Ameloblastoma is a common odontogenic benign tumor located in the jaws and is characterized by severe local bone destruction. The current study aimed to investigate the effect of interactions between tumor cells and bone marrow stromal cells (BMSCs) on osteoclast formation in ameloblastoma. The impact of ameloblastoma/BMSC interactions on cytokine production, gene expression and osteoclastogenesis was examined using an immortalized ameloblastoma cell line that the authors' previously established. The results demonstrated that interactions between ameloblastoma cells and BMSCs increased interleukin (IL)‑8 and activin A secretion by BMSCs. IL‑8 expression in BMSCs was modulated by tumor‑derived tumor necrosis factor‑α and IL‑8 contributed to osteoclast formation not only directly but also by stimulating receptor activator of NF‑κB ligand (RANKL) expression in BMSCs. Activin A secretion in BMSCs was stimulated by ameloblastoma cells via cell‑to‑cell‑mediated activation of c‑Jun N‑terminal kinase activation, acting as a cofactor of RANKL to induce osteoclast formation and function. The present study highlights the critical role of communication between BMSCs and ameloblastoma cells in bone resorption in ameloblastoma.

BACKGROUND: Despite development of several next-generation tyrosine kinase inhibitors (TKIs), crizotinib remains one of the first-line treatment options for advanced ALK-positive NSCLC and is widely used in situations where next-generation TKIs aren't yet approved or economically inaccessible. However, the pattern of failure and clinical value of radiotherapy in metastatic crizotinib-treated ALK-mutant lung cancer, with or without baseline brain metastases (BBM), are largely unknown.
METHODS: Consecutive crizotinib-treated NSCLC patients with adequate imaging and measurable disease were retrospectively enrolled. Disease progression in original sites (primary/metastatic), new sites, or both, are classified as original failure (OF), distant failure (DF) and ODF, respectively. Progression free survival, from crizotinib initiation to the first disease progression, and from that to the second disease progression, were calculated as PFS1 and PFS2.
RESULTS: Ninety-three patients were identified. With a median follow up of 22.0 (range, 2.0-72.0) months, 52 patients had crizotinib-treatment failure. The frequencies of OF, ODF, and DF, were 50.0, 26.9, and 23.1%, respectively. Histology, primary tumor size and presence of BBM, were independently associated with OF, using competing risks analyses. The brain was the most common site of initial disease progression. Patients with BBM had a significant higher possibility developing multiple-progressive lesions in the brain (p = 0.002). Importantly, four of the ten patients who had baseline oligo-metastatic cranial disease but didn't receive upfront brain radiation, developed multiple-progressive disease in the brain. Brain radiation before crizotinib could alter the disease failure patterns and improve PFS1 among patients with BBM (p = 0.006). Extracranial radiation was efficient in controlling symptoms but it was not associated with PFS1 (p = 0.223), and the majority of patients were eligible for salvage radiotherapy upon disease progression to crizotinib. By the time of data cut-off, 28 patients had second disease progression, with a median PFS2 of 7.0 (95% CI 5.4-8.6) months and salvage radiotherapy significantly prolonged PFS2 (p = 0.003). Additionally, patients receiving any radiotherapy during their treatment course had a significant longer overall survival (p = 0.048).
CONCLUSIONS: Among patients with baseline oligo-metastatic brain lesions which are suitable for stereotactic radiosurgery, upfront brain radiotherapy provides considerable clinical benefits. While, extracranial radiation may be deferred in asymptomatic patients with multiple-metastatic lesions.

Progesterone and its receptor, PR, are essential for uterine leiomyoma (LM, a.k.a., fibroid) tumorigenesis, but the underlying cellular and molecular mechanisms remain unclear. The receptor activator of NF-κB (RANKL) was recently identified as a novel progesterone/PR-responsive gene that plays an important role in promoting LM growth. Here, we used RANKL as a representative gene to investigate how steroid hormone, genetic, and epigenetic signals are integrated to regulate LM stem cell (LSC) function. We demonstrated that RANKL specifically upregulates LSC proliferation through activation of Cyclin D1. RANKL gene transcription was robustly induced by the progesterone agonist R5020, leading to a dramatically higher RANKL expression in LM compared to adjacent myometrial (MM) tissue. MethylCap-Seq revealed a differentially methylated region (DMR) adjacent to the distal PR-binding site (PRBS) 87 kb upstream of the RANKL transcription start site. Hypermethylation of the DMR inhibited recruitment of PR to the adjacent PRBS. Luciferase assays indicated that the DMR and distal PRBS constitute a novel RANKL distal regulatory element that actively regulates RANKL expression. Furthermore, MED12 physically interacts with PR in LM tissue. The interaction between MED12 and PR, binding of PR and MED12 to PRBS, and RANKL gene expression are significantly higher in LM containing a distinct MED12 mutation (G44D) than in LM with wild-type MED12. In summary, our findings suggest that DNA methylation and MED12 mutation together constitute a complex regulatory network that affects progesterone/PR-mediated RANKL gene expression, with an important role in activating stem cell proliferation and fibroid tumor development.

Bone is the most common metastatic site for breast cancer. Estrogen-related-receptor alpha (ERRα) has been implicated in cancer cell invasiveness. Here, we established that ERRα promotes spontaneous metastatic dissemination of breast cancer cells from primary mammary tumors to the skeleton. We carried out cohort studies, pharmacological inhibition, gain-of-function analyses in vivo and cellular and molecular studies in vitro to identify new biomarkers in breast cancer metastases. Meta-analysis of human primary breast tumors revealed that high ERRα expression levels were associated with bone but not lung metastases. ERRα expression was also detected in circulating tumor cells from metastatic breast cancer patients. ERRα overexpression in murine 4T1 breast cancer cells promoted spontaneous bone micro-metastases formation when tumor cells were inoculated orthotopically, whereas lung metastases occurred irrespective of ERRα expression level. In vivo, Rank was identified as a target for ERRα. That was confirmed in vitro in Rankl stimulated tumor cell invasion, in mTOR/pS6K phosphorylation, by transactivation assay, ChIP and bioinformatics analyses. Moreover, pharmacological inhibition of ERRα reduced primary tumor growth, bone micro-metastases formation and Rank expression in vitro and in vivo. Transcriptomic studies and meta-analysis confirmed a positive association between metastases and ERRα/RANK in breast cancer patients and also revealed a positive correlation between ERRα and BRCA1

Background: Expression of estrogen receptor α in breast cancer is essential for estrogen-dependent growth and partially determines the breast cancer subtype. In premenopausal women, expression of estrogen-regulated genes in estrogen receptor-positive breast cancer tissues are reportedly influenced by the menstrual cycle.
Methods: We investigated correlations between serum estradiol (E2; tested on the day of surgery) and expression of estrogen-regulated genes and proliferation genes in strongly estrogen receptor α-positive breast cancer tissues from 91 premenopausal women by quantitative reverse transcription-polymerase chain reaction. We also investigated correlations between serum progesterone levels on the day of surgery and mRNA expression of progesterone-regulated genes and proliferation genes.
Results: The serum E2 level affected expression of estrogen-regulated genes, including progesterone receptor (P = 0.016, Rs = 0.07) but showed no correlation with expression of genes associated with proliferation. We also observed strong positive correlations between mRNA expression of ESR1 and that of estrogen-regulated genes (P < 0.0001, Rs = 0.329-0.756) and proliferation genes (P < 0.0001, Rs = 0.753-0.843). The serum progesterone level affected expression of RANKL mRNA. However, we observed no correlations between serum progesterone and expression of Wnt-4 or proliferation genes.
Conclusions: The serum E2 level on the day of surgery influences estrogen-regulated gene expression moderately in patients found to be strongly positive for estrogen receptor α by immunohistochemistry. Changes in serum E2 levels might influence the results of molecular profiling tests in premenopausal women with breast cancer.

BACKGROUND: Myeloma bone disease (MBD) can cause bone destruction and increase the level of Ca
METHODS: To investigate the expression of TRPV2 in MM, we analyzed publicly available MM data sets and performed immunohistochemistry in MM patients. The correlations between TRPV2 expression levels and osteoclast-related cytokines were analyzed. Fluo-4 staining and ELISA assays were used to assess the regulated function of TRPV2 in intracellular Ca
RESULTS: The functional expression of TRPV2, involved in the osteolysis through gating the calcium influx, was changed in the MM cells cultured in a high Ca
CONCLUSIONS: Our study uncovers the possible roles of TRPV2, which enhances MBD, suggesting that targeting osteocyte-MM cells interactions through blockade of TRPV2 channel may provide a promising treatment strategy in MM.

Giant-cell tumor (GCT) of the bone is an invasiveness and high recurrent bone tumor that is considered borderline or potentially malignant. To explore the molecular mechanism leading to bone destruction and identify novel targets for treatment, we conducted silencing of miR-223 and miR-19a in stromal giant cells and identified TWIST and Runx2 as their target genes. We investigated the impact of these microRNAs and their target genes on stromal giant cells that promote the differentiation of monocyte/macrophages into osteoclast cells and recruitment to the bone microenvironment, which in turn enhances the bone destruction capacity of GCT. MiR-223 and miR-19a were found to regulate the expression of TWIST and Runx2, influence the RANKL-RANK pathway and the expression of MCP-1, and finally regulate the pathophysiological process of osteolytic bone destruction. Our results indicate that re-expression of miR-223 and miR-19a induces an inhibitory effect on the bone destruction capacity of GCT, suggesting that re-expression of miR-223 and miR-19a can be a novel strategy for the treatment of GCT.

The survival and growth of multiple myeloma (MM) cells are facilitated by cell-cell interactions with bone marrow stromal cells and the bone marrow microenvironment. These interactions induce de novo drug resistance known as cell adhesion-mediated drug resistance. Our previous results recently revealed that the receptor activator of NF-κB (RANK) ligand (RANKL), which is expressed by bone marrow stromal cells, contributes to anti-cancer drug resistance through the activation of various signaling molecules and suppression of Bim expression in RANK-expressing MM cells. However, the detailed mechanisms underlying RANKL-induced drug resistance remain uncharacterized. In the present study, we investigated the mechanism of RANKL-induced drug resistance in RANK-expressing MM cell lines. We found treatment of MM cells with RANKL-induced c-Src phosphorylation and activation of the downstream signaling molecules Akt, mTOR, STAT3, JNK, and NF-κB. In addition, treatment with dasatinib, a c-Src inhibitor, overcame RANKL- and bone marrow stromal cell-induced drug resistance to adriamycin, vincristine, dexamethasone, and melphalan by suppressing c-Src, Akt, mTOR, STAT3, JNK, and NF-κB activation and enhancing expression of Bim. Overall, RANKL- and bone marrow stromal cell-induced drug resistance correlated with the activation of c-Src signaling pathways, which caused a decrease in Bim expression. Dasatinib treatment of RANK-expressing MM cells re-sensitized them to anti-cancer drugs. Therefore, inhibition of c-Src may be a new therapeutic approach for overcoming RANKL-induced drug resistance in patients with MM.

Background and Objective: Reduced expression of syndecan-1 (CD138), increased proliferation index, and modifications in the expression of the molecular RANK/RANKL/OPG triad are related to an intensified potential of aggressiveness and invasion of diverse tumors and cysts. The aim was to compare the expression of Ki-67, CD138, and the molecular triad RANK, RANKL, and OPG in odontogenic keratocysts (OKC), unicystic ameloblastomas (UA), and dentigerous cysts (DC).
Methods: Immunohistochemistry for Ki-67, CD138, RANK, RANKL, and OPG was performed in 58 odontogenic cystic lesions (22 OKC, 17 DC, and 19 UA).
Results: A higher expression of Ki-67 was identified in OKC as compared to UA (
Conclusion: Higher RANKL expression together with the reduction on CD138 expression in UA could be linked to a greater invasive and destructive potential, while the increased proliferation rate observed in OKC could be related to its continuous intrabony growth. The expansion of DC does not seem to be related to such factors, justifying the different therapeutic approaches proposed for each of these entities.

Hypoxia plays a significant role in cancer progression, including metastatic bone tumors. We previously reported that transcutaneous carbon dioxide (CO2) application could decrease tumor progression through the improvement of intratumor hypoxia. Therefore, we hypothesized that decreased hypoxia using transcutaneous CO2 could suppress progressive bone destruction in cancer metastasis. In the present study, we examined the effects of transcutaneous CO2 application on metastatic bone destruction using an animal model. The human breast cancer cell line MDA-MB-231 was cultured in vitro under three different oxygen conditions, and the effect of altered oxygen conditions on the expression of osteoclast-differentiation and osteolytic factors was assessed. An in vivo bone metastatic model of human breast cancer was created by intramedullary implantation of MDA-MB-231 cells into the tibia of nude mice, and treatment with 100% CO2 or a control was performed twice weekly for two weeks. Bone volume of the treated tibia was evaluated by micro-computed tomography (µCT), and following treatment, histological evaluation was performed by hematoxylin and eosin staining and immunohistochemical staining for hypoxia-inducible factor (HIF)-1α, osteoclast-differentiation and osteolytic factors, and tartrate-resistant acid phosphatase (TRAP) staining for osteoclast activity. In vitro experiments revealed that the mRNA expression of RANKL, PTHrP and IL-8 was significantly increased under hypoxic conditions and was subsequently reduced by reoxygenation. In vivo results by µCT revealed that bone destruction was suppressed by transcutaneous CO2, and that the expression of osteoclast-differentiation and osteolytic factors, as well as HIF-1α, was decreased in CO2-treated tumor tissues. In addition, multinucleated TRAP-positive osteoclasts were significantly decreased in CO2-treated tumor tissues. Hypoxic conditions promoted bone destruction in breast cancer metastasis, and reversal of hypoxia by transcutaneous CO2 application significantly inhibited metastatic bone destruction along with decreased osteoclast activity. The findings in this study strongly indicated that transcutaneous CO2 application could be a novel therapeutic strategy for treating metastatic bone destruction.

It is increasingly evident that the microenvironment of bone can influence cancer phenotype in many ways that favor growth in bone. CD147, a transmembrane protein of the immunoglobulin (Ig) superfamily, was identified independently in different species and has many designations across different species. However, expression levels of CD147 mRNA in bone cancer have not been described. In this study, we have used real-time fluorescence quantification (RT-PCR) to demonstrate CD147 expression in malignant bone cancer and benign bone tumor tissues. The results suggested that the expression of CD147 gene was significantly up-regulated in malignant bone cancer. Moreover, we found that over-expressed RANKL progressively enhanced osteoclast formation up to 48 h, which suggested that RANKL could promote the formation of osteoclast, indicating that both CD147 and RANKL play important roles in the formation of osteoclasts. Furthermore, the expressions of four osteoclast specific expression genes, including TRACP, MMP-2, MMP-9 and c-Src, were analyzed using RT-PCR. The results indicated that four osteoclast-specific expression genes were detectable in all osteoclast with different treatments. However, the highest expression level of these four osteoclast-specific expression genes appears in the CD147+ RANKL group and the lowest expression level of these four osteoclast-specific expression genes appears with si-RANKL treatment. Characterization of the role of CD147 in the development of tumors should lead to a better understanding of the changes occurring at the molecular level during the development and progression of primary human bone cancer.

BACKGROUND: The process of marsupialization involves the release of intracystic pressure and the fluid contained within. Marsupialization of cystic ameloblastoma is controversial; therefore, we investigated how hydrostatic pressure influences biological behaviours of ameloblastoma cells and its underlying mechanisms.
MATERIALS AND METHODS: An ameloblastoma epithelial cell line, hTERT
RESULTS: Elevated hydrostatic pressure promoted migration and invasion of ameloblastoma cells, but inhibited proliferation. Expression of MMP-2, MMP-9, LEF-1, cyclin D1, c-Jun and c-Myc was significantly upregulated under elevated hydrostatic pressure, and these effects could be abolished by DKK1. Expression of RANKL, which is thought to be a downstream target of Wnt signalling, did not significantly change under elevated hydrostatic pressure.
CONCLUSIONS: This study indicates that elevated hydrostatic pressure promotes the migration and invasion of ameloblastoma cells by activating the Wnt/β-catenin pathway, thereby increasing expression of MMP-2, MMP-9 and other Wnt signalling downstream targets. This suggests that marsupialization may reduce invasiveness and reverse the bone resorption process by lowering intracystic hydrostatic pressure in cystic ameloblastoma.

The system integrated by the receptor activator of nuclear factor kappa B (RANK) and its ligand, RANKL, modulates the role of hormones in the genesis and progression of breast tumors. We investigated whether the expression of RANK was related with clinicopathological features of primary endometrial tumors. Immunohistochemistry was used in an endometrial cancer tissue array containing samples from 36 tumors. The amount of RANK mRNA was examined in a tissue scan cDNA array containing cDNA from 40 tumors. Normal endometrium was examined for comparison. Immunohistochemical analyses showed that RANK expression was higher in malignant than in normal endometrium (

The RANK/RANKL axis emerges as a key regulator of breast cancer initiation, progression, and metastasis. RANK-c is a RANK receptor isoform produced through alternative splicing of the TNFRSF11A (RANK) gene and a dominant-negative regulator of RANK-induced nuclear factor-κB (NF-κB) activation. Here we report that RANK-c transcript is expressed in 3.2% of cases in The Cancer Genome Atlas breast cancer cohort evenly between ER-positive and ER-negative cases. Nevertheless, the ratio of RANK to RANK-c (RANK/RANK-c) is increased in ER-negative breast cancer cell lines compared to ER-positive breast cancer cell lines. In addition, forced expression of RANK-c in ER-negative breast cancer cell lines inhibited stimuli-induced NF-κB activation and attenuated migration, invasion, colony formation, and adhesion of cancer cells. Further, RANK-c expression in MDA-MB-231 cells inhibited lung metastasis and colonization in vivo. The RANK-c-mediated inhibition of cancer cell aggressiveness and nuclear factor-κB (NF-κB) activation in breast cancer cells seems to rely on a RANK-c/TNF receptor-associated factor-2 (TRAF2) protein interaction. This was further confirmed by a mutated RANK-c that is unable to interact with TRAF2 and abolishes the ability to attenuate NF-κB activation, migration, and invasion. Additional protein interaction characterization revealed epidermal growth factor receptor (EGFR) as a novel interacting partner for RANK-c in breast cancer cells with a negative effect on EGFR phosphorylation and EGF-dependent downstream signaling pathway activation. Our findings further elucidate the complex molecular biology of the RANKL/RANK system in breast cancer and provide preliminary data for RANK-c as a possible marker for disease progression and aggressiveness.

PURPOSE: Denosumab, a new monoclonal antibody that inhibits receptor activator for nuclear factor Kβ ligand (RANKL), has recently been approved by FDA for the treatment of aggressive giant cell tumor of bone (GCTB). So we initiated this study to evaluate the clinical benifits of denosumab used preoperatively or postoperatively.
METHODS: Patients diagnosed with classic sacral GCT without metastasis were included in this study. Patients were assigned into 3 groups according to the use of denosumab: control group 1, post-operative group 2 and neoadjuvant group 3. The latter two groups were treated with 120 mg of subcutaneous denosumab every 4 weeks with loading doses on days 8 and 15 of the first cycle. The primary endpoints were event-free-survival (EFS) and objective response rate (OPR) based on RECIST criteria. A system (MUD system) proposed by our center was applied to score the sacral nerve deficit changes before surgery in group 3.
RESULTS: A total 30 patients (13 men and 17 women, mean age 34.7 years, range 15-56) were enrolled from April 2014 to July 2016. Group 1 included 10 patients, group 2 9 and group 3 11. The study ended in March 01, 2017, and followup ranged from 3 to 36 months (mean 18.3). Two patients with PET-CT showed SUV max uptake down to muscle tissue level. In the neoadjuvant group 3 7 patients had partial responses and 4 stable disease (ORR 63.6%; 95% CI 35-92). Most (80%) patients achieved significant improvement in pain and great relief in the bladder and bowel functions. In 4 patients the urocatheter was removed after neoadjuvant denosumab.
CONCLUSION: Neoadjuvant therapy with denosumab can significantly relieve the symptoms and neurologic deficits.

Context: Uterine leiomyomas are the most common type of gynecologic tumor in women.
Objective: To determine the role of the cytokine receptor activator of nuclear factor κ-Β ligand (RANKL); its receptor, receptor activator of nuclear factor κ-Β (RANK); and the RANKL/RANK pathway inhibitor RANK-Fc in leiomyoma growth.
Design: Messenger RNA (mRNA) or protein levels of RANKL, RANK, and proliferation markers cyclin D1 and Ki67 were assessed in various leiomyoma tissues and cell populations. Human xenograft experiments were performed to determine the effects of RANK-Fc on leiomyoma growth in vivo.
Setting: Research laboratory.
Patients: Twenty-four regularly cycling premenopausal women (age 28 to 49 years) who were not receiving hormone therapy.
Interventions: None.
Main Outcome Measure: Tumor growth in a murine xenograft model following targeting of the RANKL/RANK pathway with RANK-Fc.
Results: RANKL mRNA levels in leiomyoma were significantly higher than those in myometrial tissues. The highest RANK levels were found in the leiomyoma stem cell population, which is deficient in progesterone receptor (PR). Conversely, the highest RANKL levels were found in the PR-rich leiomyoma intermediate cell (LIC) population. R5020, a PR agonist, specifically increased RANKL expression in LICs. RANK-Fc blocked RANKL-induced expression of the proliferative gene cyclin D1. Treatment with RANK-Fc also significantly decreased tumor growth in vivo and diminished the expression of proliferation marker Ki67 in tumors (P < 0.01; n = 4).
Conclusions: Treatment with the RANKL/RANK pathway inhibitor RANK-Fc significantly decreased human leiomyoma cell proliferation and tumor growth. This suggests that the RANKL/RANK pathway could serve as a potential target for the prevention and treatment of uterine leiomyoma.

Cytosine methylation plays a major role in the regulation of sequential and tissue-specific expression of genes. De novo aberrant DNA methylation and demethylation are also crucial processes in tumorigenesis and tumor progression. The mechanisms of how and when such aberrant methylation and demethylation occur in tumor cells are still obscure, however. To evaluate subtle epigenetic alteration among minor subclonal populations, morphology-oriented epigenetic analysis is requisite, especially where heterogeneity and flexibility are as notable as in the process of cancer progression and cellular differentiation at critical stages. Therefore, establishment of reliable morphology-oriented epigenetic studies has become increasingly important in not only the experimental but also the diagnostic field. By selecting a subset of cells based on characteristic morphological features disclosed by microdissection or in situ hybridization, we discovered how methylation at certain CpG sites outside of CpG islands would play a crucial epigenetic role in the versatility and flexibility of gene expression during cancer progression. In this review, we first introduce technical aspects of two morphology-oriented epigenetic studies: (1) histoendonuclease-linked detection of methylated sites of DNA (HELMET), and (2) padlock probe and rolling circle amplification (RCA) for in situ identification of methylated cytosine in a sequence-dependent manner. We then present our observation of a novel MeCP2-mediated gene-silencing mechanism through the addition of methylation to a single-CpG-locus upstream of the TATA-box of the receptor activator of NF-κB ligand (RANKL) and of secreted frizzled-related protein 4 (SFRP4) gene promoters.

BACKGROUND: Giant cell tumor of bone (GCTB) is an osteolytic, locally aggressive, rarely metastazing bone tumor. This is a retrospective study evaluating a large series of GCTB patients treated with denosumab in routine practice in 6 European reference centers.
METHODS: Patients with locally advanced, unresectable or metastatic GCTB, treated with denosumab outside clinical trials were eligible. Primary end-point was progression-free survival (PFS) for all patients; secondary end-points were: type of surgery, relapse rate and event-free survival for patients after preoperative denosumab + surgery.
RESULTS: We identified 138 patients treated in the period 2011-2016. In 40/43 cases the diagnosis was confirmed by H3F3A gene mutation. Median follow-up time was 23 months (range 6-48). Primary tumor was located in lower limb (38%) - mostly in femur and tibia, in upper limb (34%), and in pelvis/axial skeleton/ribs (28%). 110 (80%) patients had primary tumors, 28 (22%) recurrent tumors after previous surgical procedures (+/- radiotherapy). 89/138 patients had locally advanced GCTB and underwent neoadjuvant denosumab. The median denosumab treatment duration was 8 months (median number of cycles 11), 98% had clinical benefit from therapy. 39 (44%) had wide en-bloc resection - WE (+implantation of the prosthesis in 17 cases), the other 50 (56%) cases had intralesional curettage - C. Progression after surgical treatment was observed in 19 patients, 16 of them after C (32%); 13 patients underwent denosumab re-challenge, and all responded. Two-year progression-free survival (PFS; from denosumab start) rate was 81%; 2-year EventFS (from surgery) was significantly better in WE group (93%) vs 55% in C group (p = 0.006). Treatment was well tolerated with only 2 cases of grade 3 toxicity and one osteonecrosis of the jaw.
CONCLUSION: Our retrospective study confirms that denosumab is extremely efficient in unresectable/metastatic disease as well as in a neoadjuvant setting. Our data confirm excellent efficacy and short-term tolerability of this drug. Our data suggest that neoadjuvant therapy with denosumab is the option for treatment of initially locally advanced tumors to facilitate complete surgical resection or avoid mutilating surgery. The risk of recurrences after curettage of GCTB following denosumab raises questions about the optimal management of such cases.

Bone metastasis is a frequent occurrence in prostate cancer (PCa) that is associated with severe complications such as fracture, bone pain and hypercalcemia. The cross-talk between metastatic cancer cells and bone is critical to the development and progression of bone metastases. In our previous data, we have described how the involvement of the Wnt-induced secreted protein-1/vascular cell adhesion molecule-1 (WISP-1/VCAM-1) system in this tumor-bone interaction contributes to human PCa cell motility. In this study, we found that WISP-1 regulates bone mineralization by inducing bone morphogenetic protein-2 (BMP2), BMP4 and osteopontin (OPN) expression in osteoblasts. We also found that WISP-1 inhibited RANKL-dependent osteoclastogenesis. Moreover, osteoblast-derived WISP-1 enhanced VCAM-1 expression in PCa cells and subsequently promoted the adherence of cancer cells to osteoblasts. Furthermore, endothelin-1 (ET-1) expression in PCa cells was regulated by osteoblast-derived WISP-1, which promoted integrin α4β1 expression in osteoblasts via the MAPK pathway. Pretreatment of PCa cells with VCAM-1 antibody or osteoblasts with integrin α4β1 antibody attenuated the adherence of PCa cells to osteoblasts, suggesting that integrin α4β1 serves as a ligand that captures VCAM-1

BACKGROUND: Giant Cell Tumour of Bone (GCT) is a locally aggressive primary bone tumour that usually occurs at the epiphyses of the long bones of the appendicular skeleton with a tendency to recurrence. Recurrent somatic H3F3A mutations have been described in 92% of GCT cases. GCTs involving the Clivus are extremely rare lesions and less than 15 cases are described in the literature. They represent a surgery challenge and are easily misdiagnosed. Our aim was to reveal if the genetic bases underlying Clival GCTs were the same of GCTs of long bones to improve the diagnosis and treatment.
METHODS: The targeted somatic sequencing of GCT-related genes (H3F3A, H3F3B, IDH1, IDH2 and ZNF687) was performed on Clival GCT biopsies of two different cases. Histological analyses on the same tissues were used to detect the neoplastic population and its expression profile.
RESULTS: Sanger sequencing revealed that both patients were positive for the p.Gly34Trp mutation in the H3F3A gene. Immunofluorescence assay using monoclonal antibody, specifically detecting the mutant H3.3, highlighted that the mutation only involved the mononuclear cell population and not the multinucleated giant cells. Moreover, immunohistochemistry assay showed that RANKL was highly expressed by the stromal cells within Clival GCT, mimicking what happens in GCT of the long bones. In addition, systematic literature review allowed us to generate a histology-based diagnostic algorithm of the most common clival lesions.
CONCLUSIONS: We conclude that the Clival GCT is genetically defined by somatic mutation in the H3F3A gene, linking it to the GCT of long bones. The similarity with GCTs of long bones let us to hypothesize the utility of Denosumab therapy (already effective for GCTs) in these surgically challenging cases. Moreover, H3F3A genetic screening can be combined to the histological analysis to differentiate GCTs from morphologically similar giant cell-rich sarcomas, while the histological diagnostic algorithm could help the differential diagnosis of other clival lesions.

In multiple myeloma, abnormal plasma cells accumulate and proliferate in the bone marrow. Recently, we observed that Runx2, a bone-specific transcription factor, is highly expressed in multiple myeloma cells and is a major driver of multiple myeloma progression in bone. The primary goal of the present study was to identify Runx2-targeting miRNAs that can reduce tumor growth. Expression analysis of a panel of miRNAs in multiple myeloma patient specimens, compared with healthy control specimens, revealed that metastatic multiple myeloma cells express low levels of miR-342 and miR-363 but high levels of Runx2. Reconstituting multiple myeloma cells (CAG) with miR-342 and miR-363 reduced the abundance of Runx2 and the expression of metastasis-promoting Runx2 target genes RANKL and DKK1, and suppressed Runx2 downstream signaling pathways Akt/β-catenin/survivin, which are required for multiple myeloma tumor progression. Intravenous injection of multiple myeloma cells (5TGM1), stably overexpressing miR-342 and miR-363 alone or together, into syngeneic C57Bl/KaLwRij mice resulted in a significant suppression of 5TGM1 cell growth, decreased osteoclasts and increased osteoblasts, and increased antitumor immunity in the bone marrow, compared with mice injected with 5TGM1 cells expressing a miR-Scramble control. In summary, these results demonstrate that enhanced expression of miR-342 and miR-363 in multiple myeloma cells inhibits Runx2 expression and multiple myeloma growth, decreases osteolysis, and enhances antitumor immunity. Thus, restoring the function of Runx2-targeting by miR-342 and miR-363 in multiple myeloma cells may afford a therapeutic benefit by preventing multiple myeloma progression.

BACKGROUND/AIMS: Bone morphogenetic proteins (BMPs) and BMP receptors widely participate in osteolytic metastasis of breast cancer, while their role in tumor-stromal interaction is largely unknown. In this study, we investigated whether BMP receptor type 1a (BMPR1a) can alter the interaction between metastatic cancer cells and osteoclast precursors.
METHODS: Adenovirus-mediated RNA interference was used to interrupt target genes of human breast cancer cell lines and nude mice were injected intratibially with the cancer cells. Tumor-bearing mice were examined by bioluminescence imaging and microCT. Sections of metastatic legs were measured by a series of staining methods. Murine bone marrow mononuclear cells or RAW264.7 cells were cultured with conditioned media of breast cancer cells. RT-PCR, Western blotting and ELISA were used to test mRNA and protein expressions of target molecules.
RESULTS: Expression of BMPR1a of MDA-MB-231-luc cells at tumor-bone interface was apparently stronger than that of cancer cells distant from the interface. Mice injected with BMPR1a-knockdown MDA-MB-231-luc cells showed reduced tumor growth and bone destruction compared with control groups. Knockdown (KD) of BMPR1a of MDA-MB-231-luc cells or MCF-7 cells decreased the level of receptor activator for NF-κB ligand (RANKL). Level of RANKL in MDA-MB-231-luc cells or MCF-7 cells was reduced by p38 inhibitor. Compared with control group, knockdown of p38 of breast cancer cells decreased cancer-induced osteoclastogenesis.
CONCLUSION: Knockdown of BMPR1a of breast cancer cells suppresses their production of RANKL via p38 pathway and inhibits cancer-induced osteoclastogenesis, which indicates that BMPR1a might be a possible target in breast cancer-induced osteolytic metastasis.

Recently, it has been reported that deregulation of the receptor activator of NFkB ligand (RANKL)/RANK signaling axis results in salivary gland tumor development in a mouse transgenic model. The aim of this study was to ascertain RANKL and RANK protein expression in a series of primary parotid gland carcinomas and to correlate it with clinicopathologic parameters. Formalin-fixed paraffin-embedded tumor samples from 46 consecutive cases of parotid gland carcinoma were selected for this study. For comparison, we examined a group of 40 randomly chosen parotid gland adenomas, including 20 pleomorphic adenomas, 10 myoepitheliomas, and 10 Warthin tumors. Immunohistochemical analysis for RANK and RANKL was conducted on tissue microarrays. Overall, 33 carcinomas (71.7%) were scored as positive for RANK and 25 (54.3%) for RANKL. The expression of both RANK and RANKL was significantly higher in carcinomas than in adenomas as only 6 (15%) adenomas were positive for RANK, and RANKL was negative in all benign tumors (P<0.001 for both, Fisher exact test). Some histologic types, including salivary duct carcinoma, mucoepidermoid carcinoma, and carcinoma ex-pleomorphic adenoma presented a high frequency of RANK and RANKL expression. No significant correlation was observed between RANK/RANKL expression and clinical parameters. Our study indicates that the expression of RANK and RANKL in parotid gland neoplasms is associated with the acquisition of a malignant phenotype and this pathway may represent an attractive therapeutic target in patients with parotid gland carcinomas.

OBJECTIVE: Osteolytic lesion (OL) and bone damage are common complications in multiple myeloma (MM). This study aimed to analyze the occurrence of OL in MM patient groups of different ages and genders.
PATIENTS AND METHODS: We performed a retrospective study of 762 MM patients admitted to West China Hospital from 2009 to 2014 to investigate the association between OL occurrence with patients' ages and genders. The presence or absence of OL was confirmed by X-ray, computed tomography (CT) or magnetic resonance imaging (MRI) examination. We also downloaded MM patients' published gene expression profiles and performed microarray-based analyses to identify differentially regulated genes and signaling pathways. Finally, we examined target gene expressions in MM bone marrow (BM) biopsies through immunohistochemistry (IHC).
RESULTS: We calculated the frequency of OL in female and male MM patients with different age cut-offs. From West China Hospital data, we found that in young female MM patients aged under 55, the frequency of OL was 16.67%, significantly lower than the frequencies in other groups of patients (young males: 34.38%; old males: 31.04%; old females: 29.24%; p < .05). The same was true in another independent MM cohort. Microarray-based analyses showed that Microtubule Associated Serine/Threonine Kinase Family Member 4 (MAST4), an estrogen-responsive gene, expression was up-regulated in MM patients without OL and in young female MM patients (p < .05). The expression of MAST4 in MM BM was confirmed by IHC. The perspective of cell signaling network suggested that MAST4 might interact with phosphatase and tensin homolog (PTEN) and control the expression of a panel of osteoclast-regulatory cytokines, such as TNFSF11 and CCL2.
CONCLUSIONS: Young female (<55 years) MM patients have significantly lower OL frequency than other groups. MAST4 gene expression is thought to be associated with this phenomenon.

Butyrate, an essential factor for colonocytes and regulator in the development of colon cancer, is partially absorbed by the gut. It influences the proliferation and differentiation of several cell types including osteoblasts. We evaluated the effects of different doses of butyrate on differentiation and functionality of osteosarcoma cells in vitro and the expression of a pro-inflammatory phenotype in a normal or inflammatory environment. SaOS-2 osteosarcoma cells were induced to differentiate and contemporarily treated for 24 h, 48 h, or 7 days with sodium butyrate 10

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

Bone metastases associated with breast cancer remain a clinical challenge due to their associated morbidity, limited therapeutic intervention and lack of prognostic markers. With a continually evolving understanding of bone biology and its dynamic microenvironment, many potential new targets have been proposed. In this chapter, we discuss the roles of well-established bone markers and how their targeting, in addition to tumour-targeted therapies, might help in the prevention and treatment of bone metastases. There are a vast number of bone markers, of which one of the best-known families is the bone morphogenetic proteins (BMPs). This chapter focuses on their role in breast cancer-associated bone metastases, associated signalling pathways and the possibilities for potential therapeutic intervention. In addition, this chapter provides an update on the role receptor activator of nuclear factor-κB (RANK), RANK ligand (RANKL) and osteoprotegerin (OPG) play on breast cancer development and their subsequent influence during the homing and establishment of breast cancer-associated bone metastases. Beyond the well-established bone molecules, this chapter also explores the role of other potential factors such as activated leukocyte cell adhesion molecule (ALCAM) and its potential impact on breast cancer cells' affinity for the bone environment, which implies that ALCAM could be a promising therapeutic target.

Giant cell tumors of bone (GCTBs) are characterized by mononuclear stromal cells and osteoclast-like giant cells; up to 95% have H3F3A gene mutation. The RANKL inhibitor denosumab, when used for the treatment of GCTB, leads to histological changes such as new bone formation and giant cell depletion. Here we assessed the diagnostic utility of immunohistochemical staining with the antibodies against histone H3.3 G34W, G34R and G34V mutant proteins for GCTB and other histologically similar bone and joint lesions. H3.3 G34W, G34R and G34V expressions were detected in mononuclear stromal cells in 47/51 (92%), 1/51 (2%) and 3/51 (6%) cases of primary GCTBs, respectively, in a mutually exclusive manner. All recurrent/metastatic GCTBs (n=14), post-denosumab GCTBs (n=8) and secondary malignant GCTBs (n=2) were positive for H3.3 G34W. The immunohistochemical results were essentially correlated with the H3F3A genotype determined by mutation analysis. In post-denosumab GCTBs, H3.3 G34W expression was seen in immature bone-forming cells. H3.3 G34W, G34R and G34V were negative in 121/122 cases of non-GCTB, including chondroblastoma, osteosarcoma, primary aneurysmal bone cyst and other giant cell-rich lesions. The exception was a single case of undifferentiated high-grade pleomorphic sarcoma that was positive for H3.3 G34W, suggesting the possibility of sarcomatous overgrowth of primary malignant GCTB. Therefore, H3.3 G34W/R/V mutant-specific antibodies are useful surrogate markers for the H3F3A genotype and helpful for the diagnosis of GCTB and its variants. The expression of H3.3 G34W mutant protein in post-denosumab GCTB suggests that neoplastic stromal cells may play a role in new bone formation.

AIMS: Denosumab, a human monoclonal antibody directed against the receptor activator of nuclear factor-κB ligand (RANKL), is a therapeutic agent for giant cell tumour of bone (GCTB). Although some studies have reported that denosumab shrinks tumours and induces bone formation, the actual effects of RANKL suppression on GCTB remain unclear. A mutation in the H3 histone family member 3A gene (H3F3A) was recently identified as a genetic signature for GCTB. The aim of this study was to investigate the histopathological features and H3F3A mutation status of GCTBs treated with denosumab.
METHODS AND RESULTS: Nine biopsy-diagnosed patients with GCTB, who underwent curettage after neoadjuvant denosumab therapy, were reviewed. Immunohistochemistry for NFATc1 (an osteoclast marker), RUNX2 (an osteoblast marker) and histone H3.3 G34W (G34W, a GCTB marker) was performed; furthermore, H3F3A mutation status was examined with direct sequencing. Before therapy, GCTBs comprised NFATc1+ and RUNX2+ cells. All cases were G34W+ and contained H3F3A mutations. After therapy, the osteoclast-like giant cells disappeared. Areas of slender spindle cell proliferation and reticular woven bone that were NFATc1- and RUNX2+ replaced the lesions in various proportions. However, all post-therapy lesions still contained many G34W+ cells and harboured H3F3A mutations. Immunofluorescence double staining revealed that RUNX2+ mononuclear cells coexpressed G34W in pre-therapy and post-therapy lesions. Two patients experienced radiologically detected local recurrence within 2 years.
CONCLUSIONS: Denosumab therapy effectively decreases the number of osteoclastic cells in GCTBs. However, the neoplastic cells with H3F3A mutation survive denosumab treatment and undergo dramatic histological changes in response to this agent.

BACKGROUND: The cytokine system RANKL (receptor activator of NF-κB ligand), its receptor RANK and the antagonist OPG (osteoprotegerin) play a critical role in bone turnover. Our investigation was conducted to describe the gene expression at primary tumour site in prostate cancer patients and correlate the results with Gleason Score and PSA level.
METHODS: Seventy-one samples were obtained from prostate cancer patients at the time of radical prostatectomy and palliative prostate resection (n = 71). Patients with benign prostate hyperplasia served as controls (n = 60). We performed real-time RT-PCR after microdissection of the samples.
RESULTS: The mRNA expression of RANK was highest in tumour tissue from patients with bone metastases (p < 0.001) as compared to BPH or locally confined tumours, also shown in clinical subgroups distinguished by Gleason Score (< 7 or ≥ 7, p = 0.028) or PSA level (< 10 or ≥ 10 µg/l, p = 0.004). RANKL and OPG mRNA expression was higher in tumour tissue from patients with metastatic compared to local disease. The RANKL/OPG ratio was low in normal prostate tissue and high tumours with bone metastases (p < 0.05). Expression of all three cytokines was high in BPH tissue but did not exceed as much as in the tumour tissue.
CONCLUSION: We demonstrated that RANK, RANKL and OPG are directly expressed by prostate cancer cells at the primary tumour site and showed a clear correlation with Gleason Score, serum PSA level and advanced disease. In BPH, mRNA expression is also detectable, but RANK expression does not exceed as much as compared to tumour tissue.