Receptor activator of NF-κB Ligand (RANKL) expression is associated with epithelial to mesenchymal transition in human prostate cancer cells

Overexpression of TNFSF11 reduces GPX4 levels and increases sensitivity to ferroptosis inducers in lung adenocarcinoma

BACKGROUND

Lung adenocarcinoma (LUAD), the most common and lethal subtype of lung cancer, continues to be a major health concern worldwide. Despite advances in targeted and immune therapies, only a minority of patients derive substantial benefits. As a result, the urgent need for novel therapeutic strategies to improve lung cancer treatment outcomes remains undiminished.

METHODS

In our study, we employed the TIMER database to scrutinize TNFSF11 expression across various cancer types. We further examined the differential expression of TNFSF11 in normal and tumor tissues utilizing the TCGA-LUAD dataset and tissue microarray, and probed the associations between TNFSF11 expression and clinicopathological parameters within the TCGA-LUAD dataset. We used the GSE31210 dataset for external validation. To identify genes strongly linked to TNFSF11, we engaged LinkedOmics and conducted a KEGG pathway enrichment analysis using the WEB-based Gene SeT AnaLysis Toolkit. Moreover, we investigated the function of TNFSF11 through gene knockdown or overexpression approaches and explore its function in tumor cells. The therapeutic impact of ferroptosis inducers in tumors overexpressing TNFSF11 were also investigated through in vivo and in vitro experiments. Through these extensive analyses, we shed light on the potential role of TNFSF11 in lung adenocarcinoma, underscoring potential therapeutic targets for this malignancy.

RESULTS

This research uncovers the overexpression of TNFSF11 in LUAD patients and its inverse correlation with peroxisome-related enzymes. By utilizing gene knockdown or overexpression assays, we found that TNFSF11 was negatively associated with GPX4. Furthermore, cells with TNFSF11 overexpression were relatively more sensitive to the ferroptosis inducers.

CONCLUSIONS

Our research has provided valuable insights into the role of TNFSF11, revealing its negative regulation of GPX4, which could be influential in crafting therapeutic strategies. These findings set the stage for further exploration into the mechanisms underpinning the relationship between TNFSF11 and GPX4, potentially opening up new avenues for precision medicine in the treatment of LUAD.

Co-expression of Twist and Snai1: predictor of poor prognosis and biomarker of treatment resistance in untreated prostate cancer

BACKGROUND

Prostate cancer (PCa) remains one of the most complex tumors in men. The assessment of gene expression is expected to have a profound impact on cancer diagnosis, prognosis, and treatment decisions. The aim of this study was to determine the utility of the epithelial-mesenchymal transition (EMT) transcription factors Twist and Snai1 in the treatment of naïve prostate cancer.

METHODS AND RESULTS

We analyzed formalin-fixed paraffin-embedded (FFPE) prostate tissues from 108 PCa patients and 20 control biopsies using real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR) and 2-ΔΔCt methods for Twist and Snail gene expression. The expression of Twist and Snai1 mRNA was significantly overexpressed in primary tissues of PCa patients compared with controls using ROC curve. Statistical analysis showed that the mRNAs of these two genes expression Snai1 and Twist were positively correlated with tumor development and prognostic parameters as Gleason score (p < 0.001; r = 0.707) and (p < 0.001; r = 0.627) respectively. The results of Kaplan-Meier analysis showed that mRNA expression of Snai1 and Twist genes expression were significant predictors of poor overall survival (OS) (Log rank p < 0.001) and progression-free survival (PFS) of patients (Log rank p < 0.001). Furthermore, our results showed that the expression of Snai1 and Twist genes expression in primary tissues of PCa patients could predict resistance to androgen deprivation therapy (p < 0.001) and resistance to the acidic drugs abiraterone or enzalutamide (p < 0.001). However, these two transcription factors failed to predict taxanes resistance at the time of diagnosis (p > 0.05).

CONCLUSION

These results suggest that Snai1 and Twist are overexpressed during the onset and progression of PCa malignancies and may be theranostic markers of resistance to ADT, abiraterone, or enzalutamide therapy.

Blocking the interaction between circTNRC18 and LIN28A promotes trophoblast epithelial-mesenchymal transformation and alleviates preeclampsia

Defects in migration and invasion caused by dysregulation of trophoblastic epithelial-mesenchymal transformation (EMT) play a vital role in preeclampsia (PE). We have previously shown that circTNRC18 inhibits the migration and EMT of trophoblasts; however, its role in PE remains unknown. Herein, we demonstrate that circTNRC18 interacts with an RNA-binding protein, lin-28 homolog A (LIN28A), and this interaction is enhanced in PE placental tissue. LIN28A overexpression suppresses circTNRC18-mediated inhibition of trophoblast migration, invasion, and EMT, whereas LIN28A knockdown promotes them. The intracellular distribution of LIN28A is regulated by circTNRC18, where it promotes the expression of insulin-like growth factor II by stabilizing its mRNA. circTNRC18 also promotes complex formation between GATA-binding factor 1 (GATA1) and sine oculis homeobox 1 (SIX1) by inhibiting LIN28A-GATA1 interaction. GATA1-SIX1 promotes transcription of grainyhead-like protein 2 homolog and circTNRC18-mediated regulation of cell migration and invasion. Moreover, blocking circTNRC18-LIN28A interaction with antisense nucleotides alleviates PE in a mouse model of reduced uterine perfusion pressure. Thus, targeting the circTNRC18-LIN28A regulatory axis may be a novel PE treatment method.

Current use of Molecular Mechanisms and Signaling Pathways in Targeted Therapy of Prostate Cancer

Prostate cancer (PC) is identified as a heterogeneous disease. About 20 to 30% of PC patients experience cancer recurrence, characterized by an increase in the antigen termed serum prostate-specific antigen (PSA). Clinical recurrence of PC commonly occurs after five years. Metastatic castration-resistant prostate cancer (mCRPC) has an intricate genomic background. Therapies that target genomic changes in DNA repair signaling pathways have been progressively approved in the clinic. Innovative therapies like targeting signaling pathways, bone niche, immune checkpoint, and epigenetic marks have been gaining promising results for better management of PC cases with bone metastasis. This review article summarizes the recent consideration of the molecular mechanisms and signaling pathways involved in local and metastatic prostate cancer, highlighting the clinical insinuations of the novel understanding.

RANKL biology

Since the receptor activator of nuclear factor-kappa B ligand (RANKL), its cognate receptor activator of nuclear factor-kappa B (RANK), and the decoy receptor osteoprotegerin (OPG) were discovered, a number of studies have uncovered the crucial role of the RANKL-RANK-OPG pathway in controlling the key aspect of bone homeostasis, the immune system, inflammation, cancer, and other systems under pathophysiological condition. These findings have expanded the understanding of the multifunctional biology of the RANKL-RANK-OPG pathway and led to the development of therapeutic potential targeting this pathway. The successful development and application of anti-RANKL antibody in treating diseases causing bone loss validates the utility of therapeutic approaches based on the modulation of this pathway. Moreover, recent studies have demonstrated the involvement of the RANKL-RANK pathway in osteoblast differentiation and bone formation, shedding light on the RANKL-RANK dual signaling in coupling bone resorption and bone formation. In this review, we will summarize the current understanding of the RANKL-RANK-OPG system in the context of the bone and the immune system as well as the impact of this pathway in disease conditions, including cancer development and metastasis.

Novel combination therapy of prostate cancer cells with arsenic trioxide and flutamide: An in-vitro study

OBJECTIVE

The study objective was to assess the therapeutic potential of Arsenic Trioxide (ATO) and Flutamide combination for metastatic prostate cancer (PCa) treatment.

MATERIAL AND METHOD

LNCaP and PC3 cell lines were treated with different concentrations of ATO and PCa conventional drug Flutamide alone and/or in combination to find effective doses and IC₅₀ values. Percentages of apoptotic cells were evaluated by Annexin/PI staining and the proliferative inhibitory effect was assessed by Micro Culture Tetrazolium Test (MTT). Expression of SNAIL, KLK2, E-cadherin, and angiogenesis genes (VEGFA and VEGFC), and apoptosis genes (Bcl₂, and P53) were examined by real-time PCR.

RESULTS

The combination of Flutamide and ATO significantly increased the percentage of apoptotic cells and inhibited PCa cells proliferation compared with each drug alone in LNCaP and PC3 cell lines. Generally, both cell lines treated with the combination of Flutamide and ATO showed a decrease in expression of KLK2, angiogenesis genes (VEGFA and VEGFC), and apoptosis gene (Bcl₂), and an increase in expression of E-cadherin and P53 genes; however, contradictory findings were found regarding SNAIL expression in LNCaP and PC3 cells.

CONCLUSION

The combination therapy with ATO and flutamide has augmented the anti-tumor effect on LNCaP and PC3 cells, which probably originates from their potential to induce apoptosis and inhibit the proliferation of PCa cells simultaneously.

Silencing ACTG1 Expression Induces Prostate Cancer Epithelial Mesenchymal Transition Through MAPK/ERK Signaling Pathway

Purpose: Metastatic prostate cancer (PCa) has become a major obstacle in the treatment of PCa. The study's purpose is to find biomarkers of tumor metastasis by proteomics and enzyme-linked immunosorbent assay (ELISA), and to design related experiments to study its role in the progress and metastasis of PCa. Method: We analyzed serum from primary PCa stage and metastatic stage of 12 patients to find metastatic PCa serum protein biomarkers using isobaric tags for relative and absolute quantitation (iTRAQ). An effective diagnostic model based on validated biomarkers using logistic regression was established. In vivo and in vitro biological behavior experiments (wound healing, CCK8, and Transwell tests) were carried out after obtaining the biomarkers. Related mechanism has been studied, which may be associated with metastatic PCa. Result: Actin gamma 1 (ACTG1) is a potential biomarker in the metastasis of PCa. Bioinformatics and related experiments show that ACTG1 is high-expressed in PCa tissues and cells. In vivo and in vitro experiments illustrated that the ability of proliferation, migration, and invasion of PCa cells was significantly inhibited after the knockdown of ACTG1 expression. Surprisingly, ERK protein expression was downregulated after ACTG1 knockdown. At the same time, the expression of epithelial-mesenchymal transition-related markers in PCa cells decrease after treated with ERK1/2 inhibitor, which indicating that ACTG1 may affect the metastatic ability of PCa cells through MAPK/ERK signaling pathway. Conclusion: ACTG1 is a marker of metastasis PCa. It mediates cell proliferation and may regulate the metastasis of PCa through MAPK/ERK signaling pathway, which provides a useful theoretical basis for exploring the treatment of PCa.

RANKL immunisation inhibits prostate cancer metastasis by modulating EMT through a RANKL-dependent pathway

Prostate cancer (PCa) morbidity in the majority of patients is due to metastatic events, which are a clinical obstacle. Therefore, a better understanding of the mechanism underlying metastasis is imperative if we are to develop novel therapeutic strategies. Receptor activator of nuclear factor kappa-B (NF-κB) ligand (RANKL) regulates bone remodelling. Thus, agents that suppress RANKL signalling may be useful pharmacological treatments. Here, we used preclinical experimental models to investigate whether an inactive form of RANKL affects bone metastasis in RANKL-induced PCa. RANKL was associated with epithelial–mesenchymal transition (EMT) and expression of metastasis-related genes in PC3 cells. Therefore, we proposed a strategy to induce anti-cytokine antibodies using mutant RANKL as an immunogen. RANKL promoted migration and invasion of PC3 cells through EMT, and induced a significant increase in binding of β-catenin to TCF-4, an EMT-induced transcription factor in PCa cells, via mitogen-activated protein kinase and β-catenin/TCF-4 signalling. Thus, RANKL increased EMT and the metastatic properties of PC3 cells, suggesting a role as a therapeutic target to prevent PCa metastasis. Treatment with mutant RANKL reduced EMT and metastasis of PC3 PCa cells in an experimental metastasis model. Thus, mutant RANKL could serve as a potential vaccine to prevent and treat metastatic PCa.

Receptor Activator of NF Kappa B (RANK) Expression Indicates Favorable Prognosis in Patients with Muscle-invasive Bladder Cancer

BACKGROUND

Receptor activator of NF kappa B (RANK) and its ligand have an essential role in T-cell regulation and the development of bone metastases. The role of RANK expression in muscle-invasive bladder cancer (MIBC) is unknown.

OBJECTIVE

To assess the relevance of RANK expression in patients with MIBC.

DESIGN, SETTING, AND PARTICIPANTS

Expression of RANK was assessed via immunohistochemistry of benign urothelium, MIBC tissue, and lymph node metastases from 153 patients undergoing radical cystectomy. Expression data from The Cancer Genome Atlas (TCGA) cohort were analyzed for potential associations with molecular subtypes and outcome.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

RANK expression was correlated with clinical and pathological parameters and to individual data for the clinical course of MIBC.

RESULTS AND LIMITATIONS

Expression of RANK was significantly higher in both primary tumors (p = 0.02) and lymph node metastases (p = 0.01) compared to normal urothelium. In tumor tissue, RANK expression was significantly lower in patients with locally advanced disease and lymph node involvement compared to those with organ-confined disease (p = 0.0009) and node-negative MIBC (p = 0.0002). In univariable and multivariable analyses, high expression of RANK was associated with a longer time to recurrence (p = 0.0005 and 0.01) and better cancer-specific (p = 0.0004 and 0.007) and overall survival (p = 0.002 and 0.04). High expression of RANK was associated with better outcome for patients with luminal infiltrated tumors in the TCGA cohort.

CONCLUSIONS

RANK expression is increased in bladder cancer tissue compared to benign urothelium, with higher expression in organ-defined compared to locally advanced disease. High RANK expression indicates a favorable prognosis in MIBC. The prognostic role differs in tumors of different molecular subtypes.

PATIENT SUMMARY

Expression of a protein involved in bone turnover regulation (RANK) is higher in bladder cancer tissue than in benign bladder tissue. However, high levels of RANK on tumor cells indicate favorable prognosis for patients with bladder cancer that invades the muscle layer of the bladder.

The safety profile of denosumab in oncology beyond the safety of denosumab as an anti-osteoporotic agent: still more to learn

INTRODUCTION

Initially endorsed as an antiosteoporotic agent, denosumab ‒ human monoclonal antibody inhibiting the receptor activator of nuclear factor kappa-B ligand (RANKL)‒ has currently shown an anticancer potential, rationalizing its exploitation in oncology. A prerequisite for leveraging denosumab in oncology is a favorable safety profile.

AREAS COVERED

The present review provides an overview of the adverse events of denosumab in oncology, with a focus on hypocalcemia, medication-related osteonecrosis of the jaw, atypical femoral fracture(s), post-denosumab vertebral fractures, increased risk of infections, and excess of second primary cancer. Representative studies addressing the safety and efficacy of denosumab compared to bisphosphonates in oncology are summarized. Critical gaps in the literature concerning the safety of denosumab in oncology are highlighted as opposed to plenty of available safety data on denosumab as an antiosteoporotic agent.

EXPERT OPINION

Despite the generally acceptable safety profile of denosumab in oncology, many issues remain unresolved. Further research is mandatory to counteract current challenges, namely: (i) validation of risk factors for adverse events; (ii) elucidation of the pathophysiology of the adverse events in search of actionable molecular pathways; (iii) illumination of the association of denosumab with increased risk of infections and/or second primary cancer; (iv) establishment of optimal diagnostic, and therapeutic protocols.

Targeting the RANKL/RANK/OPG Axis for Cancer Therapy

RANKL and RANK are expressed in different cell types and tissues throughout the body. They were originally described for their essential roles in bone remodeling and the immune system but have subsequently been shown to provide essential signals from regulating mammary gland homeostasis during pregnancy to modulating tumorigenesis. The success of RANKL/RANK research serves as a paragon for translational research from the laboratory to the bedside. The case in point has been the development of Denosumab, a RANKL-blocking monoclonal antibody which has already helped millions of patients suffering from post-menopausal osteoporosis and skeletal related events in cancer. Here we will provide an overview of the pathway from its origins to its clinical relevance in disease, with a special focus on emerging evidence demonstrating the therapeutic value of targeting the RANKL/RANK/OPG axis not only in breast cancer but also as an addition to the cancer immunotherapy arsenal.

Cytokines and Chemokines as Mediators of Prostate Cancer Metastasis

The consequences of prostate cancer metastasis remain severe, with huge impact on the mortality and overall quality of life of affected patients. Despite the convoluted interplay and cross talk between various cell types and secreted factors in the metastatic process, cytokine and chemokines, along with their receptors and signaling axis, constitute important factors that help drive the sequence of events that lead to metastasis of prostate cancer. These proteins are involved in extracellular matrix remodeling, epithelial-mesenchymal-transition, angiogenesis, tumor invasion, premetastatic niche creation, extravasation, re-establishment of tumor cells in secondary organs as well as the remodeling of the metastatic tumor microenvironment. This review presents an overview of the main cytokines/chemokines, including IL-6, CXCL12, TGFβ, CXCL8, VEGF, RANKL, CCL2, CX3CL1, IL-1, IL-7, CXCL1, and CXCL16, that exert modulatory roles in prostate cancer metastasis. We also provide extensive description of their aberrant expression patterns in both advanced disease states and metastatic sites, as well as their functional involvement in the various stages of the prostate cancer metastatic process.

RANK and RANKL Expression in Salivary Gland Tumors

OBJECTIVES

The pathogenesis and molecular basis of salivary gland tumors (SGT) are not well understood. We investigated the expression of receptor activator of nuclear factor κB (RANK) and RANK ligand (RANKL) in benign and malignant SGTs and their relationship with clinicopathological features.

METHODS

Fifty malignant and 38 benign SGTs were analyzed in this study. We evaluated the correlation between RANK and RANKL expression and benign and malignant tumors, as well as the correlation between clinicopathological prognostic parameters and RANK and RANKL expression.

RESULTS

Receptor activator of nuclear factor κB was positive in 82% (41) malignant SGTs and in 34.2% (13) benign SGTs. Receptor activator of nuclear factor κB ligand was expressed in 28% (14) malignant and 5.3% (2) benign tumors. Receptor activator of nuclear factor κB and RANKL expression were significantly different between benign and malignant SGTs (P < .001, P = .006, respectively). However, a relationship was not found between positive expression of RANK or RANKL and clinicopathological features.

CONCLUSIONS

In our study, RANK and RANKL expression was found to be higher in malignant SGTs compared to benign SGTs and RANK was more sensitive than RANKL. In addition, RANK and RANKL expression was higher in some malignant histological subtypes. Based on these results, we think that RANK and RANKL expression in SGTs and its potential as a target for treatment should continue to be investigated.

3D porous chitosan-chondroitin sulfate scaffolds promote epithelial to mesenchymal transition in prostate cancer cells

Prostate cancer (PCa) is a common cancer in men that is curable prior to metastasis, when its prognosis worsens. Chondroitin sulfate (CS) is found in the extracellular matrix of normal prostate tissue and PCa, with greater content in metastatic PCa. Biomaterial scaffolds containing CS have yet to be evaluated for tumor microenvironment applications. Three-dimensional porous chitosan-CS (C-CS) scaffolds were developed and evaluated for PCa culture. Three C-CS scaffold compositions were prepared with 4 w/v% chitosan and 0.1, 0.5, and 1.0 w/v% CS and named 4-0.1, 4-0.5, and 4-1, respectively. The C-CS scaffolds had 90-95% porosity, average pore sizes between 143 and 166 μm, and no significant difference in scaffold stiffness. PC-3 and 22Rv1 PCa cells were cultured on the C-CS scaffolds to study the effect of CS on PCa growth and epithelial to mesenchymal transition (EMT). All C-CS scaffold compositions supported PCa growth and the 4-1 scaffolds had the greatest cell numbers for both PC-3 and 22Rv1. The C-CS scaffolds promoted upregulated EMT marker expression compared to 2D cultures with the greatest EMT marker expression in 4-1 scaffolds. Increasing CS concentration promoted upregulated vimentin expression in PC-3 cultures and N-cadherin and MMP-2 expression in 22Rv1 cultures. C-CS scaffolds promoted docetaxel drug resistance in PC-3 and 22Rv1 cultures and the 4-1 scaffold cultures had the greatest drug resistance. These results indicate that C-CS scaffolds are a promising in vitro platform for PCa.

Effects of the Bone/Bone Marrow Microenvironments on Prostate Cancer Cells and CD59 Expression

Objective

To evaluate the effects of human bone marrow mesenchymal stem cells (hBMSCs) and osteoblasts (hFOB1.19) on PC3 prostate cancer cells.

Methods

To simulate the in vivo interaction between the bone/bone marrow microenvironments and prostate cancer cells, we established cocultures of PC3 cells with hBMSC or hFOB1.19 cells and evaluated their effects on the proliferation, cell cycle distribution, cell migration, and invasion of PC3 cells. Quantitative reverse transcription polymerase chain reaction was used to detect CD59 mRNA expression in PC3 cells. The expression of receptor activator of nuclear factor- (NF-) κB (RANK), RANK ligand (RANKL), osteoprotegerin (OPG), CD59, NF-κB (p50 subunit), and cyclin D1 in PC3 cells was analyzed by immunofluorescence and western blotting.

Results

hBMSCs and hFOB1.19 cells enhanced the proliferation, migration, and invasion of PC3 cells; increased the proportion of PC3 cells in the S and G₂/M phases of the cell cycle; and upregulated RANK, RANKL, OPG, CD59, cyclin D1, and NF-κB (p50 subunit) expression by PC3 cells. The RANKL inhibitor, scutellarin, inhibited these effects in PC3-hFOB1.19 cocultures.

Conclusion

hBMSCs and hFOB1.19 cells modulate the phenotype of PC3 prostate cancer cells and the expression of CD59 by activating the RANK/RANKL/OPG signaling pathway.

Histone Demethylase JMJD1A Promotes Tumor Progression via Activating Snail in Prostate Cancer

The histone demethylase JMJD1A plays a key functional role in spermatogenesis, sex determination, stem cell renewal, and cancer via removing mono- and di-methyl groups from H3K9 to epigenetically control gene expression. However, its role in prostate cancer progression remains unclear. Here, we found JMJD1A was significantly elevated in prostate cancer tissue compared with matched normal tissue. Ectopic JMJD1A expression in prostate cancer cells promoted proliferation, migration, and invasion in vitro, and tumorigenesis in vivo; JMJD1A knockdown exhibited the opposite effects. Mechanically, we revealed that JMJD1A directly interacted with the Snail gene promoter and regulated its transcriptional activity, promoting prostate cancer progression both in vitro and in vivo. Furthermore, we found that JMJD1A transcriptionally activated Snail expression via H3K9me1 and H3K9me2 demethylation at its special promoter region. In summary, our studies reveal JMJD1A plays an important role in regulating proliferation and progression of prostate cancer cells though Snail, and thus highlight JMJD1A as potential therapeutic target for advanced prostate cancer. IMPLICATIONS: Our studies identify that JMJD1A promotes the proliferation and progression of prostate cancer cells through enabling Snail transcriptional activation, and thus highlight JMJD1A as potential therapeutic target for advanced prostate cancer.

Harnessing the versatile role of OPG in bone oncology: counterbalancing RANKL and TRAIL signaling and beyond

More than 2 decades ago, the discovery of osteoprotegerin (OPG) as inhibitor of the receptor of activator of nuclear factor Kb (RANK) ligand (RANKL) revolutionized our understanding of bone biology and oncology. Besides acting as decoy receptor for RANKL, OPG acts as decoy receptor for tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). OPG, RANKL, and TRAIL are ubiquitously expressed, stimulating per se pivotal signaling cascades implicated in cancer. In the context of cancer cell-bone cell interactions, cancer cells skew the OPG/RANKL/RANK (RANKL cognate receptor) balance towards bone destruction and tumor growth through favoring the RANKL/RANK interface, circumventing OPG. Numerous preclinical and clinical studies demonstrate the dual role of OPG in cancer: antitumor and tumor-promoting. OPG potentially conveys an antitumor signal through inhibiting the tumor-promoting RANKL signaling-both the osteoclast-dependent and the osteoclast-independent-and the tumor-promoting TRAIL signaling. On the other hand, the presumed tumor-promoting functions of OPG are: (i) abrogation of TRAIL-induced apoptosis of cancer cells; (ii) abrogation of RANKL-induced antitumor immunity; and (iii) stimulation of oncogenic and prometastatic signaling cascades downstream of the interaction of OPG with diverse proteins. The present review dissects the role of OPG in bone oncology. It presents the available preclinical and clinical data sustaining the dual role of OPG in cancer and focuses on the imbalanced RANKL/RANK/OPG interplay in the landmark "vicious cycle" of skeletal metastatic disease, osteosarcoma, and multiple myeloma. Finally, current challenges and future perspectives in exploiting OPG signaling in bone oncology therapeutics are discussed.

Cancer-bone microenvironmental interactions promotes STAT3 signaling

Prostate cancer (PCa) patients' mortality is mainly attributed to complications caused by metastasis of the tumor cells to organs critical for survival, such as bone. We hypothesized that PCa cell-bone interactions would promote paracrine signaling. A panel of PCa cell lines were cocultured with hydroxyapatite ([HA]; inorganic component of bone) of different densities. Conditioned media (CM) was collected and analyzed for calcium levels and effect on paracrine signaling, cell migration, and viability in vitro and in vivo. Our results showed that calcium levels were elevated in CM from cancer cell-bone cocultures, compared to media or cancer cells alone, and this could be antagonized by ethylene glycol-bis(2-aminoethyl ether)N,N,N',N'-tetraacetic acid (EGTA), a calcium chelator, or knockdown of Snail protein. We also observed increased signal transducer and activator of transcription 3 (STAT3) phosphorylation and paracrine cell proliferation and migration in LNCaP cells incubated with CM from various cell lines; this phosphorylation and cell migration could be antagonized by Snail knockdown or various inhibitors including EGTA, STAT3 inhibitor (WP1066) or cathepsin L inhibitor (Z-FY-CHO). In vivo, higher HA bone density increased tumorigenicity and migration of tumor cells to HA implant. Our study shows that cancer-bone microenvironment interactions lead to calcium-STAT3 signaling, which may present an area for therapeutic targeting of metastatic PCa.

The RANK-RANKL axis: an opportunity for drug repurposing in cancer?

Drug repurposing offers advantages over traditional drug development in terms of cost, speed and improved patient outcomes. The receptor activator of nuclear factor kappa B (RANK) ligand (RANKL) inhibitor denosumab is approved for the prevention of skeletal-related events in patients with advanced malignancies involving bone, including solid tumours and multiple myeloma. Following improved understanding of the role of RANK/RANKL in cancer biology, denosumab has already been repurposed as a treatment for giant cell tumour of bone. Here, we review the role of RANK/RANKL in tumourigenesis, including effects on tumour initiation, progression and metastasis and consider the impact of RANK/RANKL on tumour immunology and immune evasion. Finally, we look briefly at ongoing trials and future opportunities for therapeutic synergy when combining denosumab with anti-cancer agents such as immune checkpoint inhibitors.

Regulatory signaling network in the tumor microenvironment of prostate cancer bone and visceral organ metastases and the development of novel therapeutics

This article describes cell signaling network of metastatic prostate cancer (PCa) to bone and visceral organs in the context of tumor microenvironment and for the development of novel therapeutics. The article focuses on our recent progress in the understanding of: 1) The plasticity and dynamics of tumor–stroma interaction; 2) The significance of epigenetic reprogramming in conferring cancer growth, invasion and metastasis; 3) New insights on altered junctional communication affecting PCa bone and brain metastases; 4) Novel strategies to overcome therapeutic resistance to hormonal antagonists and chemotherapy; 5) Genetic-based therapy to co-target tumor and bone stroma; 6) PCa-bone-immune cell interaction and TBX2-WNTprotein signaling in bone metastasis; 7) The roles of monoamine oxidase and reactive oxygen species in PCa growth and bone metastasis; and 8) Characterization of imprinting cluster of microRNA, in tumor–stroma interaction. This article provides new approaches and insights of PCa metastases with emphasis on basic science and potential for clinical translation. This article referenced the details of the various approaches and discoveries described herein in peer-reviewed publications. We dedicate this article in our fond memory of Dr. Donald S. Coffey who taught us the spirit of sharing and the importance of focusing basic science discoveries toward translational medicine.

Upregulation of minichromosome maintenance complex component 3 during epithelial-to-mesenchymal transition in human prostate cancer

Metastasis is often associated with epithelial-to-mesenchymal transition (EMT). To understand the molecular mechanisms of this process, we conducted proteomic analysis of androgen-repressed cancer of the prostate (ARCaP), an experimental model of metastatic human prostate cancer. The protein signatures of epithelial (ARCaPE) and mesenchymal (ARCaPM) cells were consistent with their phenotypes. Importantly, the expression of mini-chromosome maintenance 3 (MCM3) protein, a crucial subunit of DNA helicase, was significantly higher in ARCaPM cells than that of ARCaPE cells. This increased MCM3 protein expression level was verified using Western blot analysis of the ARCaP cell lineages. Furthermore, immunohistochemical analysis of MCM3 protein levels in human prostate tissue specimens showed elevated expression in bone metastasis and advanced human prostate cancer tissue samples. Subcutaneous injection experiments using ARCaPE and ARCaPM cells in a mouse model also revealed increased MCM3 protein levels in mesenchymal-derived tumors. This study identifies MCM3 as an upregulated molecule in mesenchymal phenotype of human prostate cancer cells and advanced human prostate cancer specimens, suggesting MCM3 may be a new potential drug target for prostate cancer treatment.

BRCA1 haploinsufficiency cell-autonomously activates RANKL expression and generates denosumab-responsive breast cancer-initiating cells

Denosumab, a monoclonal antibody to the receptor activator of nuclear factor-κB ligand (RANKL), might be a novel preventative therapy for BRCA1-mutation carriers at high risk of developing breast cancer. Beyond its well-recognized bone-targeted activity impeding osteoclastogenesis, denosumab has been proposed to interfere with the cross-talk between RANKL-producing sensor cells and cancer-initiating RANK+ responder cells that reside within premalignant tissues of BRCA1-mutation carriers. We herein tested the alternative but not mutually exclusive hypothesis that BRCA1 deficiency might cell-autonomously activate RANKL expression to generate cellular states with cancer stem cell (CSC)-like properties. Using isogenic pairs of normal-like human breast epithelial cells in which the inactivation of a single BRCA1 allele results in genomic instability, we assessed the impact of BRCA1 haploinsufficiency on the expression status of RANK and RANKL. RANK expression remained unaltered but RANKL was dramatically up-regulated in BRCA1mut/+ haploinsufficient cells relative to isogenic BRCA1+/+ parental cells. Neutralizing RANKL with denosumab significantly abrogated the ability of BRCA1 haploinsufficient cells to survive and proliferate as floating microtumors or "mammospheres" under non-adherent/non-differentiating conditions, an accepted surrogate of the relative proportion and survival of CSCs. Intriguingly, CSC-like states driven by epithelial-to-mesenchymal transition or HER2 overexpression traits responded to some extent to denosumab. We propose that breast epithelium-specific mono-allelic inactivation of BRCA1 might suffice to cell-autonomously generate RANKL-addicted, denosumab-responsive CSC-like states. The convergent addiction to a hyperactive RANKL/RANK axis of CSC-like states from genetically diverse breast cancer subtypes might inaugurate a new era of cancer prevention and treatment based on denosumab as a CSC-targeted agent.

Rankl expression predicts poor prognosis in gastric cancer patients: results from a retrospective and single-center analysis

The receptor activator of nuclear factor κB ligand (RANKL)/RANK pathway plays an important role in the prognosis of several solid tumor types, but its role in gastric cancer prognosis has been poorly characterized. A total of 116 gastric cancer patients who underwent surgical resection were enrolled in this study. Expressions of RANKL and RANK in gastric cancer tissues were detected using immunohistochemical staining. Thirty-eight patients (33%) showed a high level of RANKL expression and 61 patients (53%) showed a high level of RANK expression. There was a positive correlation between expressions of RANKL and RANK (P=0.014, r=0.221). A high level of RANKL expression indicated shorter overall survival (OS) (P=0.008), and was associated with a higher pathological tumor/lymph node/metastasis (pTNM) stage (P=0.035), while no significant correlation was detected between RANK expression and clinicopathological parameters. RANKL also predicted poor prognosis in patients with high RANK expression (P=0.008) and Bormann's type III/IV (P=0.002). Furthermore, RANKL expression correlated with pTNM stage according to high RANK expression (P=0.009), while no significance was found in patients with low RANK expression (P=1.000). Together, our results revealed that high expression of RANKL could predict worse outcomes in gastric cancer especially combined with RANK detection, and thereby this pathway could be a useful prognostic indicator of gastric cancer.

Metformin reverses prostate cancer resistance to enzalutamide by targeting TGF-β1/STAT3 axis-regulated EMT

Although the newly developed second-generation anti-androgen drug enzalutamide can repress prostate cancer progression significantly, it only extends the survival of prostate cancer patients by 4–6 months mainly due to the occurrence of enzalutamide resistance. Most of the previous studies on AR antagonist resistance have been focused on AR signaling. Therefore, the non-AR pathways on enzalutamide resistance remain largely unknown. By using C4-2, CWR22Rv1 and LNCaP cell lines, as well as mice bearing CWR22Rv1 xenografts treated with either enzalutamide or metformin alone or in combination, we demonstrated that metformin is capable of reversing enzalutamide resistance and restores sensitivity of CWR22Rv1 xenografts to enzalutamide. We showed that metformin alleviated resistance to enzalutamide by inhibiting EMT. Furthermore, based on the effect of metformin on the activation of STAT3 and expression of TGF-β1, we propose that metformin exerts its effects by targeting the TGF-β1/STAT3 axis. These findings suggest that combination of metformin with enzalutamide could be a more efficacious therapeutic strategy for the treatment of castration-resistant prostate cancer.

The RANK/RANKL/OPG system in tumorigenesis and metastasis of cancer stem cell: potential targets for anticancer therapy

The molecular triad involving receptor activator of nuclear factor kβ (RANK)/RANK ligand (RANKL)/osteoprotegerin cytokine system has been well implicated in several physiological and pathological processes including bone metabolism, mammary gland development, regulation of the immune function, tumorigenesis and metastasis of cancer stem cell, thermoregulation, and vascular calcification. However, this review aimed to summarize several original and up-to-date articles focusing on the role of this signaling system in cancer cell development and metastasis as well as potential therapeutic agents targeting any of the three tumor necrotic factor super family proteins and/or their downstream signaling pathways. The RANK/RANKL axis has direct effects on tumor cell development. The system is well involved in the development of several primary and secondary tumors including breast cancer, prostate cancer, bone tumors, and leukemia. The signaling of this triad system has also been linked to tumor invasiveness in the advanced stage. Bone is by far the most common site of cancer metastasis. Several therapeutic agents targeting this system have been developed. Among them, a monoclonal antibody, denosumab, was clinically approved for the treatment of osteoporosis and cancer-related diseases.

Blocking epithelial-to-mesenchymal transition in glioblastoma with a sextet of repurposed drugs: the EIS regimen

This paper outlines a treatment protocol to run alongside of standard current treatment of glioblastoma- resection, temozolomide and radiation. The epithelial to mesenchymal transition (EMT) inhibiting sextet, EIS Regimen, uses the ancillary attributes of six older medicines to impede EMT during glioblastoma. EMT is an actively motile, therapy-resisting, low proliferation, transient state that is an integral feature of cancers’ lethality generally and of glioblastoma specifically. It is believed to be during the EMT state that glioblastoma’s centrifugal migration occurs. EMT is also a feature of untreated glioblastoma but is enhanced by chemotherapy, by radiation and by surgical trauma. EIS Regimen uses the antifungal drug itraconazole to block Hedgehog signaling, the antidiabetes drug metformin to block AMP kinase (AMPK), the analgesic drug naproxen to block Rac1, the anti-fibrosis drug pirfenidone to block transforming growth factor-beta (TGF-beta), the psychiatric drug quetiapine to block receptor activator NFkB ligand (RANKL) and the antibiotic rifampin to block Wnt- all by their previously established ancillary attributes. All these systems have been identified as triggers of EMT and worthy targets to inhibit. The EIS Regimen drugs have a good safety profile when used individually. They are not expected to have any new side effects when combined. Further studies of the EIS Regimen are needed.

Bone Metastasis of Prostate Cancer Can Be Therapeutically Targeted at the TBX2-WNT Signaling Axis

Identification of factors that mediate visceral and bone metastatic spread and subsequent bone remodeling events is highly relevant to successful therapeutic intervention in advanced human prostate cancer. TBX2, a T-box family transcription factor that negatively regulates cell-cycle inhibitor p21, plays critical roles during embryonic development, and recent studies have highlighted its role in cancer. Here, we report that TBX2 is overexpressed in human prostate cancer specimens and bone metastases from xenograft mouse models of human prostate cancer. Blocking endogenous TBX2 expression in PC3 and ARCaPM prostate cancer cell models using a dominant-negative construct resulted in decreased tumor cell proliferation, colony formation, and invasion in vitro Blocking endogenous TBX2 in human prostate cancer mouse xenografts decreased invasion and abrogation of bone and soft tissue metastasis. Furthermore, blocking endogenous TBX2 in prostate cancer cells dramatically reduced bone-colonizing capability through reduced tumor cell growth and bone remodeling in an intratibial mouse model. TBX2 acted in trans by promoting transcription of the canonical WNT (WNT3A) promoter. Genetically rescuing WNT3A levels in prostate cancer cells with endogenously blocked TBX2 partially restored the TBX2-induced prostate cancer metastatic capability in mice. Conversely, WNT3A-neutralizing antibodies or WNT antagonist SFRP-2 blocked TBX2-induced invasion. Our findings highlight TBX2 as a novel therapeutic target upstream of WNT3A, where WNT3A antagonists could be novel agents for the treatment of metastasis and for skeletal complications in prostate cancer patients. Cancer Res; 77(6); 1331-44. ©2017 AACR.

MAOA-Dependent Activation of Shh-IL6-RANKL Signaling Network Promotes Prostate Cancer Metastasis by Engaging Tumor-Stromal Cell Interactions

Metastasis is a predominant cause of death for prostate cancer (PCa) patients; however, the underlying mechanisms are poorly understood. We report that monoamine oxidase A (MAOA) is a clinically and functionally important mediator of PCa bone and visceral metastases, activating paracrine Shh signaling in tumor-stromal interactions. MAOA provides tumor cell growth advantages in the bone microenvironment by stimulating interleukin-6 (IL6) release from osteoblasts, and triggers skeletal colonization by activating osteoclastogenesis through osteoblast production of RANKL and IL6. MAOA inhibitor treatment effectively reduces metastasis and prolongs mouse survival by disengaging the Shh-IL6-RANKL signaling network in stromal cells in the tumor microenvironment. These findings provide a rationale for targeting MAOA and its associated molecules to treat PCa metastasis.

Determinants of bone specific metastasis in prostate cancer

Prostate cancer is one of the most common type of cancer in Western countries. Although the majority of patients with PCa have a minimally aggressive disease, some of them will experience relapse and formation of metastasis. Bone metastasis are a major cause of quality of life impairment and death among patients with metastatic prostate cancer. Different "bone targeted therapies" and several follow-up strategies were developed in order to optimize bone metastasis prevention and treatment. Nevertheless there is still a great clinical need of identifying patients more likely to benefit from those interventions as not all patients will develop metastatic disease and not all patients with metastatic disease will develop bone metastasis. Here we review markers predictive of bone metastasis occurrence that have been tested in clinical settings, particularly focusing on the ability of such markers to predict bone metastasis over visceral metastasis occurrence.

RANKL/RANK pathway abrogates cetuximab sensitivity in gastric cancer cells via activation of EGFR and c-Src

Overexpression of EGFR is commonly seen in gastric cancer (GC). However, patients with GC show resistance to anti-EGFR treatments. RAS mutations are rare in GC and cannot explain de novo resistance to EGFR treatments. Therefore, it is particularly important to explore the mechanisms of resistance to anti-EGFR treatments. The RANKL activates the EGFR pathway in osteoclasts, and the RANK is expressed in gastric carcinoma. Whether the RANKL/RANK pathway has an effect on the EGFR pathway in GC remains unknown. Expressions of EGFR and RANK in GC tissues were detected using immunohistochemical staining. Nineteen patients (28%) showed high-level RANKL expression, and 33 patients (48%) showed high-level RANK expression. There was a positive correlation between expression of EGFR and RANK (P<0.001). In an in vitro study, RANKL induced activation of the EGFR pathway and further abrogated cetuximab sensitivity in GC cells. Knockdown of RANK or use of the RANKL inhibitor enhanced cetuximab effect by decreasing RANKL-induced EGFR activation. Furthermore, we showed that c-SRC mediated the EGFR activation induced by the RANKL/RANK pathway and that c-SRC inhibitor reversed the suppression of RANKL on the effect of cetuximab. In conclusion, our results suggest that in GC cells, the RANKL/RANK pathway activates the EGFR pathway and thereby causes resistance to anti-EGFR treatments.

Bone: A Fertile Soil for Cancer Metastasis

Bone is one of the most common and most dangerous sites for metastatic growth across cancer types, and bone metastasis remains incurable. Unfortunately, the processes by which cancers preferentially metastasize to bone are still not well understood. In this review, we summarize the morphological features, physical properties, and cell signaling events that make bone a unique site for metastasis and bone remodeling. The signaling crosstalk between the tumor cells and bone cells begins a vicious cycle - a self-sustaining feedback loop between the tumor cells and the bone microenvironment composed of osteoclasts, osteoblasts, other bone marrow cells, bone matrix, and vasculature to support both tumor growth and bone destruction. Through this crosstalk, bone provides a fertile microenvironment that can harbor dormant tumor cells, sometimes for long periods, and support their growth by releasing cytokines as the bone matrix is destroyed, similar to providing nutrients for a seed to germinate in soil. However, few models exist to study the late stages of bone colonization by metastatic tumor cells. We describe some of the current methodologies used to study bone metastasis, highlighting the limitations of these methods and alternative future strategies to be used to study bone metastasis. While <i>in vivo</i> animal and patient studies may provide the gold standard for studying metastasis, <i>ex vivo</i> models can be used as an alternative to enable more controlled experiments designed to study the late stages of bone metastasis.

Characterization of an Abiraterone Ultraresponsive Phenotype in Castration-Resistant Prostate Cancer Patient-Derived Xenografts

Purpose: To identify the molecular signature associated with abiraterone acetate (AA) response and mechanisms underlying AA resistance in castration-resistant prostate cancer patient-derived xenografts (PDXs).Experimental Design: SCID mice bearing LuCaP 136CR, 77CR, 96CR, and 35CR PDXs were treated with AA. Tumor volume and prostate-specific antigen were monitored, and tumors were harvested 7 days after treatment or at end of study for gene expression and immunohistochemical studies.Results: Three phenotypic groups were observed based on AA response. An ultraresponsive phenotype was identified in LuCaP 136CR with significant inhibition of tumor progression and increased survival, intermediate responders LuCaP 77CR and LuCaP 96CR with a modest tumor inhibition and survival benefit, and LuCaP 35CR with minimal tumor inhibition and no survival benefit upon AA treatment. We identified a molecular signature of secreted proteins associated with the AA ultraresponsive phenotype. Upon resistance, AA ultraresponder LuCaP 136CR displayed reduced androgen receptor (AR) signaling and sustainably low nuclear glucocorticoid receptor (nGR) localization, accompanied by steroid metabolism alteration and epithelial-mesenchymal transition phenotype enrichment with increased expression of NF-κB-regulated genes; intermediate and minimal responders maintained sustained AR signaling and increased tumoral nGR localization.Conclusions: We identified a molecular signature of secreted proteins associated with AA ultraresponsiveness and sustained AR/GR signaling upon AA resistance in intermediate or minimal responders. These data will inform development of noninvasive biomarkers predicting AA response and suggest that further inhibition along the AR/GR signaling axis may be effective only in AA-resistant patients who are intermediate or minimal responders. These findings require verification in prospective clinical trials. Clin Cancer Res; 23(9); 2301-12. ©2016 AACR.

Clinical prognostic significance and pro-metastatic activity of RANK/RANKL via the AKT pathway in endometrial cancer

RANK/RANKL plays a key role in metastasis of certain malignant tumors, which makes it a promising target for developing novel therapeutic strategies for cancer. However, the prognostic value and pro-metastatic activity of RANK in endometrial cancer (EC) remain to be determined. Thus, the present study investigated the effect of RANK on the prognosis of EC patients, as well as the pro-metastatic activity of EC cells. The results indicated that those with high expression of RANK showed decreased overall survival and progression-free survival. Statistical analysis revealed the positive correlations between RANK/RANKL expression and metastasis-related factors. Additionally, RANK/RANKL significantly promoted cell migration/invasion via activating AKT/β-catenin/Snail pathway in vitro. However, RANK/RANKL-induced AKT activation could be suppressed after osteoprotegerin (OPG) treatment. Furthermore, the combination of medroxyprogesterone acetate (MPA) and RANKL could in turn attenuate the effect of RANKL alone. Similarly, MPA could partially inhibit the RANK-induced metastasis in an orthotopic mouse model via suppressing AKT/β-catenin/Snail pathway. Therefore, therapeutic inhibition of MPA in RANK/RANKL-induced metastasis was mediated by AKT/β-catenin/Snail pathway both in vitro and in vivo, suggesting a potential target of RANK for gene-based therapy for EC.

RANK/RANKL expression in prostate cancer

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Expression of RANK and RANKL genes in prostate cancer is higher than non-neoplastic prostate.

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RANK/RANKL expression is not related to pathological features.

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There is no significant correlation of RANK/RANKL expression with biochemical recurrence after radical prostatectomy.

RANK-RANKL signalling in cancer

Oncogenic events combined with a favourable environment are the two main factors in the oncological process. The tumour microenvironment is composed of a complex, interconnected network of protagonists, including soluble factors such as cytokines, extracellular matrix components, interacting with fibroblasts, endothelial cells, immune cells and various specific cell types depending on the location of the cancer cells (e.g. pulmonary epithelium, osteoblasts). This diversity defines specific "niches" (e.g. vascular, immune, bone niches) involved in tumour growth and the metastatic process. These actors communicate together by direct intercellular communications and/or in an autocrine/paracrine/endocrine manner involving cytokines and growth factors. Among these glycoproteins, RANKL (receptor activator nuclear factor-κB ligand) and its receptor RANK (receptor activator nuclear factor), members of the TNF and TNFR superfamilies, have stimulated the interest of the scientific community. RANK is frequently expressed by cancer cells in contrast with RANKL which is frequently detected in the tumour microenvironment and together they participate in every step in cancer development. Their activities are markedly regulated by osteoprotegerin (OPG, a soluble decoy receptor) and its ligands, and by LGR4, a membrane receptor able to bind RANKL. The aim of the present review is to provide an overview of the functional implication of the RANK/RANKL system in cancer development, and to underline the most recent clinical studies.

Snail promotes resistance to enzalutamide through regulation of androgen receptor activity in prostate cancer

Treatment with androgen-targeted therapies can induce upregulation of epithelial plasticity pathways. Epithelial plasticity is known to be important for metastatic dissemination and therapeutic resistance. The goal of this study is to elucidate the functional consequence of induced epithelial plasticity on AR regulation during disease progression to identify factors important for treatment-resistant and metastatic prostate cancer. We pinpoint the epithelial plasticity transcription factor, Snail, at the nexus of enzalutamide resistance and prostate cancer metastasis both in preclinical models of prostate cancer and in patients. In patients, Snail expression is associated with Gleason 9-10 high-risk disease and is strongly overexpressed in metastases as compared to localized prostate cancer. Snail expression is also elevated in enzalutamide-resistant prostate cancer cells compared to enzalutamide-sensitive cells, and downregulation of Snail re-sensitizes enzalutamide-resistant cells to enzalutamide. While activation of Snail increases migration and invasion, it is also capable of promoting enzalutamide resistance in enzalutamide-sensitive cells. This Snail-mediated enzalutamide resistance is a consequence of increased full-length AR and AR-V7 expression and nuclear localization. Downregulation of either full-length AR or AR-V7 re-sensitizes cells to enzalutamide in the presence of Snail, thus connecting Snail-induced enzalutamide resistance directly to AR biology. Finally, we demonstrate that Snail is capable of mediating-resistance through AR even in the absence of AR-V7. These findings imply that increased Snail expression during progression to metastatic disease may prime cells for resistance to AR-targeted therapies by promoting AR activity in prostate cancer.

Mouse models for studying prostate cancer bone metastasis

Once tumor cells metastasize to the bone, the prognosis for prostate cancer patients is generally very poor. The mechanisms involved in bone metastasis, however, remain elusive, because of lack of relevant animal models. In this manuscript, we describe step-by-step protocols for the xenograft mouse models that are currently used for studying prostate cancer bone metastasis. The different routes of tumor inoculation (intraosseous, intracardiac, intravenous and orthotopic) presented are useful for exploring the biology of bone metastasis.

Development of Functional Microfold (M) Cells from Intestinal Stem Cells in Primary Human Enteroids

Background & Aims

Intestinal microfold (M) cells are specialized epithelial cells that act as gatekeepers of luminal antigens in the intestinal tract. They play a critical role in the intestinal mucosal immune response through transport of viruses, bacteria and other particles and antigens across the epithelium to immune cells within Peyer’s patch regions and other mucosal sites. Recent studies in mice have demonstrated that M cells are generated from Lgr5+ intestinal stem cells (ISCs), and that infection with Salmonella enterica serovar Typhimurium increases M cell formation. However, it is not known whether and how these findings apply to primary human small intestinal epithelium propagated in an in vitro setting.

Methods

Human intestinal crypts were grown as monolayers with growth factors and treated with recombinant RANKL, and assessed for mRNA transcripts, immunofluorescence and uptake of microparticles and S. Typhimurium.

Results

Functional M cells were generated by short-term culture of freshly isolated human intestinal crypts in a dose- and time-dependent fashion. RANKL stimulation of the monolayer cultures caused dramatic induction of the M cell-specific markers, SPIB, and Glycoprotein-2 (GP2) in a process primed by canonical WNT signaling. Confocal microscopy demonstrated a pseudopod phenotype of GP2-positive M cells that preferentially take up microparticles. Furthermore, infection of the M cell-enriched cultures with the M cell-tropic enteric pathogen, S. Typhimurium, led to preferential association of the bacteria with M cells, particularly at lower inoculum sizes. Larger inocula caused rapid induction of M cells.

Conclusions

Human intestinal crypts containing ISCs can be cultured and differentiate into an epithelial layer with functional M cells with characteristic morphological and functional properties. This study is the first to demonstrate that M cells can be induced to form from primary human intestinal epithelium, and that S. Typhimurium preferentially infect these cells in an in vitro setting. We anticipate that this model can be used to generate large numbers of M cells for further functional studies of these key cells of intestinal immune induction and their impact on controlling enteric pathogens and the intestinal microbiome.

Role of EMT in Metastasis and Therapy Resistance

Epithelial-mesenchymal transition (EMT) is a complex molecular program that regulates changes in cell morphology and function during embryogenesis and tissue development. EMT also contributes to tumor progression and metastasis. Cells undergoing EMT expand out of and degrade the surrounding microenvironment to subsequently migrate from the primary site. The mesenchymal phenotype observed in fibroblasts is specifically important based on the expression of smooth muscle actin (α-SMA), fibroblast growth factor (FGF), fibroblast-specific protein-1 (FSP1), and collagen to enhance EMT. Although EMT is not completely dependent on EMT regulators such as Snail, Twist, and Zeb-1/-2, analysis of upstream signaling (i.e., TGF-β, EGF, Wnt) is necessary to understand tumor EMT more comprehensively. Tumor epithelial-fibroblast interactions that regulate tumor progression have been identified during prostate cancer. The cellular crosstalk is significant because these events influence therapy response and patient outcome. This review addresses how canonical EMT signals originating from prostate cancer fibroblasts contribute to tumor metastasis and recurrence after therapy.

MiR-548c impairs migration and invasion of endometrial and ovarian cancer cells via downregulation of Twist

BACKGROUND

MicroRNAs (miRNAs) are a class of small non-coding RNAs, which post-transcriptionally repress the expression of genes involved in cancer initiation and progression. Although some miRNAs that target many signaling pathways (also called universe miRNAs) are supposed to play a global role in diverse human tumors, their regulatory functions in gynecological cancers remain largely unknown. We investigated the biological role and underlying mechanism of miR-548c (one universe miRNA) in endometrial and ovarian cancer.

METHODS

The effects of miR-548c overexpression on cell proliferation, migration and invasion were studied in endometrial and ovarian cancer cells. TWIST1 (Twist) was identified as a direct miR-548c target by western blot analysis and luciferase activity assay. The expression of miR-548c and Twist were examined by qRT-PCR in endometrial and ovarian cancer tissues.

RESULTS

Here, we report that miR-548c is down-regulated in endometrial and ovarian cancer tissues when compared to normal tissues, and our meta-analysis reveal that decreased miR-548c expression correlates with poor prognosis in endometrial cancer patients. We show that in endometrial and ovarian cancer cells, ectopic expression of miR-548c significantly inhibits whereas knockdown of miR-548c dramatically induces cancer cell proliferation, migration and invasion. By using luciferase reporter assay, we demonstrate that Twist, a known oncogene in endometrial and ovarian cancers, is a direct target of miR-548c. Furthermore, the expression of Twist partially abrogates the tumor suppressive effects of miR-548c on cell migration and invasion.

CONCLUSION

These findings suggest that miR-548c directly downregulates Twist, and provide a novel mechanism for Twist upregulation in both endometrial and ovarian cancers. The use of miR-548c may hold therapeutic potential for the treatment of Twist-overexpressing tumors.

SNAIL transcription factor increases the motility and invasive capacity of prostate cancer cells

The incidence and mortality rates of prostate cancer (PCa) are increasing, and PCa is almost the second-leading cause of cancer-associated mortality in men. During tumor progression, epithelial cells decrease the number of adhesion molecules, change their polarity and position, rearrange their cytoskeleton and increase their migratory and invasive capacities. These changes are known under the concept of epithelial-mesenchymal transition (EMT). EMT is characterized by an upregulation of certain transcription factors, including SNAIL1, which represses genes that are characteristic of an epithelial phenotype, including E-cadherin, and indirectly increase the expression levels of genes, which are associated with the mesenchymal phenotype. It has been suggested that the transcription factor, SNAIL1, decreases the proliferation and increases the migratory and invasive capacities of PCa cell lines. The present study was performed using LNCaP and PC3 cell lines, in which the expression levels of SNAIL1 were increased or silenced through the use of lentiviral vectors. The expression levels of EMT markers were quantified using reverse transcription-quantitative polymerase chain reaction and western blot analysis. In addition, cell survival was analyzed using an MTS assay; cell proliferation was examined using an antibody targeting Ki-67; migration on plates with 8 µm pores to allow the passage of cells; and invasiveness was analyzed using a membrane chamber covered in dried basement membrane matrix solution. The levels of apoptosis were determined using a Caspase 3/7 assay containing a substrate modified by caspases 3 and 7. The results demonstrated that the overexpression and silencing of SNAIL1 decreased cell proliferation and survival. However, the overexpression of SNAIL1 decreased apoptosis, compared with cells with the SNAIL1-silenced cells, in which cell apoptosis increased. The migration and invasive capacities increased in the cells overexpressing SNAIL1, and decreased when SNAIL1 was silenced. In conclusion, PCa cells overexpressing SNAIL1 exhibited characteristics of an EMT phenotype, whereas the silencing of the SNAIL1 transcriptional repressor promoted an epithelial-like phenotype, with decreased migration and invasion, characteristic of mesenchymal cells.

Hepatocyte growth factor increases the invasive potential of PC-3 human prostate cancer cells via an ERK/MAPK and Zeb-1 signaling pathway

Hepatocyte growth factor (HGF) has been implicated in epithelial-mesenchymal transition (EMT) in numerous types of cancer. However, to the best of our knowledge, there has been no previous evidence that HGF has a role in prostate cancer. The present study aimed to investigate the effect of HGF on EMT and invasive potential, as well as the underlying molecular mechanisms, in a human prostate cancer cell line. Therefore, PC-3 cells were treated with various concentrations of HGF for varying durations. EMT-associated proteins, including E-cadherin and vimentin, were examined by western blot analysis. The effects of HGF on cell proliferation, migration, invasion and tumorigenicity were assessed using MTT, wound-healing, Transwell and soft-agar assays. Subsequently, the role of c-Met in the mediation of EMT-like changes was investigated using reverse transcription-polymerase chain reaction, western blot analysis and gene knockdown by small interfering RNA. Finally, western blot analysis was used to quantify the expression of a downstream transcription factor and extracellular signal-related kinase/mitogen activated protein kinase (ERK/MAPK) signaling pathway proteins. The results indicated that treatment with HGF induced EMT-like changes and enhanced the invasive potential of PC-3 cells. There was an increase in the expression of ERK, phosphorylated-ERK and zinc finger E-box binding homeobox-1 (Zeb-1), suggesting that EMT-like changes may be mediated through the ERK/MAPK and Zeb-1 signaling pathway. Furthermore, HGF-mediated EMT-like changes were associated with c-Met activation, and these changes were able to be blocked by c-Met knockdown. The present study demonstrated that HGF-induced EMT increased the invasive potential of PC-3 human prostate cancer cells through activating the ERK/MAPK and Zeb-1 signaling pathway.

Muscadine grape skin extract can antagonize Snail-cathepsin L-mediated invasion, migration and osteoclastogenesis in prostate and breast cancer cells

To develop new and effective chemopreventive agents against bone metastasis, we assessed the effects of muscadine grape skin extract (MSKE), whose main bioactive component is anthocyanin, on bone turnover, using prostate and breast cancer cell models overexpressing Snail transcription factor. MSKE has been shown previously to promote apoptosis in prostate cancer cells without affecting normal prostate epithelial cells. Snail is overexpressed in prostate and breast cancer, and is associated with increased invasion, migration and bone turnover/osteoclastogenesis. Cathepsin L (CatL) is a cysteine cathepsin protease that is overexpressed in cancer and involved in bone turnover. Snail overexpression in prostate (LNCaP, ARCaP-E) and breast (MCF-7) cancer cells led to increased CatL expression/activity and phosphorylated STAT-3 (pSTAT-3), compared to Neo vector controls, while the reverse was observed in C4-2 (the aggressive subline of LNCaP) cells with Snail knockdown. Moreover, CatL expression was higher in prostate and breast tumor tissue compared to normal tissue. MSKE decreased Snail and pSTAT3 expression, and abrogated Snail-mediated CatL activity, migration and invasion. Additionally, Snail overexpression promoted osteoclastogenesis, which was significantly inhibited by the MSKE as effectively as Z-FY-CHO, a CatL-specific inhibitor, or osteoprotegerin, a receptor activator of nuclear factor kappa B ligand (RANKL) antagonist. Overall, these novel findings suggest that Snail regulation of CatL may occur via STAT-3 signaling and can be antagonized by MSKE, leading to decreased cell invasion, migration and bone turnover. Therefore, inhibition using a natural product such as MSKE could potentially be a promising bioactive compound for bone metastatic cancer.