Differential gene expression in classic giant cell tumours of bone: Tenascin C as biological risk factor for local relapses and metastases

Cell Biology of Giant Cell Tumour of Bone: Crosstalk between m/wt Nucleosome H3.3, Telomeres and Osteoclastogenesis

Giant cell tumour of bone (GCTB) is a rare and intriguing primary bone neoplasm. Worrisome clinical features are its local destructive behaviour, its high tendency to recur after surgical therapy and its ability to create so-called benign lung metastases (lung 'plugs'). GCTB displays a complex and difficult-to-understand cell biological behaviour because of its heterogenous morphology. Recently, a driver mutation in histone H3.3 was found. This mutation is highly conserved in GCTB but can also be detected in glioblastoma. Denosumab was recently introduced as an extra option of medical treatment next to traditional surgical and in rare cases, radiotherapy. Despite these new insights, many 'old' questions about the key features of GCTB remain unanswered, such as the presence of telomeric associations (TAs), the reactivation of hTERT, and its slight genomic instability. This review summarises the recent relevant literature of histone H3.3 in relation to the GCTB-specific G34W mutation and pays specific attention to the G34W mutation in relation to the development of TAs, genomic instability, and the characteristic morphology of GCTB. As pieces of an etiogenetic puzzle, this review tries fitting all these molecular features and the unique H3.3 G34W mutation together in GCTB.

The identification of H3F3A mutation in giant cell tumour of the clivus and the histological diagnostic algorithm of other clival lesions permit the differential diagnosis in this location

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.

Treatment of giant cell tumor of distal radius with limited soft tissue invasion: Curettage and cementing versus wide excision

BACKGROUND

Intralesional curettage and adjuvant versus wide en bloc excision (WEE) as the best treatment method of giant cell tumor (GCT) of distal radius with limited soft tissue extension is a controversial topic.

METHODS

Prospectively, 13 patients who had GCT of distal radius with perforation of either volar or dorsal cortex of the bone and soft tissue extension which was confined to one plane were enrolled in the study. Six patients treated with ICC and seven cases cured by WEE technique and proximal fibular arthroplasty. The results were evaluated based on recurrence, range of motion of the wrist joint, rotation of the forearm, grip and pinch power.

RESULTS

The mean age of the patients treated with ICC and WEE techniques were 32.7 (range: 23-43) and 34.5 (range: 28-44), respectively. Mean follow-up period was 72 months (range: 28-148). Local recurrence was seen in 4 of 6 patients (66.7%) underwent ICC technique but in none of the 7 subjects treated with WEE technique (P value = 0.021). The overall range of flexion/extension and supination/pronation in the WEE group were 83% and 92% of the ICC group, respectively. Both of pinch and grip power were 14% less in the WEE group compared to the ICC group.

CONCLUSIONS

In GCT lesion of distal radius even with limited soft tissue extension, WEE and proximal fibular arthroplasty may be a more reasonable suggestion when the patient seeks a one-shot surgery.

The distinct clinical features of giant cell tumor of bone in pagetic and non-pagetic patients are associated with genetic, biochemical and histological differences

Giant Cell Tumor of Bone (GCT) is a tumor characterized by neoplastic mesenchymal stromal cells and a high number of osteoclast-like multinucleated giant cells. Rarely, GCT could arise in bones affected by Paget's disease of bone (GCT/PDB). Although it is already known that GCT/PDB and GCT show a different clinical profile regarding the age-onset and skeletal localization, our deep clinical comparison between the two GCT/PDB and GCT cohorts, permitted us to identify additional differences (e.g. focality, ALP serum levels, the 5-year survival rate and the familial recurrence), strongly suggesting a different molecular basis. Accordingly, driver somatic mutations in H3F3A and IDH2 were described in GCT patients, while we recently identified a germline mutation in ZNF687 as the genetic defect of GCT/PDB patients. Here, we detected H3F3A mutations in our GCT cohort, confirming its molecular screening as the elected diagnostic tool, and then we excluded the two-hit in H3F3A and IDH2 as the trigger event for the GCT/PDB development. Importantly, we also identified an alternative biochemical profile with GCT/PDB not exhibiting the up-regulation of the GCT marker FGFR2IIIc. Finally, our histological analysis also showed a different appearance of the two forms of the tumor, with GCT/PDB showing a higher number of osteoclast-like giant cells (twice), with an abnormal number of nuclei per cell, corroborating its different behaviour in terms of neoplastic properties. We demonstrated that the distinct clinical features of pagetic and conventional GCT are associated with different genetic background, resulting in a specific biochemical and histological behaviour of the tumour.

Prognosis of local recurrence in giant cell tumour of bone: what can we do?

Giant cell tumour of bone (GCTB) is classified as an intermediate tumour with rare metastasis, but is challenged by local recurrence. This review focuses on the role of radiological evaluation in terms of prognosis of local recurrence in GCTB. We hope to highlight the value of radiological evaluation by integrating studies on the impact of surgical treatments and non-surgical factors on local recurrence of GCTB and the current statuses of genetic and molecular prognostic factors of GCTB. Radiological evaluation can provide diverse information on tumours. As a non-invasive method, magnetic resonance imaging (MRI) is especially valuable for the diagnosis and evaluation of bone tumours due to its heightened sensitivity to soft tissue disease and multiplanar image acquisition. Imaging findings should be integrated with clinical characteristics, pathology and genetic and molecular prognostic factors to direct clinical approach and reduce the local recurrence of GCTB. Therefore, it is necessary to establish a multi-perspective evaluation system by which prognostic factors can be reliably determined. We further advocate more large-scale prospective studies. With the help of radiological evaluation, the clinic treatment of GCTB can be guided and local recurrence might be reduced; additionally, MR imaging can identify local recurrence of GCTB after surgical treatment in the early stage.

Prognostic role of nuclear factor/IB and bone remodeling proteins in metastatic giant cell tumor of bone: A retrospective study

Giant cell tumor of bone (GCTb) represents 5% of bone tumors, and although considered benign, 5% metastasize to the lung. The expression of proteins directly or indirectly associated with osteolysis and tumor growth was studied on 163 samples of GCTb. Of these, 33 patients developed lung metastasis during follow-up. The impact of tumor-host interaction on clinical aspects was evaluated with the aim of finding specific markers for new biological therapies, thus improving clinical management of GCTb. Protein expression was evaluated by immunohistochemical analysis on Tissue Microarray. The majority of GCTb samples from patients with metastatic disease were strongly positive to RANKL and its receptor RANK as well as to CAII and MMP-2 and to pro-survival proteins NFIB and c-Fos. Kaplan-Meier analysis indicated a significant difference in metastasis free survival curves based on protein staining. Interestingly, the statistical correlation established a strong association between all variables studied with a higher τ coefficient for RANK/RANKL, RANK/NFIB, and RANKL/NFIB pairs. At multivariate analysis co-overexpression of NFIB, RANK and RANKL significantly increased the risk of metastasis with an odds ratio of 13.59 (95%CI 4.12-44.82; p < 0.0005). In conclusion, the interconnection between matrix remodeling and tumor cell activity may identify tumor-host endpoints for new biological treatments.

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.

mTOR signal transduction pathways contribute to TN-C FNIII A1 overexpression by mechanical stress in osteosarcoma cells

Osteosarcoma is the most common primary malignant bone tumor with a very poor prognosis. Treating osteosarcoma remains a challenge due to its high transitivity. Tenascin-C, with large molecular weight variants including different combinations of its alternative spliced FNIII repeats, is specifically over expressed in tumor tissues. This study examined the expression of Tenascin-C FNIIIA1 in osteosarcoma tissues, and estimated the effect of mechanical stimulation on A1 expression in MG-63 cells. Through immunohistochemical analysis, we found that the A1 protein was expressed at a higher level in osteosarcoma tissues than in adjacent normal tissues. By cell migration assay, we observed that there was a significant correlation between A1 expression and MG-63 cell migra-tion. The relation is that Tenascin-C FNIIIA1 can promote MG-63 cell migration. According to our further study into the effect of mechanical stimulation on A1 expression in MG-63 cells, the mRNA and protein levels of A1 were significantly up-regulated under mechanical stress with the mTOR molecule proving indispensable. Meanwhile, 4E-BP1 and S6K1 (downstream molecule of mTOR) are necessary for A1 normal expression in MG-63 cells whether or not mechanical stress has been encountered. We found that Tenascin-C FNIIIA1 is over-expressed in osteosar-coma tissues and can promote MG-63 cell migration. Furthermore, mechanical stress can facilitate MG-63 cell migration though facilitating A1 overexpression with the necessary molecules (mTOR, 4E-BP1 and S6K1). In con-clusion, high expression of A1 may promote the meta-stasis of osteosarcoma by facilitating MG-63 cell migration. Tenascin-C FNIIIA1 could be used as an indicator in metastatic osteosarcoma patients.

p53 mutations may be involved in malignant transformation of giant cell tumor of bone through interaction with GPX1

Giant cell tumor of bone (GCTB) is a benign tumor with a tendency for local recurrence. Secondary malignant GCTB is rare, occurring in less than 2 % of GCTB cases. Mechanisms of malignant transformation of GCTB remain unclear. We examined 43 cases of GCTB (38 conventional cases, two lung implantation cases, and three secondary malignant cases) for p53 gene mutations and for loss of heterozygosity (LOH) of p53 when corresponding normal tissue was available. In addition, to elucidate the possible involvement of p53, GPX-1, cyclinD1, and Ki-67 in malignant transformation of GCTB, we assessed the expression of these proteins by immunohistochemistry. Mutations or LOH of p53 were found in all three malignant cases, which also showed p53 overexpression. Non-synonymous p53 mutations were detected in seven of 38 conventional cases (18 %), although none of these showed p53 overexpression, defined as more than 10 % of cells being positive. LOH at the p53 locus was detected in eight of 37 informative cases, although this was not associated with p53 overexpression in conventional GCT. Expression of GPX-1 was higher in the recurrent group, which included metastatic and malignant cases, and patients with high GPX-1 expression were at greater risk for early relapse. We also observed a positive correlation between high p53 expression and high GPX-1 expression in GCTB. Given that GPX-1 is shown to be a target of p53, these results suggest that p53 mutations play a role in tumor recurrence and malignant transformation of GCTB through interactions with GPX-1.

Protease expression in giant cell tumour of bone: a comparative study on feline and human samples

Human giant cell tumour of bone (GCTB) is a rare low grade of malignancy tumour with tendency to recur. During tumourigenesis the bone remodeling balance is subverted by the tumour cellular components that interacting with bone matrix induce release of growth factors and cytokines, promoting cell proliferation and bone resorption. The master regulators of this positive feed-back are acid and neutral proteases that destroying extracellular matrix increase osteolysis. In contrast, in cats, very few data are reported on GCTB biological activity. In this study, histological features and metalloproteinase (MMPs) and urokinase plasminogen activator system (uPA) expression were compared in human and feline GCTB and differences in distribution and intensity related to histological pattern and clinical behaviour were determined. In both species, the overexpression of these molecules suggested a strong and complex cross-talk between tumour and microenvironment.

Tartrate-Resistant Acid Phosphatase 5b is a Useful Serum Marker for Diagnosis and Recurrence Detection of Giant Cell Tumor of Bone

Serum tartrate-resistant acid phosphatase (TRACP) 5b was investigated for use as a marker for diagnosis of giant cell tumor (GCT) of bone and for detection of its recurrence.

Four patients with GCT of bone who were initially referred to our hospital were classified as a primary group. Three patients who had local recurrence following curettage were classified as a local recurrence group. Five with no recurrence were classified as a no-recurrence group. Eighteen patients with primary and metastatic malignant bone tumors were also enrolled in the study as a control group. Serum TRACP 5b was measured before the biopsy in all patients and was measured periodically after the operation in patients with GCT of bone. Student t-tests were used for statistical analyses.

TRACP 5b was greater than 1500 Um/dL in all primary group patients. Mean TRACP 5b values decreased gradually with post-operative time, showing lower values until local recurrence. The mean value of TRACP 5b of the local recurrence group (753 ± 68.7 mU/dL) was significantly higher than that of the no-recurrence group (340.6 ± 78.3 mU/dL). The mean value of TRACP 5b of the control group (466.9 ± 130.3 mU/dL) was much lower than that of the primary group and markedly lower than that of the local recurrence group. However, no significant difference was found between the no-recurrence group and the control group.

Serum TRACP 5b is a useful and convenient marker for diagnosing GCT of bone and for predicting its recurrence.

How do tenascins influence the birth and life of a malignant cell?

Tenascins are large glycoproteins found in embryonic and adult extracellular matrices. Of the four family members, two have been shown to be overexpressed in the microenvironment of solid tumours: tenascin-C and tenascin-W. The regular presence of these proteins in tumours suggests a role in tumourigenesis, which has been investigated intensively for tenascin-C and recently for tenascin-W as well. In this review, we follow a malignant cell starting from its birth through its potential metastatic journey and describe how tenascin-C and tenascin-W contribute to these successive steps of tumourigenesis. We consider the importance of the mechanical aspect in tenascin signalling. Furthermore, we discuss studies describing tenascin-C as an important component of stem cell niches and present examples reporting its role in cancer therapy resistance.

Regulation of tenascin expression in bone

Tenascins regulate cell interaction with the surrounding pericellular matrix. Within bone, tenascins C and W influence osteoblast adhesion and differentiation, although little is known about the regulation of tenascin expression. In this study we examined the effect of osteogenic differentiation, bone morphogenetic protein (BMP) and Wnt growth factors, and mechanical loading on tenascin expression in osteogenic cells. Osteogenic differentiation increased tenascin C (TnC), and decreased tenascin W (TnW), expression. Both growth factors and mechanical loading increased both TnC and TnW expression, albeit via distinct signaling mechanisms. Both BMP-2 and Wnt5a induction of tenascin expression were mediated by MAP kinases. These data establish a role for BMP, Wnts, and mechanical loading in the regulation of tenascin expression in osteoblasts.

Orthopaedic research in italy: state of the art

The most significant results in experimental and clinical orthopaedic research in Italy within the last three years have been primarily in major congenital diseases, bone tumors, regenerative medicine, joint replacements, spine, tendons and ligaments. The data presented in the following discussion is comparable with leading international results, highlighting Italian orthopaedic research excellemce as well as its shortcomings.

Advances in tenascin-C biology

Tenascin-C is an extracellular matrix glycoprotein that is specifically and transiently expressed upon tissue injury. Upon tissue damage, tenascin-C plays a multitude of different roles that mediate both inflammatory and fibrotic processes to enable effective tissue repair. In the last decade, emerging evidence has demonstrated a vital role for tenascin-C in cardiac and arterial injury, tumor angiogenesis and metastasis, as well as in modulating stem cell behavior. Here we highlight the molecular mechanisms by which tenascin-C mediates these effects and discuss the implications of mis-regulated tenascin-C expression in driving disease pathology.