Expression of the forkhead transcription factor FOXP1 is associated both with hypoxia inducible factors (HIFs) and the androgen receptor in prostate cancer but is not directly regulated by androgens or hypoxia

Wnt3a is a promising target in colorectal cancer

Most colorectal cancers (CRC) are associated with activated Wnt signaling, making it the fourth most prevalent type of cancer globally. To function properly, the Wnt signaling pathway requires secreted glycoproteins known as Wnt ligands (Wnts). Humans have 19 Wnts, which suggest a complicated signaling and biological process, and we still know little about their functions in developing CRC. This review aims to describe the canonical Wnt signaling in CRC, particularly the Wnt3a expression pattern, and their association with the angiogenesis and progression of CRC. This review also sheds light on the inhibition of Wnt3a signaling in CRC. Despite some obstacles, a thorough understanding of Wnts is essential for effectively managing CRC.

Transcriptomics unravels molecular players shaping dorsal lip hypertrophy in the vacuum cleaner cichlid, Gnathochromis permaxillaris

BACKGROUND

Teleosts display a spectacular diversity of craniofacial adaptations that often mediates ecological specializations. A considerable amount of research has revealed molecular players underlying skeletal craniofacial morphologies, but less is known about soft craniofacial phenotypes. Here we focus on an example of lip hypertrophy in the benthivorous Lake Tangnayika cichlid, Gnathochromis permaxillaris, considered to be a morphological adaptation to extract invertebrates out of the uppermost layer of mud bottom. We investigate the molecular and regulatory basis of lip hypertrophy in G. permaxillaris using a comparative transcriptomic approach.

RESULTS

We identified a gene regulatory network involved in tissue overgrowth and cellular hypertrophy, potentially associated with the formation of a locally restricted hypertrophic lip in a teleost fish species. Of particular interest were the increased expression level of apoda and fhl2, as well as reduced expression of cyp1a, gimap8, lama5 and rasal3, in the hypertrophic lip region which have been implicated in lip formation in other vertebrates. Among the predicted upstream transcription factors, we found reduced expression of foxp1 in the hypertrophic lip region, which is known to act as repressor of cell growth and proliferation, and its function has been associated with hypertrophy of upper lip in human.

CONCLUSION

Our results provide a genetic foundation for future studies of molecular players shaping soft and exaggerated, but locally restricted, craniofacial morphological changes in fish and perhaps across vertebrates. In the future, we advocate integrating gene regulatory networks of various craniofacial phenotypes to understand how they collectively govern trophic and behavioural adaptations.

miR-375-3p contributes to hypoxia-induced apoptosis by targeting forkhead box P1 (FOXP1) and Bcl2 like protein 2 (Bcl2l2) in rat cardiomyocyte h9c2 cells

miRNAs have been pointed to play critical role in the development of congenital heart disease (CHD). miRNA-375-3p (miR-375-3p) was involved in cardiac dysfunction and cardiogenesis. However, no prior study had established a therapeutic role of miR-375-3p in CHD. We intended to investigate the effect and mechanism of miR-375-3p on apoptosis in hypoxic cardiomyocytes in vitro. Expression of miR-375-3p, forkhead box P1 (FOXP1) and Bcl2 like protein 2 (Bcl2l2) was detected using real-time quantitative PCR and western blot. Apoptosis was measured with MTT assay, flow cytometry and caspase-3 activity assay. The potential target binding between miR-375-3p and FOXP1/Bcl2l2 was predicted on DianaTools, and was validated by luciferase reporter assay and RNA pull-down assay. As a result, miR-375-3p was upregulated and FOXP1/Bcl2l2 was downregulated in maternal serum of women with fetal CHD and hypoxia-induced rat cardiomyocyte h9c2 cells. Hypoxia induced apoptosis rate elevation, caspase-3 activity promotion and viability inhibition in h9c2 cells; overexpression of miR-375-3p promoted, whereas knockdown of miR-375-3p antagonized hypoxia-induced effects in h9c2 cells. In addition, miR-375-3p was validated to negatively regulate FOXP1 and Bcl2l2 expression through target binding, and silencing of FOXP1 and Bcl2l2 could independently abate the anti-apoptosis role of miR-375-3p knockdown in hypoxic h9c2 cells. Collectively, blocking miR-375-3p suppressed hypoxia-evoked apoptosis of cardiomyocytes by targeting and upregulating FOXP1 and Bcl2l2. Our results might suggest maternal serum miR-375-3p as a potential biomarker for prenatal detection of fetal CHD.

G9a regulates tumorigenicity and stemness through genome-wide DNA methylation reprogramming in non-small cell lung cancer

Background

Eukaryotic histone methyltransferases 2 (EHMT2 or G9A) has been regarded as a potential target for non-small cell lung cancer (NSCLC) therapy. This study investigated the regulatory roles of G9A in tumorigenesis and stemness in NSCLC. We isolated and enriched tumor-initiating cells (TIC) from surgically resected NSCLC tissues by FACS and sphere formation assays. We then knocked down G9A using shRNA and carried out genome-wide 850K methylation array and RNA sequencing analyses. We carried out in vivo tumorigenecity asssay using mice xenografts and examined G9A interactions with its novel target using chromatin Immunoprecipitation (ChIP).

Results

We identified 67 genes hypomethylated and 143 genes upregulated following G9A knockdown of which 43 genes were both hypomethylated and upregulated. We selected six genes (CDYL2, DPP4, SP5, FOXP1, STAMBPL1, and ROBO1) for validation. In addition, G9A expression was higher in TICs and targeting G9a by shRNA knockdown or by selective inhibitor UNC0642 significantly inhibited the expression of cancer stem cell markers and sphere forming capacity, in vitro proliferation, and in vivo growth. Further, transient overexpression of FOXP1, a protein may promote normal stem cell differentiation, in TICs resulted in downregulation of stem cell markers and sphere forming capacity and cell proliferation in vitro indicating that the genes we identified are directly regulated by G9A through aberrant DNA methylation and subsequent expression. Similarly, ChIP assay has shown that G9a interacts with its target genes through H3K9me2 and downregulation of H3K9me2 following G9a knockdown disrupts its interaction with its target genes.

Conclusions

These data suggest that G9A is involved in lung cancer stemness through epigenetic mechanisms of maintaining DNA methylation of multiple lung cancer stem cell genes and their expression. Further, targeting G9A or its downstream genes could be a novel therapeutic approach in treating NSCLC patients.

Neural Transcription Factors in Disease Progression

Progression to the malignant state is fundamentally dependent on transcriptional regulation in cancer cells. Optimum abundance of cell cycle proteins, angiogenesis factors, immune evasion markers, etc. is needed for proliferation, metastasis or resistance to treatment. Therefore, dysregulation of transcription factors can compromise the normal prostate transcriptional network and contribute to malignant disease progression.The androgen receptor (AR) is considered to be a key transcription factor in prostate cancer (PCa) development and progression. Consequently, androgen pathway inhibitors (APIs) are currently the mainstay in PCa treatment, especially in castration-resistant prostate cancer (CRPC). However, emerging evidence suggests that with increased administration of potent APIs, prostate cancer can progress to a highly aggressive disease that morphologically resembles small cell carcinoma, which is referred to as neuroendocrine prostate cancer (NEPC), treatment-induced or treatment-emergent small cell prostate cancer. This chapter will review how neuronal transcription factors play a part in inducing a plastic stage in prostate cancer cells that eventually progresses to a more aggressive state such as NEPC.

Cytoplasmic FOXP1 expression is correlated with ER and calpain II expression and predicts a poor outcome in breast cancer

BACKGROUND

Nuclear forkhead box protein P1 (N-FOXP1) expression in invasive breast cancer has been documented in the literature. However, the FOXP1 expression patterns at different stages of breast cancer progression are largely unknown, and the significance of cytoplasmic FOXP1 (C-FOXP1) expression in breast cancer has not been well illustrated. The aims of this study were to investigate FOXP1 expression patterns in invasive ductal carcinoma (IDC), ductal carcinoma in situ (DCIS), atypical ductal hyperplasia (ADH) and usual ductal hyperplasia (UDH), and to analyze the clinicopathological relevance of C-FOXP1 and its prognostic value in IDC.

METHODS

N-FOXP1 and C-FOXP1 expression in cases of IDC, DCIS, ADH and UDH was determined using immunohistochemistry. The correlation between C-FOXP1 expression and clinicopathological parameters as well as the overall survival (OS) and disease-free survival (DFS) rates of patients with IDC were analyzed.

RESULTS

Exclusive N-FOXP1 expression was found in 85.0% (17/20), 40.0% (8/20), 12.2% (5/41) and 10.8% (9/83) of UDH, ADH, DCIS, and IDC cases, respectively, and exclusive C-FOXP1 expression was observed in 0% (0/20), 0% (0/20), 4.9% (2/41), and 31.3% (26/83) of the cases, respectively. Both N- and C-FOXP1 staining were observed in 15.0% (3/20), 60.0% (12/20), 82.9% (34/41) and 48.2% (40/83) of the above cases, respectively, while complete loss of FOXP1 expression was observed in only 9.6% (8/83) of IDC cases. Estrogen receptor (ER) expression in C-FOXP1-positive IDC cases (31/66, 47.0%) was significantly lower than that in C-FOXP1-negative cases (13/17, 76.5%) (p = 0.030). Calpain II expression was observed in 83.3% (55/66) of C-FOXP1-positive IDC cases, which was significantly higher than that in C-FOXP1-negative cases (9/17, 52.9%) (p = 0.007). Calpain II was significantly associated with pAKT (p = 0.029), pmTOR (p = 0.011), p4E-BP1 (p < 0.001) and p-p70S6K (p = 0.003) expression levels. The 10-year OS and DFS rates of the C-FOXP1-positive patients were 60.5% and 48.7%, respectively, both of which were lower than those of the C-FOXP1-negative patients (93.3, 75.3%). The OS curve showed a dramatic impact of C-FOXP1 status on OS (p = 0.045).

CONCLUSIONS

Cytoplasmic relocalization of FOXP1 protein was a frequent event in breast IDC. Calpain II might play an important role in nucleocytoplasmic trafficking of FOXP1 and the AKT pathway might be involved in this process. C-FOXP1 expression was inversely associated with ER expression and might be a predictor of poor OS in patients with IDC.

The untold stories of the speech gene, the FOXP2 cancer gene

FOXP2 encodes a transcription factor involved in speech and language acquisition. Growing evidence now suggests that dysregulated FOXP2 activity may also be instrumental in human oncogenesis, along the lines of other cardinal developmental transcription factors such as DLX5 and DLX6 [1-4]. Several FOXP familymembers are directly involved during cancer initiation, maintenance and progression in the adult [5-8]. This may comprise either a pro-oncogenic activity or a deficient tumor-suppressor role, depending upon cell types and associated signaling pathways. While FOXP2 is expressed in numerous cell types, its expression has been found to be down-regulated in breast cancer [9], hepatocellular carcinoma [8] and gastric cancer biopsies [10]. Conversely, overexpressed FOXP2 has been reported in multiple myelomas, MGUS (Monoclonal Gammopathy of Undetermined Significance), several subtypes of lymphomas [5,11], as well as in neuroblastomas [12] and ERG fusion-negative prostate cancers [13]. According to functional evidences reported in breast cancer [9] and survey of recent transcriptomic and proteomic analyses of different tumor biopsies, we postulate that FOXP2 dysregulation may play a main role throughout cancer initiation and progression. In some cancer conditions, FOXP2 levels are now considered as a critical diagnostic marker of neoplastic cells, and in many situations, they even bear strong prognostic value [5]. Whether FOXP2 may further become a therapeutic target is an actively explored lead. Knowledge reviewed here may help improve our understanding of FOXP2 roles during oncogenesis and provide cues for diagnostic, prognostic and therapeutic analyses.

Epstein-Barr virus encoded miR-BART11 promotes inflammation-induced carcinogenesis by targeting FOXP1

Epstein-Barr virus (EBV) infection and chronic inflammation are closely associated with the development and progression of nasopharyngeal carcinoma (NPC) and gastric cancer (GC), and the infiltration of inflammatory cells, including tumor-associated macrophages (TAMs), is often observed in these cancers. EBV encodes 44 mature micro RNAs (miRNAs), but the roles of only a few EBV-encoded miRNA targets are known in cancer development, and here, our aim was to elucidate the effects of EBV-miR-BART11 on FOXP1 expression, and potential involvement in inflammation-induced carcinogenesis. We constructed an EBV miRNA-dependent gene regulatory network and predicted that EBV-miR-BART11 is able to target forkhead box P1 (FOXP1), a key molecule involved in monocyte to macrophage differentiation. Here, using luciferase reporter assay, we confirmed that EBV-miR-BART11 directly targets the 3′-untranslated region of FOXP1 gene, inhibits FOXP1 induction of TAM differentiation, and the secretion of inflammatory cytokines into the tumor microenvironment, inducing the proliferation of NPC and GC cells. FOXP1 overexpression hindered monocyte differentiation and inhibited NPC and GC cells growth. Our results demonstrated that EBV-miR-BART11 plays a crucial role in the promotion of inflammation-induced NPC and GC carcinogenesis by inhibiting FOXP1 tumor-suppressive effects. We showed a novel EBV-dependent mechanism that may induce the carcinogenesis of NPC and GC, which may help define new potential biomarkers and targets for NPC and GC diagnosis and treatment.

FOXP1 enhances tumor cell migration by repression of NFAT1 transcriptional activity in MDA-MB-231 cells

Until now, forkhead box P1 (FOXP1) has been identified as a tumor suppressor in several correlation studies in breast cancer. Although FOXP1 is defined as a transcriptional repressor that interacts with other transcription factors in various mechanistic studies, there is no study that explains its repressor functions in breast cancer biology. This study demonstrated the repressor function of FOXP1 on nuclear factor of activated T cells (NFAT1) and the migratory effect of this repression in MDA-MB-231 breast cancer cells. Co-immunoprecipitation experiments were performed for the investigation of protein-protein interaction between two transcription factors. Protein-protein interaction on DNA was investigated with EMSA and transcriptional effects of FOXP1 on NFAT1, luciferase reporter assay was performed. Wound healing assay was used to analyze the effects of overexpression of FOXP1 on tumor cell migration. This study showed that FOXP1 has protein-protein interaction with NFAT1 on DNA and enhances breast cancer cell migration by repressing NFAT1 transcriptional activity and FOXP1 shows oncogenic function by regulating breast cancer cell motility.

The significance of FOXP1 in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of mature B-cell lymphoma. While the majority of patients are cured with immunochemotherapy incorporating the anti-CD20 monoclonal antibody rituximab (R-CHOP), relapsed and refractory patients still have a dismal prognosis. DLBCL subtypes including an aggressive activated B-cell-like (ABC) and a more favorable prognosis germinal center-like (GCB) DLBCL have been identified by gene expression profiling and are characterized by distinct genetic abnormalities and oncogenic pathways. This identification of novel molecular targets is now enabling clinical trials to evaluate more effective personalized approaches to DLBCL therapy. The forkhead transcription factor FOXP1 is highly expressed in the ABC-DLBCL gene signature and has been extensively studied within the context of DLBCL for more than a decade. Here, we review the significance of FOXP1 in the pathogenesis of DLBCL, summarizing data supporting its utility as a prognostic and subtyping marker, its targeting by genetic aberrations, the importance of specific isoforms, and emerging data demonstrating a functional role in lymphoma biology. FOXP1 is one of the critical transcription factors whose deregulated expression makes important contributions to DLBCL pathogenesis. Thus, FOXP1 warrants further study as a potential theranostic in ABC-DLBCL.

Expression of FOXP1 and Colorectal Cancer Prognosis

BACKGROUND

Forkhead box gene P1 (FOXP1) has proven to be a valuable prognostic biomarker in lymphomas, but little is known about this gene in colorectal cancer (CRC).

OBJECTIVES

To investigate the expression of FOXP1 in CRC and its potential associations with outcome in CRC.

METHODS

We studied the expression pattern of FOXP1 retrospectively via immunohistochemistry in a series of 165 - CRC cases. Fluorescent in situ hybridization and RNA sequencing on FOXP1 knockdown cell lines were performed to investigate the mechanism of action and target genes of FOXP1.

RESULTS

Complete loss of nuclear FOXP1 expression was observed in 11.5% of the subjects. A total of 70.9% of subjects showed a heterogeneous FOXP1 expression pattern, and 17.6% of them had high FOXP1 expression. Impaired expression of FOXP1 was significantly correlated with reduced survival rates by multivariate analysis (P = .004). We found no chromosomal aberrations involving FOXP1 in individuals with FOXP1 negativity via immunohistochemical testing. RNA sequencing revealed that genes involved in inflammation and cell proliferation were differentially expressed after FOXP1 knockdown.

CONCLUSIONS

In our case series, loss of FOXP1 was associated with reduced survival rates in CRC tissue. Also, FOXP1 affects proliferation and inflammatory reaction in colorectal neoplasia.

Downregulation of FOXP2 promoter human hepatocellular carcinoma cell invasion

Hepatocellular carcinoma (HCC) is a major health concern with a high morbidity and mortality rate worldwide. However, the mechanism underlying hepatocarcinogenesis remains unclear. Forkhead box P2 (FOXP2) has been implicated in various human cancer types. However, the role of FOXP2 in HCC remains unknown. Western blot and immunohistochemistry were used to measure the expression of FOXP2 protein in HCC and adjacent normal tissues in 50 patients. Wound healing and transwell assays were used to determine the cell invasion ability. We showed that the level of FOXP2 was significantly reduced in HCC compared with the adjacent non-tumorous tissue. There was statistical significance between the expression of FOXP2 and vein invasion (P = 0.017), number of tumor nodes (P = 0.028), and AFP (P = 0.033). Low expression of FOXP2 correlated with poor survival. Moreover, wound healing and transwell assays showed that FOXP2 could decrease cell invasion and affect the expression of vimentin and E-cadherin. Our results suggested that FOXP2 expression was downregulated in HCC tumor tissues, and reduced FOXP2 expression was associated with poor overall survival. In addition, downregulation of FOXP2 significantly enhanced cell invasiveness. These findings uncover that FOXP2 might be a new prognostic factor and be closely correlated with HCC cell invasion.

FOXP1 regulation via the PI3K/Akt/p70S6K signaling pathway in breast cancer cells

Loss of Forkhead box P1 (FOXP1) protein expression confers a poor prognosis in sporadic and familial breast cancer patients, and the FOXP1 gene maps to a tumor suppressor locus at chromosome 3p14. Although correlation studies have indicated that FOXP1 has a role in tumor suppression, determination of the regulatory mechanism of FOXP1 is required to establish its function in breast cancer. It has previously been identified that FOXP1 is regulated by estrogen in breast cancer and that treatment with bisphenol A is effective for regulating the transformation of the normal human breast epithelial cell line, MCF-10F. In addition, FOXO-regulated activation of FOXP1 inhibits the apoptosis of MCF-10F cells following tamoxifen and Akt inhibitor VIII administration. The present study indicates that FOXP1 regulation occurs via a PI3K/Akt/p70S6 kinase (p70S6K) signaling pathway. Following treatment with wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3K)/Akt, MCF7 and MDA-MB-231 breast cancer cells demonstrated decreased FOXP1 protein expression levels; this result was also observed in the small interfering (si)RNA silencing of Akt. By contrast, overexpression of Akt resulted in increased FOXP1 protein expression levels in the MDA-MB-231 cells compared with the control cell lysates. Furthermore, treatment with rapamycin, a specific inhibitor of the mammalian target of rapamycin/p70S6K cascade, resulted in decreased FOXP1 expression in the MCF7 cells, but not in the MDA-MB-231 cells, which were resistant to rapamycin-induced inhibition. In addition, silencing of p70S6K using siRNA produced a marked decrease in FOXP1 expression. These data indicate that FOXP1 protein expression is regulated by a PI3K/Akt/p70S6K signaling cascade in breast cancer.

The expression and correlation between the transcription factor FOXP1 and estrogen receptors in epithelial ovarian cancer

BACKGROUND

Estrogen plays an important role in the progression of ovarian cancer in humans. FOXP1 belongs to the forkhead/winged-helix transcription factor family, and previous research indicated that FOXP1 functioned as a tumor suppressor gene. FOXP1 may be similar to FOXA1 and is closely related to steroid hormone receptors, but the relationship between FOXP1 and ER currently remains unclear.

METHODS

Ovarian tumors (60 malignant cases, 26 borderline cases, and 13 benign cases) and 14 normal ovarian tissues were collected retrospectively. Immunohistochemistry, western blotting and real-time PCR were used to characterize the expression patterns of FOXP1, ERα, and ERβ both at the mRNA and protein levels. We also used co-immunoprecipitation and immunofluorescent colocalization to investigate whether a correlation exists between FOXP1 and ERα/ERβ in ovarian cancer tissues.

RESULTS

The mRNA level for FOXP1 and ERβ in ovarian carcinoma tissues decreased, while the expression level of ERα mRNA increased compared with normal ovarian tissues. With an increase in the degree of ovarian carcinoma malignancy, the ERα expression level also increased. The expression pattern of ERβ in ovarian neoplasms was similar to that of the FOXP1 protein; presenting nuclear staining decreased, while cytoplasmic expression increased. Colocalization of FOXP1, ERα, and ERβ was present in the cytoplasm, with ERβ specific co-localization with FOXP1 in the perinuclear area. While immunoprecipitates created with FOXP1 mouse anti-human monoclonal antibody showed a positive reaction to an anti-ER antibody, immunoprecipitates containing anti-ER antibody and react to anti-FOXP1 antibody.

CONCLUSION

Interactions between FOXP1 and ER may play a pivotal role in the progression of ovarian cancer, and the activation or induction of FOXP1 and ERβ expression in cancer cells may inhibit tumor proliferation.

FOXP1 has a low expression in human gliomas and its overexpression inhibits proliferation, invasion and migration of human glioma U251 cells

The present study aimed to examine the clinical characteristics of forkhead box protein P1 (FoxP1) in gliomas and its role in the proliferation, invasiveness, migration and apoptosis of the human glioma U251 cell line. The expression levels of FOXP1 were first studied in operation resection specimens of glioma and normal peripheral brain tissues. The enhanced green fluorescent protein (EGFP) expression vector of FOXP1 was prepared and transfected into U251 cells. MTT, cell invasion, transwell and scratch assays were utilized to investigate the cell growth activity and the rate of apoptosis of the cells was tested by flow cytometry. Western blot analysis and quantitative polymerase chain reaction assays were employed to measure the transfection efficacy. The results revealed that FOXP1 was highly expressed in glioma, as compared with low levels detected in normal brain tissues. Following transfection with pEGFP-N1-FOXP1, the proliferation, invasiveness and migration capabilities of cells significantly decreased, whilst the rate of apoptosis was markedly enhanced (P<0.01). Furthermore, the expression of FOXP1 in U251 cells was enhanced (P<0.01). In conclusion, the present study indicated that FOXP1 is closely associated with tumorigenesis and development of glioma, as demonstrated by a reduction in the proliferation, migration and invasion of glioma cells upon FOCP1 overexpression.

Recurrent deletion of 3p13 targets multiple tumour suppressor genes and defines a distinct subgroup of aggressive ERG fusion-positive prostate cancers

Deletion of 3p13 has been reported from about 20% of prostate cancers. The clinical significance of this alteration and the tumour suppressor gene(s) driving the deletion remain to be identified. We have mapped the 3p13 deletion locus using SNP array analysis and performed fluorescence in situ hybridization (FISH) analysis to search for associations between 3p13 deletion, prostate cancer phenotype and patient prognosis in a tissue microarray containing more than 3200 prostate cancers. SNP array analysis of 72 prostate cancers revealed a small deletion at 3p13 in 14 (19%) of the tumours, including the putative tumour suppressors FOXP1, RYBP and SHQ1. FISH analysis using FOXP1-specific probes revealed deletions in 16.5% and translocations in 1.2% of 1828 interpretable cancers. 3p13 deletions were linked to adverse features of prostate cancer, including advanced stage (p < 0.0001), high Gleason grade (p = 0.0125), and early PSA recurrence (p = 0.0015). In addition, 3p13 deletions were linked to ERG(+) cancers and to PTEN deletions (p < 0.0001 each). A subset analysis of ERG(+) tumours revealed that 3p13 deletions occurred independently from PTEN deletions (p = 0.3126), identifying tumours with 3p13 deletion as a distinct molecular subset of ERG(+) cancers. mRNA expression analysis confirmed that all 3p13 genes were down regulated by the deletion. Ectopic over-expression of FOXP1, RYBP and SHQ1 resulted in decreased colony-formation capabilities, corroborating a tumour suppressor function for all three genes. In summary, our data show that deletion of 3p13 defines a distinct and aggressive molecular subset of ERG(+) prostate cancers, which is possibly driven by inactivation of multiple tumour suppressors.

Forkhead Box P family members at the crossroad between tolerance and immunity: a balancing act

Maintaining an immune balance between a chronic inflammatory state and autoimmunity is regulated at multiple levels by complex cellular signaling mechanisms. Numerous immune stimulatory and inhibitory signals converge on a large variety of transcriptional regulators. One key transcriptional regulator of immune homeostasis is FOXP3, which is a member of the Forkhead Box P subfamily of transcription factors and was shown to be essential for the development and maintenance of regulatory T cells. However, other FOXP members have received less attention in relation to a role in immune regulation. Still, recent developments point toward a general important regulatory role for FOXP proteins in the development and function of the adaptive immune system and establishment of a balanced immune response. Here, we discuss the current knowledge on the role of FOXP proteins in establishing immune homeostasis with an emphasis on T-cell biology. Furthermore, we review and speculate about different modes of regulating general FOXP activity and the function of this in health and disease.

Androgen receptors in hormone-dependent and castration-resistant prostate cancer

In the United States, prostate cancer (PCa) is the most commonly diagnosed non-cutaneous cancer in males and the second leading cause of cancer-related death for men. The prostate is an androgen-dependent organ and PCa is an androgen-dependent disease. Androgen action is mediated by the androgen receptor (AR), a hormone activated transcription factor. The primary treatment for metastatic PCa is androgen deprivation therapy (ADT). For the most part, tumors respond to ADT, but most become resistant to therapy within two years. There is persuasive evidence that castration resistant (also termed castration recurrent) PCa (CRPC) remains AR dependent. Recent studies have shown that there are numerous factors that contribute to AR reactivation despite castrate serum levels of androgens. These include changes in AR expression and structure through gene amplification, mutation, and alternative splicing. Changes in steroid metabolism, cell signaling, and coregulator proteins are also important contributors to AR reactivation in CRPC. Most AR targeted therapies have been directed at the hormone binding domain. The finding that constitutively active AR splice variants that lack the hormone binding domain are frequently expressed in CRPC highlights the need to develop therapies that target other portions of AR. In this review, the role of AR in normal prostate, in PCa, and particularly the mechanisms for its reactivation subsequent to ADT are summarized. In addition, recent clinical trials and novel approaches to target AR are discussed.

Forkhead box proteins: tuning forks for transcriptional harmony

Forkhead box (FOX) proteins are multifaceted transcription factors that are responsible for fine-tuning the spatial and temporal expression of a broad range of genes both during development and in adult tissues. This function is engrained in their ability to integrate a multitude of cellular and environmental signals and to act with remarkable fidelity. Several key members of the FOXA, FOXC, FOXM, FOXO and FOXP subfamilies are strongly implicated in cancer, driving initiation, maintenance, progression and drug resistance. The functional complexities of FOX proteins are coming to light and have established these transcription factors as possible therapeutic targets and putative biomarkers for specific cancers.

Expression of hypoxia-inducible factor-1α and -2α in whole-mount prostate histology: relation with dynamic contrast-enhanced MRI and Gleason score

The aim of this study was to investigate the association between the immunohistochemical expression of hypoxia-inducible factor (HIF)-1α and HIF-2α and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) parameters Ktrans and kep in prostate cancer. Therefore, 15 patients with biopsy-confirmed prostate cancer underwent a pre-operative 3T DCE-MRI scan. Immunohistochemical analysis of HIF-1α and HIF-2α, and of CD31 for microvessel density (MVD) was performed. Tumor areas were delineated on whole-mount histopathological sections. Nuclear HIF expression was correlated with the quantitative DCE-MRI parameters Ktrans and kep, MVD and Gleason score. HIF expression was highly heterogeneous within tumors and between patients. Pronounced expression of HIF-2α was present, while HIF-1α expression was more limited. Larger tumors showed higher HIF-2α expression (p=0.041). A correlation between HIF-2α and Ktrans p5th was found (r=0.30, p=0.02), but no differences in Ktrans, kep and MVD were observed for different levels of HIF expression. HIF expression was not associated with Gleason score. In conclusion, in this whole-mount prostate cancer study, larger prostate tumors showed frequently high HIF-2α expression, suggesting that larger tumors are clinically most relevant. However, HIF-1α and HIF-2α were not correlated with DCE-MRI parameters. Given the pronounced expression of HIF-2α and independence of Gleason score, HIF expression may function as a biomarker to guide boost dose prescription.

FOXP1 and estrogen signaling in breast cancer

Breast cancers are considered to be primarily regulated by estrogen signaling pathways because estrogen-dependent proliferation is observed in the majority of breast cancer cases. Thus, hormone therapy using antiestrogen drugs such as tamoxifen is effective for breast cancers expressing estrogen receptor α (ERα). However, acquired resistance during the endocrine therapy is a critical unresolved problem in breast cancer. Recently, a forkhead transcription factor FOXA1 has been reported to play an important role in the regulation of ERα-mediated transcription and proliferation of breast cancer. Interestingly, immunohistochemical analysis of breast cancer specimens has revealed that nuclear immunoreactivities of FOXP1 as well as those of FOXA1 are positively correlated with hormone receptor status, including ERα and progesterone receptor. In particular, the double-positive immunoreactivities of FOXP1 and FOXA1 are significantly associated with a favorable prognosis for survival of breast cancer patients receiving adjuvant tamoxifen therapy. The functions of FOXP1 and FOXA1 have been characterized in cultured cells; further, similar to FOXA1, FOXP1 is assumed to be a critical transcription factor for ERα signaling, and both forkhead transcription factors can serve as predictive factors for acquired endocrine resistance in breast cancer.

High expression of FoxP1 is associated with improved survival in patients with non-small cell lung cancer

FoxP1 has been reported to be expressed in several types of human malignant tumors, and has been associated with metastasis and patient prognosis. Quantitative real-time polymerase chain reaction (PCR) and immunohistochemical analysis with tissue microarray were used to characterize the expression of FoxP1 in non-small cell lung cancer (NSCLC). It was revealed that the expression of FoxP1 messenger RNA (mRNA) and protein was significantly higher in NSCLC tissue than in corresponding peritumoral tissue (P = .013 and P < .001, respectively). The expression of FoxP1 protein in NSCLC was related to gender, histologic type, and 5-year survival rate (all P < .05). Finally, we evaluated the prognostic significance of the expression of FoxP1 in a group of patients. Kaplan-Meier survival and Cox regression analyses showed that low expression of FoxP1 (P < .001) and later stage grouping by TNM (P = .022) were independent factors predicting poor prognosis for NSCLC.

Association of double-positive FOXA1 and FOXP1 immunoreactivities with favorable prognosis of tamoxifen-treated breast cancer patients

Breast cancer is primarily a hormone-dependent tumor that can be regulated by the status of the steroid hormones estrogen and progesterone. Forkhead box A1 (FOXA1) is a member of the forkhead box transcription factor family and functions as a pioneer factor of the estrogen receptor (ER) in breast cancer. In the present study, we demonstrate that FOXA1 mRNA was upregulated by estrogen and that estrogen receptor-α (ERα) recruitment to ER-binding sites in the vicinity of the FOXA1 gene was increased by estrogen in ERα-positive MCF-7 breast cancer cells. The estrogen-induced FOXA1 upregulation was repressed by 4-hydroxytamoxifen treatment. We also demonstrated that the proliferation and the migration of MCF-7 cells were decreased by FOXA1-specific small interfering RNA (siRNA; siFOXA1). Furthermore, siFOXA1 decreased the estrogen response element-driven transcription and the estrogen-dependent upregulation of ERα target genes in MCF-7 cells. Next, the immunohistochemical analyses of FOXA1 were performed using two groups of breast cancer specimens. The nuclear immunoreactivity of FOXA1 was detected in 80 (74%) of 108 human invasive breast cancers and was negatively correlated with tumor grade and positively correlated with hormone receptor status, including ERα and progesterone receptor, pathological tumor size, and immunoreactivity of FOXP1, another FOX family transcription factor. FOXA1 immunoreactivity was significantly elevated in the relapse-free breast cancer patients treated with tamoxifen. Notably, the double-positive immunoreactivities of FOXA1 and FOXP1 were significantly associated with a favorable prognosis for the relapse-free and overall survival of patients with tamoxifen-treated breast cancer, with lower P values compared with FOXA1 or FOXP1 immunoreactivity alone. These results suggest that FOXA1 plays an important role in the proliferation and migration of breast cancer cells by modulating estrogen signaling and that the double-positive immunoreactivities of FOXA1 and FOXP1 are associated with a favorable prognosis of tamoxifen-treated breast cancer.

Investigation on tumor hypoxia in resectable primary prostate cancer as demonstrated by 18F-FAZA PET/CT utilizing multimodality fusion techniques

PURPOSE

As hypoxia is believed to play an important role in the development and progression of prostate cancer, we evaluated whether 18F-labeled fluoroazomycin arabinoside (18F-FAZA) would be useful to identify tumor hypoxia in resectable prostate cancer.

METHODS

Positron emission tomography (PET)/CT was performed on 14 patients with untreated localized primary prostate cancer 3 h post-injection of approximately 390 MBq of 18F-FAZA using forced diuresis to decrease radioactivity in the urinary bladder. Anatomical trans-pelvic coil and pre- and post-contrast 1.5 T MRI with endorectal coil were performed on the same day. Patients underwent radical prostatectomy and ex vivo 3 T MRI of the prostatectomy specimen within 14 days following in vivo imaging. Imaging results were verified by whole mount histopathology plus tissue microarray (TMA) immunohistochemical (IHC) analysis for carbonic anhydrase IX (CAIX) and hypoxia-inducible factor 1α (HIF-1α). Registration of in vivo imaging with histology was achieved using mutual information software and performing ex vivo MRI of the prostatectomy specimen and whole mount sectioning with block face photography as intermediate steps.

RESULTS

Whole mount histology identified 43 tumor nodules, 19 of them larger than 1 ml as determined on coregistered volumes featuring 18F-FAZA, MRI, and histological 3-D image information. None of these lesions was found to be positive for CAIX or visualized by 18F-FAZA PET/CT while IHC for HIF-1α showed variable staining of tumor tissues. Accordingly, no correlation was found between 18F-FAZA uptake and Gleason scores.

CONCLUSION

Our data based on 18F-FAZA PET/CT and CAIX IHC do not support the presence of clinically relevant hypoxia in localized primary prostate cancer including high-grade disease. Activation of HIF-1α may be independent of tissue hypoxia in primary prostate cancer.

FOXQ1 is overexpressed in colorectal cancer and enhances tumorigenicity and tumor growth

Forkhead box Q1 (FOXQ1) is a member of the forkhead transcription factor family, and it has recently been proposed to participate in gastric acid secretion and mucin gene expression in mice. However, the role of FOXQ1 in humans and especially in cancer cells remains unknown. We found that FOXQ1 mRNA is overexpressed in clinical specimens of colorectal cancer (CRC; 28-fold/colonic mucosa). A microarray analysis revealed that the knockdown of FOXQ1 using small interfering RNA resulted in a decrease in p21(CIP1/WAF1) expression, and a reporter assay and a chromatin immunoprecipitation assay showed that p21 was one of the target genes of FOXQ1. Stable FOXQ1-overexpressing cells (H1299/FOXQ1) exhibited elevated levels of p21 expression and inhibition of apoptosis induced by doxorubicin or camptothecin. Although cellular proliferation was decreased in H1299/FOXQ1 cells in vitro, H1299/FOXQ1 cells significantly increased tumorigenicity [enhanced green fluorescent protein (EGFP): 2/15, FOXQ1: 7/15] and enhanced tumor growth (437 +/- 301 versus 1735 +/- 769 mm3, P < 0.001) in vivo. Meanwhile, stable p21 knockdown of H1299/FOXQ1 cells increased tumor growth, suggesting that FOXQ1 promotes tumor growth independent of p21. Microarray analysis of H1299/EGFP and H1299/FOXQ1 revealed that FOXQ1 overexpression upregulated several genes that have positive roles for tumor growth, including VEGFA, WNT3A, RSPO2, and BCL11A. CD31 and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining of the tumor specimens showed that FOXQ1 overexpression mediated the angiogenic and antiapoptotic effect in vivo. In conclusion, FOXQ1 is overexpressed in CRC and enhances tumorigenicity and tumor growth presumably through its angiogenic and antiapoptotic effects. Our findings show that FOXQ1 is a new member of the cancer-related FOX family.

Expression of the forkhead box transcription factor FOXP1 is associated with oestrogen receptor alpha, oestrogen receptor beta and improved survival in familial breast cancers

Background:

The role of FOXP1 in sporadic breast cancers has been widely studied but its role in familial breast cancers is yet unexplored.

Aims:

To investigate FOXP1 expression in different molecular subtypes of familial breast cancers and to correlate its expression with clinicopathological parameters, oestrogen receptors (ER) and survival.

Methods:

Immunohistochemical staining for FOXP1 was performed in 126 familial breast carcinomas comprising 35 BRCA1, 34 BRCA2 and 57 BRCAX.

Results:

Nuclear FOXP1 expression ranged from focal weak to widespread strong expression. Expression of FOXP1 was higher in familial breast cancers (54%) compared with sporadic cancers (46%) (p<0.001). There was a significant correlation between FOXP1 with ERα (p = 0.038) and ERβ (p = 0.007) in familial breast cancers. FOXP1 was more highly expressed in familial breast cancers compared with sporadic cancers for luminal (p = 0.021) and basal (p<0.001), but not HER2 and null phenotypes (both p>0.05). The absence of FOXP1 expression was associated with a shorter relapse-free (p = 0.025) and overall survival (p = 0.009) in familial breast cancer. Negativity for FOXP1 was associated with a significantly worse overall survival in BRCA2 cancers (p = 0.021) and there was a non-significant separation of the survival curves for BRCA1 cancers (p = 0.183). No differences in survival were seen for BRCAX cancers (p = 0.762).

Conclusion:

Results suggest that FOXP1 demonstrates different expression patterns in familial breast cancers than sporadic tumours, even in tumours showing similar phenotypes. They also suggest a different role of FOXP1 as a tumour suppressor in familial tumours, which is unrelated to ER expression and may impact on therapeutic options.

Critical role and regulation of transcription factor FoxM1 in human gastric cancer angiogenesis and progression

The mammalian forkhead box (Fox) transcription factor FoxM1b is implicated in tumorigenesis. However, the presence of expression and role of FoxM1b in gastric cancer remain unknown. Therefore, we investigated FoxM1b expression in 86 cases of primary gastric cancer and 57 normal gastric tissue specimens. We further investigated the underlying mechanisms of altered FoxM1b expression in and the effect of this altered expression on gastric cancer growth and metastasis using in vitro and animal models of gastric cancer. We found weak expression of FoxM1b protein in the mucous neck region of gastric mucosa, whereas we observed strong staining for FoxM1b in tumor cell nuclei in various gastric tumors and lymph node metastases. A Cox proportional hazards model revealed that FoxM1b expression was an independent prognostic factor in multivariate analysis (P < 0.001). Experimentally, overexpression of FoxM1b by gene transfer significantly promoted the growth and metastasis of gastric cancer cells in orthotopic mouse models, whereas knockdown of FoxM1b expression by small interfering RNA did the opposite. Promotion of gastric tumorigenesis by FoxM1b directly and significantly correlated with transactivation of vascular endothelial growth factor expression and elevation of angiogenesis. Given the importance of FoxM1b to regulation of the expression of genes key to cancer biology overall, dysregulated expression and activation of FoxM1b may play important roles in gastric cancer development and progression.

Androgen receptor and growth factor signaling cross-talk in prostate cancer cells

Androgens promote the growth and differentiation of prostate cells through ligand activation of the androgen receptor (AR). Sensitization of the androgenic response by multifunctional growth factor signaling pathways is one of the mechanisms via which AR contributes to the emergence of androgen-independent prostate tumors. The ability of AR to cross-talk with key growth factor signaling events toward the regulation of cell cycle, apoptosis, and differentiation outcomes in prostate cancer cells is established. In this paper, we review the functional interaction between AR and an array of growth factor signal transduction events (including epidermal growth factor; fibroblast growth factor; IGF1; vascular endothelial growth factor; transforming growth factor-beta) in prostate tumors. The significance of this derailed cross-talk between androgens and key signaling networks in prostate cancer progression and its value as a therapeutic forum targeting androgen-independent metastatic prostate cancer is discussed.

Expression of the forkhead transcription factor FOXP1 is associated with that of estrogen receptor-beta in primary invasive breast carcinomas

We previously identified a correlation between estrogen receptor alpha (ERalpha) and the candidate tumour suppressor gene Forkhead Box P1 (FOXP1), whose nuclear protein expression in breast tumours was associated with improved patient survival. However, the expression pattern of FOXP1 in normal breast tissue is more reminiscent of the second receptor, ERbeta, which has an emerging role as a tumour suppressor in breast cancer and critically may underlie the ability of some ERalpha-negative tumours to respond to tamoxifen. In a series of 283 breast cancers, in which ERalpha-positive tumours were treated with tamoxifen, the nuclear expression of ERbeta correlated significantly with ERalpha (p = 0.004), low-tumour grade (p = 0.008) and nuclear FOXP1 (p = 0.01). High-grade tumours exhibited significantly more cytoplasmic ERbeta than the low-grade tumours (p = 0.006). Regression analysis demonstrated that FOXP1 expression was most closely related to nuclear ERbeta (p = 0.021). Neither, nuclear or cytoplasmic ERbeta expression demonstrated prognostic significance. FOXP1 is not estrogen regulated and silencing FOXP1 expression, using siRNA, did not affect ERalpha, ERbeta or progesterone receptor expression, suggesting ER and FOXP1 co-expression may reflect a common regulatory mechanism.

FOXP1: a potential therapeutic target in cancer

Forkhead Box P1 (FOXP1) is a member of the FOX family of transcription factors which have a broad range of functions. Foxp1 is widely expressed and has been shown to have a role in cardiac, lung and lymphocyte development. FOXP1 is targeted by recurrent chromosome translocations and its overexpression confers a poor prognosis in a number of types of lymphomas, suggesting it may function as an oncogene. In contrast, FOXP1 localises to a tumour suppressor locus at 3p14.1 and loss of FOXP1 expression in breast cancer is associated with a worse outcome, suggesting FOXP1 may function as a tumour suppressor in other tissue types. These data suggest that FOXP1 may not only be useful in prognosis but also may be used to develop FOXP1-directed therapeutic strategies.

FOXP1: a potential therapeutic target in cancer

Forkhead Box P1 (FOXP1) is a member of the FOX family of transcription factors which have a broad range of functions. Foxp1 is widely expressed and has been shown to have a role in cardiac, lung and lymphocyte development. FOXP1 is targeted by recurrent chromosome translocations and its overexpression confers a poor prognosis in a number of types of lymphomas, suggesting it may function as an oncogene. In contrast, FOXP1 localises to a tumour suppressor locus at 3p14.1 and loss of FOXP1 expression in breast cancer is associated with a worse outcome, suggesting FOXP1 may function as a tumour suppressor in other tissue types. These data suggest that FOXP1 may not only be useful in prognosis but also may be used to develop FOXP1-directed therapeutic strategies.