LEF1 in androgen-independent prostate cancer: regulation of androgen receptor expression, prostate cancer growth, and invasion

A distinct isoform of lymphoid enhancer binding factor 1 (LEF1) epigenetically restricts EBV reactivation to maintain viral latency

As a human tumor virus, EBV is present as a latent infection in its associated malignancies where genetic and epigenetic changes have been shown to impede cellular differentiation and viral reactivation. We reported previously that levels of the Wnt signaling effector, lymphoid enhancer binding factor 1 (LEF1) increased following EBV epithelial infection and an epigenetic reprogramming event was maintained even after loss of the viral genome. Elevated LEF1 levels are also observed in nasopharyngeal carcinoma and Burkitt lymphoma. To determine the role played by LEF1 in the EBV life cycle, we used in silico analysis of EBV type 1 and 2 genomes to identify over 20 Wnt-response elements, which suggests that LEF1 may bind directly to the EBV genome and regulate the viral life cycle. Using CUT&RUN-seq, LEF1 was shown to bind the latent EBV genome at various sites encoding viral lytic products that included the immediate early transactivator BZLF1 and viral primase BSLF1 genes. The LEF1 gene encodes various long and short protein isoforms. siRNA depletion of specific LEF1 isoforms revealed that the alternative-promoter derived isoform with an N-terminal truncation (ΔN LEF1) transcriptionally repressed lytic genes associated with LEF1 binding. In addition, forced expression of the ΔN LEF1 isoform antagonized EBV reactivation. As LEF1 repression requires histone deacetylase activity through either recruitment of or direct intrinsic histone deacetylase activity, siRNA depletion of LEF1 resulted in increased histone 3 lysine 9 and lysine 27 acetylation at LEF1 binding sites and across the EBV genome. Taken together, these results indicate a novel role for LEF1 in maintaining EBV latency and restriction viral reactivation via repressive chromatin remodeling of critical lytic cycle factors.

Effects of S-Adenosylhomocysteine Hydrolase Downregulation on Wnt Signaling Pathway in SW480 Cells

S-adenosylhomocysteine hydrolase (AHCY) deficiency results mainly in hypermethioninemia, developmental delay, and is potentially fatal. In order to shed new light on molecular aspects of AHCY deficiency, in particular any changes at transcriptome level, we enabled knockdown of AHCY expression in the colon cancer cell line SW480 to simulate the environment occurring in AHCY deficient individuals. The SW480 cell line is well known for elevated AHCY expression, and thereby represents a suitable model system, in particular as AHCY expression is regulated by MYC, which, on the other hand, is involved in Wnt signaling and the regulation of Wnt-related genes, such as the β-catenin co-transcription factor LEF1 (lymphoid enhancer-binding factor 1). We selected LEF1 as a potential target to investigate its association with S-adenosylhomocysteine hydrolase deficiency. This decision was prompted by our analysis of RNA-Seq data, which revealed significant changes in the expression of genes related to the Wnt signaling pathway and genes involved in processes responsible for epithelial-mesenchymal transition (EMT) and cell proliferation. Notably, LEF1 emerged as a common factor in these processes, showing increased expression both on mRNA and protein levels. Additionally, we show alterations in interconnected signaling pathways linked to LEF1, causing gene expression changes with broad effects on cell cycle regulation, tumor microenvironment, and implications to cell invasion and metastasis. In summary, we provide a new link between AHCY deficiency and LEF1 serving as a mediator of changes to the Wnt signaling pathway, thereby indicating potential connections of AHCY expression and cancer cell phenotype, as Wnt signaling is frequently associated with cancer development, including colorectal cancer (CRC).

International Union of Basic and Clinical Pharmacology CXIII: Nuclear Receptor Superfamily-Update 2023

The NR superfamily comprises 48 transcription factors in humans that control a plethora of gene network programs involved in a wide range of physiologic processes. This review will summarize and discuss recent progress in NR biology and drug development derived from integrating various approaches, including biophysical techniques, structural studies, and translational investigation. We also highlight how defective NR signaling results in various diseases and disorders and how NRs can be targeted for therapeutic intervention via modulation via binding to synthetic lipophilic ligands. Furthermore, we also review recent studies that improved our understanding of NR structure and signaling. SIGNIFICANCE STATEMENT: Nuclear receptors (NRs) are ligand-regulated transcription factors that are critical regulators of myriad physiological processes. NRs serve as receptors for an array of drugs, and in this review, we provide an update on recent research into the roles of these drug targets.

Carcinogenesis promotion in oral squamous cell carcinoma: KDM4A complex-mediated gene transcriptional suppression by LEF1

Oral squamous cell carcinoma (OSCC) is the most prevalent cancer of the mouth, characterised by rapid progression and poor prognosis. Hence, an urgent need exists for the development of predictive targets for early diagnosis, prognosis determination, and clinical therapy. Dysregulation of lymphoid enhancer-binding factor 1 (LEF1), an important transcription factor involved in the Wnt-β-catenin pathway, contributes to the poor prognosis of OSCC. Herein, we aimed to explore the correlation between LEF1 and histone lysine demethylase 4 A (KDM4A). Results show that the KDM4A complex is recruited by LEF1 and specifically binds the LATS2 promoter region, thereby inhibiting its expression, and consequently promoting cell proliferation and impeding apoptosis in OSCC. We also established NOD/SCID mouse xenograft models using CAL-27 cells to conduct an in vivo analysis of the roles of LEF1 and KDM4A in tumour growth, and our findings show that cells stably suppressing LEF1 or KDM4A have markedly decreased tumour-initiating capacity. Overall, the results of this study demonstrate that LEF1 plays a pivotal role in OSCC development and has potential to serve as a target for early diagnosis and treatment of OSCC.

Hyperphosphorylated PTEN exerts oncogenic properties

PTEN is a multifaceted tumor suppressor that is highly sensitive to alterations in expression or function. The PTEN C-tail domain, which is rich in phosphorylation sites, has been implicated in PTEN stability, localization, catalytic activity, and protein interactions, but its role in tumorigenesis remains unclear. To address this, we utilized several mouse strains with nonlethal C-tail mutations. Mice homozygous for a deletion that includes S370, S380, T382 and T383 contain low PTEN levels and hyperactive AKT but are not tumor prone. Analysis of mice containing nonphosphorylatable or phosphomimetic versions of S380, a residue hyperphosphorylated in human gastric cancers, reveal that PTEN stability and ability to inhibit PI3K-AKT depends on dynamic phosphorylation-dephosphorylation of this residue. While phosphomimetic S380 drives neoplastic growth in prostate by promoting nuclear accumulation of β-catenin, nonphosphorylatable S380 is not tumorigenic. These data suggest that C-tail hyperphosphorylation creates oncogenic PTEN and is a potential target for anti-cancer therapy.

Transcription networks rewire gene repertoire to coordinate cellular reprograming in prostate cancer

Transcription factors (TFs) represent the most commonly deregulated DNA-binding class of proteins associated with multiple human cancers. They can act as transcriptional activators or repressors that rewire the cistrome, resulting in cellular reprogramming during cancer progression. Deregulation of TFs is associated with the onset and maintenance of various cancer types including prostate cancer. An emerging subset of TFs has been implicated in the regulation of multiple cancer hallmarks during tumorigenesis. Here, we discuss the role of key TFs which modulate transcriptional cicuitries involved in the development and progression of prostate cancer. We further highlight the role of TFs associated with key cancer hallmarks, including, chromatin remodeling, genome instability, DNA repair, invasion, and metastasis. We also discuss the pluripotent function of TFs in conferring lineage plasticity, that aids in disease progression to neuroendocrine prostate cancer. At the end, we summarize the current understanding and approaches employed for the therapeutic targeting of TFs and their cofactors in the clinical setups to prevent disease progression.

Advances in the Current Understanding of the Mechanisms Governing the Acquisition of Castration-Resistant Prostate Cancer

Despite aggressive treatment and androgen-deprivation therapy, most prostate cancer patients ultimately develop castration-resistant prostate cancer (CRPC), which is associated with high mortality rates. However, the mechanisms governing the development of CRPC are poorly understood, and androgen receptor (AR) signaling has been shown to be important in CRPC through AR gene mutations, gene overexpression, co-regulatory factors, AR shear variants, and androgen resynthesis. A growing number of non-AR pathways have also been shown to influence the CRPC progression, including the Wnt and Hh pathways. Moreover, non-coding RNAs have been identified as important regulators of the CRPC pathogenesis. The present review provides an overview of the relevant literature pertaining to the mechanisms governing the molecular acquisition of castration resistance in prostate cancer, providing a foundation for future, targeted therapeutic efforts.

Non-small molecule PROTACs (NSM-PROTACs): Protein degradation kaleidoscope

The proteolysis targeting chimeras (PROTACs) technology has been rapidly developed since its birth in 2001, attracting rapidly growing attention of scientific institutes and pharmaceutical companies. At present, a variety of small molecule PROTACs have entered the clinical trial. However, as small molecule PROTACs flourish, non-small molecule PROTACs (NSM-PROTACs) such as peptide PROTACs, nucleic acid PROTACs and antibody PROTACs have also advanced considerably over recent years, exhibiting the unique characters beyond the small molecule PROTACs. Here, we briefly introduce the types of NSM-PROTACs, describe the advantages of NSM-PROTACs, and summarize the development of NSM-PROTACs so far in detail. We hope this article could not only provide useful insights into NSM-PROTACs, but also expand the research interest of NSM-PROTACs.

The circRAB3IP Mediated by eIF4A3 and LEF1 Contributes to Enzalutamide Resistance in Prostate Cancer by Targeting miR-133a-3p/miR-133b/SGK1 Pathway

An increasing number of studies have shown that circRNAs are closely related to the carcinogenesis and development of prostate cancer (PCa). However, little is known about the effect of the biological functions of circRNAs on the enzalutamide resistance of PCa. Through bioinformatic analysis and experiments, we investigated the expression pattern of circRNAs in enzalutamide-resistant PCa cells. Quantitative real-time PCR was used to detect the expression of circRAB3IP, and plasmids that knock down or overexpress circRAB3IP were used to evaluate its effect on the enzalutamide sensitivity of PCa cells. Mechanistically, we explored the potential regulatory effects of eIF4A3 and LEF1 on the biogenesis of circRAB3IP. Our in vivo and in vitro data indicated that increased expression of circRAB3IP was found in enzalutamide-resistant PCa, and knockdown of circRAB3IP significantly enhanced enzalutamide sensitivity in PCa cells. However, upregulation of circRAB3IP resulted in the opposite effects. Further mechanistic research demonstrated that circRAB3IP could regulate the expression of serum and glucocorticoid-regulated kinase 1 (SGK1) by serving as a sponge that directly targets miR-133a-3p/miR-133b. Then, we showed that circRAB3IP partially exerted its biological functions via SGK1 signaling. Furthermore, we discovered that eIF4A3 and LEF1 might increase circRAB3IP expression in PCa.

Lef1 restricts ectopic crypt formation and tumor cell growth in intestinal adenomas

Somatic mutations in APC or CTNNB1 genes lead to aberrant Wnt signaling and colorectal cancer (CRC) initiation and progression via-catenin–T cell factor/lymphoid enhancer binding factor TCF/LEF transcription factors. We found that Lef1 was expressed exclusively in Apc-mutant, Wnt ligand–independent tumors, but not in ligand-dependent, serrated tumors. To analyze Lef1 function in tumor development, we conditionally deleted Lef1 in intestinal stem cells of Apcfl/fl mice or broadly from the entire intestinal epithelium of Apcfl/fl or ApcMin/+ mice. Loss of Lef1 markedly increased tumor initiation and tumor cell proliferation, reduced the expression of several Wnt antagonists, and increased Myc proto-oncogene expression and formation of ectopic crypts in Apc-mutant adenomas. Our results uncover a previously unknown negative feedback mechanism in CRC, in which ectopic Lef1 expression suppresses intestinal tumorigenesis by restricting adenoma cell dedifferentiation to a crypt-progenitor phenotype and by reducing the formation of cancer stem cell niches.

A Review of the Pathophysiological Mechanisms Underlying Castration-resistant Prostate Cancer

Androgen deprivation therapy or ADT is one of the cornerstones of management of locally advanced or metastatic prostate cancer, alongside radiation therapy. However, despite early response, most advanced prostate cancers progress into an androgen unresponsive or castrate resistant state, which hitherto remains an incurable entity and the second leading cause of cancer-related mortality in men in the US. Recent advances have uncovered multiple complex and intermingled mechanisms underlying this transformation. While most of these mechanisms revolve around androgen receptor (AR) signaling, novel pathways which act independently of the androgen axis are also being discovered. The aim of this article is to review the pathophysiological mechanisms that help bypass the apoptotic effects of ADT to create castrate resistance. The article discusses castrate resistance mechanisms under two categories: 1. Direct AR dependent pathways such as amplification or gain of function mutations in AR, development of functional splice variants, posttranslational regulation, and pro-oncogenic modulation in the expression of coactivators vs corepressors of AR. 2. Ancillary pathways involving RAS/MAP kinase, TGF-beta/SMAD pathway, FGF signaling, JAK/STAT pathway, Wnt-Beta catenin and hedgehog signaling as well as the role of cell adhesion molecules and G-protein coupled receptors. miRNAs are also briefly discussed. Understanding the mechanisms involved in the development and progression of castration-resistant prostate cancer is paramount to the development of targeted agents to overcome these mechanisms. A number of targeted agents are currently in development. As we strive for more personalized treatment across oncology care, treatment regimens will need to be tailored based on the type of CRPC and the underlying mechanism of castration resistance.

Cell Plasticity and Prostate Cancer: The Role of Epithelial-Mesenchymal Transition in Tumor Progression, Invasion, Metastasis and Cancer Therapy Resistance

Simple Summary

Although epithelial-to-mesenchymal transition (EMT) is a well-known cellular process involved during normal embryogenesis and wound healing, it also has a dark side; it is a complex process that provides tumor cells with a more aggressive phenotype, facilitating tumor metastasis and even resistance to therapy. This review focuses on the key pathways of EMT in the pathogenesis of prostate cancer and the development of metastases and evasion of currently available treatments.

Abstract

Prostate cancer, the second most common malignancy in men, is characterized by high heterogeneity that poses several therapeutic challenges. Epithelial–mesenchymal transition (EMT) is a dynamic, reversible cellular process which is essential in normal embryonic morphogenesis and wound healing. However, the cellular changes that are induced by EMT suggest that it may also play a central role in tumor progression, invasion, metastasis, and resistance to current therapeutic options. These changes include enhanced motility and loss of cell–cell adhesion that form a more aggressive cellular phenotype. Moreover, the reverse process (MET) is a necessary element of the metastatic tumor process. It is highly probable that this cell plasticity reflects a hybrid state between epithelial and mesenchymal status. In this review, we describe the underlying key mechanisms of the EMT-induced phenotype modulation that contribute to prostate tumor aggressiveness and cancer therapy resistance, in an effort to provide a framework of this complex cellular process.

High expression of LEF1 correlates with poor prognosis in solid tumors, but not blood tumors: a meta-analysis

BACKGROUND

Previously published studies have indicated that lymphoid enhancer-binding factor 1 (LEF1) expression could be recognized as a valuable biomarker to evaluate clinical outcome for various types of malignant cancer, but the results remained controversial. Therefore, we conducted this meta-analysis to pool the published estimates and discuss the relationship of LEF1 expression with cancer prognosis.

METHODS

Five electronic databases Pubmed, Web of Science, Embase, CNKI, and Wanfang were systematically searched for eligible literatures. Hazard ratios (HRs) and 95% confidence intervals (CIs) from the included studies were combined to estimate the effect of LEF1 expression on cancer patients' survival.

RESULTS

Eleven original studies met the criteria and were enrolled for analysis. The results indicated that compared with patients in low LEF1 expression group, patients in high LEF1 expression group tended to have shorter overall survival (HR = 1.74, 95% CI: 1.06-2.86, P=0.029), especially for patients with solid tumors (HR = 2.39, 95% CI: 1.86-3.08, P=0.000).

CONCLUSIONS

Individual evidence about the prognostic value of LEF1 expression in human cancers was limited. Our meta-analysis supported the suggestion that elevated LEF1 expression could function as a promising biomarker to predict the clinical outcomes for malignant cancers, especially solid tumors. More high-quality clinical studies are warranted to highlight the prognostic value of LEF1 expression in human cancers.

Targeting Oncogenic WNT Signalling with WNT Signalling-Derived Peptides

WNT signalling is known to be a crucial regulator of embryonic development and tissue homeostasis. Aberrant expression of WNT signalling elements or their mutations has been implicated in carcinogenesis and/or the progression of several different cancer types. Investigations of how WNT signalling affects carcinogenesis and cancer progression have revealed that it has essential roles in the regulation of proliferation, apoptosis, and cancer stemness and in angiogenesis and metastasis. Consequently, WNT-targeted therapy has gained much attention and has resulted in the development of several small molecules, the majority of which act as inhibitors of different WNT signalling events. However, although numerous inhibitory WNT signalling drug candidates have been included in clinical trials, no significant breakthroughs have been made. This could possibly be due to problems with inefficient binding to the target, compensatory signalling mechanisms and toxicity towards normal cells. Therapeutic peptides targeting WNT signalling in cancer cells have been developed as an alternative approach, with the hope that they might overcome the limitations reported for small WNT inhibitory molecules. In this chapter, we describe recent developments made in the design and characterization of WNT signalling-derived peptides aiming at their use as alternative cancer therapeutics and/or combined adjuvant therapy to conventional therapies.

MicroRNAs in treatment-induced neuroendocrine differentiation in prostate cancer

Prostate cancer is a condition commonly associated with men worldwide. Androgen deprivation therapy remains one of the targeted therapies. However, after some years, there is biochemical recurrence and metastatic progression into castration-resistant prostate cancer (CRPC). CRPC cases are treated with second-line androgen deprivation therapy, after which, these CRPCs transdifferentiate to form neuroendocrine prostate cancer (NEPC), a highly aggressive variant of CRPC. NEPC arises via a reversible transdifferentiation process, known as neuroendocrine differentiation (NED), which is associated with altered expression of lineage markers such as decreased expression of androgen receptor and increased expression of neuroendocrine lineage markers including enolase 2, chromogranin A and synaptophysin. The etiological factors and molecular basis for NED are poorly understood, contributing to a lack of adequate molecular biomarkers for its diagnosis and therapy. Therefore, there is a need to fully understand the underlying molecular basis for this cancer. Recent studies have shown that microRNAs (miRNAs) play a key epigenetic role in driving therapy-induced NED in prostate cancer. In this review, we briefly describe the role of miRNAs in prostate cancer and CRPCs, discuss some key players in NEPCs and elaborate on miRNA dysregulation as a key epigenetic process that accompanies therapy-induced NED in metastatic CRPC. This understanding will contribute to better clinical management of the disease.

Pluripotent stem cell differentiation as an emerging model to study human prostate development

Prostate development is a complex process, and knowledge about this process is increasingly required for both basic developmental biology studies and clinical prostate cancer research, as prostate tumorigenesis can be regarded as the restoration of development in the adult prostate. Using rodent animal models, scientists have revealed that the development of the prostate is mainly mediated by androgen receptor (AR) signaling and that some other signaling pathways also play indispensable roles. However, there are still many unknowns in human prostate biology, mainly due to the limited availability of proper fetal materials. Here, we first briefly review prostate development with a focus on the AR, WNT, and BMP signaling pathways is necessary for prostate budding/BMP signaling pathways. Based on the current progress in in vitro prostatic differentiation and organoid techniques, we propose human pluripotent stem cells as an emerging model to study human prostate development.

LEF1/Id3/HRAS axis promotes the tumorigenesis and progression of esophageal squamous cell carcinoma

Our previous study demonstrated that lymphoid enhancer-binding factor 1 (LEF1) could promote the progression of esophageal squamous cell carcinoma (ESCC). However, the regulatory mechanism of LEF1 was not clear thoroughly. Herein, we continued to explore the downstream mechanism of LEF1 in ESCC. In this study, we applied western blotting, quantitative real-time polymerase chain reaction (qRT-PCR), immunohistochemistry, RNA-Seq analysis, a luciferase reporter assay, chromatin immunoprecipitation (ChIP), bioinformatics analysis, and a series of functional assays in vitro and in vivo. The results demonstrated that LEF1 regulated directly the expression of Id3. Id3 was highly expressed in ESCC tissues and correlated with histologic differentiation (p=0.011), pT stage (p<0.01) and AJCC stage (p<0.01) in ESCC patients. Moreover, Id3 could serve as a prognostic factor of ESCC. By various functional experiments, overexpression of Id3 promoted the proliferation, migration, invasion, EMT, and tumorgenicity. Mechanistically, Id3 could regulate ERK/MAPK signaling pathway via activating HRAS to perform its biological function. Furthermore, activating ERK/MAPK signaling pathway promoted the expression of Id3 gene in turn, indicating that a positive regulatory loop between Id3 and ERK/MAPK pathway may exist in ESCC. In summary, LEF1/Id3/HRAS axis could promote the tumorigenesis and progression of ESCC via activating ERK/MAPK signaling pathway. Targeting this cascade may provide a valid antitumor strategy to delay ESCC progress.

Quercetin Inhibits Lef1 and Resensitizes Docetaxel-Resistant Breast Cancer Cells

Drug resistance is a major problem for breast cancer patients. Docetaxel is an anti-mitotic agent that serves as first line of treatment in metastatic breast cancer, however it is susceptible to cellular drug resistance. Drug-resistant cells are able to spread during treatment, leading to treatment failure and eventually metastasis, which remains the main cause for cancer-associated death. In previous studies, we used single-cell technologies and identified a set of genes that exhibit increased expression in drug-resistant cells, and they are mainly regulated by Lef1. Furthermore, upregulating Lef1 in parental cells caused them to become drug resistant. Therefore, we hypothesized that inhibiting Lef1 could resensitize cells to docetaxel. Here, we confirmed that Lef1 inhibition, especially on treatment with the small molecule quercetin, decreased the expression of Lef1 and resensitized cells to docetaxel. Our results demonstrate that Lef1 inhibition also downregulated ABCG2, Vim, and Cav1 expression and equally decreased Smad-dependent TGF-β signaling pathway activation. Likewise, these two molecules worked in a synergetic manner, greatly reducing the viability of drug-resistant cells. Prior studies in phase I clinical trials have already shown that quercetin can be safely administered to patients. Therefore, the use of quercetin as an adjuvant treatment in addition to docetaxel for the treatment of breast cancer may be a promising therapeutic approach.

MiR-34a-5p Inhibits Proliferation, Migration, Invasion and Epithelial-mesenchymal Transition in Esophageal Squamous Cell Carcinoma by Targeting LEF1 and Inactivation of the Hippo-YAP1/TAZ Signaling Pathway

Background: Our previous studies reported that lymphoid enhancer-binding factor 1 (LEF1) was upregulated in esophageal squamous cell carcinoma (ESCC) and the positive expression of LEF1 was correlated with aberrant clinicopathological characteristics in ESCC patients. However, the upstream mechanism of regulating LEF1 is not clear fully. In this study, we explored the role of miR-34a-5p in ESCC and the possible regulatory mechanism. Methods: In this study, we applied western blotting, quantitative real-time polymerase chain reaction (qRT-PCR), bioinformatics analysis, a luciferase reporter assay, and a series of functional assays to show the potential role of miR-34a-5p in regulating LEF1 in ESCC. Results: By various functional assays, we demonstrated that LEF1 promoted proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) in ESCC cells. By bioinformatics analysis and luciferase reporter assay, miR-34a-5p was identified for directly targeting LEF1. Then we investigated the expression of miR-34a-5p and LEF1 in ESCC. As a result, miR-34a-5p was downregulated while LEF1 was upregulated in ESCC tissue and cell lines. Overexpression of miR-34a-5p could inhibit proliferation, migration, invasion and EMT of ESCC cells. The rescue experiment showed that re-expression of LEF1 reversed the suppressive effect caused by miR-34a-5p. At last, we found that miR-34a-5p could suppress Hippo-YAP1/TAZ signaling pathway in ESCC. Conclusion: Our results indicate miR-34a-5p inhibits proliferation, migration, invasion and EMT in ESCC by targeting LEF1 and suppressing the Hippo-YAP1/TAZ signaling pathway, which may provide a new antitumor strategy to delay ESCC progress.

Wntless promotes cellular viability and resistance to enzalutamide in castration-resistant prostate cancer cells

BACKGROUND

De-regulation of Wnt signaling pathways has been shown to be associated with progression of castration-resistant prostate cancer and more recently, studies indicate that both canonical and non-canonical Wnt pathways may mediate resistance to anti-androgen therapies such as enzalutamide. However, the mechanisms by which Wnt signaling is altered in prostate cancer remain poorly understood. Wnt pathway function begins with Wnt biogenesis and secretion from Wnt signal sending cells. While previous studies have investigated downstream mechanisms of Wnt pathway alterations in prostate cancer, little is known on the role of Wnt secretion mediating proteins. Wntless (WLS) is thought to be essential for the secretion of all Wnts. In this study, we sought to understand the role of WLS in prostate cancer.

METHODS

RNA-seq and gene set enrichment analysis were used to understand expression profile changes in enzalutamide-resistant C4-2B-MDVR (MDVR) cells versus parental C4-2B cells. Quantitative-PCR and western blot were used to confirm RNA-seq data and to assess expression changes of gene targets of interest. Rv1 cells were used as a separate model of enzalutamide-resistant prostate cancer. RNAi was used to inhibit WLS expression. Cell viability, colony formation, and PSA ELISA assays were used to assess cell growth and survival.

RESULTS

Transcriptomic profiling revealed enriched Wnt pathway signatures in MDVR versus parental C4-2B cells. We further show that MDVR cells upregulate Wnt signaling and overexpress WLS. Inhibition of WLS decreases Wnt signaling, markedly attenuates prostate cancer cell viability, induces apoptosis, and re-sensitizes enzalutamide-resistant cells to enzalutamide treatment. Lastly, we show that inhibition of WLS reduces AR and AR-variants expression and downstream signaling.

CONCLUSIONS

Our findings support a role for WLS in the progression of prostate cancer to a treatment-resistant state. Further efforts to understand Wnt signaling pathway alterations in this disease may lead to the development of novel treatments.

Single-Cell Analysis Reveals a Preexisting Drug-Resistant Subpopulation in the Luminal Breast Cancer Subtype

Drug resistance is a major obstacle in the treatment of breast cancer. Surviving cells lead to tumor recurrence and metastasis, which remains the main cause of cancer-related mortality. Breast cancer is also highly heterogeneous, which hinders the identification of individual cells with the capacity to survive anticancer treatment. To address this, we performed extensive single-cell gene-expression profiling of the luminal-type breast cancer cell line MCF7 and its derivatives, including docetaxel-resistant cells. Upregulation of epithelial-to-mesenchymal transition and stemness-related genes and downregulation of cell-cycle-related genes, which were mainly regulated by LEF1, were observed in the drug-resistant cells. Interestingly, a small number of cells in the parental population exhibited a gene-expression profile similar to that of the drug-resistant cells, indicating that the untreated parental cells already contained a rare subpopulation of stem-like cells with an inherent predisposition toward docetaxel resistance. Our data suggest that during chemotherapy, this population may be positively selected, leading to treatment failure. SIGNIFICANCE: This study highlights the role of breast cancer intratumor heterogeneity in drug resistance at a single-cell level.

DNA-Dependent Protein Kinase Drives Prostate Cancer Progression through Transcriptional Regulation of the Wnt Signaling Pathway

PURPOSE

Protein kinases are known to play a prominent role in oncogenic progression across multiple cancer subtypes, yet their role in prostate cancer progression remains underexplored. The purpose of this study was to identify kinases that drive prostate cancer progression.Experimental Design: To discover kinases that drive prostate cancer progression, we investigated the association between gene expression of all known kinases and long-term clinical outcomes in tumor samples from 545 patients with high-risk disease. We evaluated the impact of genetic and pharmacologic inhibition of the most significant kinase associated with metastatic progression in vitro and in vivo.

RESULTS

DNA-dependent protein kinase (DNAPK) was identified as the most significant kinase associated with metastatic progression in high-risk prostate cancer. Inhibition of DNAPK suppressed the growth of both AR-dependent and AR-independent prostate cancer cells. Gene set enrichment analysis nominated Wnt as the top pathway associated with DNAPK. We found that DNAPK interacts with the Wnt transcription factor LEF1 and is critical for LEF1-mediated transcription.

CONCLUSIONS

Our data show that DNAPK drives prostate cancer progression through transcriptional regulation of Wnt signaling and is an attractive therapeutic target in aggressive prostate cancer.

Wnt/Beta-Catenin Signaling and Prostate Cancer Therapy Resistance

Metastatic or locally advanced prostate cancer (PCa) is typically treated with androgen deprivation therapy (ADT). Initially, PCa responds to the treatment and regresses. However, PCa almost always develops resistance to androgen deprivation and progresses to castrate-resistant prostate cancer (CRPCa), a currently incurable form of PCa. Wnt/β-Catenin signaling is frequently activated in late stage PCa and contributes to the development of therapy resistance. Although activating mutations in the Wnt/β-Catenin pathway are not common in primary PCa, this signaling cascade can be activated through other mechanisms in late stage PCa, including cross talk with other signaling pathways, growth factors and cytokines produced by the damaged tumor microenvironment, release of the co-activator β-Catenin from sequestration after inhibition of androgen receptor (AR) signaling, altered expression of Wnt ligands and factors that modulate the Wnt signaling, and therapy-induced cellular senescence. Research from genetically engineered mouse models indicates that activation of Wnt/β-Catenin signaling in the prostate is oncogenic, enables castrate-resistant PCa growth, induces an epithelial-to-mesenchymal transition (EMT), promotes neuroendocrine (NE) differentiation, and confers stem cell-like features to PCa cells. These important roles of Wnt/β-Catenin signaling in PCa progression underscore the need for the development of drugs targeting this pathway to treat therapy-resistant PCa.

Design of Peptoid-peptide Macrocycles to Inhibit the β-catenin TCF Interaction in Prostate Cancer

New chemical inhibitors of protein-protein interactions are needed to propel advances in molecular pharmacology. Peptoids are peptidomimetic oligomers with the capability to inhibit protein-protein interactions by mimicking protein secondary structure motifs. Here we report the in silico design of a macrocycle primarily composed of peptoid subunits that targets the β-catenin:TCF interaction. The β-catenin:TCF interaction plays a critical role in the Wnt signaling pathway which is over-activated in multiple cancers, including prostate cancer. Using the Rosetta suite of protein design algorithms, we evaluate how different macrocycle structures can bind a pocket on β-catenin that associates with TCF. The in silico designed macrocycles are screened in vitro using luciferase reporters to identify promising compounds. The most active macrocycle inhibits both Wnt and AR-signaling in prostate cancer cell lines, and markedly diminishes their proliferation. In vivo potential is demonstrated through a zebrafish model, in which Wnt signaling is potently inhibited.

The VTI1A-TCF4 colon cancer fusion protein is a dominant negative regulator of Wnt signaling and is transcriptionally regulated by intestinal homeodomain factor CDX2

Sequencing of primary colorectal tumors has identified a gene fusion in approximately 3% of colorectal cancer patients of the VTI1A and TCF7L2 genes, encoding a VTI1A-TCF4 fusion protein containing a truncated TCF4. As dysregulation of the Wnt signaling pathway is associated with colorectal cancer development and progression, the functional properties and transcriptional regulation of the VTI1A-TCF4 fusion protein may also play a role in these processes. Functional characteristics of the VTI1A-TCF4 fusion protein in Wnt signaling were analyzed in NCI-H508 and LS174T colon cancer cell lines. The NCI-H508 cell line, containing the VTI1A-TCF7L2 fusion gene, showed no active Wnt signaling, and overexpression of the VTI1A-TCF4 fusion protein in LS174T cells along with a Wnt signaling luciferase reporter plasmid showed inhibition of activity. The transcriptional regulation of the VTI1A-TCF4 fusion gene was investigated in LS174T cells where the activity of the VTI1A promoter was compared to that of the TCF7L2 promoter, and the transcription factor CDX2 was analyzed for gene regulatory activity of the VTI1A promoter through luciferase reporter gene assay using colon cancer cell lines as a model. Transfection of LS174T cells showed that the VTI1A promoter is highly active compared to the TCF7L2 promoter, and that CDX2 activates transcription of VTI1A. These results suggest that the VTI1A-TCF4 fusion protein is a dominant negative regulator of the Wnt signaling pathway, and that transcription of VTI1A is activated by CDX2.

Revisiting the role of Wnt/β-catenin signaling in prostate cancer

The androgen receptor (AR) is a widely accepted therapeutic target in prostate cancer and multiple studies indicate that the AR and Wnt/β-catenin pathways intersect. Recent genome-wide analysis of prostate cancer metastases illustrate the importance of the Wnt/β-catenin pathway in prostate cancer and compel us to reexamine the interaction of the AR and Wnt/β-catenin signaling pathways. This review includes newer areas of interest such as non-canonical Wnt signaling and the role of Wnts in prostate cancer stem cells. The effort to develop Wnt modulating therapeutics, both biologics and small molecules, is also discussed.

HIPK2 polymorphisms rs2058265, rs6464214, and rs7456421 were associated with kidney stone disease in Chinese males not females

BACKGROUND AND AIM

Recent studies have shown that genetic factors are involved in the development of kidney stone disease (KSD). A case-control association analysis was performed to investigate the association between homeodomain-interacting protein kinase 2 (HIPK2; OMIM *606868) polymorphisms and KSD.

METHODS

A total of 890 KSD patients and 920 healthy subjects were analyzed. Polymorphisms were genotyped using SNPscanTM high-throughput SNP classification technology. The genotypic and allelic frequencies in KSD patients and healthy individuals were analyzed using a Chi-square test.

RESULTS

The genotype and allele distributions of the three polymorphisms (rs2058265, rs6464214, and rs7456421 in HIPK2) displayed strong associations with KSD in males (rs2058265: odds ratio [OR] 2.480,95%confidence interval [CI] 1.205-5.106, p = 0.014; rs6464214: OR 2.466, 95%CI 1.198-5.078, p = 0.014; rs7456421: OR 2.846, 95%CI 1.362-5.947, p = 0.005; perallele: r2058265T, OR 1.357, 95%CI 1.073-1.715, p = 0.011; rs6464214G, OR 1.340, 95%CI 1.060-1.693, p = 0.014; rs7456421C, OR 1.356, 95%CI 1.073-1.713, p = 0.011). Patients carrying the T allele of rs2058265, the G allele of rs6464214, or the C allele of rs7456421 showed higher systolic blood pressure, creatinine, and uric acid levels compared with wild-genotype individuals after adjusting for age, gender, and body mass index (p < 0.005).

CONCLUSION

The association of HIPK2 gene polymorphisms with KSD was only observed in males but not in females. HIPK2 gene polymorphisms were also involved in the changes of KSD-related metabolic traits.

Cytoplasmic, full length and novel cleaved variant, TBLR1 reduces apoptosis in prostate cancer under androgen deprivation

TBLR1/TBL1XR1, a core component of the nuclear receptor corepressor (NCoR) complex critical for the regulation of multiple nuclear receptors, is a transcriptional coactivator of androgen receptor (AR) and functions as a tumor suppressor when expressed in the nucleus in prostate. Subcellular localization of a protein is critical for its function, and although TBLR1, as a transcriptional cofactor, has been primarily viewed as a nuclear protein, many cells also express variable levels of cytoplasmic TBLR1 and its cytoplasmic specific functions have not been studied. Prostate cancer (PCa) cells express moderately higher level of cytoplasmic TBLR1 compared to benign prostate cells. When comparing androgen-dependent (AD) to androgen-independent (AI) PCa, AI cells contain very high levels of TBLR1 cytoplasmic expression and low levels of nuclear expression. Overexpression of cytoplasmic TBLR1 in AD cells inhibits apoptosis induced by androgen deprivation therapy, either in an androgen free condition or in the presence of bicalutamide. Additionally, we identified a cytoplasmic specific isoform of TBLR1 (cvTBLR1) approximately 5 kDa lower in molecular weight, that is expressed at higher levels in AI PCa cells. By immunoprecipitation, we purified cvTBLR1 and using mass spectrometry analysis combined with N-terminal TMPP labeling and Edman degradation, we identified the cleavage site of cvTBLR1 at amino acid 89, truncating the first 88 amino acids of the N-terminus of the full length protein. Functionally, cvTBLR1 expressed in the cytoplasm reduced apoptosis in PCa cells and promoted growth, migration, and invasion. Finally, we identified a nuclear export signal sequence for TBLR1 cellular localization by deletion and site-directed mutagenesis. The roles of TBLR1 and cvTBLR1 provide novel insights into the mechanism of castration resistance and new strategies for PCa therapy.

Epstein-Barr virus stably confers an invasive phenotype to epithelial cells through reprogramming of the WNT pathway

Epstein-Barr virus (EBV)-associated carcinomas, such as nasopharyngeal carcinoma (NPC), exhibit an undifferentiated and metastatic phenotype. To determine viral contributions involved in the invasive phenotype of EBV-associated carcinomas, EBV-infected human telomerase-immortalized normal oral keratinocytes (NOK) were investigated. EBV-infected NOK were previously shown to undergo epigenetic reprogramming involving CpG island hypermethylation and delayed responsiveness to differentiation. Here, we show that EBV-infected NOK acquired an invasive phenotype that was epigenetically retained after viral loss. The transcription factor lymphoid enhancer factor 1 (LEF1) and the secreted ligand WNT5A, expressed in NPC, were increased in EBV-infected NOK with sustained expression for more than 20 passages after viral loss. Increased LEF1 levels involved four LEF1 variants, and EBV-infected NOK showed a lack of responsiveness to β-catenin activation. Although forced expression of WNT5A and LEF1 enhanced the invasiveness of parental NOK, LEF1 knockdown reversed the invasive phenotype of EBV-infected NOK in the presence of WNT5A. Viral reprogramming of LEF1 and WNT5A was observed several passages after EBV infection, suggesting that LEF1 and WNT5A may provide a selective advantage to virally-infected cells. Our findings suggest that EBV epigenetically reprogrammed epithelial cells with features of basal, wound healing keratinocytes, with LEF1 contributing to the metastatic phenotype of EBV-associated carcinomas.

AP4 modulated by the PI3K/AKT pathway promotes prostate cancer proliferation and metastasis of prostate cancer via upregulating L-plastin

The transition from androgen-dependent to metastatic castration-resistant prostate cancer (PCa) is a lethal event of uncertain molecular aetiology. Our previous studies demonstrated that L-plastin is involved in PCa invasion and metastasis and is upregulated by androgen and oestrogen in the hormone-dependent PCa cell line LNCaP. We recently found that L-plastin expression is consistently activated even after androgen deprivation, suggesting that androgen-independent transcription factors may regulate its expression. Herein, we performed sequential deletion and luciferase analysis of the L-plastin promoter and found that an androgen-independent regulatory factor prominently located in the region close to the transcription initiation site (−216 to +118) may facilitate L-plastin upregulation. AP4 was then identified as the relevant transcription activator that directly binds to the L-plastin promoter, as confirmed by EMSAs, supershift assays and CHIP-qPCR experiments. Moreover, we determined that the AP4/L-plastin axis is regulated by the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, contributing to PCa metastasis and castration resistance. Furthermore, we found that AP4 promotes PCa metastasis by upregulating L-plastin expression in vitro and in vivo. We collected a total of 136 PCa tissues and corresponding adjacent normal tissues from patients who underwent prostatectomy at Sun Yat-Sen Memorial Hospital from 2005 to 2015 and measured AP4 and L-plastin protein levels by immunohistochemistry. The results showed that AP4 levels strongly correlated with those of its downstream target gene L-plastin, were significantly upregulated in PCa tissues, were positively correlated with lymph node metastasis and Gleason scores over 7, and were an independent prognostic factor for patient survival. In summary, these findings support a plausible mechanism by which the AP4/L-plastin axis is regulated by the PI3K/AKT pathway in human PCa and may represent a novel therapeutic target in PCa treatment.

Wnt signaling pathway protein LEF1 in cancer, as a biomarker for prognosis and a target for treatment

Transcription factors are regulatory proteins that either activate or repress the transcription of genes via binding to DNA regulatory sequences and regulating recruitment of transcriptional complexes. Lymphoid enhancer-binding factor 1 (LEF1), a member of the T-cell Factor (TCF)/LEF1 family of high-mobility group transcription factors, is a downstream mediator of the Wnt/β-catenin signaling pathway, but can also modulate gene transcription independently. LEF1 is essential in stem cell maintenance and organ development, especially in its role in epithelial-mesenchymal transition (EMT) by activating the transcription of hallmark EMT effectors including N-Cadherin, Vimentin, and Snail. Aberrant expression of LEF1 is implicated in tumorigenesis and cancer cell proliferation, migration, and invasion. LEF1's activity in particular cancer cell types, such as chronic lymphocytic leukemia (CLL), Burkitt lymphoma (BL), acute lymphoblastic leukemia (ALL), oral squamous cell carcinoma (OSCC), and colorectal cancer (CRC), makes it a valuable biomarker in predicting patient prognosis. Additionally, due to aberrant LEF1 activity resulting in cancer progression, knockdown and inhibition treatments designed to target LEF1 have proven effective in alleviating cancer growth, migration, and invasion in CLL, CRC, glioblastoma multiforme (GBM), and renal cell carcinoma (RCC). In prostate cancer cells, LEF1 promotes androgen receptor expression and activity in an androgen-independent manner, ultimately increasing prostate cancer growth regardless of androgen ablation therapy. In this review, we review LEF1 regulation, its role in tumorigenesis in several cancer types, and its clinical value as a biomarker for predicting prognoses and as a target for treatment.

A Tale of Two Signals: AR and WNT in Development and Tumorigenesis of Prostate and Mammary Gland

Prostate cancer (PCa) is one of the most common cancers and among the leading causes of cancer deaths for men in industrialized countries. It has long been recognized that the prostate is an androgen-dependent organ and PCa is an androgen-dependent disease. Androgen action is mediated by the androgen receptor (AR). Androgen deprivation therapy (ADT) is the standard treatment for metastatic PCa. However, almost all advanced PCa cases progress to castration-resistant prostate cancer (CRPC) after a period of ADT. A variety of mechanisms of progression from androgen-dependent PCa to CRPC under ADT have been postulated, but it remains largely unclear as to when and how castration resistance arises within prostate tumors. In addition, AR signaling may be modulated by extracellular factors among which are the cysteine-rich glycoproteins WNTs. The WNTs are capable of signaling through several pathways, the best-characterized being the canonical WNT/β-catenin/TCF-mediated canonical pathway. Recent studies from sequencing PCa genomes revealed that CRPC cells frequently harbor mutations in major components of the WNT/β-catenin pathway. Moreover, the finding of an interaction between β-catenin and AR suggests a possible mechanism of cross talk between WNT and androgen/AR signaling pathways. In this review, we discuss the current knowledge of both AR and WNT pathways in prostate development and tumorigenesis, and their interaction during development of CRPC. We also review the possible therapeutic application of drugs that target both AR and WNT/β-catenin pathways. Finally, we extend our review of AR and WNT signaling to the mammary gland system and breast cancer. We highlight that the role of AR signaling and its interaction with WNT signaling in these two hormone-related cancer types are highly context-dependent.

Nuclear TBLR1 as an ER corepressor promotes cell proliferation, migration and invasion in breast and ovarian cancer

Estrogen receptors (ER) play important roles in the development and progression of breast and ovarian cancers. ERs mediate transcriptional regulation through interaction with cofactors and binding to response elements within the regulatory elements of target genes. Here, we examined the expression and function of TBLR1/TBL1XR1, a core component of NCoR (nuclear receptor corepressor) and SMRT (silencing mediator of retinoic acid and thyroid receptor) corepressor complexes, in breast and ovarian cancers. We found that although TBLR1 is present in both the nucleus and cytoplasm of normal and neoplastic breast and ovarian cells, it is expressed at significantly higher levels in the nucleus of malignant breast and ovarian cells compared to benign cells. TBLR1 functions as an ER corepressor to inhibit ER-mediated transcriptional activation in both breast and ovarian cell lines, but it has no effect on androgen receptor (AR) mediated transcriptional activation in these cells. Furthermore, ectopic expression of nuclear TBLR1 in breast and ovarian cancer cells stimulates cell proliferation. The increased cell proliferation by nuclear TBLR1 is through both ER-independent and ER-dependent mechanisms as evidenced by increased growth in hormone-free medium and estrogen medium, as well as reduced growth with ER knockdown by siRNA. Nuclear TBLR1 overexpression also increased migration and invasion in both breast and ovarian cancer cells. Determining the functional relationship between TBLR1 and ER may provide insights to develop novel treatment strategies and improve response to hormonal therapy in breast and ovarian cancers.

Genetic variants of the Wnt signaling pathway as predictors of aggressive disease and reclassification in men with early stage prostate cancer on active surveillance

Little is known about the genetic predictors of prostate cancer aggressiveness and reclassification in men with localized prostate cancer undergoing active surveillance. The Wnt signaling pathway is important for prostate cancer development and progression. Identifying genetic variants associated with prostate cancer aggressiveness and reclassification may have a potential role in the management of localized patients. In this study, we used a three-phase design. In phases I and II prostate cancer patient cohort, 578 single nucleotide polymorphisms (SNPs) from 45 genes of the Wnt signaling pathway were analyzed in 1762 localized prostate cancer patients. Twelve SNPs from four regions were significantly associated with aggressive disease, among which, three linked SNPs in CSNK1A1 at 5q32 (represented by rs752822) may differentiate GS 4+3 from GS 3+4 patients (OR = 1.44, 95% CI = 1.12-1.87, P = 4.76×10(-3)). In phase III active surveillance (AS) cohort, genotyping of rs752822 (candidate from phases I and II) and previously identified rs2735839 were determined in 494 GS ≤7 patients. We found a significant association between rs2735839 and prostate cancer reclassification in the AS cohort (AG + AA versus GG, HR = 1.59, 95% CI = 1.11-2.28, P = 0.012) and a suggestive association of rs752822. Jointly, rs752822 and rs2735839 showed good potentials in risk-stratifying GS 7 patients and predicting disease reclassification (OR = 2.71, 95% CI = 1.62-4.51, P = 1×10(-4) in phase II; HR = 1.89, 95% CI = 1.13-3.18, P = 0.016 in phase III). In summary, rs752822 and rs2735839 may assist in risk-stratifying GS 7 patients and predict prostate cancer reclassification. The significant associations were independent from GS, T stage and PSA levels at baseline.

Progress in the mechanism and drug development of castration-resistant prostate cancer

Although prostate cancer can initially respond to androgen deprivation therapy, it will inevitably relapse and switch to a castration-resistant state. The progress in understanding the mechanism of castration-resistant prostate cancer (CRPC) has led to the evolution of novel agents, including sipuleucel-T as an immunomodulant agent, enzalutamide as an androgen receptor antagonist, docetaxel as a chemotherapeutic agent and radium-223 as a radiopharmaceutical agent. In this review, we discuss the main mechanisms of CRPC and the development of promising agents along with the novel therapies in the clinic. New therapeutic challenges remain, such as the identification of predictive biomarkers and the optimal combinations of agents. Future investigation is still needed for a better understanding of CRPC.

ROR-γ drives androgen receptor expression and represents a therapeutic target in castration-resistant prostate cancer

The androgen receptor (AR) is overexpressed and hyperactivated in human castration-resistant prostate cancer (CRPC). However, the determinants of AR overexpression in CRPC are poorly defined. Here we show that retinoic acid receptor-related orphan receptor γ (ROR-γ) is overexpressed and amplified in metastatic CRPC tumors, and that ROR-γ drives AR expression in the tumors. ROR-γ recruits nuclear receptor coactivator 1 and 3 (NCOA1 and NCOA3, also known as SRC-1 and SRC-3) to an AR-ROR response element (RORE) to stimulate AR gene transcription. ROR-γ antagonists suppress the expression of both AR and its variant AR-V7 in prostate cancer (PCa) cell lines and tumors. ROR-γ antagonists also markedly diminish genome-wide AR binding, H3K27ac abundance and expression of the AR target gene network. Finally, ROR-γ antagonists suppressed tumor growth in multiple AR-expressing, but not AR-negative, xenograft PCa models, and they effectively sensitized CRPC tumors to enzalutamide, without overt toxicity, in mice. Taken together, these results establish ROR-γ as a key player in CRPC by acting upstream of AR and as a potential therapeutic target for advanced PCa.

microRNA-449a functions as a tumor suppressor in neuroblastoma through inducing cell differentiation and cell cycle arrest

microRNA-449a (miR-449a) has been identified to function as a tumor suppressor in several types of cancers. However, the role of miR-449a in neuroblastoma has not been intensively investigated. We recently found that the overexpression of miR-449a significantly induces neuroblastoma cell differentiation, suggesting its potential tumor suppressor function in neuroblastoma. In this study, we further investigated the mechanisms underlying the tumor suppressive function of miR-449a in neuroblastoma. We observed that miR-449a inhibits neuroblastoma cell survival and growth through 2 mechanisms--inducing cell differentiation and cell cycle arrest. Our comprehensive investigations on the dissection of the target genes of miR-449a revealed that 3 novel targets- MFAP4, PKP4 and TSEN15 -play important roles in mediating its differentiation-inducing function. In addition, we further found that its function in inducing cell cycle arrest involves down-regulating its direct targets CDK6 and LEF1. To determine the clinical significance of the miR-449a-mediated tumor suppressive mechanism, we examined the correlation between the expression of these 5 target genes in neuroblastoma tumor specimens and the survival of neuroblastoma patients. Remarkably, we noted that high tumor expression levels of all the 3 miR-449a target genes involved in regulating cell differentiation, but not the target genes involved in regulating cell cycle, are significantly correlated with poor survival of neuroblastoma patients. These results suggest the critical role of the differentiation-inducing function of miR-449a in determining neuroblastoma progression. Overall, our study provides the first comprehensive characterization of the tumor-suppressive function of miR-449a in neuroblastoma, and reveals the potential clinical significance of the miR-449a-mediated tumor suppressive pathway in neuroblastoma prognosis.

Integrated network model provides new insights into castration-resistant prostate cancer

Castration-resistant prostate cancer (CRPC) is the main challenge for prostate cancer treatment. Recent studies have indicated that extending the treatments to simultaneously targeting different pathways could provide better approaches. To better understand the regulatory functions of different pathways, a system-wide study of CRPC regulation is necessary. For this purpose, we constructed a comprehensive CRPC regulatory network by integrating multiple pathways such as the MEK/ERK and the PI3K/AKT pathways. We studied the feedback loops of this network and found that AKT was involved in all detected negative feedback loops. We translated the network into a predictive Boolean model and analyzed the stable states and the control effects of genes using novel methods. We found that the stable states naturally divide into two obvious groups characterizing PC3 and DU145 cells respectively. Stable state analysis further revealed that several critical genes, such as PTEN, AKT, RAF, and CDKN2A, had distinct expression behaviors in different clusters. Our model predicted the control effects of many genes. We used several public datasets as well as FHL2 overexpression to verify our finding. The results of this study can help in identifying potential therapeutic targets, especially simultaneous targets of multiple pathways, for CRPC.

Prognostic significance of lymphoid enhancer-binding factor-1 expression in egyptian adult B-acute lymphocytic leukemia patients

Objective:

Lymphoid enhancer-binding factor-1 (LEF-1) is a key transcription factor of wingless-type (Wnt) signaling in various tumors and it is associated with a number of malignant diseases such as leukemia. We explored the expression profile of LEF-1 in acute lymphoblastic leukemia (ALL) and determined its specific prognostic significance in this disease.

Materials and Methods:

We studied LEF-1 expression in 56 newly diagnosed B-acute ALL adult patients using real-time quantitative polymerase chain reaction to investigate whether LEF-1 expression was associated with clinical patient characteristics and treatment outcomes.

Results:

High LEF-1 expression was associated with significantly poorer disease-free survival (p=0.03) and overall survival (p=0.005). Patients with high LEF-1 expression had a significantly higher relapse rate compared with low LEF-1 expression (p=0.01).

Conclusion:

We provide evidence that high LEF-1 expression is a prognostic marker in adult B-acute ALL patients.

EphB4 localises to the nucleus of prostate cancer cells

The EphB4 receptor tyrosine kinase is over-expressed in a variety of different epithelial cancers including prostate where it has been shown to be involved in survival, migration and angiogenesis. We report here that EphB4 also resides in the nucleus of prostate cancer cell lines. We used in silico methods to identify a bipartite nuclear localisation signal (NLS) in the extracellular domain and a monopartite NLS sequence in the intracellular kinase domain of EphB4. To determine whether both putative NLS sequences were functional, fragments of the EphB4 sequence containing each NLS were cloned to create EphB4NLS-GFP fusion proteins. Localisation of both NLS-GFP proteins to the nuclei of transfected cells was observed, demonstrating that EphB4 contains two functional NLS sequences. Mutation of the key amino residues in both NLS sequences resulted in diminished nuclear accumulation. As nuclear translocation is often dependent on importins we confirmed that EphB4 and importin-α can interact. To assess if nuclear EphB4 could be implicated in gene regulatory functions potential EphB4-binding genomic loci were identified using chromatin immunoprecipitation and Lef1 was confirmed as a potential target of EphB4-mediated gene regulation. These novel findings add further complexity to the biology of this important cancer-associated receptor.

LEF1 targeting EMT in prostate cancer invasion is mediated by miR-181a

Lymphoid enhancer-binding factor-1 (LEF1) is a key transcription factor mediating Wnt signaling pathway. Our previous studies indicate that LEF1 is highly expressed in androgen-independent prostate cancer (PCa) and enhances invasion ability in androgen-independent PCa cells. However, the molecular mechanism of LEF1 effect on invasion remains largely unknown. Using microRNA profiling analysis comparing androgen-independent LNCaP-AI PCa cells with high levels of endogenous LEF1 to LNCaP-AI cells with LEF1 knockdown by LEF1shRNA, we found miR-181a to be increased 12.3-fold in LNCaP-AI cells. We confirmed a positive correlation between LEF1 and miR-181a expression across multiple PCa cell lines. Additionally, we showed that in PCa cells, overexpression of LEF1 increased miR-181a expression and subsequently induced EMT associated migration and invasion, whereas LEF1 knockdown decreased miR-181a expression and subsequently resulted in inhibition of EMT, migration and invasion. Mechanistically, we demonstrated by chromatin immunoprecipitation assays that LEF1 could enhance miR-181a expression via its binding to the promoter regions of hsa-miR-181a. Overall, this study identified a novel LEF1-miR-181a-EMT axis in regulation of PCa migration and invasion.

LEF1 Targeting EMT in Prostate Cancer Invasion Is Regulated by miR-34a

The microRNA-34a (miR-34a), a tumor-suppressive microRNA (miRNA), is implicated in epithelial-mesenchymal transition (EMT) and cancer stem cells. Lymphoid enhancer-binding factor-1 (LEF1) is a key transcription factor in the Wnt signaling pathway, and has been suggested to be involved in regulation of cell proliferation and invasion. Here, the molecular mechanism of miR-34a and LEF1 in cooperatively regulating prostate cancer cell invasion is described. Molecular profiling analysis of miRNA levels in prostate cancer cells revealed a negative correlation between miR-34a and LEF1 expression, and the downregulation of LEF1 by miR-34a was confirmed by luciferase assays. Furthermore, miR-34a specifically repressed LEF1 expression through direct binding to its 3'-untranslated regions (3'-UTR). miR-34a modulated the levels of LEF1 to regulate EMT in prostate cancer cells. Functionally, miR-34a negatively correlated with the migration and invasion of prostate cancer cells through LEF1. An analysis of miR-34a expression levels in matched human tumor and benign tissues demonstrated consistent and statistically significant downregulation of miR-34a in primary prostate cancer specimens. These data strongly suggest that miR-34a/LEF1 regulation of EMT plays an important role in prostate cancer migration and invasion.

IMPLICATIONS

The miR-34a-LEF1 axis represents a potential molecular target for novel therapeutic strategies in prostate cancer.

Overexpression of lymphoid enhancer-binding factor 1 (LEF1) in solid-pseudopapillary neoplasms of the pancreas

Solid-pseudopapillary neoplasms are rare, but are distinctive pancreatic tumors of low-malignant potential. While the histogenesis of these tumors is unclear, they are often associated with gain-of-function mutations in the catenin (cadherin-associated protein), beta 1 (88 kDa), or CTNNB1 gene, resulting in nuclear accumulation of CTNNB1. CTNNB1 is a central component of the Wnt signaling pathway and mediates gene expression through the lymphoid enhancer-binding factor 1 (LEF1) /T-cell factor transcription complex. Although LEF1 has a pivotal role in the transactivation of Wnt/CTNNB1 responsive genes, the status of LEF1 in solid-pseudopapillary neoplasms and other pancreatic tumors has not been examined. We analyzed both LEF1 and CTNNB1 in a large cohort of pancreatic tumors (n=155). In all cases of solid-pseudopapillary neoplasms including surgical resections (n=27) and cytologic samples (n=8) had strong and diffuse nuclear labeling for both LEF1 and CTNNB1. The surrounding uninvolved pancreatic parenchyma was devoid of any LEF1 staining. All resection and cytologic specimens from well-differentiated pancreatic neuroendocrine tumors (n=44; n=29, respectively), high-grade pancreatic neuroendocrine carcinomas (n=2; n=1), pancreatic ductal adenocarcinomas (n=25; n=12), and acinar cell carcinomas (n=9; n=2) studied were negative for both nuclear LEF1 and CTNNB1. However, nuclear LEF1 and CTNNB1 were detected in all four resected pancreatoblastomas (no cytologic specimens were available for immunolabeling), but primarily centered around and within squamoid corpuscles. In summary, abnormal CTNNB1 accumulation was accompanied by nuclear LEF1 overexpression in both solid-pseudopapillary neoplasms and pancreatoblastomas. But, in contrast to pancreatoblastomas, a diffuse, nuclear labeling was observed in solid-pseudopapillary neoplasms and further implicates the CTNNB1/LEF1 transcriptional complex in the development of solid-pseudopapillary neoplasms. In addition, as part of an immunohistochemical panel, LEF1 can be a useful ancillary stain in the diagnosis of solid-pseudopapillary neoplasms.

Expression and proliferation-promoting role of lymphoid enhancer-binding factor 1 in human clear cell renal carcinoma

Lymphoid enhancer-binding factor 1 (LEF1) has been regarded as an important gene for carcinogenesis in many malignancies, however, the role of LEF1 in the progression of human renal cell carcinoma (RCC) has not been well studied. In this study, we investigated the expression of LEF1 in human RCC and the effect on proliferative ability of RCC cells. RCC samples from 138 patients who underwent radical nephrectomy were used in this study, the expression of LEF1 protein was determined by immunohistochemistry and Western blot, mRNA expression was analyzed by RT-PCR and real-time PCR. To investigate the effect of LEF1 on the proliferation of RCC cells, a LEF1 vector was transfected into RCC cells and LEF1 expression was also decreased by using siRNA. Proliferative ability of RCC cells was examined by WST-1 assay and a xenograft study with BALB/C nude mice. Our results indicated that LEF1 expression was significantly increased in stage III, IV and grade 3 RCC than in normal kidney, however, decreased LEF1 expression was found in low-stage and grade RCC compared to that in normal kidney, the expression of LEF1 was correlated to tumor stages, histologic grade, and tumor sizes in RCC. The effect of LEF1 on the proliferation in RCC was also analyzed, our results suggested that RCC cells expressing high levels of LEF1 had significantly increased proliferative ability compared to control cell lines, in contrast, RCC cells with a low LEF1 expression had lower proliferative ability. Moreover, LEF1 promoted proliferation of RCC cells depending on suppressing G2/M cell-cycle arrest. Our study demonstrated that the expression of LEF1 is associated with the progression of RCC and that LEF1 maybe involved in the development of RCC, these suggested LEF1 play a key role and might serve as a therapeutic target in treating advanced RCC.