Bone metastasis in prostate cancer: emerging therapeutic strategies

Moesin activation controls bone resorption and tunneling nanotube-dependent osteoclast fusion

Osteoclasts are multinucleated cells unique in their ability to resorb bone. Osteoclastogenesis involves several steps of actin-driven rearrangements that participate not only in the cell-cell fusion process, but also in the formation of the sealing zone, the adhesive structure determining the resorption area. Despite the importance of these actin cytoskeleton-based processes, their precise mechanisms of regulation are still poorly characterized. Here, we found that moesin, a member of the Ezrin/Radixin/Moesin (ERM) protein family, is activated during osteoclast maturation and plays an instrumental role for both osteoclast fusion and function. In mouse and human osteoclast precursors, moesin is negatively regulated to potentiate their ability to fuse and degrade bone. Accordingly, we demonstrated that moesin depletion decreases membrane-to-cortex attachment and enhances formation of tunneling nanotubes (TNTs), F-actin-containing intercellular bridges that we revealed to trigger osteoclast fusion. In addition, via a β3-integrin/RhoA/SLK pathway and independently of its role in fusion, moesin regulates the number and organization of sealing zones in mature osteoclast, and thus participates in the control of bone resorption. Supporting these findings, we found that moesin-deficient mice are osteopenic with a reduced density of trabecular bones and increased osteoclast abundance and activity. These findings provide a better understanding of the regulation of osteoclast biology, and open new opportunities to specifically target osteoclast activity in bone disease therapy.

Targeting SphK1/2 by SKI-178 inhibits prostate cancer cell growth

Sphingosine kinases (SphK), including SphK1 and SphK2, are important enzymes promoting progression of prostate cancer. SKI-178 is a novel and highly potent SphK1/2 dual inhibitor. We here tested the potential anti-prostate cancer cell activity of SKI-178. Bioinformatics analyses and results from local tissues demonstrated that that both SphK1 and SphK2 are upregulated in human prostate cancer tissues. Ectopic overexpression of SphK1 and SphK2, by lentiviral constructs, promoted primary prostate cancer cell proliferation and migration. In primary human prostate cancer cells and immortalized cell lines, SKI-178 potently inhibited cell viability, proliferation, cell cycle progression and cell migration, causing robust cell death and apoptosis. SKI-178 impaired mitochondrial functions, causing mitochondrial depolarization, reactive oxygen species production and ATP depletion.SKI-178 potently inhibited SphK activity and induced ceramide production, without affecting SphK1/2 expression in prostate cancer cells. Further, SKI-178 inhibited Akt-mTOR activation and induced JNK activation in prostate cancer cells. Contrarily, a constitutively-active Akt1 construct or the pharmacological JNK inhibitors attenuated SKI-178-induced cytotoxicity in prostate cancer cells. In vivo, daily intraperitoneal injection of a single dose of SKI-178 potently inhibited PC-3 xenograft growth in nude mice. SphK inhibition, ceramide production, ATP depletion and lipid peroxidation as well as Akt-mTOR inactivation and JNK activation were detected in PC-3 xenograft tissues with SKI-178 administration. Together, targeting SphK1/2 by SKI-178 potently inhibited prostate cancer cell growth in vitro and in vivo.

Macrophages promote anti-androgen resistance in prostate cancer bone disease

Metastatic castration-resistant prostate cancer (PC) is the final stage of PC that acquires resistance to androgen deprivation therapies (ADT). Despite progresses in understanding of disease mechanisms, the specific contribution of the metastatic microenvironment to ADT resistance remains largely unknown. The current study identified that the macrophage is the major microenvironmental component of bone-metastatic PC in patients. Using a novel in vivo model, we demonstrated that macrophages were critical for enzalutamide resistance through induction of a wound-healing-like response of ECM-receptor gene expression. Mechanistically, macrophages drove resistance through cytokine activin A that induced fibronectin (FN1)-integrin alpha 5 (ITGA5)-tyrosine kinase Src (SRC) signaling cascade in PC cells. This novel mechanism was strongly supported by bioinformatics analysis of patient transcriptomics datasets. Furthermore, macrophage depletion or SRC inhibition using a novel specific inhibitor significantly inhibited resistant growth. Together, our findings elucidated a novel mechanism of macrophage-induced anti-androgen resistance of metastatic PC and a promising therapeutic approach to treat this deadly disease.

Quantitative assessment of 99mTc-methylene diphosphonate bone SPECT/CT for assessing bone metastatic burden and its prognostic value in patients with castration-resistant prostate cancers: initial results in a single-center retrospective study

PURPOSE

To evaluate the prognostic value of the quantitative assessment of ^99mTc-methylene diphosphonate (^99mTc-MDP) bone SPECT/CT in castration-resistant prostate cancer (CRPC) patients with bone metastases.

METHODS

A total of 103 patients who underwent ^99mTc-MDP bone SPECT/CT imaging from the neck to the proximal femur were included. First, in 65 patients without bone metastases, the normal range of standardized uptake value (SUV) of non-pathological bone was evaluated to determine an SUV threshold to reliably exclude most normal osseous activity. Then, in 38 CRPC patients with bone metastases, lesion uptake volume (LUV), which is the extracted volume of bone metastases exhibiting high accumulation above the SUV threshold, was calculated. The relation between LUV and prostate-related mortality was statistically evaluated.

RESULTS

Based on the SUV measurements of non-pathological bones, the optimal SUV threshold, which defines abnormal bone SPECT uptake, was determined to be 8. Median LUV was 39 mL (interquartile range 4.0-104.3 mL) in the CRPC subjects with bone metastases. Kaplan-Meier survival analysis showed a significant relation between prostate cancer-specific survival and LUV (cut-off value, 19.95 mL; P = 0.001). Multivariate analysis revealed LUV as an independent prognostic factor for the survival (P = 0.008, hazard ratio 23.424). Global chi-square test showed that LUV had significant incremental prognostic value in addition to prostate-specific antigen and the interval from progression to CRPC until bone SPECT/CT (P = 0.022).

CONCLUSION

Quantitative assessment of ^99mTc-MDP bone SPECT images can provide valuable prognostic information in CRPC patients with bone metastases.

Metastatic prostate cancer-derived extracellular vesicles facilitate osteoclastogenesis by transferring the CDCP1 protein

Bone metastases are still incurable and result in the development of clinical complications and decreased survival for prostate cancer patients. Recently, a number of studies have shown that extracellular vesicles (EVs) play important roles in tumour progression. Here, we show that EVs from metastatic prostate cancer cells promote osteoclast formation in the presence of receptor activator of NF-κB ligand (RANKL). EV characterization followed by functional siRNA screening identified CUB-domain containing protein 1 (CDCP1), a transmembrane protein, as an inducer of osteoclastogenesis. Additionally, CDCP1 expression on plasma-derived EVs was upregulated in bone metastatic prostate cancer patients. Our findings elucidate the effect of EVs from metastatic prostate cancer cells on osteoclast formation, which is promoted by CDCP1 located on EVs. Furthermore, our data suggested that CDCP1 expression on EVs might be useful to detect bone metastasis of prostate cancer.

Adaptive and non-adaptive gene expression responses in prostate cancer during androgen deprivation

Androgen deprivation therapy is the cornerstone treatment of advanced prostate cancer. Eventually prostate cancer cells overcome androgen deprivation therapy, giving rise to castration resistant prostate cancer (CRPC) characterized by increased androgen receptor (AR) activity. Understanding the cellular mechanisms leading to CRPC is needed for development of novel treatments. We used long-term cell cultures to model CRPC; a testosterone-dependent cell line (VCaP-T) and cell line adapted to grow in low testosterone (VCaP-CT). These were used to uncover persistent and adaptive responses to testosterone level. RNA was sequenced to study AR-regulated genes. Expression level changed due to testosterone depletion in 418 genes in VCaP-T (AR-associated genes). To evaluate significance for CRPC growth, we compared which of them were adaptive i.e., restored expression level in VCaP-CT. Adaptive genes were enriched to steroid metabolism, immune response and lipid metabolism. The Cancer Genome Atlas Prostate Adenocarcinoma data were used to assess the association with cancer aggressiveness and progression-free survival. Expressions of 47 AR-associated or association gaining genes were statistically significant markers for progression-free survival. These included genes related to immune response, adhesion and transport. Taken together, we identified and clinically validated multiple genes being linked with progression of prostate cancer and propose several novel risk genes. Possible use as biomarkers or therapeutic targets should be studied further.

An accurate prediction of the origin for bone metastatic cancer using deep learning on digital pathological images

BACKGROUND

Determining the origin of bone metastatic cancer (OBMC) is of great significance to clinical therapeutics. It is challenging for pathologists to determine the OBMC with limited clinical information and bone biopsy.

METHODS

We designed a regional multiple-instance learning algorithm to predict the OBMC based on hematoxylin-eosin (H&E) staining slides alone. We collected 1041 cases from eight different hospitals and labeled 26,431 regions of interest to train the model. The performance of the model was assessed by ten-fold cross validation and external validation. Under the guidance of top3 predictions, we conducted an IHC test on 175 cases of unknown origins to compare the consistency of the results predicted by the model and indicated by the IHC markers. We also applied the model to identify whether there was tumor or not in a region, as well as distinguishing squamous cell carcinoma, adenocarcinoma, and neuroendocrine tumor.

FINDINGS

In the within-cohort, our model achieved a top1-accuracy of 91.35% and a top3-accuracy of 97.75%. In the external cohort, our model displayed a good generalizability with a top3-accuracy of 97.44%. The top1 consistency between the results of the model and the immunohistochemistry markers was 83.90% and the top3 consistency was 94.33%. The model obtained an accuracy of 98.98% to identify whether there was tumor or not and an accuracy of 93.85% to differentiate three types of cancers.

INTERPRETATION

Our model demonstrated good performance to predict the OBMC from routine histology and had great potential for assisting pathologists with determining the OBMC accurately.

FUNDING

National Science Foundation of China (61875102 and 61975089), Natural Science Foundation of Guangdong province (2021A15-15012379 and 2022A1515 012550), Science and Technology Research Program of Shenzhen City (JCYJ20200109110606054 and WDZC20200821141349001), and Tsinghua University Spring Breeze Fund (2020Z99CFZ023).

Construction and validation of web-based nomograms for detecting and prognosticating in prostate adenocarcinoma with bone metastasis

Bone metastasis (BM) is one of the most common sites of metastasis in prostate adenocarcinoma (PA). PA with BM can significantly diminish patients' quality of life and result in a poor prognosis. The objective of this study was to establish two web-based nomograms to estimate the risk and prognosis of BM in PA patients. From the Surveillance, Epidemiology, and End Results (SEER) database, data on 308,332 patients diagnosed with PA were retrieved retrospectively. Logistic and Cox regression, respectively, were used to determine independent risk and prognostic factors. Then, We constructed two web-based nomograms and the results were validated by receiver operating characteristic (ROC) curves, calibration curves, decision curve analysis (DCA) , and the Kaplan-Meier analyses. The independent risk factors for BM in PA patients included race, PSA, ISUP, T stage, N stage, brain, liver, lung metastasis, surgery, radiation and chemotherapy. The independent prognostic predictors for overall survival (OS) were age, marital status, PSA, ISUP and liver metastasis. Both nomograms could effectively predict risk and prognosis of BM in PA patients according to the results of ROC curves, calibration, and DCA in the training and validation sets. And the Kaplan-Meier analysis illustrated that the prognostic nomogram could significantly distinguish the population with different survival risks. We successfully constructed the two web-based nomograms for predicting the incidence of BM and the prognosis of PA patients with BM, which may assist clinicians in optimizing the establishment of individualized treatment programs and enhancing patients' prognoses.

Osteoblasts and osteoclasts: an important switch of tumour cell dormancy during bone metastasis

Bone metastasis occurs when tumour cells dissociate from primary tumours, enter the circulation (circulating tumour cells, CTCs), and colonize sites in bone (disseminated tumour cells, DTCs). The bone marrow seems to be a particularly dormancy-inducing environment for DTCs, yet the mechanisms of dormancy initiation, reactivation, and interaction within the bone marrow have to be elucidated. Intriguingly, some evidence has suggested that dormancy is a reversible state that is switched 'on' or 'off' depending on the presence of various bone marrow resident cells, particularly osteoclasts and osteoblasts. It has become clear that these two cells contribute to regulating dormant tumour cells in bone both directly (interaction) and indirectly (secreted factors). The involved mechanisms include TGFβ signalling, the Wnt signalling axis, the Notch2 pathway, etc. There is no detailed review that specifically focuses on ascertaining the dynamic interactions between tumour cell dormancy and bone remodelling. In addition, we highlighted the roles of inflammatory cytokines during this 'cell-to-cell' communication. We also discussed the potential clinical relevance of remodelling the bone marrow niche in controlling dormant tumour cells. Understanding the unique role of osteoclasts and osteoblasts in regulating tumour dormancy in bone marrow will provide new insight into preventing and treating tumour bone metastasis.

Optimization and Characterization of a Bone Culture Model to Study Prostate Cancer Bone Metastasis

Nearly 90% of patients with advanced prostate cancer manifest bone metastases. Distinct from the osteolytic metastasis mostly observed in other cancer types, prostate cancer bone metastasis is typically more osteoblastic, which is relatively understudied due to the lack of reliable and efficient models to resemble the indolent cellular growth and complexity of metastatic progression. In our previous studies, we developed bone-in-culture array (BICA) to primarily model the osteoblast-involved, pre-osteolytic stage of breast cancer bone metastasis. Given that the progression of prostate cancer bone metastasis is largely osteoblastic, it is reasonable to speculate that the original BICA model can be adjusted to investigate prostate cancer bone metastases. In this study, we refined BICA by reducing the surgical labor and improving its reproducibility and capacity. The optimized BICA can successfully recapitulate important features of prostate cancer bone metastasis such as the osteoblastic phenotype, indolent growth, cancer-niche interactions, and response to hormones. Our efforts address the long-standing need for reliable and efficient models to study prostate cancer bone metastasis.

Extracellular Regucalcin Suppresses the Growth, Migration, Invasion and Adhesion of Metastatic Human Prostate Cancer Cells

Regucalcin plays a multifunctional role in the regulation of cellular function including metabolism, signaling process and transcriptional activity in maintaining cell homeostasis. Downregulated expression or activity of regucalcin contributes to the development of malignancies in various types of human cancer. Survival of cancer patients, including metastatic prostate cancer, is prolonged with high expression of regucalcin in the tumor tissues. Furthermore, we elucidate whether extracellular regucalcin conquers the growth, migration, invasion and adhesion of metastatic human prostate cancer PC-3 and DU-145 cells. Extracellular regucalcin (0.1, 1, and 10 nM) of physiologic levels inhibited colony formation and growth of PC-3 and DU-145 cells, while it did not have an effect on cell death. Repressive effects of extracellular regucalcin on the proliferation were not exhibited by the presence of inhibitors of cell cycle, intracellular signaling process and transcriptional activity, suggesting that the signals of extracellular regucalcin are transmitted to block cell growth. Furthermore, extracellular regucalcin (0.1, 1, or 10 nM) inhibited migration, invasion and adhesion of PC-3 and DU-145 cells. Mechanistically, extracellular regucalcin (10 nM) decreased the levels of various signaling proteins including Ras, hosphatidylinositol-3 kinase, mitogen-activated protein kinase, mTOR, RSK-2, caveolin-1 and integrin β1 in PC-3 cells. Thus, extracellular regucalcin may play a suppressive role in growth, migration, invasion and adhesion, which are involved in metastatic activity of human prostate cancer cells, via affecting diverse signaling processes. This study may provide a new strategy in preventing metastatic prostate cancer with exogenous regucalcin.

Radium-223 Dichloride in Peritoneal Dialysate Following Treatment of Metastatic Castration-resistant Prostate Cancer

ABSTRACT

Radium-223 dichloride was administrated to a patient with castration-resistant metastatic prostate cancer (mCRPC) undergoing in-home peritoneal dialysis. The peritoneal dialysate and tubing sets were collected following four treatment cycles and analyzed for removable contamination, dose rate, and radioactivity. The purpose of the study was to assess radiation safety concerns and compare data with patients having normal renal function. Sixty-two liters of dialysate in 22 samples were collected over 4 mo. The mean surface dose rate of the dialysate bags was 0.16 μSv h-1 (range 0.11-0.23 μSv h-1). The highest measured removable surface activity was 150 dpm per 100 cm2. The mean cumulative percent of administered activity was 1.7% (range 1.4-1.9%). The mean concentration of 223Ra in dialysate was 4.0 kBq L-1 (range 0.56-14.1 kBq L-1). There was no association between the measured 223Ra activity in dialysate with peritoneal dwell time or the number of exchanges following administration. The measurement of the 211Bi and 223Ra ratio in the dialysate compared with a standard showed an increase of 23% by 40 h post administration. The data presented suggest that 223Ra dialysate can be safely managed in the home without risk of radiation dose or contamination if minimal precautions are taken. Patients with normal renal function have been shown to excrete up to six times more 223Ra in urine compared to those undergoing hemodialysis or peritoneal dialysis. A potential consequence may be an increase in 223Ra activity transiting GI tract leading to intestinal effects.

Evolving cancer-niche interactions and therapeutic targets during bone metastasis

Many cancer types metastasize to bone. This propensity may be a product of genetic traits of the primary tumour in some cancers. Upon arrival, cancer cells establish interactions with various bone-resident cells during the process of colonization. These interactions, to a large degree, dictate cancer cell fates at multiple steps of the metastatic cascade, from single cells to overt metastases. The bone microenvironment may even influence cancer cells to subsequently spread to multiple other organs. Therefore, it is imperative to spatiotemporally delineate the evolving cancer-bone crosstalk during bone colonization. In this Review, we provide a summary of the bone microenvironment and its impact on bone metastasis. On the basis of the microscopic anatomy, we tentatively define a roadmap of the journey of cancer cells through bone relative to various microenvironment components, including the potential of bone to function as a launch pad for secondary metastasis. Finally, we examine common and distinct features of bone metastasis from various cancer types. Our goal is to stimulate future studies leading to the development of a broader scope of potent therapies.

Exosomes derived from PC-3 cells suppress osteoclast differentiation by downregulating miR-148a and blocking the PI3K/AKT/mTOR pathway

Prostate cancer is a leading malignancy in men that can also disrupt the bone tissue balance. Among all urological cancers, prostate cancer is associated with the highest rate of bone metastases, which can greatly reduce a patient's quality of life. In recent years, cell-derived exosomes, which can contain a wide range of biologically active molecules, have been reported as a novel method of communication among individual cells. However, the specific role that exosomes serve in this disease has not been fully elucidated. The prostate cancer cell line PC-3 were applied in the present study, where its exosomes were isolated to explore their potential effects on osteoclast differentiation. Exosomes are extracellular vesicles secreted by cells. The size of exosomes is 30-150 nm. They have double membrane structure and saucer-like morphology. They contain rich contents (including nucleic acid, protein and lipid) and participate in molecular transmission between cells. The combined results of tartrate-resistant acid phosphatase staining (to identify osteoclasts obtained from human peripheral blood mononuclear cells), reverse transcription-quantitative PCR and western blotting showed that PC-3-derived exosomes attenuated osteoclast differentiation by downregulating marker genes associated with osteoclastic maturation, including V-maf musculoaponeurotic fibrosarcoma oncogene homolog B, matrix metalloproteinase 9 and integrin β3. microRNA (miR)-148a expression was also found to be downregulated in osteoclasts by PC-3-derived exosomes. In addition, the mTOR and AKT signaling pathways were blocked after exposure to these PC-3 cell-derived exosomes. Therefore, results from the present study suggest that miR-148a mimics may be a new therapeutic approach for the prevention of prostate cancer bone metastases.

Inhibition of circ_0081234 reduces prostate cancer tumor growth and metastasis via miR-1/MAP3K1 axis

INTRODUCTION

Circular RNAs (circRNAs) are crucial regulators in tumor occurrence and progression, and circRNAs are enriched and stable in exosomes. This study aimed to explore the role and potential mechanism of cancer-derived exosomal circ_0081234 in prostate cancer (PCa).

METHODS

Exosomes were extracted using the ExoQuick Precipitation Kit. The levels of circ_0081234, miR-1 and mitogen-activated protein kinase kinase kinase 1 (MAP 3K1) were examined using qRT-PCR or western blot. Cell migration and invasion were evaluated via transwell assay. The protein levels of N-cadherin, Vimentin and E-cadherin were detected by western blot. The interaction between miR-1 and circ_0081234 or MAP 3K1 was verified via dual-luciferase reporter assay and RNA pull-down assay.

RESULTS

Circ_0081234 level was increased in PC a tissues with spinal metastasis (SM) in comparison to primary PCa tissues without SM. Exosomal circ_0081234 promoted the migration, invasion and epithelial-mesenchymal transition (EMT) of PCa cells. Knockdown of circ_0081234 blocked PCa cell progression via regulating miR-1. In addition, miR-1 overexpression suppressed PCa cell progression by repressing MAP 3K1. Moreover, circ_0081234 increased MAP 3K1 level via sponging miR-1. Depletion of circ_0081234 inhibited tumor growth in vivo.

CONCLUSION

Exosomal circ_0081234 promoted migration, invasion and EMT of PCa cells by regulating the miR-1/MAP 3K1 axis.

Implication of Prophetic Variables and their Impulsive Interplay in CA Prostate Patients Experiencing Osteo-Metastasis

AIMS

To identify variables having a critical role in prostate cancer patients experiencing osteometastasis.

BACKGROUND

Prostatic carcinoma is a multifactorial complex disorder that exhibits an increased propensity to develop bone metastasis. An interplay of inflammatory and bone remodeling parameters promotes the formation of pre-metastatic niches in bones of patients, which could render them more vulnerable to skeletal disabilities.

OBJECTIVE

To evaluate the multi-dynamic inter-relationship of circulating variables in prostate cancer patients experiencing osteo-metastasis.

MATERIALS AND METHODS

Fifty-seven (n=57) men with clinically confirmed prostate cancer, fifty-nine (n=59) with skeletal metastases, and one hundred (n=100) healthy subjects i.e., men aging from 53-84 years with no clinical evidence of prostate were recruited from the Jinnah Hospital Lahore, Pakistan. Informed consent was obtained, and a venous blood sample was drawn and stored at -70oC until assayed. Levels of variables were evaluated using appropriate methods. Levels of Matrix Metalloproteinases (MMPs), Osteopontin (OPN), TGH- β, and sRANKL were estimated by the ELISA method. Each sample was suspended and the given protocol was employed. ELISA readings were obtained for the estimation of all variables.

RESULTS

Highly significant (P˂0.05) differential expression of oxidative stress, inflammatory cytokines, and bone remodeling variables were observed in localized and osteo-metastatic CA prostate patients. A strong positive correlation was revealed among OPN, sRANKL, MMP-7, MMP-9, PSA, and TGF-β (OPN vs. MMP-7, r=0.698* and OPN vs. MMP-9, r=0.765**, OPN vs. RANKL, =0.856*, sRANKL vs. MMP-9, r=0.825**, TGF- β vs. RANKL, r=0.868* and PSA vs. TGF- β, r=0.752*); lower levels of OPG were estimated in metastasized patients, showing that both osteolytic and osteoblastic phases of bone remodeling occur simultaneously.

CONCLUSION

The altered oxidative and inflammatory responses endorse Matrix Metalloproteinases (MMPs) increased activity, RANKL/OPG imbalance, and enhanced bone matrix proteins turnover, which can foster the process of osteo-metastasis. The perturbed RANKL/OPG drift and enhanced PSA levels are associated with increased TGF-β activity to aggravate Epithelial Mesenchymal transition (EM) and osteo-tropism of prostate cancer. Thus, designing novel targets of these major variables can minimize the incidence of prostate cancer patients.

Tumor- and osteoclast-derived NRP2 in prostate cancer bone metastases

Understanding the role of neuropilin 2 (NRP2) in prostate cancer cells as well as in the bone microenvironment is pivotal in the development of an effective targeted therapy for the treatment of prostate cancer bone metastasis. We observed a significant upregulation of NRP2 in prostate cancer cells metastasized to bone. Here, we report that targeting NRP2 in cancer cells can enhance taxane-based chemotherapy with a better therapeutic outcome in bone metastasis, implicating NRP2 as a promising therapeutic target. Since, osteoclasts present in the tumor microenvironment express NRP2, we have investigated the potential effect of targeting NRP2 in osteoclasts. Our results revealed NRP2 negatively regulates osteoclast differentiation and function in the presence of prostate cancer cells that promotes mixed bone lesions. Our study further delineated the molecular mechanisms by which NRP2 regulates osteoclast function. Interestingly, depletion of NRP2 in osteoclasts in vivo showed a decrease in the overall prostate tumor burden in the bone. These results therefore indicate that targeting NRP2 in prostate cancer cells as well as in the osteoclastic compartment can be beneficial in the treatment of prostate cancer bone metastasis.

Antiprostate Cancer Activity of Ineupatolide Isolated from Carpesium cernuum L

Objective

The aim of the study was to investigate the antiprostate cancer effects and mechanism of ineupatolide (T-21), a natural product isolated from the Compositae plant Carpesium cernuum L., on PC-3 human prostate cancer cells.

Methods

The effect of T-21 on the proliferation of PC-3 cells was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, cell migration, and invasion experiments; the morphology of cell apoptosis was observed by Hoechst-propidium iodide staining; the effects of T-21 on PC-3 cell apoptosis and the cell cycle were evaluated by flow cytometry; and the effect of T-21 on the expression levels of phosphorylated protein kinase B (p-AKT), AKT, X-linked inhibitor of apoptosis protein (xlAP), procaspase-3, and poly (ADP-ribose) polymerase (PARP) in PC-3 cells was measured by western blotting.

Results

T-21 significantly inhibited the proliferation of cells, and its half-maximal inhibitory concentrations at 12, 24, and 48 h were 38.46 ± 1.01, 24.63 ± 0.70, and 7.36 ± 0.58 μM, respectively. T-21 may promote cell apoptosis in a concentration-dependent manner and block the cell cycle in the G2 and S phases. In addition, T-21 significantly reduced the protein expression levels of p-AKT, AKT, xlAP, procaspase-3, and PARP.

Conclusion

T-21 exhibits antiproliferation effects on PC-3 cells by promoting apoptosis and arresting the cell cycle in the G2 and S phases. The possible mechanism underlying its potential therapeutic effects against prostate cancer is related to the AKT/xlAP pathway.

An Ammonia-Induced Calcium Phosphate Nanostructure: A Potential Assay for Studying Osteoporosis and Bone Metastasis

Osteoclastic resorption of bones plays a central role in both osteoporosis and bone metastasis. A reliable in vitro assay that simulates osteoclastic resorption in vivo would significantly speed up the process of developing effective therapeutic solutions for those diseases. Here, we reported the development of a novel and robust nanostructured calcium phosphate coating with unique functions on the track-etched porous membrane by using an ammonia-induced mineralization (AiM) technique. The calcium phosphate coating uniformly covers one side of the PET membrane, enabling testing for osteoclastic resorption. The track-etched pores in the PET membrane allow calcium phosphate mineral pins to grow inside, which, on the one hand, enhances coating integration with a membrane substrate and, on the other hand, provides diffusion channels for delivering drugs from the lower chamber of a double-chamber cell culture system. The applications of the processed calcium phosphate coating were first demonstrated as a drug screening device by using alendronate, a widely used drug for osteoporosis. It was confirmed that the delivery of alendronate significantly decreased both the number of monocyte-differentiated osteoclasts and coating resorption. To demonstrate the application in studying bone metastasis, we delivered a PC3 prostate cancer-conditioned medium and confirmed that both the differentiation of monocytes into osteoclasts and the osteoclastic resorption of the calcium phosphate coating were significantly enhanced. This novel assay thus provides a new platform for studying osteoclastic activities and assessing drug efficacy in vitro.

EWI-2 controls nucleocytoplasmic shuttling of EGFR signaling molecules and miRNA sorting in exosomes to inhibit prostate cancer cell metastasis

Early and accurate diagnosis of prostate cancer (PCa) is extremely important, as metastatic PCa remains hard to treat. EWI-2, a member of the Ig protein subfamily, is known to inhibit PCa cell migration. In this study, we found that EWI-2 localized on both the cell membrane and exosomes regulates the distribution of miR-3934-5p between cells and exosomes. Interestingly, we observed that EWI-2 is localized not only on the plasma membrane but also on the nuclear envelope (nuclear membrane), where it regulates the nuclear translocation of signaling molecules and miRNA. Collectively, these functions of EWI-2 found in lipid bilayers appear to regulate PCa cell metastasis through the epidermal growth factor receptor-mitogen-activated protein kinase-extracellular-signal-regulated kinase (EGFR-MAPK-ERK) pathway. Our research provides new insights into the molecular function of EWI-2 on PCa metastasis, and highlights EWI-2 as a potential PCa biomarker.

Exploiting bone niches: progression of disseminated tumor cells to metastasis

Many solid cancers metastasize to the bone and bone marrow (BM). This process may occur even before the diagnosis of primary tumors, as evidenced by the discovery of disseminated tumor cells (DTCs) in patients without occult malignancies. The cellular fates and metastatic progression of DTCs are determined by complicated interactions between cancer cells and BM niches. Not surprisingly, these niches also play important roles in normal biology, including homeostasis and turnover of skeletal and hematopoiesis systems. In this Review, we summarize recent findings on functions of BM niches in bone metastasis (BoMet), particularly during the early stage of colonization. In light of the rich knowledge of hematopoiesis and osteogenesis, we highlight how DTCs may progress into overt BoMet by taking advantage of niche cells and their activities in tissue turnover, especially those related to immunomodulation and bone repair.

The botanical component p-hydroxycinnamic acid suppresses the growth and bone metastatic activity of human prostate cancer PC-3 cells in vitro

Bone metastatic prostate cancer is one of the most common malignancies in developed countries and the second leading cause of cancer-related death in men. There remains no effective treatment for metastatic prostate cancer. We investigate here the anticancer effects of botanical component p-hydroxycinnamic acid (HCA) on the PC-3 cells in vitro model of bone metastatic human prostate cancer. Culturing with HCA (10-1000 nM) suppressed colony formation and growth of PC-3 cells. Mechanistically, culturing with HCA decreased protein levels of Ras, PI3K, Akt, MAPK, NF-κB p65 and β-catenin related to processes of cell signaling and transcription, and it increased levels of p21, p53, retinoblastoma and regucalcin, which are suppressors in carcinogenesis. These alterations can lead to suppression of cell growth. Furthermore, culturing with HCA increased cell death and caspase-3 levels. The effects of HCA on the growth and death of PC-3 cells were blocked by culturing with CH223191, an antagonist of aryl hydrocarbon receptor (AHR), suggesting that HCA effects are partly involved in AHR signaling. Interestingly, HCA suppressed the stimulatory effects of Bay K 8644, an agonist of L-type calcium channel, on the growth of PC-3 cells. Coculturing of PC-3 cells and preosteoblastic MC-3T3 E1 cells increased osteoblastic mineralization. This increase was not attenuated by treatment of HCA that stimulated mineralization. Notably, osteoclastogenesis from preosteoclastic RAW264.7 cells was enhanced by coculturing with PC-3 cells, and this enhancement was suppressed by treatment with HCA (10-1000 nM). Thus, HCA has anticancer effects on bone metastatic human prostate cancer, potentially providing a novel therapeutic tool.

Extracellular vesicle mimics made from iPS cell-derived mesenchymal stem cells improve the treatment of metastatic prostate cancer

BACKGROUND

Extracellular vesicles (EVs) and their mimics from mesenchymal stem cells (MSCs) are promising drug carriers to improve cancer treatment, but their application is hindered by donor variations and expansion limitations of conventional tissue-derived MSCs. To circumvent these issues, we made EV-mimicking nanovesicles from standardized MSCs derived from human induced pluripotent stem cells (iPSCs) with a theoretically limitless expandability, and examined the targeting capacity of these nanovesicles to prostate cancer.

METHODS

Nanovesicles are made from intact iPSC-MSCs through serial extrusion. The selective uptake of fluorescently labeled nanovesicles by prostate cancer cells vs. non-tumor cells was examined with flow cytometry. For in vivo tracing, nanovesicles were labeled with fluorescent dye DiR or renilla luciferase. In mice carrying subcutaneous or bone metastatic PC3 prostate cancer, the biodistribution of systemically infused nanovesicles was examined with in vivo and ex vivo imaging of DiR and luminescent signals. A chemotherapeutic drug, docetaxel, was loaded into nanovesicles during extrusion. The cytotoxicities of nanovesicle-encapsulated docetaxel on docetaxel-sensitive and -resistant prostate cancer cells and non-tumor cells were examined in comparison with free docetaxel. Therapeutic effects of nanovesicle-encapsulated docetaxel were examined in mice carrying subcutaneous or bone metastatic prostate cancer by monitoring tumor growth in comparison with free docetaxel.

RESULTS

iPSC-MSC nanovesicles are more selectively taken up by prostate cancer cells vs. non-tumor cells in vitro compared with EVs, membrane-only EV-mimetic nanoghosts and liposomes, which is not affected by storage for up to 6 weeks. In mouse models of subcutaneous and bone metastatic PC3 prostate cancer, systemically infused nanovesicles accumulate in tumor regions with significantly higher selectivity than liposomes. The loading of docetaxel into nanovesicles was efficient and did not affect the selective uptake of nanovesicles by prostate cancer cells. The cytotoxicities of nanovesicle-encapsulated docetaxel are significantly stronger on docetaxel-resistant prostate cancer cells and weaker on non-tumor cells than free docetaxel. In mouse models of subcutaneous and bone metastatic prostate cancer, nanovesicle-encapsulated docetaxel significantly decreased the tumor growth and toxicity to white blood cells compared with free docetaxel.

CONCLUSIONS

Our data indicate that EV-mimicking iPSC-MSC nanovesicles are promising to improve the treatment of metastatic prostate cancer.

Targeted nanomedicines for the treatment of bone disease and regeneration

Targeted delivery by either passive or active targeting of therapeutics to the bone is an attractive treatment for various bone related diseases such as osteoporosis, osteosarcoma, multiple myeloma, and metastatic bone tumors. Engineering novel drug delivery carriers can increase therapeutic efficacy and minimize the risk of side effects. Developmnet of nanocarrier delivery systems is an interesting field of ongoing studies with opportunities to provide more effective therapies. In addition, preclinical nanomedicine research can open new opportunities for preclinical bone-targeted drug delivery; nevertheless, further research is needed to progress these therapies towards clinical applications. In the present review, the latest advancements in targeting moieties and nanocarrier drug delivery systems for the treatment of bone diseases are summarized. We also review the regeneration capability and effective delivery of nanomedicines for orthopedic applications.

MicroRNA-122 regulates docetaxel resistance of prostate cancer cells by regulating

Prostate cancer (PCa), an epithelial malignancy that occurs in the prostate, is the second leading cause of cancer death worldwide. MicroRNAs (miRs/miRNAs) are reported to have important applications in the field of cancer diagnosis and treatment. The present study aimed to investigate the function of miRNA-122 in the chemoresistance of PCa cells and the underlying mechanism. Significantly decreased miR-122 and increased pyruvate kinase (PKM2) levels were observed in docetaxel-resistant PCa cells, and PKM2 was negatively correlated with miR-122. MiR-122 mimic transfection in docetaxel-resistant LNCaP cells significantly inhibited cell proliferation, promoted apoptosis and decreased glucose uptake and lactate production, which was counteracted by PKM2 overexpression. Inhibition of miR-122 in LNCaP cells had an opposite effect to miR-122 mimic transfection. In addition, miR-122 mimic transfection significantly increased the sensitivity of docetaxel-resistant LNCaP cells to docetaxel, while inhibition of miR-122 significantly decreased the sensitivity of LNCaP cells to docetaxel. Luciferase reporter assays showed that miR-122 regulated PKM2 expression by binding to the 3'-untranslated region of PKM2. The results suggest that upregulation of miR-122 could enhance docetaxel sensitivity, inhibit cell proliferation and promote apoptosis in PCa cells,possibly through the downregulation of its target protein PKM2.

Progression-free survival of prostate cancer patients is prolonged with a higher regucalcin expression in the tumor tissues: Overexpressed regucalcin suppresses the growth and bone activity in human prostate cancer cells

Prostate cancer, which is a bone metastatic cancer, is the second leading cause of cancer-related death in men. There is no effective treatment for metastatic prostate cancer. Regucalcin has been shown to contribute as a suppressor in various types of human cancers. In the present study, furthermore, we investigate an involvement of regucalcin in suppression of prostate cancer. Regucalcin expression was compared in 131 primary tumor tissues and 19 metastatic tumor tissues in prostate cancer patients. Regucalcin expression in the metastatic tumor was found to be reduced as compared with that in primary tumor. The progression-free survival rate was prolonged in patients with a higher regucalcin expression. Translationally, overexpression of regucalcin in bone metastatic human prostate cancer PC-3 and DU-145 cells suppressed colony formation and cell growth in vitro. Mechanistically, overexpressed regucalcin enhanced the levels of p53, Rb, and p21, and decreased the levels of Ras, PI3 kinase, Akt, and mitogen-activated protein kinase, leading to suppression of cell growth. Furthermore, higher regucalcin expression suppressed the levels of nuclear factor-κB p65, β-catenin, and signal transducer and activator of transcription 3, which regulate a transcription activity. Cell growth was promoted by culturing with the calcium agonist Bay K 8644. This effect was blocked by overexpression of regucalcin. Notably, overexpressed regucalcin suppressed bone metastatic activity of PC-3 and DU-145 cells when cocultured with preosteoblastic or preosteoclastic cells. Regucalcin may suppress the development of human prostate cancer, suggesting that gene delivery systems in which its expression is forced may be a novel therapeutic strategy.

Bone Tropism in Cancer Metastases

Bone is a frequent site of metastases in many cancers. Both bone properties and the tumor-intrinsic traits are associated with the metastatic propensity to bone (i.e., the bone tropism). Whereas an increasing body of mechanistic studies expanded our understanding on bone tropism, they also revealed complexity across the bone lesions originated from different cancer types. In this review, we will discuss the physical, chemical, and biological properties of bone microenvironment, identify potential players in every stage of bone metastases, and introduce some of the known mechanisms regulating the bone colonization. Our objectives are to integrate the knowledge established in different biological contexts and highlight the determinants of bone tropism.

Spinal cannabinoid receptor 2 activation reduces hypersensitivity associated with bone cancer pain and improves the integrity of the blood-spinal cord barrier

Background

Disruption of the blood–spinal cord barrier (BSCB) can facilitate inflammation that results in pain hypersensitivity. Proinflammatory cytokines produced by activated microglia and astrocytes damage the BSCB. This study aims to explore whether the BSCB is damaged in the bone cancer pain (BCP) model and to investigate a potential role and mechanism of JWH015 ((2-methyl-1-propyl-1H-indol-3-yl)−1-naphthalenylmethanone), a selective cannabinoid receptor 2 (CB2R) agonist, in preserving the BSCB integrity in the BCP model.

Methods

We used a male mouse model of BCP. Pain hypersensitivity was measured over time. Evans blue dye extravasation, transmission electron microscopy and Western blotting were performed to investigate the permeability and structural integrity of the BSCB. Immunofluorescence staining and western blotting were used to investigate the effect of JWH015 on the activation of glial cells and the levels of proinflammatory cytokines.

Results

A single intrathecal injection of JWH015 ameliorated pain hypersensitivity, the BSCB disruption and microglia and astrocyte activation. Decreases in the expression of ZO-1 and claudin-5 were partially restored by JWH015. The levels of the proinflammatory cytokines interleukin-1β and tumor necrosis factor-α and the enzyme MMP9 were reduced by JWH015. However, all effects were prevented by pretreatment with a CB2R-selective antagonist, AM630 ((6-iodo-2-methyl-1-(2-morpholinoethyl)−1H-indol-3-yl)(4-methoxyphenyl)methanone).

Conclusions

JWH015 alleviates neuroinflammation and maintains the BSCB integrity and permeability in a mouse model of BCP, which is probably mediated by inhibiting glial cells activation. This study reveals the new analgesic mechanism of JWH015 on BCP and provides a perspective to explore novel drugs that target the BSCB to control BCP.

LINC00992 contributes to the oncogenic phenotypes in prostate cancer via targeting miR-3935 and augmenting GOLM1 expression

Background

Accumulating evidence has revealed the critical role of long non-coding RNAs (lncRNAs) in cellular processes during tumor progression. As documented in cancer-related literatures, LINC00992 expression is associated with cancer progression, whereas its function in tumors including prostate cancer has not been characterized yet.

Methods

Data from GEPIA database suggested LINC00992 expression in prostate cancer tissues. The expression levels of RNAs were monitored via qRT-PCR. Western blot evaluated the levels of proteins. The proliferation, apoptosis and migration of prostate cancer cells were assessed by CCK-8, EdU, TUNEL, Transwell and wound healing assays. Luciferase reporter, RNA pull down and RIP assays were applied to detect the interplays among LINC00992, miR-3935 and GOLM1.

Results

Elevated levels of LINC00992 and GOLM1 were detected in prostate cancer tissues and cells. LINC00992 exerted facilitating functions in prostate cancer cell proliferation and migration. Mechanically, LINC00992 interacted with and negatively regulated miR-3935 to elevate GOLM1 expression in prostate cancer cells. In addition, the in vitro suppressive effect of silenced LINC00992 on prostate cancer cell proliferation and migration was reversed by GOLM1 upregulation. Likewise, LINC00992 depletion restrained tumor growth in vivo was offset by enhanced GOLM1 expression.

Conclusions

LINC00992 competitively bound with miR-3935 to elevate GOLM1 expression and therefore facilitate the oncogenic phenotypes of prostate cancer cells, implying a potential LINC00992-targeted therapy for prostate cancer.

LINC00992 contributes to the oncogenic phenotypes in prostate cancer via targeting miR-3935 and augmenting GOLM1 expression

BACKGROUND

Accumulating evidence has revealed the critical role of long non-coding RNAs (lncRNAs) in cellular processes during tumor progression. As documented in cancer-related literatures, LINC00992 expression is associated with cancer progression, whereas its function in tumors including prostate cancer has not been characterized yet.

METHODS

Data from GEPIA database suggested LINC00992 expression in prostate cancer tissues. The expression levels of RNAs were monitored via qRT-PCR. Western blot evaluated the levels of proteins. The proliferation, apoptosis and migration of prostate cancer cells were assessed by CCK-8, EdU, TUNEL, Transwell and wound healing assays. Luciferase reporter, RNA pull down and RIP assays were applied to detect the interplays among LINC00992, miR-3935 and GOLM1.

RESULTS

Elevated levels of LINC00992 and GOLM1 were detected in prostate cancer tissues and cells. LINC00992 exerted facilitating functions in prostate cancer cell proliferation and migration. Mechanically, LINC00992 interacted with and negatively regulated miR-3935 to elevate GOLM1 expression in prostate cancer cells. In addition, the in vitro suppressive effect of silenced LINC00992 on prostate cancer cell proliferation and migration was reversed by GOLM1 upregulation. Likewise, LINC00992 depletion restrained tumor growth in vivo was offset by enhanced GOLM1 expression.

CONCLUSIONS

LINC00992 competitively bound with miR-3935 to elevate GOLM1 expression and therefore facilitate the oncogenic phenotypes of prostate cancer cells, implying a potential LINC00992-targeted therapy for prostate cancer.

Does bone scintigraphy still have a role in the era of 68 Ga-PSMA PET/CT in prostate cancer?

OBJECTION

We aimed to evaluate the role of bone scintigraphy (BS) which has long been the imaging modality of choice in prostate cancer (PCa) and performed a head-to-head comparison between BS, BS + SPECT/CT and 68 Ga-PSMA-PET/CT, for the detection of bone metastasis of PCa.

METHODS

We evaluated 138 PCa patients who underwent BS and 68 Ga-PSMA PET/CT and SPECT/CT of 102 of 138 patients. Images were interpreted retrospectively and areas of abnormally increased tracer uptake related to PCa were documented as benign, metastatic or equivocal. Equivocal uptakes were finally diagnosed based on a consensus review of correlative imaging. Patient- and lesion-based analysis was performed. Patients with superscan images were excluded from lesion-based analysis.

RESULTS

At least one metastatic or equivocal uptake in skeleton was defined in 76 of 138 (55%) BS, in 33 of 102 (32.3%) SPECT/CT, and in 49 of 138 (35.5%) 68 Ga-PSMA PET/CT. 23 (16.7%) patients had also superscan findings on BS and 68 Ga-PSMA PET/CT. For patient-based analysis, sensitivity, specificity, accuracy, PPV, and NPV were calculated as 91.1%, 64.5%, 73.1%, 55.4% and 93.7% for BS; 95.5%, 82.7%, 86.9%, 72.8% and 96.2% for BS + SPECT/CT; 97.7%, 95.7%, 95.6%, 91.6% and 98.8% for 68 Ga-PSMA PET/CT. For lesion-based analysis, sensitivity, specificity, accuracy, PPV, and NPV were 53%, 63.9%, 60.1%, 42.8% and 71.8% for BS; 59.2%, 87.6%, 77.7%, 62.6% and 80% for BS + SPECT/CT; 96.4%, 98.1%, 97.5%, 96.4% and 98.1% for 68 Ga-PSMA PET/CT.

CONCLUSION

This study has shown that 68 Ga-PSMA PET/CT overcomes the limitations of BS and proves superiority in detecting bone metastases, even in patients with SPECT/CT. Our findings present important implications that 68 Ga-PSMA PET/CT can replace BS in future practice.

Conditional reprogramming: Modeling urological cancer and translation to clinics

Patient-derived models, including cell models (organoids and conditionally reprogrammed cells [CRCs]) and patient-derived xenografts, are urgently needed for both basic and translational cancer research. Conditional reprogramming (CR) technique refers to a co-culture system of primary human normal or tumor cells with irradiated murine fibroblasts in the presence of a Rho-associated kinase inhibitor to allow the primary cells to acquire stem cell properties and the ability to proliferate indefinitely in vitro without any exogenous gene or viral transfection. Considering its robust features, the CR technique may facilitate cancer research in many aspects. Under in vitro culturing, malignant CRCs can share certain genetic aberrations and tumor phenotypes with their parental specimens. Thus, tumor CRCs can promisingly be utilized for the study of cancer biology, the discovery of novel therapies, and the promotion of precision medicine. For normal CRCs, the characteristics of normal karyotype maintenance and lineage commitment suggest their potential in toxicity testing and regenerative medicine. In this review, we discuss the applications, limitations, and future potential of CRCs in modeling urological cancer and translation to clinics.

miR-103a-3p Suppresses Cell Proliferation and Invasion by Targeting Tumor Protein D52 in Prostate Cancer

Growing evidence points at an association between microRNAs and tumor development. Although dysregulation of microRNA-103a-3p (miR-103a-3p) in multiple human cancers has been reported, its expression in prostate cancer (PCa) remains unknown and there is currently no research on the relationship between miR-103a-3p and tumor protein D52 (TPD52) in PCa. Our aim in this study was to explore the effect and potential mechanism of miR-103a-3p in PCa. qRT-PCR was performed to detected the level of miR-103a-3p in PCa tissues and cells, and in normal tissues. Colony, wound-healing, invasion, proliferation, and apoptosis assays were performed in search miR-103a-3p effect in PCa. TargetScan was used to predict potential targets of miR-103a-3p. Additionally, dual-luciferase reporter, western blot, and immunofluorescence assays were performed to detected the target gene of miR-103a-3p. Finally, we explore the differences in tumor xenograft experiments between nude mice injected with stably miR-103a-3p expressing cells and those expressing a miR-negative control. Low level of miR-103a-3p was detected in PCa tissues and cells, when compared with normal tissues. Enhancement of miR-103a-3p significantly inhibited migration and invasion of PCa cells, and negatively regulated expression of the oncogenic tumor protein D52 (TPD52) through direct binding to its 3'-UTR. Interestingly, overexpression of TPD52 significantly attenuated the effect of mir-103a-3p on PCa. Our study provides the first evidence that miR-103a-3p directly targets TPD52 and inhibits the proliferation and invasion of PCa. This finding helps clarify the role of mir-103a-3p-TPD52 axis in PCa and may provide new therapeutic targets for the disease.

Diet and Lifestyle in Prostate Cancer

A variety of diet and lifestyle factors have been studied with respect to prostate cancer risk in large, prospective cohort studies. In spite of this work, and in contrast to other common cancers, few modifiable risk factors have been firmly established as playing a role in prostate cancer. There are several possible explanations for the lack of well-established risk factors. First, prostate cancer has among the highest heritability of all common cancers; second, early life exposures may play an important role in risk, rather than mid- and later-life exposures assessed in most epidemiological studies. Finally, prostate-specific antigen (PSA) screening plays a critical role in prostate cancer detection and incidence rates, which has important implications for epidemiological studies.Among modifiable risk factors, smoking and obesity are consistently associated with higher risk specifically of advanced prostate cancer. There is also considerable evidence for a positive association between dairy intake and overall prostate cancer risk, and an inverse association between cooked tomato/lycopene intake and risk of advanced disease. Several other dietary factors consistently associated with risk in observational studies, including selenium and vitamin E, have been cast into doubt by results from clinical trials. Results for other well-studied dietary factors, including fat intake, red meat, fish, vitamin D, soy and phytoestrogens are mixed.In practical terms, men concerned with prostate cancer risk should be encouraged to stop smoking, be as physically active as possible, and achieve or maintain a healthy weight. These recommendations also have the advantage of having a positive impact on risk of type 2 diabetes, cardiovascular disease, and other chronic diseases. Reducing dairy intake while increasing consumption of fish and tomato products is also reasonable advice.

Endoplasmic Reticulum Stress Contributes to Nociception via Neuroinflammation in a Murine Bone Cancer Pain Model

BACKGROUND

Prolonged endoplasmic reticulum stress has been identified in various diseases. Inflammatory mediators, which have been shown to induce endoplasmic reticulum stress in several studies, have been suggested to serve as the important modulators in pain development. In this study, the authors hypothesized that the endoplasmic reticulum stress triggered by inflammatory mediators contributed to pain development.

METHODS

The authors used a male mouse model of bone cancer pain. The control mice were intrathecally injected with tumor necrosis factor-α (TNF-α) and lipopolysaccharide, the bone cancer pain mice were intrathecally injected with the endoplasmic reticulum stress inhibitors 4-PBA and GSK2606414. The nociceptive behaviors, endoplasmic reticulum stress markers, and inflammatory mediators were assessed.

RESULTS

Increased expression of the p-RNA-dependent protein kinase-like endoplasmic reticulum kinase and p-eukaryotic initiation factor 2α were found in the spinal neurons during bone cancer pain, along with upregulation of inflammatory mediators (TNF-α, interleukin 1β, and interleukin 6). Intrathecal administration of TNF-α or lipopolysaccharide increased the expression of endoplasmic reticulum stress markers in control mice. Inhibition of endoplasmic reticulum stress by intrathecal administration of 4-PBA (baseline vs. 3 h: 0.34 ± 0.16 g vs. 1.65 ± 0.40 g in paw withdrawal mechanical threshold, 8.00 ± 1.20 times per 2 min vs. 0.88 ± 0.64 times per 2 min in number of spontaneous flinches, P < 0.001, n = 8) or GSK2606414 (baseline vs. 3 h: 0.37 ± 0.08 g vs. 1.38 ± 0.11 g in paw withdrawal mechanical threshold, 8.00 ± 0.93 times per 2 min vs. 3.25 ± 1.04 times per 2 min in number of spontaneous flinches, P < 0.001, n = 8) showed time- and dose-dependent antinociception. Meanwhile, decreased expression of inflammatory mediators (TNF-α, interleukin 1β, and interleukin 6), as well as decreased activation of astrocytes in the spinal cord, were found after 4-PBA or GSK2606414 treatment.

CONCLUSIONS

Inhibition of inflammatory mediator-triggered endoplasmic reticulum stress in spinal neurons attenuates bone cancer pain via modulation of neuroinflammation, which suggests new approaches to pain relief.

Mathematical modelling of the role of Endo180 network in the development of metastatic bone disease in prostate cancer

Metastatic bone disease (MBD) is a common complication of advanced cancer and recent research suggests that Endo180 expression is dysregulated through the TGFβ-TGFβR-SMAD2/3 signalling pathway during the invasion of tumour cells in the development of MBD. We here provide a model for the dysregulation of the Endo180 network to demonstrate its vital contribution to bone destruction as well as tumour cell growth. The model consisted of a set of ordinary differential equations and reconstructed variations in the bone cells, resultant bone volume, and biochemical factors involved in the TGFβ-TGFβR-SMAD2/3 signalling pathway over time. The model also investigated the underlying mechanism in which the change of TGFβ affects the TGFβ-TGFβR-SMAD2/3 signalling pathway and the resultant Endo180 expression in osteoblastic and tumour cells. The model links the appearance of tumour cells with the inhibition of TGFβ binding to its receptors on osteoblastic cells, to affect TGFβ-TGFβR-SMAD2/3 signalling and Endo180 expression. Temporal variation in bone cells, bone volume, and the biochemical factors involved in the TGFβ-TGFβR-SMAD2/3 pathway as demonstrated in the model simulations agree with published experimental data. The model can be refined based on further discoveries but allows the influence of Endo180 network dysregulation on bone remodelling in MBD to be established. This model could aid in the development of Endo180 targeted therapies for MBD in the future.

Combination radium-223 therapies in patients with bone metastases from castration-resistant prostate cancer: A review

Chemotherapeutic agents (docetaxel, cabazitaxel), hormonal therapies (abiraterone, enzalutamide) and radium-223 improve survival in patients with bone metastatic castration-resistant prostate cancer (mCRPC). Combinations of radium-223 with these agents or novel drugs have been investigated in order to improve survival and decrease bone-related morbidity. In mCRPC, clinical and preclinical data indicate that radium-223, abiraterone and enzalutamide have a direct effect on prostate cancer cells and bone microenvironment when administered as single agents. Initial results from studies of radium-223 and abiraterone, enzalutamide or docetaxel demonstrated efficacy without any safety concern in pre-treated mCRPC; however, this safety profile changed when radium-based combination therapies were administered in un-pretreated mCRPC. This review underline the biological rationale for combining radium strategies, investigating their effects on bone in terms of control of skeletal-related events and bone disease progression. The aim is to understand the possible reasons why different radium-based combination treatments can led to different clinical outcomes.

Prostate-specific antigen modulates the osteogenic differentiation of MSCs via the cadherin 11-Akt axis

BACKGROUND

A high prevalence of osteoblastic bone metastases is characteristic of prostate cancer. Prostate-specific antigen (PSA) is a serine protease uniquely produced by prostate cancer cells and is an important serological marker for prostate cancer. However, whether PSA modulates the osteogenic process remains largely unknown. In this study, we explored the effect of PSA on modulating the osteoblastic differentiation of mesenchymal stem cells (MSCs). In this study, we used flow cytometry, CCK-8 assay, Alizarin red S (ARS) staining and quantification, alkaline phosphatase (ALP) activity and staining, Western blotting, and quantitative real-time PCR (qRT-PCR) to explore the effect of PSA on osteogenic differentiation of MSCs.

RESULTS

We first demonstrated that although PSA did not affect the proliferation, morphology, or phenotype of MSCs, it significantly promoted the osteogenic differentiation of MSCs in a concentration-dependent manner. Furthermore, we demonstrated that PSA promoted the osteogenic differentiation of MSCs by elevating the expression of Cadherin 11 in MSCs and, thus, activating the Akt signaling pathway.

CONCLUSIONS

In conclusion, we demonstrated that PSA could promote the osteogenesis of MSCs through Akt signaling pathway activation by elevating the expression of cadherin-11 in MSCs. These findings imply a possible role of PSA in osteoblastic bone metastases in prostate cancer.

Proanthocyanidins attenuate breast cancer-induced bone metastasis by inhibiting Irf-3/c-jun activation

We have previously demonstrated the pivotal role of Jnk-mediated Irf-3/c-Jun in regulating nuclear factor kappa-Β ligand (RANKL)-induced osteoclastogenesis. Here, we demonstrated that proanthocyanidins (PACs) target Irf-3 to alleviate breast cancer-induced activation of osteoclasts. We also found that PACs induced apoptosis of osteoclast precursors by upregulating the ratio of bax/bcl-2 and activating caspase-3 activity. Such bone protective effect also could be observed in a bone metastasis model of breast cancer. These findings provided a novel therapeutic intervention targeting abnormal bone metabolism to alleviate bone metastasis of breast cancer.

Cannabinoid receptor 2‑selective agonist JWH015 attenuates bone cancer pain through the amelioration of impaired autophagy flux induced by inflammatory mediators in the spinal cord

Bone cancer pain (BCP) is a severe complication of advanced bone cancer. Although cannabinoid receptor 2 (CB2) agonists may have an analgesic effect, the underlying mechanism remains unclear. CB2 serves a protective role in various pathological states through the activation of autophagy. Therefore, the present study aimed to determine whether the analgesic effects of the selective CB2 agonist JWH015 was mediated by the activation of autophagy in BCP. BCP was induced by the intra‑femur implantation of NCTC2472 fibrosarcoma cells in C3H/HeN mice. The pain behaviors were assessed on the following postoperative days. The selective CB2 agonist JWH015 (1 and 2 µg) was intrathecally administered on day 14 following implantation. AM630 (1 µg), a CB2 antagonist, was injected 30 min before JWH015 administration. Lipopolysaccharide (LPS; 100 nM)‑stimulated primary neurons were treated with JWH015 (1 µM) and AM630 (1 µM) to further verify the mechanism by which CB2 affects autophagy. The results demonstrated that autophagy flux was impaired in spinal neurons during BCP, as indicated by the increased ratio of microtubule‑associated protein 1 light chain 3β (LC3B)‑II/LC3B‑I and increased expression of p62. Intrathecal administration of JWH015 attenuated BCP, which was accompanied by the amelioration of impaired autophagy flux (decreased LC3B‑II/LC3B‑I ratio and decreased p62expression). In addition, the activation of glia cells and upregulation of the glia‑derived inflammatory mediators, interleukin (IL)‑1β and IL‑6 were suppressed by JWH015. In LPS‑stimulated primary neurons, IL‑1β and IL‑6 were increased, and autophagy flux was impaired; whereas treatment with JWH015 decreased the expression of IL‑1β and IL‑6, LC3B‑II/LC3B‑I ratio and expression of p62. These effects were by pretreatment with the CB2‑selective antagonist AM630. The results of the present study suggested that the impairment of autophagy flux was induced by glia‑derived inflammatory mediators in spinal neurons. Intrathecal administration of the selective CB2 agonist JWH015 ameliorated autophagy flux through the downregulation of IL‑1β and IL‑6 and attenuated BCP.

Female sex is associated with a lower risk of bone metastases and favourable prognosis in non-sex-specific cancers

Background

The objectives were to investigate the disparity in the prevalence of bone metastases (BM) between the sexes and to assess the effect of female sex on the development and prognosis of BM.

Methods

Cases of invasive non-sex-specific cancers diagnosed between 2010 and 2015 in the Surveillance, Epidemiology, and End Results (SEER) program were used. The prevalence of BM was calculated by combining the prevalence of BM among different cancers. Multivariable logistic regression and proportion hazard regression were conducted to investigate the effect of female sex, and the results were pooled by meta-analysis.

Results

The pooled prevalence of BM among male and female patients was 2.3% (95% CI: 1.6–3.2%) and 1.8% (95% CI: 1.2–2.6%), respectively. The pooled prevalence of BM dramatically decreased for patients aged 11–40 years old, plateaued for patients aged 41–90 years old and increased for patients aged > 90 years old in both male and female patients. Meta-analysis suggested that female sex had a protective effect on the development of BM (pooled OR = 0.80; 95% CI: 0.75–0.84; p < .001) and a favourable prognosis for respiratory system cancers (pooled HR = 0.81; 95% CI: 0.71–0.92; p < .001). However, no significant associations existed for other cancers. Male non-sex-specific cancer patients and those with male-leaning genetic variations or hormonal status have a greater likelihood of developing BM than female patients.

Conclusions

Female sex was associated with fewer BM in various non-sex-specific cancers, and the effect was constant with changes in age. Female sex showed a protective effect exclusively on the prognosis of respiratory system cancers.

Humanized bone facilitates prostate cancer metastasis and recapitulates therapeutic effects of zoledronic acid in vivo

Advanced prostate cancer (PCa) is known for its high prevalence to metastasize to bone, at which point it is considered incurable. Despite significant effort, there is no animal model capable of recapitulating the complexity of PCa bone metastasis. The humanized mouse model for PCa bone metastasis used in this study aims to provide a platform for the assessment of new drugs by recapitulating the human-human cell interactions relevant for disease development and progression. The humanized tissue-engineered bone construct (hTEBC) was created within NOD-scid IL2rgnull (NSG) mice and was used for the study of experimental PC3-Luc bone metastases. It was confirmed that PC3-Luc cells preferentially grew in the hTEBC compared with murine bone. The translational potential of the humanized mouse model for PCa bone metastasis was evaluated with two clinically approved osteoprotective therapies, the non-species-specific bisphosphonate zoledronic acid (ZA) or the human-specific antibody Denosumab, both targeting Receptor Activator of Nuclear Factor Kappa-Β Ligand. ZA, but not Denosumab, significantly decreased metastases in hTEBCs, but not murine femora. These results highlight the importance of humanized models for the preclinical research on PCa bone metastasis and indicate the potential of the bioengineered mouse model to closely mimic the metastatic cascade of PCa cells to human bone. Eventually, it will enable the development of new effective antimetastatic treatments.

A Novel Small Molecule Inhibits Tumor Growth and Synergizes Effects of Enzalutamide on Prostate Cancer

Prostate cancer (PCa) is the second leading cause of cancer-related death for men in the United States. Approximately 35% of PCa recurs and is often transformed to castration-resistant prostate cancer (CRPCa), the most deadly and aggressive form of PCa. However, the CRPCa standard-of-care treatment (enzalutamide with abiraterone) usually has limited efficacy. Herein, we report a novel molecule (PAWI-2) that inhibits cellular proliferation of androgen-sensitive and androgen-insensitive cells (LNCaP and PC-3, respectively). In vivo studies in a PC-3 xenograft model showed that PAWI-2 (20 mg/kg per day i.p., 21 days) inhibited tumor growth by 49% compared with vehicle-treated mice. PAWI-2 synergized currently clinically used enzalutamide in in vitro inhibition of PCa cell viability and resensitized inhibition of in vivo PC-3 tumor growth. Compared with vehicle-treated mice, PC-3 xenograft studies also showed that PAWI-2 (20 mg/kg per day i.p., 21 days) and enzalutamide (5 mg/kg per day i.p., 21 days) inhibited tumor growth by 63%. Synergism was mainly controlled by the imbalance of prosurvival factors (e.g., Bcl-2, Bcl-xL, Mcl-1) and antisurvival factors (e.g., Bax, Bak) induced by affecting mitochondrial membrane potential/mitochondria dynamics. Thus, PAWI-2 utilizes a distinct mechanism of action to inhibit PCa growth independently of androgen receptor signaling and overcomes enzalutamide-resistant CRPCa. SIGNIFICANCE STATEMENT: Castration-resistant prostate cancer (CRPCa) is the most aggressive human prostate cancer (PCa) but standard chemotherapies for CRPCa are largely ineffective. PAWI-2 potently inhibits PCa proliferation in vitro and in vivo regardless of androgen receptor status and uses a distinct mechanism of action. PAWI-2 has greater utility in treating CRPCa than standard-of-care therapy. PAWI-2 possesses promising therapeutic potency in low-dose combination therapy with a clinically used drug (e.g., enzalutamide). This study describes a new approach to address the overarching challenge in clinical treatment of CRPCa.

Exosomes Derived from miR-143-Overexpressing MSCs Inhibit Cell Migration and Invasion in Human Prostate Cancer by Downregulating TFF3

Exosomes are membrane-enclosed nanovesicles that shuttle active cargoes, such as mRNAs and microRNAs (miRNAs), between different cells. Mesenchymal stem cells (MSCs) are able to migrate to the tumor sites and exert complex functions over tumor progress. We investigated the effect of human bone marrow-derived MSC (BMSC)-derived exosomal miR-143 on prostate cancer. During the co-culture experiments, we disrupted exosome secretion by the inhibitor GW4869 and overexpressed exosomal miR-143 using miR-143 plasmid. miR-143 was involved in the progression of prostate cancer via trefoil factor 3 (TFF3). Moreover, miR-143 was downregulated while TFF3 was upregulated in prostate cancer cells and tissues, and miR-143 was found to specifically inhibit TFF3 expression. Human MSC-derived exosomes enriched miR-143 and transferred miR-143 to prostate cancer cells. Furthermore, elevated miR-143 or exosome-miR-143 or silencing TFF3 inhibited the expression of TFF3, proliferating cell nuclear antigen (PCNA), matrix metalloproteinase (MMP)-2, and MMP-9 and PC3 cell proliferation, migration, invasion, and tumor growth, whereas it promoted apoptosis. In conclusion, hMSC-derived exosomal miR-143 directly and negatively targets TFF3 to suppress prostate cancer.

c-Src is required for hypoxia-induced metastasis-associated functions in prostate cancer cells

Background: Metastasis is the major cause of therapeutic failure in prostate cancer patients, and hypoxia has been shown to promote metastatic functions. However, whether Src family kinases (SFKs) can be upregulated under hypoxia is unclear.

Materials and methods: In the current study, we evaluated the effects of hypoxia on cellular functions and activities of different SFK members (c-Src, Lyn, Fyn) in prostate cancer cells. Prostate cancer cell functions were determined in vitro including migration (wound-healing assay), invasion (Matrigel-based transwell assay) and clonogenic cell survival (colony formation assay). Protein expression was detected by Western blotting and gene knockdown was accomplished by siRNA transfection.

Results:SRC, but not LYN and FYN, is associated with overall survival in prostate cancer patients, while all three phosphorylated proteins are highly expressed in tumors compared to normal tissues. Short-term hypoxic exposure significantly enhances cell migration, invasion, clonogenic survival, and consistently, c-Src phosphorylation in both PC-3ML and C4-2B cells. Knockdown of SRC, but not LYN or FYN, abolished hypoxia-induced functions. Finally, small molecule Src inhibitors strongly inhibited cell behaviors and c-Src activation under hypoxic conditions.

Conclusion: Our data show that hypoxia is able to enhance metastatic-associated cell functions by activating c-Src in prostate cancer cells. Importantly, SFK inhibition by small molecule inhibitors was able to impair hypoxia-induced metastasis associated cell functions, suggesting a possible role of SFK inhibitors for prostate cancer treatment.

CTBP1 depletion on prostate tumors deregulates miRNA/mRNA expression and impairs cancer progression in metabolic syndrome mice

About 20% of prostate cancer (PCa) patients progress to metastatic disease. Metabolic syndrome (MeS) is a pathophysiological disorder that increases PCa risk and aggressiveness. C-terminal binding protein (CTBP1) is a transcriptional corepressor that is activated by high-fat diet (HFD). Previously, our group established a MeS/PCa mice model that identified CTBP1 as a novel link associating both diseases. Here, we integrated in vitro (prostate tumor cell lines) and in vivo (MeS/PCa NSG mice) models with molecular and cell biology techniques to investigate MeS/CTBP1 impact over PCa progression, particularly over cell adhesion, mRNA/miRNA expression and PCa spontaneous metastasis development. We found that CTBP1/MeS regulated expression of genes relevant to cell adhesion and PCa progression, such as cadherins, integrins, connexins, and miRNAs in PC3 xenografts. CTBP1 diminished PCa cell adhesion, membrane attachment to substrate and increased filopodia number by modulating gene expression to favor a mesenchymal phenotype. NSG mice fed with HFD and inoculated with CTBP1-depleted PC3 cells, showed a decreased number and size of lung metastases compared to control. Finally, CTBP1 and HFD reduce hsa-mir-30b-5p plasma levels in mice. This study uncovers for the first time the role of CTBP1/MeS in PCa progression and its molecular targets.

Mutant Kras-induced upregulation of CD24 enhances prostate cancer stemness and bone metastasis

Prostate cancer (PCA), one of the most common malignant tumors in men, is the second leading cause of cancer deaths in males worldwide. We report here that PCA models harboring conditional LSL/KrasG12D or BRAFF-V600E allele with prostate-specific abrogated p53 function recapitulate human PCA precursor lesions, histopathology, and clinical behaviors. We found that the development of reprogrammed EMT-like phenotypes and skeleton metastatic behavior requires concurrent activated Kras and p53 depletion in PCA. Microarray analyses of primary PCA cells derived from these models identified several cancer stemness genes including CD24, EpCAM, and CD133 upregulated by KRASG12D. Among these stemness markers, we identified CD24 as a key driver of tumorigenesis and metastasis in vivo. These data demonstrate that specific factors involved in cancer stemness are critical for metastatic conversion of PCA and may be ideal targets for therapeutic intervention.