Prostate cancer bone metastases acquire resistance to androgen deprivation via WNT5A-mediated BMP-6 induction

Identification of a 9-gene signature to enhance biochemical recurrence prediction in primary prostate cancer: A benchmarking study using ten machine learning methods and twelve patient cohorts

Prostate cancer (PCa) is a prevalent malignancy among men worldwide, and biochemical recurrence (BCR) after radical prostatectomy (RP) is a critical turning point commonly used to guide the development of treatment strategies for primary PCa. However, the clinical parameters currently in use are inadequate for precise risk stratification and informing treatment choice. To address this issue, we conducted a study that collected transcriptomic data and clinical information from 1662 primary PCa patients across 12 multicenter cohorts globally. We leveraged 101 algorithm combinations that consisted of 10 machine learning methods to develop and validate a 9-gene signature, named BCR SCR, for predicting the risk of BCR after RP. Our results demonstrated that BCR SCR generally outperformed 102 published prognostic signatures. We further established the clinical significance of these nine genes in PCa progression at the protein level through immunohistochemistry on Tissue Microarray (TMA). Moreover, our data showed that patients with higher BCR SCR tended to have higher rates of BCR and distant metastasis after radical radiotherapy. Through drug target prediction analysis, we identified nine potential therapeutic agents for patients with high BCR SCR. In conclusion, the newly developed BCR SCR has significant translational potential in accurately stratifying the risk of patients who undergo RP, monitoring treatment courses, and developing new therapies for the disease.

BMP Stimulation Differentially Affects Phosphorylation and Protein Stability of β-Catenin in Breast Cancer Cell Lines

Increased expression and nuclear translocation of β-CATENIN is frequently observed in breast cancer, and it correlates with poor prognosis. Current treatment strategies targeting β-CATENIN are not as efficient as desired. Therefore, detailed understanding of β-CATENIN regulation is crucial. Bone morphogenetic proteins (BMP) and Wingless/Integrated (WNT) pathway crosstalk is well-studied for many cancer types including colorectal cancer, whereas it is still poorly understood for breast cancer. Analysis of breast cancer patient data revealed that BMP2 and BMP6 were significantly downregulated in tumors. Since mutation frequency in genes enhancing β-CATENIN protein stability is relatively low in breast cancer, we aimed to investigate whether decreased BMP ligand expression could contribute to a high protein level of β-CATENIN in breast cancer cells. We demonstrated that downstream of BMP stimulation, SMAD4 is required to reduce β-CATENIN protein stability through the phosphorylation in MCF7 and T47D cells. Consequently, BMP stimulation reduces β-CATENIN levels and prevents its nuclear translocation and target gene expression in MCF7 cells. Conversely, BMP stimulation has no effect on β-CATENIN phosphorylation or stability in MDA-MB-231 and MDA-MB-468 cells. Likewise, SMAD4 modulation does not alter the response of those cells, indicating that SMAD4 alone is insufficient for BMP-induced β-CATENIN phosphorylation. While our data suggest that considering BMP activity may serve as a prognostic marker for understanding β-CATENIN accumulation risk, further investigation is needed to elucidate the differential responsiveness of breast cancer cell lines.

BMP signaling in cancer stemness and differentiation

The BMP (Bone morphogenetic protein) signaling pathway plays a central role in metazoan biology, intricately shaping embryonic development, maintaining tissue homeostasis, and influencing disease progression. In the context of cancer, BMP signaling exhibits context-dependent dynamics, spanning from tumor suppression to promotion. Cancer stem cells (CSCs), a modest subset of neoplastic cells with stem-like attributes, exert substantial influence by steering tumor growth, orchestrating therapy resistance, and contributing to relapse. A comprehensive grasp of the intricate interplay between CSCs and their microenvironment is pivotal for effective therapeutic strategies. Among the web of signaling pathways orchestrating cellular dynamics within CSCs, BMP signaling emerges as a vital conductor, overseeing CSC self-renewal, differentiation dynamics, and the intricate symphony within the tumor microenvironment. Moreover, BMP signaling's influence in cancer extends beyond CSCs, intricately regulating cellular migration, invasion, and metastasis. This multifaceted role underscores the imperative of comprehending BMP signaling's contributions to cancer, serving as the foundation for crafting precise therapies to navigate multifaceted challenges posed not only by CSCs but also by various dimensions of cancer progression. This article succinctly encapsulates the diverse roles of the BMP signaling pathway across different cancers, spanning glioblastoma multiforme (GBM), diffuse intrinsic pontine glioma (DIPG), colorectal cancer, acute myeloid leukemia (AML), lung cancer, prostate cancer, and osteosarcoma. It underscores the necessity of unraveling underlying mechanisms and molecular interactions. By delving into the intricate tapestry of BMP signaling's engagement in cancers, researchers pave the way for meticulously tailored therapies, adroitly leveraging its dualistic aspects-whether as a suppressor or promoter-to effectively counter the relentless march of tumor progression.

Wnt Signaling and Therapeutic Resistance in Castration-Resistant Prostate Cancer

Purpose of Review

Castration-resistant prostate cancer (CRPC) is a lethal form of prostate cancer (PCa) due to the development of resistance to androgen deprivation therapy and anti-androgens. Here, we review the emerging role of Wnt signaling in therapeutic resistance of CRPC.

Recent Findings

Convincing evidence have accumulated that Wnt signaling is aberrantly activated through genomic alterations and autocrine and paracrine augmentations. Wnt signaling plays a critical role in a subset of CRPC and in resistance to anti-androgen therapies. Wnt signaling navigates CRPC through PCa heterogeneity, neuroendocrine differentiation, DNA repair, PCa stem cell maintenance, epithelial-mesenchymal-transition and metastasis, and immune evasion.

Summary

Components of Wnt signaling can be harnessed for inhibiting PCa growth and metastasis and for developing novel therapeutic strategies to manage metastatic CRPC. There are many Wnt pathway-based potential drugs in different stages of pre-clinical development and clinical trials but so far, no Wnt signaling-specific drug has been approved by FDA for clinical use in CRPC.

WNT ligands in non-small cell lung cancer: from pathogenesis to clinical practice

Non-small cell lung cancer (NSCLC) is the malignant tumor with the highest morbidity and leading cause of death worldwide, whereas its pathogenesis has not been fully elucidated. Although mutations in some crucial genes in WNT pathways such as β-catenin and APC are not common in NSCLC, the abnormal signal transduction of WNT pathways is still closely related to the occurrence and progression of NSCLC. WNT ligands (WNTs) are a class of secreted glycoproteins that activate WNT pathways through binding to their receptors and play important regulatory roles in embryonic development, cell differentiation, and tissue regeneration. Therefore, the abnormal expression or dysfunction of WNTs undoubtedly affects WNT pathways and thus participates in the pathogenesis of diseases. There are 19 members of human WNTs, WNT1, WNT2, WNT2b, WNT3, WNT3a, WNT4, WNT5a, WNT5b, WNT6, WNT7a, WNT7b, WNT8a, WNT8b, WNT9a, WNT9b, WNT10a, WNT10b, WNT11 and WNT16. The expression levels of WNTs, binding receptors, and activated WNT pathways are diverse in different tissue types, which endows the complexity of WNT pathways and multifarious biological effects. Although abundant studies have reported the role of WNTs in the pathogenesis of NSCLC, it still needs further study as therapeutic targets for lung cancer. This review will systematically summarize current research on human WNTs in NSCLC, from molecular pathogenesis to potential clinical practice.

Wnt Signaling in the Development of Bone Metastasis

Wnt signaling occurs through evolutionarily conserved pathways that affect cellular proliferation and fate decisions during development and tissue maintenance. Alterations in these highly regulated pathways, however, play pivotal roles in various malignancies, promoting cancer initiation, growth and metastasis and the development of drug resistance. The ability of cancer cells to metastasize is the primary cause of cancer mortality. Bone is one of the most frequent sites of metastases that generally arise from breast, prostate, lung, melanoma or kidney cancer. Upon their arrival to the bone, cancer cells can enter a long-term dormancy period, from which they can be reactivated, but can rarely be cured. The activation of Wnt signaling during the bone metastasis process was found to enhance proliferation, induce the epithelial-to-mesenchymal transition, promote the modulation of the extracellular matrix, enhance angiogenesis and immune tolerance and metastasize and thrive in the bone. Due to the complexity of Wnt pathways and of the landscape of this mineralized tissue, Wnt function during metastatic progression within bone is not yet fully understood. Therefore, we believe that a better understanding of these pathways and their roles in the development of bone metastasis could improve our understanding of the disease and may constitute fertile ground for potential therapeutics.

Epigenetic Silencing of BMP6 by the SIN3A-HDAC1/2 Repressor Complex Drives Melanoma Metastasis via FAM83G/PAWS1

Aberrant epigenetic transcriptional regulation is linked to metastasis, a primary cause of cancer-related death. Dissecting the epigenetic mechanisms controlling metastatic progression may uncover important insights to tumor biology and potential therapeutic targets. Here, we investigated the role of the SIN3A histone deacetylase 1 and 2 (SIN3A-HDAC1/2) complex in cancer metastasis. Using a mouse model of melanoma metastasis, we found that the SIN3A-HDAC1/2 transcription repressor complex silences BMP6 expression, causing increased metastatic dissemination and tumor growth via suppression of BMP6-activated SMAD5 signaling. We further discovered that FAM83G/PAWS1, a downstream effector of BMP6-SMAD5 signaling, contributes critically to metastatic progression by promoting actin-dependent cytoskeletal dynamics and cell migration. Pharmacologic inhibition of the SIN3A-HDAC1/2 complex reduced the numbers of melanoma cells in the circulation and inhibited metastatic tumor growth by inducing disseminated cell dormancy, highlighting the SIN3A-HDAC1/2 repressor complex as a potential therapeutic target for blocking cancer metastasis. IMPLICATIONS: This study identifies the novel molecular links in the metastatic progression to target cytoskeletal dynamics in melanoma and identifies the SIN3A-HDAC1/2 complex and FAM83G/PAWS1 as potential targets for melanoma adjuvant therapy.

Altered Wnt5a expression affects radiosensitivity of non-small cell lung cancer via the Wnt/β-catenin pathway

It has been reported that upregulation of wingless-type protein 5a (Wnt5a) is associated with poor prognosis in patients with non-small cell lung cancer (NSCLC). Wnt5a expression is often upregulated in radiation-resistant NSCLC cells. However, the biological functions or molecular mechanisms of radiosensitivity in NSCLC remain unknown. In the present study, MTT assay and flow cytometric analysis were performed to assess the effect of overexpression or knockdown of Wnt5a and/or radiation on the proliferation and apoptosis of NSCLC cells. Furthermore, western blot analysis was performed to detect canonical Wnt signaling (β-catenin) in H1650 and A549 cells. The results demonstrated that Wnt5a knockdown combined with irradiation inhibited proliferation and induced apoptosis in NSCLC cells compared with Wnt5a knockdown or radiotherapy alone. In addition, the combination of Wnt5a knockdown and irradiation decreased nuclear and increased cytoplasmic β-catenin expression in H1650 and A549 cells, the effects of which were reversed following overexpression of Wnt5a. The combination of overexpressing Wnt5a and irradiation resulted in significant tumor regression, while β-catenin knockdown reversed Wnt5a overexpression-induced NSCLC cell proliferation. Taken together, these results suggest that Wnt5a may be involved in the activation of β-catenin-dependent canonical Wnt signaling, and thus may influence the effectiveness of radiation therapy in NSCLC.

Role of the BMP6 protein in breast cancer and other types of cancer

The BMP6 protein (Bone Morphogenetic Protein 6) is part of the superfamily of transforming growth factor-beta (TGF-β) ligands, participates in iron homeostasis, inhibits invasion by increasing adhesions and cell-cell type interactions and induces angiogenesis directly on vascular endothelial cells. BMP6 is coded by a tumor suppressor gene whose subexpression is related to the development and cancer progression; during neoplastic processes, methylation is the main mechanism by which gene silencing occurs. This work presents a review on the role of BMP6 protein in breast cancer (BC) and other types of cancer. The studies carried out to date suggest the participation of the BMP6 protein in the epithelial-mesenchymal transition (EMT) phenotype, cell growth and proliferation; however, these processes are affected in a variable way in the different types of cancer, the methylated CpG sites in BMP6 gene promoter, as well as the interaction with other proteins could be the cause of such variation.

Mechanisms of the Osteogenic Switch of Smooth Muscle Cells in Vascular Calcification: WNT Signaling, BMPs, Mechanotransduction, and EndMT

Characterized by the hardening of arteries, vascular calcification is the deposition of hydroxyapatite crystals in the arterial tissue. Calcification is now understood to be a cell-regulated process involving the phenotypic transition of vascular smooth muscle cells into osteoblast-like cells. There are various pathways of initiation and mechanisms behind vascular calcification, but this literature review highlights the wingless-related integration site (WNT) pathway, along with bone morphogenic proteins (BMPs) and mechanical strain. The process mirrors that of bone formation and remodeling, as an increase in mechanical stress causes osteogenesis. Observing the similarities between the two may aid in the development of a deeper understanding of calcification. Both are thought to be regulated by the WNT signaling cascade and bone morphogenetic protein signaling and can also be activated in response to stress. In a pro-calcific environment, integrins and cadherins of vascular smooth muscle cells respond to a mechanical stimulus, activating cellular signaling pathways, ultimately resulting in gene regulation that promotes calcification of the vascular extracellular matrix (ECM). The endothelium is also thought to contribute to vascular calcification via endothelial to mesenchymal transition, creating greater cell plasticity. Each of these factors contributes to calcification, leading to increased cardiovascular mortality in patients, especially those suffering from other conditions, such as diabetes and kidney failure. Developing a better understanding of the mechanisms behind calcification may lead to the development of a potential treatment in the future.

MCM3AP-AS1/miR-876-5p/WNT5A axis regulates the proliferation of prostate cancer cells

BACKGROUND

Although the fact that long non-coding RNA MCM3AP antisense RNA 1 (MCM3AP-AS1) is oncogenic in several cancers is well documented, very few researchers investigate its expression and function in prostate cancer.

METHODS

Paired prostate cancer samples were selected, and expressions of MCM3AP-AS1, miR-876-5p and WNT5A were examined by qRT-PCR. MCM3AP-AS1 shRNA was transfected into LNCaP and PC-3 cell lines, and then the proliferative activity and apoptosis of cancer cells were detected by CCK-8 assay, EdU assay and flow cytometry analysis, respectively. qRT-PCR and Western blot were used to analyze the changes of miR-876-5p and WNT5A. Luciferase reporter gene assay was employed to determine the regulatory relationship between miR-876-5p and MCM3AP-AS1, miR-876-5p and WNT5A.

RESULTS

MCM3AP-AS1 was significantly up-regulated in cancerous tissues of prostate cancer samples, positively correlated with the expression of WNT5A, while negatively related with miR-876-5p. After transfection of MCM3AP-AS1 shRNA into prostate cancer cells, the proliferative ability of cancer cells was signally inhibited, but the apoptosis of cancer cells was increased. MCM3AP-AS1 shRNA could reduce the expression of WNT5A on both mRNA and protein levels. Besides, MCM3AP-AS1 was identified as a sponge of miR-876-5p. WNT5A was validated as a target gene of miR- 876-5p.

CONCLUSION

MCM3AP-AS1 is abnormally up-regulated in prostate cancer tissues and can modulate the proliferation and apoptosis of prostate cancer cells, which has the potential to be the "ceRNA" to regulate the expression of WNT5A by targeting miR-876-5p.

<p>Expression Level of Wnt5a Was Related to the Therapeutic Effects of First-Generation EGFR-TKIs</p>

Background and Objective

Methods

Results

Conclusion

Comprehensive Analysis Identifying Wnt Ligands Gene Family for Biochemical Recurrence in Prostate Adenocarcinoma and Construction of a Nomogram

There is little research to explore the relationship between Wnt ligands gene family and biochemical recurrence of prostate adenocarcinoma. The purpose of this study was to systematically evaluate the role of Wnt ligands gene family in biochemical recurrence in prostate adenocarcinoma. RNA-seq transcriptome data and clinicopathological data of 489 prostate adenocarcinoma tissues and 51 nontumor tissues were obtained from The Cancer Genome Atlas. We developed a risk score model with the least absolute shrinkage and selection operator Cox regression algorithm. We used the X-tile program to derive the best threshold for risk scores, dividing patients into high-, intermediate-, and low-risk groups. Gene set enrichment analysis (GSEA) was performed. Nomogram was constructed based on the risk score and clinical features. The risk score = (0.192 × expression level of Wnt9A) + (0.732 × expression level of Wnt8B) + (0.051 × expression level of Wnt7B) + (-0.320 × expression level of Wnt3A). The risk score was an independent prognostic factor, with a hazard ratio of 1.298 (95% confidence interval: 1.046-1.612; p = 0.018). GSEA revealed that the Kyoto Encyclopedia of Genes and Genomes pathway of the four selected genes was closely related to malignancy-related biological processes. Nomogram was constructed based on the risk score and clinical features. The C index was 0.719, and the calibration curve showed that the nomogram performed well. In general, we comprehensively evaluated the association between Wnt ligands gene family and biochemical recurrence of prostate cancer. We developed a risk score model based on messenger RNA expression levels of several selected Wnt ligand family genes (Wnt3A, Wnt7B, Wnt8B, and Wnt9A), which was significantly associated with biochemical recurrence of prostate cancer. Our results might be helpful for future molecular studies focusing on the biochemical recurrence of prostate cancer.

Endocrinotherapy resistance of prostate and breast cancer: Importance of the NF‑κB pathway (Review)

Prostate cancer (PCa) and breast cancer (BCa) are two common sex hormone‑related cancer types with high rates of morbidity, and are leading causes of cancer death globally in men and women, respectively. The biological function of androgen or estrogen is a key factor for PCa or BCa tumorigenesis, respectively. Nevertheless, after hormone deprivation therapy, the majority of patients ultimately develop hormone‑independent malignancies that are resistant to endocrinotherapy. It is widely recognized, therefore, that understanding of the mechanisms underlying the process from hormone dependence towards hormone independence is critical to discover molecular targets for the control of advanced PCa and BCa. This review aimed to dissect the important mechanisms involved in the therapeutic resistance of PCa and BCa. It was concluded that activation of the NF‑κB pathway is an important common mechanism for metastasis and therapeutic resistance of the two types of cancer; in particular, the RelB‑activated noncanonical NF‑κB pathway appears to be able to lengthen and strengthen NF‑κB activity, which has been a focus of recent investigations.

Mating induces switch from hormone-dependent to hormone-independent steroid receptor-mediated growth in Drosophila secondary cells

Male reproductive glands like the mammalian prostate and the paired Drosophila melanogaster accessory glands secrete seminal fluid components that enhance fecundity. In humans, the prostate, stimulated by environmentally regulated endocrine and local androgens, grows throughout adult life. We previously showed that in fly accessory glands, secondary cells (SCs) and their nuclei also grow in adults, a process enhanced by mating and controlled by bone morphogenetic protein (BMP) signalling. Here, we demonstrate that BMP-mediated SC growth is dependent on the receptor for the developmental steroid ecdysone, whose concentration is reported to reflect sociosexual experience in adults. BMP signalling appears to regulate ecdysone receptor (EcR) levels via one or more mechanisms involving the EcR's N terminus or the RNA sequence that encodes it. Nuclear growth in virgin males is dependent on ecdysone, some of which is synthesised in SCs. However, mating induces additional BMP-mediated nuclear growth via a cell type-specific form of hormone-independent EcR signalling, which drives genome endoreplication in a subset of adult SCs. Switching to hormone-independent endoreplication after mating allows growth and secretion to be hyperactivated independently of ecdysone levels in SCs, permitting more rapid replenishment of the accessory gland luminal contents. Our data suggest mechanistic parallels between this physiological, behaviour-induced signalling switch and altered pathological signalling associated with prostate cancer progression.

TCF4 induces enzalutamide resistance via neuroendocrine differentiation in prostate cancer

In treating patients with castration resistant prostate cancer (CRPC), enzalutamide, the second-generation androgen receptor (AR) antagonist, is an accepted standard of care. However, clinical benefits are limited to a median time of 4.8 months because resistance inevitably emerges. To determine the mechanism of treatment resistance, we carried out a RNA sequence analysis and found increased expression levels of neuroendocrine markers in the enzalutamide-resistant LNCaP human prostate cancer (CaP) cell line when compared to the parental cell line. Subsequent studies demonstrated that Transcription Factor-4 (TCF4), a transcription factor implicated in WNT signaling, mediated neuroendocrine differentiation (NED) in response to enzalutamide treatment and was elevated in the enzalutamide-resistant LNCaP. In addition, we observed that PTHrP mediated enzalutamide resistance in tissue culture and inducible TCF4 overexpression resulted in enzalutamide-resistance in a mouse xenograft model. Finally, small molecule inhibitors of TCF4 or PTHrP partially reversed enzalutamide resistance in CaP cells. When tissues obtained from men who died of metastatic CaP were examined, a positive correlation was found between the expression levels of TCF4 and PTHrP. Taken together, the current results indicate that TCF4 induces enzalutamide resistance via NED in CaP.

An Autocrine Wnt5a Loop Promotes NF-κB Pathway Activation and Cytokine/Chemokine Secretion in Melanoma

Wnt5a signaling has been implicated in the progression of cancer by regulating multiple cellular processes, largely migration and invasion, epithelial-mesenchymal transition (EMT), and metastasis. Since Wnt5a signaling has also been involved in inflammatory processes in infectious and inflammatory diseases, we addressed the role of Wnt5a in regulating NF-κB, a pivotal mediator of inflammatory responses, in the context of cancer. The treatment of melanoma cells with Wnt5a induced phosphorylation of the NF-κB subunit p65 as well as IKK phosphorylation and IκB degradation. By using cDNA overexpression, RNA interference, and dominant negative mutants we determined that ROR1, Dvl2, and Akt (from the Wnt5a pathway) and TRAF2 and RIP (from the NF-κB pathway) are required for the Wnt5a/NF-κB crosstalk. Wnt5a also induced p65 nuclear translocation and increased NF-κB activity as evidenced by reporter assays and a NF-κB-specific upregulation of RelB, Bcl-2, and Cyclin D1. Further, stimulation of melanoma cells with Wnt5a increased the secretion of cytokines and chemokines, including IL-6, IL-8, IL-11, and IL-6 soluble receptor, MCP-1, and TNF soluble receptor I. The inhibition of endogenous Wnt5a demonstrated that an autocrine Wnt5a loop is a major regulator of the NF-κB pathway in melanoma. Taken together, these results indicate that Wnt5a activates the NF-κB pathway and has an immunomodulatory effect on melanoma through the secretion of cytokines and chemokines.

Systematically understanding the immunity leading to CRPC progression

Prostate cancer (PCa) is the most commonly diagnosed malignancy and the second leading cause of cancer-related death in American men. Androgen deprivation therapy (ADT) has become a standard treatment strategy for advanced PCa. Although a majority of patients initially respond to ADT well, most of them will eventually develop castration-resistant PCa (CRPC). Previous studies suggest that ADT-induced changes in the immune microenvironment (mE) in PCa might be responsible for the failures of various therapies. However, the role of the immune system in CRPC development remains unclear. To systematically understand the immunity leading to CRPC progression and predict the optimal treatment strategy in silico, we developed a 3D Hybrid Multi-scale Model (HMSM), consisting of an ODE system and an agent-based model (ABM), to manipulate the tumor growth in a defined immune system. Based on our analysis, we revealed that the key factors (e.g. WNT5A, TRAIL, CSF1, etc.) mediated the activation of PC-Treg and PC-TAM interaction pathways, which induced the immunosuppression during CRPC progression. Our HMSM model also provided an optimal therapeutic strategy for improving the outcomes of PCa treatment.

SOX4: The unappreciated oncogene

SOX4 is an essential developmental transcription factor that regulates stemness, differentiation, progenitor development, and multiple developmental pathways including PI3K, Wnt, and TGFβ signaling. The SOX4 gene is frequently amplified and overexpressed in over 20 types of malignancies, and multiple lines of evidence support that notion that SOX4 is an oncogene. Its overexpression is due to both gene amplification and to activation of PI3K, Wnt, and TGFβ pathways that SOX4 regulates. SOX4 interacts with multiple other transcription factors, rendering many of its impacts on gene expression context and tissue-specific. Nevertheless, there are common themes that run through many of the effects of SOX4 hyperactivity, such as the promotion of cell survival, stemness, the epithelial to mesenchymal transition, migration, and metastasis. Specific targeting of SOX4 remains a challenge for future cancer research and drug development.

Phospholipase C (PLC)ε Promotes Androgen Receptor Antagonist Resistance via the Bone Morphogenetic Protein (BMP)-6/SMAD Axis in a Castration-Resistant Prostate Cancer Cell Line

Background

Primary therapy for patients with advanced prostate cancer (PCa) consists of androgen deprivation therapy targeting the androgen receptor (AR) axis. However, most tumors progress to castration-resistant prostate cancer (CRPC) within 18–24 months. The purpose of the present study was to investigate the mechanisms through which PCa acquires drug resistance after long-term treatment with AR antagonists.

Material/Methods

Online database analysis and bioinformatics analysis were performed to identify signaling activated during anti-androgen treatment. MTT assay was used to detect cell viability. RT-qPCR was performed to examine the mRNA expression of the indicated genes. Colony formation assay was performed to observe cell proliferation. Transwell assay was conducted to demonstrate invasive ability. Protein levels were determined by Western blot analysis and immunofluorescence assays.

Results

An online database search and bioinformatics analysis indicated that bone morphogenetic protein (BMP)-6/SMAD signaling was activated in enzalutamide-resistant LNCaP cells. Furthermore, this signaling interaction was experimentally verified in bicalutamide- and enzalutamide-resistant LNCaP cells, which may be regulated by phospholipase C (PLC)ɛ and induced cell proliferation and invasion. Of note, a positive correlation was observed between PLCɛ and BMP-6 in CRPC tissue samples, which may promote bone metastasis and suggests a poor prognosis.

Conclusions

The present results suggest that targeting of PLCɛ/BMP-6/SMAD signaling may increase the sensitivity of CRPC to AR antagonists and inhibit tumor progression.

Prognostic significance of bone morphogenetic protein 6 (BMP6) expression, clinical and pathological factors in clinically node-negative oral squamous cell carcinoma (OSCC)

Bone morphogenetic protein 6 (BMP6) has unique properties regarding structure and function in supporting bone formation during development and adult life. Despite its known role in various malignant tumors, the prognostic significance of BMP6 expression in oral squamous cell carcinoma (OSCC) remains unknown. The aim of the study was to investigate immunohistochemical expression of BMP6 in OSCC in correlation with clinical and pathological parameters, disease recurrence and survival. In addition, we investigated other parameters in order to identify prognosticators of neck metastases and final outcome. The study included 120 patients with clinically T1-3N0 OSCC who were primarily surgically treated between 2003 and 2008. There were 99 (82.5%) male and 21 (17.5%) female patients. The five-year disease-specific survival for the whole cohort was 79.7%. Tumors smaller than 2 cm in diameter showed higher incidence of strong BMP6 expression. No statistical correlation was observed between other clinico-pathological factors and BMP6 expression. Expression of BMP6 was not associated with disease recurrence and survival. BMP6 may not serve as prognosticator of final outcome or recurrence in clinically node-negative OSCC subjects. In multivariate analysis predictors of poorer survival were positive surgical margin, moderate tumor cell differentiation and pathological involvement of levels IV and/or V.

Molecular underpinnings of enzalutamide resistance

Prostate cancer (PCa) is among the most common adult malignancies, and the second leading cause of cancer-related death in men. As PCa is hormone dependent, blockade of the androgen receptor (AR) signaling is an effective therapeutic strategy for men with advanced metastatic disease. The discovery of enzalutamide, a compound that effectively blocks the AR axis and its clinical application has led to a significant improvement in survival time. However, the effect of enzalutamide is not permanent, and resistance to treatment ultimately leads to development of lethal disease, for which there currently is no cure. This review will focus on the molecular underpinnings of enzalutamide resistance, bridging the gap between the preclinical and clinical research on novel therapeutic strategies for combating this lethal stage of prostate cancer.

Role of key players in paradigm shifts of prostate cancer bone metastasis

The decreased bone mineral density and compromised bone strength predispose individuals to skeletal osteoporosis. Both prostate cancer and bone metastasis caused by cancer invasion have remained a great challenge to researchers. With the advancement in the fields of biochemistry and biomechanics, the molecular mechanisms that make prostate cancer metastasize to bone have recently been identified, and they provide new molecular targets for drug development. Many biochemical by-products have been identified to help in understanding the interaction between the bone and the tumor. Enhanced clinical management of patients with bone metastases was reported during the past decade; however, the anticipated risk and the response to the therapy are still challenging to assess. In this review, the key players that play a dominant role in secondary osteoporosis are addressed. An attempt is made to provide the readers with a clear understanding of the communication pathways between each of the cell types involved in this vicious cycle. Furthermore, the role of Wnts, sclerostin, RANKL, PTHrP, and their respective clinical studies are addressed in this study.

miR-129-5p targets Wnt5a to block PKC/ERK/NF-κB and JNK pathways in glioblastoma

Therapeutic application of microRNAs (miRNAs) in Wnt-driven glioma has been valuable; however, their specific roles and mechanisms have not been completely investigated. Real-time quantitative PCR (RT-qPCR) was used to analyse the expression of microRNA-129-5p (miR-129-5p) in human glioma samples. Cell-Counting Kit 8 (CCK-8), flow cytometry, EdU, angiogenesis, Transwell invasion, wound healing, in vitro 3D migration and neurosphere formation assays were employed to assess the role of miR-129-5p in glioblastoma multiforme (GBM) cells. Moreover, we performed the luciferase reporter assay and the RNA-ChIP (chromatin immunoprecipitation) assay to confirm whether Wnt5a was a direct target of miR-129-5p. We also confirmed the correlation between the expression profile of miR-129-5p and Wnt5a in glioma patients from the Chinese Glioma Genome Atlas (CGGA) and investigated the overall survival of GBM patients using two data sets, namely, TCGA and GSE16011, according to their Wnt5a expression status. MiR-129-5p expression levels were downregulated and inversely correlated with Wnt5a expression levels in CGGA glioma patients. Restored expression of miR-129-5p blocked GBM cell proliferation, invasion, migration, angiogenesis, neurosphere formation and resistance to temozolomide. We reported that miR-129-5p directly targeted Wnt5a in glioma. Furthermore, we observed that overexpression of miR-129-5p inhibited the expression of Wnt5a, thus blocking the protein kinase C(PKC)/ERK/NF-κB and JNK pathways. Inhibiting Wnt5a rescued the effects of miR-129-5p loss and increased Wnt5a expression was associated with reduced overall survival of GBM patients. We also demonstrated the inhibitory effect of miR-129-5p on tumour growth in GBM using an in vivo model. The miR-129-5p/Wnt5a-axis-mediated PKC/ERK/NF-κB and JNK pathways have therapeutic potential in GBM treatment.

A novel non-canonical Wnt signature for prostate cancer aggressiveness

Activation of the Canonical Wnt pathway (CWP) has been linked to advanced and metastatic prostate cancer, whereas the Wnt5a-induced non-canonical Wnt pathway (NCWP) has been associated with both good and poor prognosis. A newly discovered NCWP, Wnt5/Fzd2, has been shown to induce epithelial-to-mesenchymal transition (EMT) in cancers, but has not been investigated in prostate cancer. The aim of this study was to investigate if the CWP and NCWP, in combination with EMT, are associated with metabolic alterations, aggressive disease and biochemical recurrence in prostate cancer. An initial analysis was performed using integrated transcriptomics, ex vivo and in vivo metabolomics, and histopathology of prostatectomy samples (n=129), combined with at least five-year follow-up. This analysis detected increased activation of NCWP through Wnt5a/ Fzd2 as the most common mode of Wnt activation in prostate cancer. This activation was associated with increased expression of EMT markers and higher Gleason score. The transcriptional association between NCWP and EMT was confirmed in five other publicly available patient cohorts (1519 samples in total). A novel gene expression signature of concordant activation of NCWP and EMT (NCWP-EMT) was developed, and this signature was significantly associated with metastasis and shown to be a significant predictor of biochemical recurrence. The NCWP-EMT signature was also associated with decreased concentrations of the metabolites citrate and spermine, which have previously been linked to aggressive prostate cancer. Our results demonstrate the importance of NCWP and EMT in prostate cancer aggressiveness, suggest a novel gene signature for improved risk stratification, and give new molecular insight.

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.

CAPE suppresses migration and invasion of prostate cancer cells via activation of non-canonical Wnt signaling

Prostate cancer (PCa) was the fifth most common cancer overall in the world. More than 80% of patients died from PCa developed bone metastases. Caffeic acid phenethyl ester (CAPE) is a main bioactive component of honeybee hive propolis. Transwell and wound healing assays demonstrated that CAPE treatment suppressed the migration and invasion of PC-3 and DU-145 PCa cells. Gelatin zymography and Western blotting indicated that CAPE treatment reduced the abundance and activity of MMP-9 and MMP-2. Analysis using Micro-Western Array (MWA), a high-throughput antibody-based proteomics platform with 264 antibodies detecting signaling proteins involved in important pathways indicated that CAPE treatment induced receptor tyrosine kinase-like orphan receptor 2 (ROR2) in non-canonical Wnt signaling pathway but suppressed abundance of β-catenin, NF-κB activity, PI3K-Akt signaling, and epithelial-mesenchymal transition (EMT). Overexpression or knockdown of ROR2 suppressed or enhanced cell migration of PC-3 cells, respectively. TCF-LEF promoter binding assay revealed that CAPE treatment reduced canonical Wnt signaling. Intraperitoneal injection of CAPE reduced the metastasis of PC-3 xenografts in tail vein injection nude mice model. Immunohistochemical staining demonstrated that CAPE treatment increased abundance of ROR2 and Wnt5a but decreased protein expression of Ki67, Frizzle 4, NF-κB p65, MMP-9, Snail, β-catenin, and phosphorylation of IκBα. Clinical evidences suggested that genes affected by CAPE treatment (CTNNB1, RELA, FZD5, DVL3, MAPK9, SNAl1, ROR2, SMAD4, NFKBIA, DUSP6, and PLCB3) correlate with the aggressiveness of PCa. Our study suggested that CAPE may be a potential therapeutic agent for patients with advanced PCa.

Differential regulation of hepcidin in cancer and non-cancer tissues and its clinical implications

Hepcidin is a crucial peptide for regulating cellular iron efflux. Because iron is essential for cell survival, especially for highly active cells, such as tumor cells, it is imperative to understand how tumor cells manipulate hepcidin expression for their own metabolic needs. Studies suggest that hepcidin expression and regulation in tumor cells show important differences in comparison with those in non-tumorous cells. These differences should be investigated to develop new strategies to fight cancer cells. Manipulating hepcidin expression to starve cancer cells for iron may prove to be a new therapy in the anticancer arsenal.

WNT5A induces castration-resistant prostate cancer via CCL2 and tumour-infiltrating macrophages

BACKGROUND

Although the standard treatment for the patients with recurrent and metastatic prostate cancer (CaP) is androgen deprivation therapy, castration-resistant prostate cancer (CRPC) eventually emerges. Our previous report indicated that bone morphogenetic protein 6 (BMP6) induced CRPC via tumour-infiltrating macrophages. In a separate line of study, we have observed that the WNT5A/BMP6 loop in CaP bone metastasis mediates resistance to androgen deprivation in tissue culture. Simultaneously, we have reported that BMP6 induced castration resistance in CaP cells via tumour-infiltrating macrophages. Therefore, our present study aims to investigate the mechanism of WNT5A and its interaction with macrophages on CRPC.

METHODS

Doxycycline inducible WNT5A overexpression prostate cancer cell line was used for detailed mechanical study.

RESULTS

WNT5A was associated with increased expression of chemokine ligand 2 (CCL2) in the human CaP cell line, LNCaP. Mechanistically, this induction of CCL2 by WNT5A is likely to be mediated via the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signalling pathway. Our in vivo experiments demonstrated that the overexpression of WNT5A in LNCaP cells promoted castration resistance. Conversely, this resistance was inhibited with the removal of macrophages via clodronate liposomes. When patient-derived CaP LuCaP xenografts were analysed, high levels of WNT5A were correlated with increased levels of CCL2 and BMP6. In addition, higher levels of CCL2 and BMP6 were more commonly observed in intra-femoral transplanted tumours as compared to subcutaneous-transplanted tumours in the patient-derived PCSD1 bone-niche model.

CONCLUSIONS

These findings collectively suggest that WNT5A may be a key gene that induces CRPC in the bone niche by recruiting and regulating macrophages through CCL2 and BMP6, respectively.

Daam1 activates RhoA to regulate Wnt5a‑induced glioblastoma cell invasion

The signaling pathway of dishevelled-associated activator of morphogenesis 1 (Daam1) triggered by Wnt5a drives cell movement and migration during breast cancer metastasis. However, Wnt5a signaling in glioblastoma progression remains poorly defined. Wnt5a expression and activations of RhoA, Cdc42, and Rac1 were detected in human glioblastoma tissues by using ELISA assays and small G-protein activation assays, respectively. The cell invasion rate and Daam1 activation of glioblastoma U251 and T98MG cells were determined by cell invasion assays and pull-down assays, respectively. According to our experiments, Wnt5a expression and RhoA activation were upregulated in invasive glioblastoma tissues, with a significant positive correlation between them. Wnt5a activated Daam1 and RhoA, and subsequently promoted the invasion of glioblastoma U251 and T98MG cells. This process was abolished by secreted frizzled-related protein 2 (sFRP2), an antagonist that directly binds to Wnt5a. Specific small interfering RNA (siRNA) targeting Daam1 markedly inhibited Wnt5a-induced RhoA activation, stress fiber formation and glioblastoma cell invasion. CCG-1423, a RhoA inhibitor, decreased Wnt5a-induced stress fiber formation and glioblastoma cell invasion. Finally, siRNA targeting Daam1 or CCG-1423 treatment did not alter the cell proliferation of glioblastoma U251 and T98MG cells. We thus concluded that Wnt5a promoted glioblastoma cell invasion via Daam1/RhoA signaling pathway.

Wnt5a promotes epithelial-to-mesenchymal transition and metastasis in non-small-cell lung cancer

A recent study indicated that high Wnt5a expression is associated with poor prognosis in non-small-cell lung cancer (NSCLC) patients; however, the underlying mechanism was not clear yet. Immunohistochemistry and Western blotting were performed to examine the protein expression level in NSCLC tissues and cell lines. The role of Wnt5a in clone formation, invasiveness, migration, and epithelial-to-mesenchymal transition (EMT) of NSCLC cells was studied. Luciferase reporter assay was used to evaluate the Tcf/Lef transcriptional activity. For assessing the effects of Wnt5a on tumor growth and metastasis in vivo, A549 cells transfected with sh-Wnt5a were subcutaneously or orthotopically injected into nude mice. In NSCLC tissues, higher expression levels of Wnt5a and ROR2 were found, β-Catenin was expressed exceptionally, and EMT was prompted. Wnt5a overexpression increased clone formation, migration, and invasion, as well as prompted EMT of NSCLC cell in vitro, whereas Wnt5a knockdown showed the absolutely reversed results. Wnt5a overexpression enhanced the Tcf/Lef transcriptional activity and elevated the nuclear β-catenin level in NSCLC cells, without altering the ROR2 expression. We also demonstrated that si-β-catenin antagonized Wnt5a overexpression nduced EMT and invasiveness. Besides, in vivo experiment showed that sh-Wnt5a significantly increased tumor volume and tumor weight, and prompted EMT in A549 tumor-bearing mice as compared with the control. No metastasis was found in the liver tissue after sh-Wnt5a-transfected cells were orthotopically injected into nude mice as compared with the control. In conclusion, Wnt5a promotes EMT and metastasis in NSCLC, which is involved in the activation of β-catenin-dependent canonical Wnt signaling.

Estrogen related receptor alpha in castration-resistant prostate cancer cells promotes tumor progression in bone

Bone metastases are one of the main complications of prostate cancer and they are incurable. We investigated whether and how estrogen receptor-related receptor alpha (ERRα) is involved in bone tumor progression associated with advanced prostate cancer. By meta-analysis, we first found that ERRα expression is correlated with castration-resistant prostate cancer (CRPC), the hallmark of progressive disease. We then analyzed tumor cell progression and the associated signaling pathways in gain-of-function/loss-of-function CRPC models in vivo and in vitro. Increased levels of ERRα in tumor cells led to rapid tumor progression, with both bone destruction and formation, and direct impacts on osteoclasts and osteoblasts. VEGF-A, WNT5A and TGFβ1 were upregulated by ERRα in tumor cells and all of these factors also significantly and positively correlated withERRα expression in CRPC patient specimens. Finally, high levels of ERRα in tumor cells stimulated the pro-metastatic factor periostin expression in the stroma, suggesting that ERRα regulates the tumor stromal cell microenvironment to enhance tumor progression. Taken together, our data demonstrate that ERRα is a regulator of CRPC cell progression in bone. Therefore, inhibiting ERRα may constitute a new therapeutic strategy for prostate cancer skeletal-related events.

Wnt5a Signaling in Cancer

Wnt5a is involved in activating several non-canonical WNT signaling pathways, through binding to different members of the Frizzled- and Ror-family receptors. Wnt5a signaling is critical for regulating normal developmental processes, including proliferation, differentiation, migration, adhesion and polarity. However, the aberrant activation or inhibition of Wnt5a signaling is emerging as an important event in cancer progression, exerting both oncogenic and tumor suppressive effects. Recent studies show the involvement of Wnt5a in regulating cancer cell invasion, metastasis, metabolism and inflammation. In this article, we review findings regarding the molecular mechanisms and roles of Wnt5a signaling in various cancer types, and highlight Wnt5a in ovarian cancer.

WNT5A and Its Receptors in the Bone-Cancer Dialogue

Wnt signaling is critical for tumorigenesis and skeletal remodeling. However, its contribution to the formation of metastatic bone lesions remains poorly defined. One major challenge of unraveling its role in cancer progression is the high complexity of Wnt signaling, which includes numerous ligands, receptors, and inhibitors, with intricate biological effects and specific signaling pathways depending on the cellular context. In this perspective, we summarize the role of the noncanonical Wnt ligand WNT5A in the development and metastatic process of osteotropic cancer entities. We focus on its tumor-suppressive function in breast cancer, tumor promoting effects in melanoma, and ambiguous role in prostate cancer, and discuss potential challenges and opportunities that may be associated with targeting Wnt signaling for cancer therapy and treatment of bone metastases. © 2016 American Society for Bone and Mineral Research.

The Drosophila Accessory Gland as a Model for Prostate Cancer and Other Pathologies

The human prostate is a gland of the male reproductive tract, which together with the seminal vesicles, is responsible for most seminal fluid production. It is a common site of cancer, and unlike other glands, it typically enlarges in aging men. In flies, the male accessory glands make many major seminal fluid components. Like their human equivalents, they secrete proteins from several conserved families, including proteases, lectins, and cysteine-rich secretory proteins, some of which interact with sperm and affect fertility. A key protein, sex peptide, is not conserved in vertebrates but plays a central role in mediating long-term effects on females after mating. Although postmitotic, one epithelial cell type in the accessory glands, the secondary cell, continues to grow in adults. It secretes microvesicles called exosomes from the endosomal multivesicular body, which, after mating, fuse with sperm. They also appear to affect female postmating behavior. Remarkably, the human prostate epithelium also secretes exosomes, which fuse to sperm in vitro to modulate their activity. Exosomes from prostate and other cancer cells are increasingly proposed to play fundamental roles in modulating the tumor microenvironment and in metastasis. Here we review a diverse accessory gland literature, which highlights functional analogies between the male reproductive glands of flies and humans, and a critical role for extracellular vesicles in allowing seminal fluid to promote male interests within the female. We postulate that secondary cells and prostate epithelial cells use common mechanisms to control growth, secretion, and signaling, which are relevant to prostate and other cancers, and can be genetically dissected in the uniquely tractable fly model.

Over-expression of ROR2 and Wnt5a cooperatively correlates with unfavorable prognosis in patients with non-small cell lung cancer

We investigated the expression of receptor tyrosine kinase-like orphan receptor (ROR) 2 and Wnt5a and their prognostic significance in non-small cell lung cancer (NSCLC). Tissue microarray-based immunohistochemical analysis was performed to determine the expression of ROR2 and Wnt5a in 219 patients. mRNA expression of ROR2 and Wnt5a was examined in 20 pairs of NSCLC and matched adjacent normal tissues by real-time PCR. Compared with non-tumorous tissues, both mRNA expression and protein product of ROR2 and Wnt5a genes were significantly increased in NSCLC. c² analysis revealed that high ROR2 or Wnt5a expression in NSCLC was significantly associated with advanced TNM stage. High expression of both ROR2 and Wnt5a was also related to advanced TNM stage. Multivariate analyses suggested that ROR2, Wnt5a and TNM stage were independent prognostic factors in NSCLC. Our clinical findings suggest that high ROR2 or Wnt5a expression is associated with poor prognosis in NSCLC, and combined detection of ROR2 and Wnt5a is helpful in predicting the prognosis of NSCLC.

Dragon (repulsive guidance molecule b, RGMb) is a novel gene that promotes colorectal cancer growth

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers and a major cause of cancer death. However, the molecular mechanisms underlying CRC initiation, growth and metastasis are poorly understood. Dragon (RGMb), a member of the repulsive guidance molecule (RGM) family, has been recently identified as a co-receptor for bone morphogenetic protein (BMP) signaling, but the role of Dragon in CRC development is undefined. Here, we show that Dragon expression was increased in colon cancer tissues compared to control tissues in CAC mouse model and in human patients. Dragon promoted proliferation of CT26.WT and CMT93 colon cancer cells and accelerated tumor growth in the xenograft mouse model. Dragon's action on colon cancer development was mediated via the BMP4-Smad1/5/8 and Erk1/2 pathways. Therefore, our results have revealed that Dragon is a novel gene that promotes CRC growth through the BMP pathway. Dragon may be exploited as a potential therapeutic target for CRC treatment.

WNT-5A: signaling and functions in health and disease

WNT-5A plays critical roles in a myriad of processes from embryonic morphogenesis to the maintenance of post-natal homeostasis. WNT-5A knock-out mice fail to survive and present extensive structural malformations. WNT-5A predominantly activates β-catenin-independent WNT signaling cascade but can also activate β-catenin signaling to relay its diverse cellular effects such as cell polarity, migration, proliferation, cell survival, and immunomodulation. Moreover, aberrant WNT-5A signaling is associated with several human pathologies such as cancer, fibrosis, and inflammation. Thus, owing to its diverse functions, WNT-5A is a crucial signaling molecule currently under intense investigation with efforts to not only delineate its signaling mechanisms and functions in physiological and pathological conditions, but also to develop strategies for its therapeutic targeting.

Bone morphogenetic protein signaling in bone homeostasis

Bone morphogenetic proteins (BMPs) are cytokines belonging to the transforming growth factor-β (TGF-β) superfamily. They play multiple functions during development and tissue homeostasis, including regulation of the bone homeostasis. The BMP signaling pathway consists in a well-orchestrated manner of ligands, membrane receptors, co-receptors and intracellular mediators, that regulate the expression of genes controlling the normal functioning of the bone tissues. Interestingly, BMP signaling perturbation is associated to a variety of low and high bone mass diseases, including osteoporosis, bone fracture disorders and heterotopic ossification. Consistent with these findings, in vitro and in vivo studies have shown that BMPs have potent effects on the activity of cells regulating bone function, suggesting that manipulation of the BMP signaling pathway may be employed as a therapeutic approach to treat bone diseases. Here we review the recent advances on BMP signaling and bone homeostasis, and how this knowledge may be used towards improved diagnosis and development of novel treatment modalities. This article is part of a Special Issue entitled "Muscle Bone Interactions".

Targeting Cancer Stem Cells in Castration-Resistant Prostate Cancer

PURPOSE

Clinical evidence suggests increased cancer stem cells (CSCs) in a tumor mass may contribute to the failure of conventional therapies because CSCs seem to be more resistant than differentiated tumor cells. Thus, unveiling the mechanism regulating CSCs and candidate target molecules will provide new strategy to cure the patients.

EXPERIMENTAL DESIGN

The stem-like cell properties were determined by a prostasphere assay and dye exclusion assay. To find critical stem cell marker and reveal regulation mechanism, basic biochemical and molecular biologic methods, such as quantitative real-time PCR, Western blot, reporter gene assay, and chromatin immunoprecipitation assay, were used. In addition, to determine the effect of combination therapy targeting both CSCs and its progeny, in vitro MTT assay and in vivo xenograft model was used.

RESULTS

We demonstrate immortalized normal human prostate epithelial cells, appeared nontumorigenic in vivo, become tumorigenic, and acquire stem cell phenotype after knocking down a tumor suppressor gene. Also, those stem-like cells increase chemoresistance to conventional anticancer reagent. Mechanistically, we unveil that Wnt signaling is a key pathway regulating well-known stem cell marker CD44 by directly interacting to the promoter. Thus, by targeting CSCs using Wnt inhibitors synergistically enhances the efficacy of conventional drugs. Furthermore, the in vivo mouse model bearing xenografts showed a robust inhibition of tumor growth after combination therapy.

CONCLUSIONS

Overall, this study provides strong evidence of CSC in castration-resistant prostate cancer. This new combination therapy strategy targeting CSC could significantly enhance therapeutic efficacy of current chemotherapy regimen only targeting non-CSC cells.

Targeting the WNT Signaling Pathway in Cancer Therapeutics

The WNT signaling cascade is integral in numerous biological processes including embryonic development, cell cycle regulation, inflammation, and cancer. Hyperactivation of WNT signaling secondary to alterations to varying nodes of the pathway have been identified in multiple tumor types. These alterations converge into increased tumorigenicity, sustained proliferation, and enhanced metastatic potential. This review seeks to evaluate the evidence supporting the WNT pathway in cancer, the therapeutic strategies in modulating this pathway, and potential challenges in drug development.

Prognostic Impacts of Metastatic Site and Pain on Progression to Castrate Resistance and Mortality in Patients with Metastatic Prostate Cancer

PURPOSE

To investigate predictors of progression to castration-resistant prostate cancer (CRPC) and cancer-specific mortality (CSM) in patients with metastatic prostate cancer (mPCa).

MATERIALS AND METHODS

A retrospective analysis was performed on 440 consecutive treatment-naïve patients initially diagnosed with mPCa between August 2000 and June 2012. Patient age, body mass index (BMI), Gleason score, prostate-specific antigen (PSA), PSA nadir, American Joint Committee on Cancer stage, Visual Analogue Scale pain score, Eastern Cooperative Oncology Group performance score (ECOG PS), PSA response to hormone therapy, and metastatic sites were assessed. Cox-proportional hazards regression analyses were used to evaluate survivals and predictive variables of men with bone metastasis stratified according to the presence of pain, compared to men with visceral metastasis.

RESULTS

Metastases were most often found in bone (75.4%), followed by lung (16.3%) and liver (8.3%) tissues. Bone metastasis, pain, and high BMI were associated with increased risks of progression to CRPC, and bone metastasis, pain, PSA nadir, and ECOG PS≥1 were significant predictors of CSM. During the median follow-up of 32.0 (interquartile range 14.7-55.9) months, patients with bone metastasis with pain and patients with both bone and visceral metastases showed the worst median progression to CRPC-free and cancer-specific survivals, followed by men with bone metastasis without pain. Patients with visceral metastasis had the best median survivals.

CONCLUSION

Metastatic spread and pain patterns confer different prognosis in patients with mPCa. Bone may serve as a crucial microenvironment in the development of CRPC and disease progression.

Stromal TGF-β signaling induces AR activation in prostate cancer

AR signaling is essential for the growth and survival of prostate cancer (PCa), including most of the lethal castration-resistant PCa (CRPC). We previously reported that TGF-β signaling in prostate stroma promotes prostate tumor angiogenesis and growth. By using a PCa/stroma co-culture model, here we show that stromal TGF-β signaling induces comprehensive morphology changes of PCa LNCaP cells. Furthermore, it induces AR activation in LNCaP cells in the absence of significant levels of androgen, as evidenced by induction of several AR target genes including PSA, TMPRSS2, and KLK4. SD-208, a TGF-β receptor 1 specific inhibitor, blocks this TGF-β induced biology. Importantly, stromal TGF-β signaling together with DHT induce robust activation of AR. MDV3100 effectively blocks DHT-induced, but not stromal TGF-β signaling induced AR activation in LNCaP cells, indicating that stromal TGF-β signaling induces both ligand-dependent and ligand-independent AR activation in PCa. TGF-β induces the expression of several growth factors and cytokines in prostate stromal cells, including IL-6, and BMP-6. Interestingly, BMP-6 and IL-6 together induces robust AR activation in these co-cultures, and neutralizing antibodies against BMP-6 and IL-6 attenuate this action. Altogether, our study strongly suggests tumor stromal microenvironment induced AR activation as a direct mechanism of CRPC.

WNT5A has anti-prostate cancer effects in vitro and reduces tumor growth in the skeleton in vivo

Prostate cancer is the most frequent malignancy in men, and a major cause of prostate cancer-related death is attributable to bone metastases. WNT5A is known to influence the clinical outcome of various cancer types, including prostate cancer, but the exact mechanisms remain unknown. The goal of this study was to assess the relevance of WNT5A for the development and progression of prostate cancer. WNT5A expression was determined in a cDNA and tissue microarray of primary tumor samples in well-defined cohorts of patients with prostate cancer. Compared with benign prostate tissue, the expression of WNT5A and its receptor Frizzled-5 was higher in prostate cancer, and patients with a WNT5A expression above the median had a higher probability of survival after 10 years. Using different osteotropic human prostate cancer cell lines, the influence of WNT5A overexpression and knock-down on proliferation, migration, and apoptosis was assessed. In vitro, WNT5A overexpression induced prostate cancer cell apoptosis and reduced proliferation and migration, whereas WNT5A knock-down showed opposite effects. In vivo, different xenograft models were used to determine the effects of WNT5A on tumor growth. Local tumor growth and tumor growth in the bone microenvironment was considerably diminished after WNT5A overexpression in PC3 cells. WNT5A exhibits antitumor effects in prostate cancer cells and may be suitable as a prognostic marker and therapeutic target for prostate cancer and associated skeletal metastases.

The host microenvironment influences prostate cancer invasion, systemic spread, bone colonization, and osteoblastic metastasis

Prostate cancer (PCa) is the second leading cause of cancer death in men worldwide. Most PCa deaths are due to osteoblastic bone metastases. What triggers PCa metastasis to the bone and what causes osteoblastic lesions remain unanswered. A major contributor to PCa metastasis is the host microenvironment. Here, we address how the primary tumor microenvironment influences PCa metastasis via integrins, extracellular proteases, and transient epithelia-mesenchymal transition (EMT) to promote PCa progression, invasion, and metastasis. We discuss how the bone-microenvironment influences metastasis; where chemotactic cytokines favor bone homing, adhesion molecules promote colonization, and bone-derived signals induce osteoblastic lesions. Animal models that fully recapitulate human PCa progression from primary tumor to bone metastasis are needed to understand the PCa pathophysiology that leads to bone metastasis. Better delineation of the specific processes involved in PCa bone metastasize is needed to prevent or treat metastatic PCa. Therapeutic regimens that focus on the tumor microenvironment could add to the PCa pharmacopeia.