Basal-like breast cancer defined by FOXC1 expression offers superior prognostic value: a retrospective immunohistochemical study

Conserved role of FOXC1 in TNBC is parallel to FOXA1 in ER+ breast cancer

Triple-negative breast cancer (TNBC) is characterized by lack of the estrogen (ER) receptor, progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2), and standard receptor-targeted therapies are ineffective. FOXC1, a transcription factor aberrantly overexpressed in many cancers, drives growth, metastasis, and stem-cell-like properties in TNBC. However, the molecular function of FOXC1 is unknown, partly due to heterogeneity of TNBC. Here, we show that although FOXC1 regulates many cancer hallmarks in TNBC, its function is varied in different cell lines, highlighted by the differential response to CDK4/6 inhibitors upon FOXC1 loss. Despite this functional heterogeneity, we show that FOXC1 regulates key oncogenes and tumor suppressors and identify a set of core FOXC1 peaks conserved across TNBC cell lines. We identify the ER-associated and drug-targetable nuclear receptor NR2F2 as a cofactor of FOXC1. Finally, we show that core FOXC1 targets in TNBC are regulated in parallel by the pioneer factor FOXA1 and the nuclear receptor NR2F2 in ER + breast cancer.

N-3, a novel synthetic derivative of bifendate, inhibits metastasis of triple-negative breast cancer via decreasing p38-regulated FOXC1 protein stability

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype with high invasiveness, metastatic potential, and poor prognosis. Epithelial-mesenchymal transition (EMT) is pivotal in TNBC progression, becoming a promising target for TNBC treatment. Our study evaluated N-3, a novel synthetic bifendate derivative, which inhibited the EMT-associated migration and invasion of MDA-MB-231 and 4T1 TNBC cells. The results were consistent with the suppression of FOXC1 expression and transcriptional activity. Additional studies indicated that N-3 reduced the protein stability of FOXC1 by enhancing ubiquitination and degradation. Moreover, N-3 downregulated p-p38 expression and FOXC1 interaction, decreasing the stability of p38-regulated FOXC1. Further, N-3 blocked TNBC metastasis with an artificial lung metastasis model in vivo, related to FOXC1 suppression and EMT. These results highlight the potential of N-3 as a TNBC metastasis treatment. Therefore, FOXC1 regulation could be a novel targeted therapeutic strategy for TNBC metastasis.

FOXC1

CONTEXT.—

Few studies have investigated the features of FOXC1 protein expression in invasive breast cancer subtypes as defined by immunohistochemistry (IHC)-based surrogate molecular classification.

OBJECTIVE.—

To investigate the diagnostic utility of the IHC-based FOXC1 test in breast cancer subtyping and to evaluate the correlation between FOXC1 expression and clinicopathologic parameters in triple-negative breast cancer (TNBC).

DESIGN.—

FOXC1 expression was evaluated with IHC in a large cohort of 2443 patients with breast cancer. Receiver operating characteristic (ROC) curves were used to assess the diagnostic ability of FOXC1 expression to predict the triple-negative phenotype and to identify the best cutoff value. FOXC1 expression was correlated with the clinicopathologic parameters of TNBC.

RESULTS.—

The expression rate of FOXC1 in TNBC was significantly higher than in other subtypes. The area under the ROC curve confirmed the high diagnostic value of FOXC1 for the prediction of the triple-negative phenotype. The cutoff value of 1% showed a maximized sum of sensitivity and specificity. In TNBC, FOXC1 expression was significantly associated with aggressive tumor phenotypes. Furthermore, FOXC1 expression was primarily observed in invasive breast carcinoma of no special type and metaplastic carcinoma but rarely in invasive carcinoma with apocrine differentiation. Correspondingly, FOXC1 expression was significantly associated with the expression of basal markers but was negatively correlated with apocrine-related markers in TNBC.

CONCLUSIONS.—

In conclusion, FOXC1 is a highly specific marker for the triple-negative phenotype. Moreover, immunohistochemical detection of FOXC1 expression can be used as an additional diagnostic tool for the triple-negative phenotype and subclassification in TNBC.

Therapeutically Targeting Cancers That Overexpress FOXC1: A Transcriptional Driver of Cell Plasticity, Partial EMT, and Cancer Metastasis

Metastasis accounts for more than 90% of cancer related mortality, thus the most pressing need in the field of oncology today is the ability to accurately predict future onset of metastatic disease, ideally at the time of initial diagnosis. As opposed to current practice, what would be desirable is that prognostic, biomarker-based detection of metastatic propensity and heightened risk of cancer recurrence be performed long before overt metastasis has set in. Without such timely information it will be impossible to formulate a rational therapeutic treatment plan to favorably alter the trajectory of disease progression. In order to help inform rational selection of targeted therapeutics, any recurrence/metastasis risk prediction strategy must occur with the paired identification of novel prognostic biomarkers and their underlying molecular regulatory mechanisms that help drive cancer recurrence/metastasis (i.e. recurrence biomarkers). Traditional clinical factors alone (such as TNM staging criteria) are no longer adequately prognostic for this purpose in the current molecular era. FOXC1 is a pivotal transcription factor that has been functionally implicated to drive cancer metastasis and has been demonstrated to be an independent predictor of heightened metastatic risk, at the time of initial diagnosis. In this review, we present our viewpoints on the master regulatory role that FOXC1 plays in mediating cancer stem cell traits that include cellular plasticity, partial EMT, treatment resistance, cancer invasion and cancer migration during cancer progression and metastasis. We also highlight potential therapeutic strategies to target cancers that are, or have evolved to become, “transcriptionally addicted” to FOXC1. The potential role of FOXC1 expression status in predicting the efficacy of these identified therapeutic approaches merits evaluation in clinical trials.

Forkhead Box C1 (FOXC1) Expression in Stromal Cells within the Microenvironment of T and NK Cell Lymphomas: Association with Tumor Dormancy and Activation

PURPOSE

Forkhead box C1 (FOXC1) is critical for maintaining bone marrow microenvironments during hematopoiesis, but its role in hematological malignancies remains obscure. Here, we investigated whether FOXC1 regulates tumor dormancy and activation in the microenvironments of T and natural killer (NK) cell lymphomas.

Materials and Methods

One hundred and twenty cases of T and NK cell lymphomas were included; the immunohistochemical expression of FOXC1 was investigated in stromal cells, and numbers of FOXC1+ stromal cells were counted. Furthermore, the expression of phosphorylated p38 (p-p38) and phosphorylated ERK1/2 (p-ERK1/2) in tumor cells was investigated using immunohistochemistry.

RESULTS

FOXC1 was variably expressed in C-X-C motif chemokine 12-associated reticular stromal cells, histiocytes, (myo)fibroblasts, and endothelial cells. The phenotypes of cases were categorized as dormant (high p-p38/low p-ERK1/2; n=30, 25.0%), active (high p-ERK1/2/low p-p38; n=25, 20.8%), or intermediate (others; n=65, 54.2%). Lower FOXC1+ stromal cell infiltration was associated with the dormant phenotype, the precursor T lymphoblastic leukemia/lymphoma subtype, and inferior overall survival rates, whereas higher FOXC1+ stromal cell infiltration was associated with the active phenotype and favorable patient prognosis (p < 0.05 for all).

CONCLUSION

These results suggested that FOXC1+ stromal cells within the microenvironments of T and NK cell lymphomas might be related to tumor phenotypes.

Prognostic Significance of FOXC1 in Various Cancers: A Systematic Review and Meta-Analysis

BACKGROUND

Forkhead box C1 (FOXC1), a member of the Forkhead box (Fox) transcription factor family, plays an essential role in lymphatic vessel formation, angiogenesis and metastasis. Observational studies examining the relationship between the protein biomarker FOXC1 and breast cancer prognosis have reported conflicting findings. This systematic review and meta-analysis evaluates the prognostic value of the FOXC1 expression in association with patient survival in breast cancer and other types of cancers in order to identify the overall prognostic effectiveness of FOXC1.

METHODS

This study followed the guidelines established in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We conducted a broad search on the online bibliographic databases EMBASE, PubMed, Science Direct and Scopus, limiting search to publications from 2010 to 2018. The prognostic value was demonstrated by a random effects model meta-analysis using the hazard ratio (HR) with 95% confidence interval (CI) for overall survival (OS) in various cancer patients. The heterogeneity was measured by the I² statistic. Publication bias and quality assessment for the selected articles was performed. Subgroup analysis was conducted based on the data available from the selected articles.

RESULTS

A total of 16 studies met the predefined selection criteria established for our systematic review and meta-analysis, with multiple studies using diverse methodologies and reported on differing clinical outcomes, falling under a common banner of FOXC1 expression and survival in cancer. Overall, we observed a statistically non-significant association between FOXC1 protein expression and patients survival (HR: 1.186 and 95% CI 1.122-1.255, p = 0.000, I² = 88.83%).

CONCLUSION

In summary, FOXC1 protein expression indicated poor survival outcome in various carcinomas, especially in patients with breast cancer, suggesting it as a possible biomarker for the prognosis in multiple carcinomas. Further clinical evaluation and large-scale cohort studies are required to accurately identify its possible clinical utility.

FOXC1 Regulation of miR-31-5p Confers Oxaliplatin Resistance by Targeting LATS2 in Colorectal Cancer

Colorectal cancer (CRC) is the second leading cause of cancer-related illness worldwide and one of the most common malignancies. Therefore, colorectal cancer research and cases have gained increasing attention. Oxaliplatin (OXA) is currently used in first-line chemotherapy to treat stage III and stage IV metastatic CRC. However, patients undergoing chemotherapy often develop resistance to chemo drugs being used. Evidence has confirmed that microRNAs regulate downstream genes in cancer biology and thereby have roles related to tumor growth, proliferation, invasion, angiogenesis, and multi-drug resistance. The aim of our study is to establish whether miR-31-5p is an oncogene in human colorectal cancers that are resistant to OXA and further confirm its malignant phenotype-associated target molecule. From the results of miRNA microarray assay, we establish that miR-31-5p expression was upregulated in oxaliplatin-resistant (OR)-LoVo cells compared with parental LoVo cells. Moreover, through in vitro and in vivo experiments, we demonstrate that miR-31-5p and large tumor suppressor kinase 2 (LATS2) were inversely related and that miR-31-5p and Forkhead box C1 (FOXC1) were positively correlated in the same LoVo or OR-LoVo cells. Importantly, we reveal a novel drug-resistance mechanism in which the transcription factor FOXC1 binds to the miR-31 promoter to increase the expression of miR31-5p and regulate LATS2 expression, resulting in cancer cell resistance to OXA. These results suggest that miR-31-5p may be a novel biomarker involved in drug resistance progression in CRC patients. Moreover, the FOXC1/miR31-5p/LATS2 drug-resistance mechanism provides new treatment strategies for CRC in clinical trials.

Meta-analysis of the likelihood of FOXC1 expression in early- and late-stage tumors

Background

Aberrations in the expression of the transcription factor forkhead box C1 (FOXC1) have been linked to a number of malignancies. Here, we characterized the relationship between FOXC1 and cancer progression by conducting a meta-analysis of studies that reported the frequency of FOXC1 expression in tumors of different stages (T1, T2, T3, T4).

Materials and Method

Relevant articles were retrieved from the Medline database by searching for the terms “FOXC1” and “cancer”; then, the retrieved articles were reviewed individually, and studies that were of multivariate cohort design, evaluated FOXC1 expression via immunohistochemical staining, and assessed the relationship between FOXC1 expression and cancer T-stage were included in our meta-analysis.

Results

Our search terms identified 128 studies, 5 of which met all inclusion criteria. A total of 850 tumor samples were evaluated in the 5 studies; 452 samples were from early-stage (T1-T2) tumors, and 398 were from late-stage (T3-T4) tumors. FOXC1 was expressed in 60.7% (516/850) of all samples, in 54.6% (247/452) of early-stage tumor samples, and in 67.5% (269/398) of late-stage tumor samples. When calculated relative to early-stage samples, the pooled risk for FOXC1 expression in late-stage samples was 1.238 (95% CI = 1.061–1.444, p = 0.007).

Conclusions

The results from our meta-analysis of 5 studies indicate that FOXC1 is 23.8% more likely to be expressed in late-stage tumors than in early-stage tumors.

FOXC1 identifies basal-like breast cancer in a hereditary breast cancer cohort

Breast cancers arising in the setting of the hereditary breast cancer genes BRCA1 and BRCA2 are most commonly classified as basal-like breast cancer (BLBC) or luminal breast cancer, respectively. BLBC is an aggressive subtype of breast cancer associated with liver and lung metastases and poorer prognosis than other subtypes and for which chemotherapy is the only systemic therapy. Multiple immunohistochemical markers are used to identify the basal-like subtype, including the absence of estrogen receptor alpha, progesterone receptor, and human epidermal growth factor receptor 2. Forkhead box C1 (FOXC1) has been identified as a specific marker expressed in BLBC in general breast cancer cohorts. We examined an institutional cohort of breast cancer patients with germline BRCA1 (n=46) and BRCA2 (n=35) mutations and found that FOXC1 expression on immunohistochemical staining is associated with BRCA1 vs BRCA2 mutations [30/46 vs. 6/35]. In BRCA1 mutant tumors, FOXC1 was expressed in 28/31 BLBC tumors and 2/13 non-BLBC tumors, In BRCA2 mutant tumors, FOXC1 was expressed in 5/5 BLBC tumors and 1/30 non-BLBC tumors. In cell culture models of BRCA1-mutant breast cancer, FOXC1 is associated with increased proliferation and may serve as a marker for sensitivity to PARP-inhibitor therapy with olaparib.

FOXC1, the new player in the cancer sandbox

In recent years, rapidly accumulating evidence implicates forkhead box C1 (FOXC1) in cancer, especially in studies of basal-like breast cancer (BLBC). Other studies have followed suit, demonstrating that FOXC1 is not only a major player in this breast cancer subtype, but also in hepatocellular carcinoma (HCC), endometrial cancer, Hodgkin's lymphoma (HL), and non-Hodgkin's lymphoma (NHL). The FOXC1 gene encodes a transcription factor that is crucial to mesodermal, neural crest, and ocular development, and mutations found in FOXC1 have been found to cause dominantly inherited Axenfeld-Rieger Syndrome (ARS). Interestingly, while FOXC1 missense mutations that are associated with ARS usually reduce gene activity, increased FOXC1 function now appears to be often linked to more aggressive cancer phenotypes in BLBC, HCC, HL, and NHL. This review discusses not only the role of FOXC1 in cancer cell progression, proliferation, differentiation, and metastasis, but also the underlying mechanisms of how FOXC1 can contribute to aggressive cancer phenotypes.

miR-582-5p inhibits invasion and migration of salivary adenoid cystic carcinoma cells by targeting FOXC1

Objective

Neurotropism of salivary adenoid cystic carcinoma (SACC) and pulmonary metastasis may lead to in treatment failure. miR-582-5p plays important roles in tumorigenesis, invasion and migration. Here, we aim to determine the effect of miR-582-5p and its role in SACC invasion and metastasis.

Methods

Six primary human SACC samples and matching adjacent normal tissues were analyzed by microarray analysis. Next, quantitative real-time PCR was carried out to evaluate miR-582-5p expression in 16 primary human SACC samples and matching adjacent normal tissues. Cell invasion and migration were also analyzed, and a luciferase reporter assay and western analysis were conducted. Cell growth and apoptosis assay were performed to confirm the effect of miR-582-5p and Forkhead box C1 (FOXC1) siRNA in cell proliferation and apoptosis. SACC tumorigenesis and metastasis were investigated in vivo experiment. Clinical samples from 110 patients were analyzed using in situ hybridization and immunohistochemistry.

Results

Microarray analysis revealed that miR-582-5p was significantly downregulated in the SACC samples compared with the matching adjacent normal tissues. Regulation of miR-582-5p expression significantly influenced the migration, invasion and proliferation ability of SACC cells by targeting FOXC1. E-cadherin was increased, while vimentin and snail were decreased with downregulation of FOXC1, suggesting that FOXC1 may regulate the epithelial-to-mesenchymal transition (EMT) of SACC cells by transactivating snail. In vivo, miR-582-5p overexpression suppressed the tumorigenesis and pulmonary metastasis of SACC. Lower expression of miR-582-5p expression predicts unfavorable prognoses and high rates of metastasis.

Conclusions

miR-582-5p could suppress effect on the process of invasion and migration in SACC cell lines, and this could occur through its target gene FOXC1.

FOXC1 in cancer development and therapy: deciphering its emerging and divergent roles

Forkhead box C1 (FOXC1) is an essential member of the forkhead box transcription factors and has been highlighted as an important transcriptional regulator of crucial proteins associated with a wide variety of carcinomas. FOXC1 regulates tumor-associated genes and is regulated by multiple pathways that control its mRNA expression and protein activity. Aberrant FOXC1 expression is involved in diverse tumorigenic processes, such as abnormal cell proliferation, cancer stem cell maintenance, cancer migration, and angiogenesis. Herein, we review the correlation between the expression of FOXC1 and tumor behaviors. We also summarize the mechanisms of the regulation of FOXC1 expression and activity in physiological and pathological conditions. In particular, we focus on the pathological processes of cancer targeted by FOXC1 and discuss whether FOXC1 is good or detrimental during tumor progression. Moreover, FOXC1 is highlighted as a clinical biomarker for diagnosis or prognosis in various human cancers. The information reviewed here should assist in experimental designs and emphasize the potential of FOXC1 as a therapeutic target for cancer.

Research progress on the forkhead box C1

FOXC1 is a vital member of FOX families which play important roles in biological processes including proliferation, differentiation, apoptosis, migration, invasion, metabolism, and longevity. Here we are focusing on roles of FOXC1 and their mechanisms in cancers. FOXC1 promoted progress of many cancers, such as breast cancer (especially basal-like breast cancer), hepatocellular carcinoma, gastric cancer and so on. FOXC1 was also found to be associated with drug resistance of cancers. FOXC1 promoted metastasis of cancers by increasing expression of MMP7, NEDD9 and Snail. Proliferation and invasion of cancers were increased by FOXC1 by mediating NF-κB, MST1R and KLF4 expression. FOXC1 was associated with development by regulating expression of FGF19 and MSX1. Recently, FOXC1 was found to be required for niche of stem cells or development of stem cells by mediating expression of Gli2, CXCL12, SCF, NFATC1, BMP and Myh7. Overall, FOXC1 exerts its functions by many mechanisms and may be used as a potential biomarker for diseases.

FOXC1 overexpression is a marker of poor response to anthracycline-based adjuvant chemotherapy in sporadic triple-negative breast cancer

Purpose

Because of its aggressive characteristics and poor prognosis, triple-negative breast cancer (TNBC) has become a hot topic in cancer research. Chemotherapy is currently the only treatment for patients with TNBC. The transcription factor FOXC1 has been associated with TNBC prognosis, but little is known about its effect on chemosensitivity. The aim of this study was to investigate the effects of FOXC1 on chemosensitivity.

Methods

A case–control study was performed on 25 TNBC patients who experienced relapse and/or metastasis. Another 25 patients without relapse or metastasis were randomly selected as controls. Medical records were reviewed for relevant information, and immunohistochemistry was performed to measure FOXC1 levels. The Kaplan–Meier method and Cox analysis were used to analyze differences in disease-free survival (DFS) and overall survival (OS). The correlation of FOXC1 expression with chemosensitivity was analyzed. Data were analyzed using SPSS 21.0 software, and a P value <0.05 was considered to be statistically significant.

Results

In 15 of 22 case patients, FOXC1 was overexpressed, whereas only 8 control patients exhibited FOXC1 overexpression (P < 0.05). FOXC1 expression had no correlation with pathological indicators. An anthracycline-based regimen was administered to 21 study patients and 23 control patients. FOXC1 expression was significantly associated with a worse DFS (HR 2.62, 95% CI 1.05–6.50, P = 0.038) but presented no correlation with OS (HR 2.53, 95% CI 0.76–8.40, P = 0.131) among these 44 patients.

Conclusions

This study shows that FOXC1 is correlated with chemosensitivity to anthracycline and could be used as an indicator of chemosensitivity in sporadic TNBC.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-017-3319-4) contains supplementary material, which is available to authorized users.

FOXC1: an emerging marker and therapeutic target for cancer

The Forkhead box C1 (FOXC1) transcription factor is involved in normal embryonic development and regulates the development and function of many organs. Most recently, a large body of literature has shown that FOXC1 plays a critical role in tumor development and metastasis. Clinical studies have demonstrated that elevated FOXC1 expression is associated with poor prognosis in many cancer subtypes, such as basal-like breast cancer (BLBC). FOXC1 is highly and specifically expressed in BLBC as opposed to other breast cancer subtypes. Its functions in breast cancer have been extensively explored. This review will summarize current knowledge on the function and regulation of FOXC1 in tumor development and progression with a focus on BLBC as well as the implications of these new findings in cancer diagnosis and treatment.

MiRNA-138-5p inhibits proliferation of pancreatic cancer cells

AIM

To investigate the effect of microRNA-138-5p (miR-138-5p) on the proliferation of pancreatic cancer (PC) cells.

METHODS

We constructed lentiviral vectors for miR-138-5p overexpression or knockdown and a negative control lentiviral vector, and transfected them into human PC cell lines PANC-1 and Capan-2. Cell counting kit-8 assay (CCK-8), colony-forming assay and EdU incorporation assay were employed to detect cell proliferation in vitro. The PANC-1 and Capan-2 cells were implanted subcutaneously in Balb/c nude mice to detect cell proliferation in vivo.

RESULTS

Lentiviral vectors were successfully constructed and transfected. CCK-8 assay, colony-forming assay and EdU incorporation assay showed that overexpression of miR-138-5p inhibited cell proliferation compared with the negative control (P < 0.05), while miR-138-5p knockdown promoted cell proliferation compared with the negative control (P < 0.05). In addition, miR-138-5p suppressed tumor growth in the subcutaneous xenograft model of human PC cells in Balb/c nude mice.

CONCLUSION

Our results indicate that miR-138-5p inhibits the proliferation of PC cells, suggesting a potential new therapeutic agent for PC.

Multiscale Embedded Gene Co-expression Network Analysis

Gene co-expression network analysis has been shown effective in identifying functional co-expressed gene modules associated with complex human diseases. However, existing techniques to construct co-expression networks require some critical prior information such as predefined number of clusters, numerical thresholds for defining co-expression/interaction, or do not naturally reproduce the hallmarks of complex systems such as the scale-free degree distribution of small-worldness. Previously, a graph filtering technique called Planar Maximally Filtered Graph (PMFG) has been applied to many real-world data sets such as financial stock prices and gene expression to extract meaningful and relevant interactions. However, PMFG is not suitable for large-scale genomic data due to several drawbacks, such as the high computation complexity O(|V|3), the presence of false-positives due to the maximal planarity constraint, and the inadequacy of the clustering framework. Here, we developed a new co-expression network analysis framework called Multiscale Embedded Gene Co-expression Network Analysis (MEGENA) by: i) introducing quality control of co-expression similarities, ii) parallelizing embedded network construction, and iii) developing a novel clustering technique to identify multi-scale clustering structures in Planar Filtered Networks (PFNs). We applied MEGENA to a series of simulated data and the gene expression data in breast carcinoma and lung adenocarcinoma from The Cancer Genome Atlas (TCGA). MEGENA showed improved performance over well-established clustering methods and co-expression network construction approaches. MEGENA revealed not only meaningful multi-scale organizations of co-expressed gene clusters but also novel targets in breast carcinoma and lung adenocarcinoma.

Diagnosis of Basal-Like Breast Cancer Using a FOXC1-Based Assay

BACKGROUND

Diagnosis of basal-like breast cancer (BLBC) remains a bottleneck to conducting effective clinical trials for this aggressive subtype. We postulated that elevated expression of Forkhead Box transcription factor C1 (FOXC1) is a simple and accurate diagnostic biomarker for BLBC.

METHODS

Accuracy of FOXC1 expression in identifying BLBC was compared with the PAM50 gene expression panel in gene expression microarray (GEM) (n = 1992) and quantitative real-time polymerase chain reaction (qRT-PCR) (n = 349) datasets. A FOXC1-based immunohistochemical (IHC) assay was developed and assessed in 96 archival formalin-fixed, paraffin-embedded (FFPE) breast cancer samples that also underwent PAM50 profiling. All statistical tests were two-sided.

RESULTS

A FOXC1-based two-tier assay (IHC +/- qRT-PCR) accurately identified BLBC (AUC = 0.88) in an independent cohort of FFPE samples, validating the accuracy of FOXC1-defined BLBC in GEM (AUC = 0.90) and qRT-PCR (AUC = 0.88) studies, when compared with platform-specific PAM50-defined BLBC. The hazard ratio (HR) for disease-specific survival in patients having FOXC1-defined BLBC was 1.71 (95% CI = 1.31 to 2.23, P < .001), comparable to PAM50 assay-defined BLBC (HR = 1.74, 95% CI = 1.40 to 2.17, P < .001). FOXC1 expression also predicted the development of brain metastasis. Importantly, unlike triple-negative or Core Basal IHC definitions, a FOXC1-based definition is able to identify BLBC in both ER+ and HER2+ patients.

CONCLUSION

A FOXC1-based two-tier assay, by virtue of being rapid, simple, accurate, and cost-effective may emerge as the diagnostic assay of choice for BLBC. Such a test could substantially improve clinical trial enrichment of BLBC patients and accelerate the identification of effective chemotherapeutic options for this aggressive disease.

MicroRNA-138-5p regulates pancreatic cancer cell growth through targeting FOXC1

PURPOSE

The prognosis of pancreatic cancer ranks among the worst of all cancer types, which is primarily due to the fact that during the past decades little progress has been made in its diagnosis and treatment. Here, we set out to investigate the role of microRNA 138 (miR-138-5p) in the regulation of pancreatic cancer cell growth and to assess its role as putative therapeutic target.

METHODS

qRT-PCR was used to examine the expression of miR-138-5p in 8 pancreatic cancer cell lines and 18 primary human pancreatic cancer samples. A lentivirual vector containing miR-138-5p mimics (lv-miR-138-5p) was used to exogenously over-express miR-138-5p in the pancreatic cancer cells lines Capan-2 and PANC-1. The effect of this over-expression on cell proliferation was examined using an in vitro propidium iodide fluorescence assay. Capan-2 cells exogenously over-expressing miR-138-5p were transplanted into nude mice to examine its in vivo effect on tumor growth. A predicted target of miR-138-5p (FOXC1) was first validated using a luciferase assay and, subsequently, down-regulated by siRNA to assess its effect on pancreatic cancer cell growth.

RESULTS

We found that miR-138-5p was markedly down-regulated in both pancreatic cancer cell lines and primary human pancreatic cancer samples, compared to a human pancreas ductal epithelial (HPDE) cell line and normal pancreatic tissues, respectively (P < 0.05). In addition, we found that in the pancreatic cancer cells lines Capan-2 and PANC-1 lentiviral transfection of miR-138-5p mimicked up-regulation of the endogenous expression of miR-138-5p and, concomitantly, inhibited cancer cell proliferation (P < 0.05). The exogenous over-expression of miR-138-5p also led to a significant inhibition of tumor formation in vivo. Using a luciferase assay, we found that miR-138-5p directly targets FOXC1. In conformity with this notion, we found that FOXC1 was down-regulated upon miR-138-5p over-expression in pancreatic cancer cells. Finally, we found that silencing of FOXC1 by siRNA had an inhibitory effect on pancreatic cancer cell growth.

CONCLUSIONS

Our data indicate that miR-138-5p may play an important role in regulating pancreatic cancer cell growth, possibly through targeting FOXC1. Over-expression of miR-138-5p may serve as a novel approach for the treatment of patients with pancreatic cancer.

Effect of siRNA-mediated FOXC1 gene silencing on proliferation of pancreatic cancer cells

AIM: To investigate small interfering RNA (siRNA)-mediated silencing of fork head box protein C1 (FOXC1) gene on the proliferation human pancreatic cancer Capan-2 and PANC-1 cells and to explore the possible underlying mechanisms.

METHODS: Quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) was used to examine the expression of FOXC1 mRNA in pancreatic cancer cell lines and primary carcinoma tissues from human patients. The human pancreatic cancer cells were divided into two groups: an FOXC1 siRNA group (experimental group) and an NC siRNA group (negative control group). qRT-PCR and Western blot were used to detect FOXC1 mRNA and protein expression in pancreatic cancer cells and to determine proliferation rate after transfection with 5-ethynyl-2'-deoxyuridine (EdU). Flow cytometry was used to examine cell cycle distribution. Western blot analysis was used to detect the expression of cell cycle related proteins P21, P53, and Cyclin D1.

RESULTS: FOXC1 mRNA expression in pancreatic cancer cells and pancreatic cancer tissues were significantly higher than in normal epithelial cells and matched tumor adjacent pancreatic tissue, respectively (P < 0.05). qRT-PCR and Western blot analysis showed that FOXC1 siRNA effectively silenced the transcription and expression of FOXC1 in pancreatic cancer cells. EdU cell proliferation experiments showed that compared with the control group, silencing FOXC1 gene expression in pancreatic cancer cells significantly decreased cell proliferation (P < 0.05). FCM results showed that compared with the control group, FOXC1 silencing arrested the tumor cells in G₀/G₁ phase (P < 0.05). Western blot analysis showed that compared with the control group, Cyclin D1 expression was significantly decreased (P < 0.05), while P21 and P53 expression was unchanged.

CONCLUSION: FOXC1 siRNA can effectively silence the FOXC1 gene expression in human pancreatic cancer Capan-2 PANC-1 cells. FOXC1 silencing inhibits pancreatic cancer cell proliferation and arrests cell cycle in G₀/G₁ phase, suggesting that FOXC1 alters cell proliferation possibly by regulation of the cell cycle through, in part, regulating the expression of Cyclin D1.

Forkhead box C1 promoter upstream transcript, a novel long non-coding RNA, regulates proliferation and migration in basal-like breast cancer

Recent studies have shown that long non‑coding RNAs (lncRNAs) have crucial regulating roles in carcinogenesis. Forkhead box C1 (FOXC1) is an important cancer‑associated gene in basal‑like breast cancer (BLBC). In the present study, a novel lncRNA, FOXC1 promoter upstream transcript (FOXCUT) was investigated in BLBC patients using polymerase chain reaction analysis. The results showed that the expression of FOXCUT and FOXC1 were positively correlated. When the expression of FOXCUT was downregulated by small interfering RNA, the expression of FOXC1 was similarly reduced. Furthermore, in MDA‑MB‑231 and MDA‑MB‑468 breast cancer cells, knockdown of FOXCUT markedly inhibited cell proliferation and migration in vitro. In conclusion, FOXCUT lncRNA may be functionally involved in the tumor progression of BLBCs through the regulation of its paired mRNA, FOXC1, demonstrating that FOXCUT may serve as a novel biomarker and therapeutic target in BLBCs.

FOXC1 is a critical mediator of EGFR function in human basal-like breast cancer

BACKGROUND

Human basal-like breast cancer (BLBC) has a poor prognosis and is often identified by expression of the epidermal growth factor receptor (EGFR). BLBC remains a major clinical challenge because its pathogenesis is not well understood, thus hindering efforts to develop targeted therapies. Recent data implicate the forkhead box C1 (FOXC1) transcription factor as an important prognostic biomarker and functional regulator of BLBC, but its regulatory mechanism and impact on BLBC tumorigenesis remain unclear.

METHODS

The association between FOXC1 and EGFR expression in human breast cancer was examined by immunohistochemistry in formalin-fixed tissues and analysis of the TCGA database. The regulation of FOXC1 by EGFR activation was investigated in MDA-MB-468 cells using immunoblotting, qRT-PCR, and luciferase activity assays. This EGFR effect on FOXC1 expression was confirmed using the MDA-MB-468 xenograft model.

RESULTS

Both FOXC1 mRNA and protein levels significantly correlated with EGFR expression in human breast tumors. EGFR activation induced FOXC1 transcription through the ERK and Akt pathways in BLBC. EGFR inhibition in vivo reduced FOXC1 expression in xenograft tumors. We also found that FOXC1 knockdown impaired the effects of EGF on BLBC cell proliferation, migration, and invasion.

CONCLUSIONS

Our findings uncover a novel EGFR-FOXC1 signaling axis critical for BLBC cell functions, supporting the notion that intervention in the FOXC1 pathway may provide potential modalities for BLBC treatment.

Upregulation of E2F transcription factor 3 is associated with poor prognosis in hepatocellular carcinoma

E2F transcription factor 3 (E2F3), a member of the E2F transcription factor family and a member of the genes involved in the regulation of cell cycle, is an oncogene with strong proliferative potential. E2F3 is involved in many processes and plays important roles in the development of several types of cancer, while its relationship with prognosis in hepatocellular carcinoma (HCC) has yet to be reported. In the present study, based on 4 independent microarray data sets which covered 385 cases of HCC and 327 cases of normal livers retrieved from the Oncomine database, we demonstrated that E2F3 was upregulated at least 1.5-fold and on average 2.3-fold in HCC when compared with normal controls. Comprehensive bioinformatics analysis consisting of protein-protein interaction, gene co-occurrence, microRNA-mRNA interaction and biological process annotation indicated that E2F3 interacted with a large number of genes, proteins and microRNAs which were all associated with poor prognosis in patients with HCC and other types of cancer, suggesting that E2F3 may also serve as a biomarker for poor prognosis. Taken together, for the first time, we show that the overexpression of E2F3 may be associated with unfavorable prognosis in HCC.

A survey of immunohistochemical biomarkers for basal-like breast cancer against a gene expression profile gold standard

Gene expression profiling of breast cancer delineates a particularly aggressive subtype referred to as 'basal-like', which comprises ∼15% of all breast cancers, afflicts younger women and is refractory to endocrine and anti-HER2 therapies. Immunohistochemical surrogate definitions for basal-like breast cancer, such as the clinical ER/PR/HER2 triple-negative phenotype and models incorporating positive expression for CK5 (CK5/6) and/or EGFR are heavily cited. However, many additional biomarkers for basal-like breast cancer have been described in the literature. A parallel comparison of 46 proposed immunohistochemical biomarkers of basal-like breast cancer was performed against a gene expression profile gold standard on a tissue microarray containing 42 basal-like and 80 non-basal-like breast cancer cases. Ki67 and PPH3 were the most sensitive biomarkers (both 92%) positively expressed in the basal-like subtype, whereas CK14, IMP3 and NGFR were the most specific (100%). Among biomarkers surveyed, loss of INPP4B (a negative regulator of phosphatidylinositol signaling) was 61% sensitive and 99% specific with the highest odds ratio (OR) at 108, indicating the strongest association with basal-like breast cancer. Expression of nestin, a common marker of neural progenitor cells that is also associated with the triple-negative/basal-like phenotype and poor breast cancer prognosis, possessed the second highest OR at 29 among the 46 biomarkers surveyed, as well as 54% sensitivity and 96% specificity. As a positively expressed biomarker, nestin possesses technical advantages over INPP4B that make it a more ideal biomarker for identification of basal-like breast cancer. The comprehensive immunohistochemical biomarker survey presented in this study is a necessary step for determining an optimized surrogate immunopanel that best defines basal-like breast cancer in a practical and clinically accessible way.

FOXC1 is enriched in the mammary luminal progenitor population, but is not necessary for mouse mammary ductal morphogenesis

Expression of FOXC1, a forkhead box transcription factor, correlates with the human basal-like breast cancer (BLBC) subtype, and functional analyses have revealed its importance for in vitro invasiveness of BLBC cells. Women diagnosed with this breast tumor subtype have a poorer outcome because of the lack of targeted therapies; thus, continued investigation of factors driving these tumors is critical to uncover novel therapeutic targets. Several processes that dictate normal mammary morphogenesis parallel cancer progression, and enforced expression of FOXC1 can induce a progenitor state in more-differentiated mammary epithelial cells. Consequently, evaluating how FOXC1 functions in the normal gland is critical to further understand BLBC biology. Although FOXC1 is well known to control normal development of a number of tissues, its role in the mammary gland has not yet been investigated. Herein, we describe FOXC1 expression patterning in the normal breast, where it is localized to the basal/myoepithelium, suggesting that FOXC1 would be required for normal development. However, mammary glands lacking Foxc1 have no overt defect in ductal outgrowth, alveologenesis, or lineage specification. Of significant interest, we found that expression of FOXC1 is enriched in the normal luminal progenitor population, which is the postulated cell of origin of BLBC. These results indicate that FOXC1 is unnecessary for mammary morphogenesis and that its role in BLBC likely involves processes that are unrelated to cell lineage specification.

High expression of FOXC1 is associated with poor clinical outcome in non-small cell lung cancer patients

The aim of this study was to detect FOXC1 expression in human non-small cell lung cancer (NSCLC) and to analyze its association with prognosis of NSCLC patients. Expressional levels of FOXC1 mRNA and protein in 30 cases of NSCLC and corresponding non-tumor tissue samples were examined by quantitative real-time PCR and Western blotting. Immunohistochemistry was performed to detect the expression of FOXC1 in 125 NSCLC tissues. We found that the expression levels of FOXC1 mRNA and protein in NSCLC tissues were significantly higher than those in corresponding non-tumor tissues. High-level FOXC1 expression was correlated with poor tumor differentiation, tumor-node-metastasis stage, and lymph node metastasis. Patients with high expression levels of FOXC1 showed lower overall survival rate than those with low expression levels. Multivariate analysis showed that high FOXC1 protein expression was an independent prognostic factor for NSCLC patients. Our study suggests that over-expression of FOXC1 may play an important role in the progression of NSCLC, and FOXC1 expression may offer a valuable marker for predicting the outcome of patients with NSCLC.

High level of FOXC1 expression is associated with poor prognosis in pancreatic ductal adenocarcinoma

Accumulating evidence for overexpression of FOXC1 in various types of human cancer suggests that it plays a key role in tumor biology. However, little is known about the function of FOXC1 in pancreatic ductal adenocarcinoma (PDA). This study was to investigate the expression profile of FOXC1 in PDA and its clinical significance. We detected the expression profile of FOXC1 mRNA and protein in PDA tissue and in corresponding normal tissue by quantitative reverse-transcriptase polymerase chain reaction and western blotting. Immunohistochemistry was also used in the detection of FOXC1 protein expression. The clinicopathological implications of these proteins were analyzed statistically. Survival analysis was performed to assess prognostic significance. FOXC1 mRNA was overexpressed in PDA tissue when compared with corresponding normal tissue, so was FOXC1 protein. The overexpression of FOXC1 was significantly associated with the degree of clinical stage (p < 0.001), histological differentiation (p = 0.002), and lymph node metastases (p < 0.001). Survival analysis revealed that overexpression of FOXC1 is associated with a poorer prognosis. These observations suggest that FOXC1 plays a key role in PDA and therefore may provide an opportunity for developing a novel therapeutic target as well as a prognostic marker in PDA.

The forkhead box transcription factor FOXC1 promotes breast cancer invasion by inducing matrix metalloprotease 7 (MMP7) expression

Therapeutic options for treatment of basal-like breast cancers are limited and identification of molecular targets for novel therapies to treat this aggressive cancer is urgently needed. Recently, FOXC1, a forkhead box transcription factor, was identified as a functionally important biomarker of breast cancer aggressiveness and the basal-like breast cancer subtype. However, the mechanism through which FOXC1 controls aggressiveness of basal-like breast cancer remains to be elucidated. Here, we identify matrix metalloprotease 7 (MMP7) as a key downstream effector of FOXC1-mediated invasiveness. Expression of FOXC1 and MMP7 is significantly correlated in breast cancer samples and cell lines at both the mRNA and protein levels. Transient expression of FOXC1 in nontransformed mammary epithelial cell lines resulted in significantly increased expression of MMP7 and an MMP7-dependent increase in invasiveness. In reciprocal experiments, silencing endogenous FOXC1 in basal-like breast cancer cell lines resulted in decreased expression of MMP7 without decreased expression of other matrix metalloproteinases. We also demonstrate that elevated co-expression of FOXC1 and MMP7 is an independent predictor of patient outcome in multivariate analyses of two breast cancer patient cohorts. Together, our findings identify MMP7 as a novel mechanism through which FOXC1 may regulate the basal-like breast cancer invasive phenotype and the propensity of these cancers to metastasize. Furthermore, our findings demonstrate for the first time a correlation between MMP7 expression and basal-like breast cancers, suggesting that MMP7 may be a useful therapeutic target for treatment of this disease.

Gene expression and pathologic response to neoadjuvant chemotherapy in breast cancer

Pathologic complete response after neoadjuvant systemic treatment appears to be a valid surrogate for better overall survival in breast cancer patients. Currently, together with standard clinicopathologic assessment, novel molecular biomarkers are being exhaustively tested in order to look into the heterogeneity of breast cancer. The aim of our study was to examine an association between 23-gene real-time-PCR expression assay including ABCB1, ABCC1, BAX, BBC3, BCL2, CASP3, CYP2D6, ERCC1, FOXC1, GAPDH, IGF1R, IRF1, MAP2, MAPK 8, MAPK9, MKI67, MMP9, NCOA3, PARP1, PIK3CA, TGFB3, TOP2A, and YWHAZ receptor status of breast cancer core biopsies sampled before neoadjuvant chemotherapy (anthracycline and taxanes) and pathologic response. Core-needle biopsies were collected from 42 female patients with inoperable locally advanced breast cancer or resectable tumors suitable for downstaging, before any treatment. Expressions of 23 genes were determined by means of TagMan low density arrays. Analysis of variance was used to select genes with discriminatory potential between receptor subtypes. We introduced a correction for false discovery rates (presented as q values) due to multiple hypothesis testing. Statistical analysis showed that seven genes out of a 23-gene real-time-PCR expression assay differed significantly in relation to pathologic response regardless of breast cancer subtypes. Among these genes, we identified: BAX (p = 0.0146), CYP2D6 (p = 0.0063), ERCC1 (p = 0.0231), FOXC1 (p = 0.0048), IRF1 (p = 0.0022), MAP2 (p = 0.0011), and MKI67 (p = 0.0332). The assessment of core biopsy gene profiles and receptor-based subtypes, before neoadjuvant therapy seems to predict response or resistance and to define new signaling pathways to provide more powerful classifiers in breast cancer, hence the need for further research.