Role of the VEGF-Flt-1-FAK pathway in the pathogenesis of osteoclastic bone destruction of giant cell tumors of bone

Recent topics in diagnosis and treatment of malignant spinal tumors

The diagnosis and treatment of malignant spinal tumors are complex and require an integrated approach known as Jaffe's triangle.　This review discusses recent topics in the diagnosis and treatment of primary and metastatic malignant spinal tumors.　Integrated diagnostic methods, including the development of a dumbbell scoring system for benign-malignant differentiation and the use of positron emission tomography and magnetic resonance imaging (PET-MRI), have improved diagnostic accuracy.　Curative resection techniques such as vertebrectomy, sagittal resection, and posterior resection are crucial for primary malignant tumors.　Heavy particle radiation therapy, such as carbon-ion radiotherapy, shows promise against radiation-resistant tumors, whereas novel drug therapies, such as denosumab, are effective for giant cell tumors of the bone arising in the spine.　For metastatic spinal tumors, the collaborative efforts of the Bone Metastasis Cancer Board and minimally invasive spine stabilization have expanded surgical indications and improved patient outcomes.　The treatment system has shifted towards preventive surgery and outpatient management, aiming to maintain quality of life and continue chemotherapy.　Interdisciplinary collaboration is essential for improving treatment outcomes in both primary and metastatic malignant spinal tumors.Primary malignant spinal cord tumors (PMST) and metastatic spinal tumors (MST) are among the most difficult areas of orthopedic surgery.　Their diagnosis and treatment require multidisciplinary diagnostic and therapeutic strategies that integrate knowledge and skills in orthopedics, pathology, and diagnostic radiology (the so-called Jaffe triangle), as well as in clinical oncology and tumor biology, which have made remarkable progress in recent years.　Here, we review recent topics related to the diagnosis and treatment of PMST and MST.

Pharmacoproteogenomic approach identifies on-target kinase inhibitors for cancer drug repositioning

Drug repositioning of approved drugs offers advantages over de novo drug development for a rare type of cancer. To efficiently identify on-target drugs from clinically successful kinase inhibitors in cancer drug repositioning, drug screening and molecular profiling of cell lines are essential to exclude off-targets. We developed a pharmacoproteogenomic approach to identify on-target kinase inhibitors, combining molecular profiling of genomic features and kinase activity, and drug screening of patient-derived cell lines. This study examined eight patient-derived giant cell tumor of the bone (GCTB) cell lines, all of which harbored a signature mutation of H3-3A but otherwise without recurrent copy number variants and mutations. Kinase activity profiles of 100 tyrosine kinases with a three-dimensional substrate peptide array revealed that nine kinases were highly activated. Pharmacological screening of 60 clinically used kinase inhibitors found that nine drugs directed at 29 kinases strongly suppressed cell viability. We regarded ABL1, EGFR, and LCK as on-target kinases; among the two corresponding on-target kinase inhibitors, osimertinib and ponatinib emerged as on-target drugs whose target kinases were significantly activated. The remaining 26 kinases and seven kinase inhibitors were excluded as off-targets. Our pharmacoproteomic approach enabled the identification of on-target kinase inhibitors that are useful for drug repositioning.

Nuclear β-catenin translocation plays a key role in osteoblast differentiation of giant cell tumor of bone

Denosumab is a game-changing drug for giant cell tumor of bone (GCTB); however, its clinical biomarker regarding tumor ossification of GCTB has not been elucidated. In this study, we investigated the relationship between Wnt/β-catenin signaling and the ossification of GCTB and evaluated whether endogenous nuclear β-catenin expression predicted denosumab-induced bone formation in GCTB. Genuine patient-derived primary GCTB tumor stromal cells exhibited osteoblastic characteristics. Identified osteoblastic markers and nuclear β-catenin translocation were significantly upregulated via differentiation induction and were inhibited by treating with Wnt signaling inhibitor, GGTI-286, or selective Rac1-LEF inhibitor, NSC23766. Furthermore, we reviewed the endogenous ossification and nuclear β-catenin translocation of 86 GCTB clinical samples and elucidated that intra-tumoral ossification was significantly associated with the nuclear translocation. Three-dimensional quantitative analyses (n = 13) of tumoral CT images have revealed that the nuclear β-catenin translocation of naïve GCTB samples was significantly involved with the denosumab-induced tumor ossification. Our findings suggest a close relationship between the nuclear β-catenin translocation and the osteoblastic differentiation of GCTB. Investigations of the nuclear β-catenin in naïve GCTB samples may provide a promising biomarker for predicting the ossification of GCTB following denosumab treatment.

Serglycin induces osteoclastogenesis and promotes tumor growth in giant cell tumor of bone

Giant cell tumor of bone (GCTB) is an aggressive osteolytic bone tumor characterized by the within-tumor presence of osteoclast-like multinucleated giant cells (MGCs), which are induced by the neoplastic stromal cells and lead to extensive bone destruction. However, the underlying mechanism of the pathological process of osteoclastogenesis in GCTB is poorly understood. Here we show that the proteoglycan Serglycin (SRGN) secreted by neoplastic stromal cells plays a crucial role in the formation of MGCs and tumorigenesis in GCTB. Upregulated SRGN expression and secretion are observed in GCTB tumor cells and patients. Stromal-derived SRGN promotes osteoclast differentiation from monocytes. SRGN knockdown in stromal cells inhibits tumor growth and bone destruction in a patient-derived orthotopic xenograft model of mice. Mechanistically SRGN interacts with CD44 on the cell surface of monocytes and thus activates focal adhesion kinase (FAK), leading to osteoclast differentiation. Importantly, blocking CD44 with a neutralizing antibody reduces the number of MGCs and suppresses tumorigenesis in vivo. Overall, our data reveal a mechanism of MGC induction in GCTB and support CD44-targeting approaches for GCTB treatment.

Retrospective analysis of 51 intralesionally treated cases with progressed giant cell tumor of the bone: local adjuvant use of hydrogen peroxide reduces the risk for tumor recurrence

BACKGROUND

Giant cell tumor of the bone (GCT) has high local recurrence rates and the prognosis is hard to predict. We therefore retrospectively analyzed clinical outcome and recurrences of 51 GCT cases focusing on the effects of adjuvant local use of hydrogen peroxide.

METHODS

The series enclosed 51 advanced GCT cases of the upper and lower extremities (n = 27 Campanacci grade III; n = 24 grade II; n = 39 surgery at our institution, n = 12 elsewhere). Mean follow-up was 88.3 (± 62.0) months. Surgical details, histology, metastases, recurrences, and interview-based data on satisfaction and function including the Musculoskeletal Tumor Society (MSTS) score were evaluated. It was investigated whether hydrogen peroxide was additionally used or not to clean the tumor cavity after curettage as we hypothesized influence on recurrences. To analyze the underlying mechanisms, GCT-derived stromal cell lines were cultured in vitro and tested for cell viability and apoptosis after treatment with hydrogen peroxide. Statistical analysis was performed with Student's t tests, analysis of variance (ANOVA) with post hoc testing, Mann-Whitney U tests, chi-square tests, Kaplan-Meier analysis, and multivariate Cox regression analysis.

RESULTS

The whole series had 21 recurrences (41%). Eleven recurrences were found (28%) after surgery at our institution. Kaplan-Meier analysis of cumulative recurrence-free survival revealed at 2 years follow-up 69% (72%, only our institution) and at 10 years follow-up 54% (68%, only our institution). Intralesional resection was performed by vigorous curettage, burring, and defect filling with either polymethylmethacrylate bone cement (n = 45) or cancellous bone from the iliac crest (n = 6). Univariate chi-square analysis showed significantly lower recurrence rate after bone cement filling (2.3-fold, p = 0.024). Cleaning of the lesion cavity with hydrogen peroxide significantly reduced recurrence rate (whole collective 2.9-fold, p = 0.004; our institution 2.8-fold, p = 0.04) and significantly increased cumulative recurrence-free survival rate (whole collective at 10 years follow-up 74% versus 31%, p = 0.002; our institution 79% versus 48%, p = 0.02) compared to cases without hydrogen peroxide treatment. In multivariate analysis, significant risk factors for recurrence were pathological fracture (hazard ratio 3.7; p = 0.04), high mitosis rate (hazard ratio 15.6; p = 0.01), and lack of hydrogen peroxide use (hazard ratio 6.0; p = 0.02). In vitro cell culture analyses found apoptotic nature of hydrogen peroxide induced GCT cell death.

CONCLUSIONS

The present series proved for the first time that additional cleaning of the tumor cavity with hydrogen peroxide before defect filling significantly reduced recurrence rate and significantly increased recurrence-free survival in advanced but intralesionally treated GCT cases.

Systemic therapy for selected skull base sarcomas: Chondrosarcoma, chordoma, giant cell tumour and solitary fibrous tumour/hemangiopericytoma

This review highlights the data currently available on the activity of systemic therapy in chondrosarcoma, chordoma, giant cell tumour of the bone (GCTB) and solitary fibrous tumour, i.e., four rare sarcomas amongst mesenchymal malignancy arising from the skull base.

Differential Expression of ADAM23, CDKN2A (P16), MMP14 and VIM Associated with Giant Cell Tumor of Bone

Though benign, giant cell tumor of bone (GCTB) can become aggressive and can exhibit a high mitotic rate, necrosis and rarely vascular invasion and metastasis. GCTB has unique histologic characteristics, a high rate of multinucleated cells, a variable and unpredictable growth potential and uncertain biological behavior. In this study, we sought to identify genes differentially expressed in GCTB, thus building a molecular profile of this tumor. We performed quantitative real-time polymerase chain reaction (qPCR), immunohistochemistry and analyses of methylation to identify genes that are putatively associated with GCTB. The expression of the ADAM23 and CDKN2A genes was decreased in GCTB samples compared to normal bone tissue, measured by qPCR. Additionally, a high hypermethylation frequency of the promoter regions of ADAM23 and CDKN2A in GCTB was observed. The expression of the MAP2K3, MMP14, TIMP2 and VIM genes was significantly higher in GCTB than in normal bone tissue, a fact that was confirmed by qPCR and immunohistochemistry. The set of genes identified here furthers our understanding of the molecular basis of GCTB.

Expression of ezrin, CD44, and VEGF in giant cell tumor of bone and its significance

Background

This research aimed to study the role of ezrin, CD44, and VEGF in invasion, metastasis, recurrence, and prognosis of giant cell tumor of bone (GCTB) and its association with the clinical and pathological features of GCTB.

Methods

Expression status of ezrin, CD44, and VEGF in 80 GCTB tissues and its adjacent noncancerous tissue samples were measured with immunohistochemical and Elivison staining. Their correlation with the clinical and pathologic factors was statistically analyzed by chi-square test.

Results

The expression status of ezrin, CD44, and VEGF were significantly higher in GCTB tissue samples than in its adjacent noncancerous tissue samples and in GCTB at Campanacci stage III than in Campanacci stages I and II (P < 0.05). No significant difference was found in age and sex of the patients and locations of the tumor (P > 0.05). Survival analysis showed that the expression status of ezrin, CD44, VEGF, and Campanacci clinical stages of GCTB were positively associated with the survival rate of GCTB patients and negatively associated with ezrin and Campanacci stages of GCTB, indicating that ezrin, CD44, VEGF, and Campanacci clinical stages of GCTB are the independent factors for GCTB.

Conclusions

Ezrin, CD44, and VEGF are over-expressed in GCTB tissue and its adjacent noncancerous tissue samples and may play an important role in the occurrence, invasion, metastasis, and recurrence of GCTB. Measurement of ezrin, CD44, and VEGF expression status may contribute to the judgment of prognosis of GCTB patients.

Angiotensin-(1-7) attenuates metastatic prostate cancer and reduces osteoclastogenesis

BACKGROUND

Angiotensin-(1-7) [Ang-(1-7)] is an endogenous, heptapeptide hormone with anti-proliferative and anti-angiogenic properties. The primary objective of this study was to determine whether Ang-(1-7) effectively reduces prostate cancer metastasis in mice.

METHODS

Human PC3 prostate cancer cells were injected into the aortic arch via the carotid artery of SCID mice pre-treated with Ang-(1-7) or injected into the tibia of athymic mice, administered Ang-(1-7) for 5 weeks beginning 2 weeks post-injection. Tumor growth and volume were determined by bioluminescent and magnetic resonance imaging. The presence of tumors was confirmed by hematoxylin and eosin staining; TRAP histochemistry was used to identify osteolytic lesions. The effect of Ang-(1-7) on osteoclastogenesis was assessed in differentiated bone marrow cells.

RESULTS

Pre-treatment with Ang-(1-7) prevented metastatic tumor formation following intra-aortic injection of PC3 cells, while 83% of untreated mice developed tumors in metastatic sites. Circulating VEGF was significantly higher in control mice compared to mice administered Ang-(1-7). A 5-week regimen of the heptapeptide hormone attenuated intra-tibial tumor growth; Ang-(1-7) was significantly higher in the tibia of treated mice than in control animals. Osteoclastogenesis was reduced by 50% in bone marrow cells differentiated in the presence of Ang-(1-7), suggesting that the heptapeptide hormone prevents the formation of osteolytic lesions to reduce tumor survival in the bone microenvironment.

CONCLUSIONS

These findings suggest that Ang-(1-7) may serve as an anti-angiogenic and anti-metastatic agent for advanced prostate cancer. By extension, the heptapeptide hormone may provide effective therapy for bone metastasis produced from primary tumors of the lung and breast.

Giant cell tumor of bone: a basic science perspective

Comprehending the pathogenesis of giant cell tumor of bone (GCT) is of critical importance for developing novel targeted treatments for this locally-aggressive primary bone tumor. GCT is characterized by the presence of large multinucleated osteoclast-like giant cells distributed amongst mononuclear spindle-like stromal cells and other monocytes. The giant cells are principally responsible for the extensive bone resorption by the tumor. However, the spindle-like stromal cells chiefly direct the pathology of the tumor by recruiting monocytes and promoting their fusion into giant cells. The stromal cells also enhance the resorptive ability of the giant cells. This review encompasses many of the attributes of GCT, including the process of giant cell formation and the mechanisms of bone resorption. The significance of the receptor activator of nuclear factor-κB ligand (RANKL) in the development of GCT and the importance of proteases, including numerous matrix metalloproteinases, are highlighted. The mesenchymal lineage of the stromal cells and the origin of the hematopoietic monocytes are also discussed. Several aspects of GCT that require further understanding, including the etiology of the tumor, the mechanisms of metastases, and the development of an appropriate animal model, are also considered. By exploring the current status of GCT research, this review accentuates the significant progress made in understanding the biology of the tumor, and discusses important areas for future investigation.

Stro-1(+) stromal cells have stem-like features in giant cell tumor of bone

BACKGROUND

Giant cell tumor of bone (GCTB) is an aggressive benign bone tumor with poor prognosis whose neoplastic component is stromal cells (SCs). Tumor stem-like cells (TSCs) have been demonstrated as precursors for tumor genesis and growth. The aim of this study is to identify TSCs in GCTB.

METHODS

Stro-1(+) and Stro-1(-) cells were isolated by fluorescence-activated cell sorting (FACS). Stem-like properties of both Stro-1(+) and Stro-1(-) subpopulations were assessed using MTT colorimetric assays, cell cycle analyses, sphere formation assays, and differentiation assays. Molecular profiles were analyzed by flow cytometry, immunofluorescence, and qRT-PCR.

RESULTS

The existence of rare Stro-1(+) cells was confirmed in vitro using FACS and in vivo by immunohistochemistry. These Stro-1(+) cells exhibited higher proliferative and cisplatin-resistant potentials than Stro-1(-) cells. In serum-free suspension cultures, Stro-1(+) SCs could form cell spheres and maintain self-renewal. Furthermore, Stro-1(+) SCs could differentiate into two mesenchymal lineage cells: osteoblasts and adipocytes. Cell surface markers CD44, CD117, and CD133 and stem cell-associated genes OCT3/4, NANOG, and ABCG2 were significantly higher in the Stro-1(+) subpopulation.

CONCLUSIONS

This study demonstrates that Stro-1(+) SCs in GCTB possess stem-like biological and molecular phenotypes, indicating that they are the TSCs of GCTB.

Evaluation of a biodegradable graft substitute in rabbit bone defect model

OBJECTIVE

To evaluate a new biodegradable copolymer calcium sulfate/poly amino acid (CS/PAA) as a graft substitute for the repair of the surgically created cancellous bone defects in rabbits and its biological properties in vivo.

MATERIALS AND METHODS

Cancellous bone defects were created by drilling holes in the unilateral lateral aspect of the femoral condyle of New Zealand white rabbits. Three groups were assigned: Group A rabbits were grafted with 80% CS/PAA and group B rabbits were grafted with 95% CS/PAA as two treatment groups; group C was sham-operation control group. To study the osteogenic capability in vivo, specimens were harvested at 4, 8, 12, and 16 weeks after implantation and were evaluated by gross assessment, X-ray, histological examination, and histomorphometry. In order to identify the molecular mechanism of bone defect repair, the expression of bone morphogenetic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF) was detected using Western blot at 4 weeks.

RESULTS

Group A and group B showed more vigorous and rapid repair leading to regeneration of cancellous bone than sham-operation control group on gross observation, radiology, and histomorphometry. There was no significant difference between groups A and B. Morphological observation and histological examination showed that the copolymers degraded in sync with the new bone formation process. The expression of BMP-2 and VEGF in implantation groups was higher than that in control group by western blot.

CONCLUSION

These findings demonstrated that the novel biodegradable copolymers can repair large areas of cancellous bone defects. With its controllable degradation rate, it suggests that CS/PAA may be a series of useful therapeutic substitute for bone defects.