Epigenetic Inactivation of the Potential Tumor Suppressor Gene FOXF1 in Breast Cancer

Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Cancer Research (Impact Factor: 9.33). 07/2010; 70(14):6047-58. DOI: 10.1158/0008-5472.CAN-10-1576
Source: PubMed


The expression of several members of the FOX gene family is known to be altered in a variety of cancers. We show that in breast cancer, FOXF1 gene is a target of epigenetic inactivation and that its gene product exhibits tumor-suppressive properties. Loss or downregulation of FOXF1 expression is associated with FOXF1 promoter hypermethylation in breast cancer cell lines and in invasive ductal carcinomas. Methylation of FOXF1 in invasive ductal carcinoma (37.6% of 117 cases) correlated with high tumor grade. Pharmacologic unmasking of epigenetic silencing in breast cancer cells restored FOXF1 expression. Re-expression of FOXF1 in breast cancer cells with epigenetically silenced FOXF1 genes led to G(1) arrest concurrent with or without apoptosis to suppress both in vitro cell growth and in vivo tumor formation. FOXF1-induced G(1) arrest resulted from a blockage at G(1)-S transition of the cell cycle through inhibition of the CDK2-RB-E2F cascade. Small interfering RNA-mediated depletion of FOXF1 in breast cancer cells led to increased DNA re-replication, suggesting that FOXF1 is required for maintaining the stringency of DNA replication and genomic stability. Furthermore, expression profiling of cell cycle regulatory genes showed that abrogation of FOXF1 function resulted in increased expression of E2F-induced genes involved in promoting the progression of S and G(2) phases. Therefore, our studies have identified FOXF1 as a potential tumor suppressor gene that is epigenetically silenced in breast cancer, which plays an essential role in regulating cell cycle progression to maintain genomic stability.

Download full-text


Available from: Helen Sadik
  • Source
    • "Recently, E-cadherin has been shown to be a target of FOXF1, which in turn has been shown to be a target of p53, regulating cancer cell migration and invasiveness [37]. Additionally, FOXF1 expression has been shown to be changed in numerous human malignancies [38]–[45]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Alveolar Capillary Dysplasia with Misalignment of Pulmonary Veins (ACDMPV) is a developmental disorder of the lungs, primarily affecting their vasculature. FOXF1 haploinsufficiency due to heterozygous genomic deletions and point mutations have been reported in most patients with ACDMPV. The majority of mice with heterozygous loss-of-function of Foxf1 exhibit neonatal lethality with evidence of pulmonary hemorrhage in some of them. By comparing transcriptomes of human ACDMPV lungs with control lungs using expression arrays, we found that several genes and pathways involved in lung development, angiogenesis, and in pulmonary hypertension development, were deregulated. Similar transcriptional changes were found in lungs of the postnatal day 0.5 Foxf1+/- mice when compared to their wildtype littermate controls; 14 genes, COL15A1, COL18A1, COL6A2, ESM1, FSCN1, GRINA, IGFBP3, IL1B, MALL, NOS3, RASL11B, MATN2, PRKCDBP, and SIRPA, were found common to both ACDMPV and Foxf1 heterozygous lungs. Our results advance knowledge toward understanding of the molecular mechanism of ACDMPV, lung development, and its vasculature pathology. These data may also be useful for understanding etiologies of other lung disorders, e.g. pulmonary hypertension, bronchopulmonary dysplasia, or cancer.
    Full-text · Article · Apr 2014 · PLoS ONE
  • Source
    • "Recent studies have shown that several members of the FOX family of transcription factors are alternatively expressed in cancers, correlate with tumor progression and metastasis, and are especially linked to the biological characteristics of breast cancer. FOXF1 exhibits tumor-suppressive properties in breast cancer, and plays an essential role in regulating cell cycle progression to maintain genomic stability [19]. FOXA1 expression positively correlates with ER and PR expression in breast cancer, and low expression of FOXA1 predicts poor prognosis for all patients and luminal subtype patients [20], [21], [22]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The transcription factor, FOXF2, plays an important role in tissue development, extracellular matrix synthesis, and epithelial-mesenchymal interactions, implying that it may be associated with the metastatic capabilities of cancer cells. However, the relationship between FOXF2 expression and breast cancer progression, metastasis, and prognosis, remains to be elucidated. In this study, FOXF2 mRNA levels in 305 primary breast cancer tissues were examined using RT-QPCR. Results showed that FOXF2 mRNA levels in primary breast cancer were negatively associated with tumor progression, including tumor size, number of metastatic lymph nodes, and clinical stage. Patients with low FOXF2 mRNA levels had a high risk of relapse and metastasis within three years. Low FOXF2 mRNA levels could predict shorter disease-free survival for those patients with histological grade II and triple-negative breast cancer. Taken together, we conclude that decreased FOXF2 expression indicates the early-onset metastasis and poor prognosis for patients with histological grade II and triple-negative breast cancer.
    Full-text · Article · Apr 2013 · PLoS ONE
  • Source
    • "All three are targets of inactivation in breast cancer and both FOXC1 and FOXF1 are subjected to promoter methylation [28-30]. Most intriguing is the description of FOXF1 as an inducer of G1-S and S-G2 cell cycle arrest, indicating a possible role in oncogene-induced senescence in breast cancer [29]. Our finding that FOXF1 was downregulated in the BRAF mutated cohort suggests that this gene might also play a role in oncogene-induced senescence in colon cancer. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background Cancer-specific hypermethylation of (promoter) CpG islands is common during the tumorigenesis of colon cancer. Although associations between certain genetic aberrations, such as BRAF mutation and microsatellite instability, and the CpG island methylator phenotype (CIMP), have been found, the mechanisms by which these associations are established are still unclear. We studied genome-wide DNA methylation differences between colorectal tumors carrying a BRAF mutation and BRAF wildtype tumors. Results Using differential methylation hybridization on oligonucleotide microarrays representing 32,171 CpG-rich regions, we identified 1,770 regions with differential methylation between colorectal tumor and paired normal colon. Next, we compared the tumor/normal methylation ratios between different groups of patients. Related to CIMP, we identified 749 differentially methylated regions, of which 86% had a higher tumor/normal methylation ratio in the CIMP-positive group. We identified 758 regions with a BRAF mutation-specific methylation change, of which 96% had a higher tumor/normal methylation ratio in the BRAF mutant group. Among the genes affected by BRAF mutation-specific methylation changes, we found enrichment of several cancer-related pathways, including the PI3 kinase and Wnt signaling pathways. To focus on genes that are silenced in a tumor-specific rather than a lineage-specific manner, we used information on the epigenetic silencing mark H3K27me3 in embryonic stem (ES) cells. Among the genes showing BRAF mutation-specific promoter methylation but no H3K27me3 mark in ES cells were forkhead box (FOX) transcription factors associated with the PI3 kinase pathway, as well as MLH1 and SMO. Repression of FOXD3 gene expression in tumors could be related to its promoter hypermethylation. Conclusions We identified new BRAF mutation-specific methylation changes in colorectal cancer. Epigenetic downregulation of these targets may contribute to mutationally active BRAF-driven tumorigenesis, explaining its association with aberrant DNA methylation.
    Full-text · Article · Jan 2013
Show more