 or c-Met. These results indicate that a positive feedback loop controls the EMT and migration of TSCC cells induced by FoxM1 and c-Met through AKT. Furthermore, the expression levels of FoxM1, pAKT, and c-Met were found to significantly increase in TSCC tissues compared with normal tissues, and these three biomarkers were concomitantly expressed in TSCC tissues. Clinical association analyses indicated that the expression of FoxM1, c-Met, and pAKT was associated with clinicopathological characteristics of patients with TSCC including tumor stage, tumor size, and lymph node metastasis. Taken together, our findings suggest that FoxM1 promotes the EMT, invasion and migration of TSCC cells, and cross-talks with c-Met/AKT signaling to form a positive feedback loop to promote TSCC development.

Propofol has been widely used in lung cancer resections. Some studies have demonstrated that the effects of propofol might be mediated by microRNAs (miRNAs). This study aimed to investigate the effects and mechanisms of propofol on lung cancer cells by regulation of miR-1284. A549 cells were treated with different concentrations of propofol, while transfected with miR-1284 inhibitor, si-FOXM1, and their negative controls. Cell viability, migration, and invasion, and the expression of miR-1284, FOXM1, and epithelial-mesenchymal transition (EMT) factors were detected by CCK-8, Transwell, qRT-PCR, and Western blot assays, respectively. In addition, the regulatory and binding relationships among propofol, miR-1284, and FOXM1 were assessed, respectively. Results showed that propofol suppressed A549 cell viability, migration, and invasion, upregulated E-cadherin, and downregulated N-cadherin, vimentin, and Snail expressions. Moreover, propofol significantly promoted the expression of miR-1284. miR-1284 suppression abolished propofol-induced decreases of cell viability, migration, and invasion, and increased FOXM1 expression and the luciferase activity of FOXM1-wt. Further, miR-1284 negatively regulated FOXM1 expression. FOXM1 knockdown reduced cell viability, migration, and invasion by propofol treatment plus miR-1284 suppression. In conclusion, our study indicated that propofol could inhibit cell viability, migration, invasion, and the EMT process in lung cancer cells by regulation of miR-1284.

Forkhead box protein M1 (FOXM1), an important regulator of tumorigenesis in various human tumors, has recently been reported to play a role in the modulation of radiosensitivity in glioma and breast cancer cells. The present study aimed to investigate the effects of FOXM1 on radiotherapy resistance in human lung cancer and to explore the related molecular mechanisms. The results revealed that FOXM1 expression was upregulated in A549 and H1299 cells after IR (Ionizing radiation). FOXM1 inhibition impeded survival fractions, impeded proliferation, and triggered apoptosis after IR. Moreover, the silencing of FOXM1 dampened cell migration, invasion, and EMT (epithelial-mesenchyman transition) in A549 and H1299 cells treated by IR. In addition, KIF20A was also highly expressed in IR-treated A549 cells and downregulated by FOXM1 inhibition. Knockdown of KIF20A inhibited the survival fraction. Reintroduction of KIF20A partly reversed the effects of FOXM1 on the proliferation, apoptosis, and metastasis of A549 cells. Taken together, these results indicated that FOXM1 might enhance radioresistance partly through the induction of KIF20A expression.CI - Copyright (c) 2018 Elsevier B.V. All rights reserved.