Molecular analysis of primary and recurrent giant cell tumors of bone

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.

Primary aneurysmal bone cyst of the mandibular condyle with USP6-CDH11 fusion

Primary aneurysmal bone cyst (ABC) is a cystic bone neoplasm characterized by disease-defining gene fusions involving the USP6/Tre2 gene. The literature describing gnathic ABC is limited. This case report describes a 27-year-old man presenting with a long-standing left-sided facial asymmetry. Multi-detector computed tomography imaging demonstrated a large expansile lesion positioned within the left condylar head. The lesion was biopsied and resected. The specimen showed a giant cell-rich cystic neoplasm, with fibrous tissue lined by multinucleated giant cells. Next-generation sequencing confirmed the presence of a USP6-CDH11 fusion gene, consistent with classification as a primary ABC, the first reported to be translocation-positive in the head of the mandibular condyle.

Giant cell tumor of bone revisited

Giant cell tumor (GCT) of bone is a locally aggressive benign neoplasm that is associated with a large biological spectrum ranging from latent benign to highly recurrent and occasionally metastatic malignant bone tumor. It accounts for 4–10% of all bone tumors and typically affects the meta-epiphyseal region of long bones of young adults. The most common site involved is the distal femur, followed by the distal radius, sacrum, and proximal humerus. Clinical symptoms are nonspecific and may include local pain, swelling, and limited range of motion of the adjacent joint. Radiographs and contrast-enhanced magnetic resonance imaging (MRI) are the imaging modalities of choice for diagnosis. Surgical treatment with curettage is the optimal treatment for local tumor control. A favorable clinical outcome is expected when the tumor is excised to tumor-free margins, however, for periarticular lesions this is usually accompanied with a suboptimal functional outcome. Local adjuvants have been used for improved curettage, in addition to systematic agents such as denosumab, bisphosphonates, or interferon alpha. This article aims to discuss the clinicopathological features, diagnosis, and treatments for GCT of bone.

Giant cell tumour of bone in the denosumab era

Giant cell tumour of bone (GCTB) is an intermediate locally aggressive primary bone tumour, occurring mostly at the meta-epiphysis of long bones. Overexpression of receptor activator of nuclear factor kappa-B ligand (RANKL) by mononuclear neoplastic stromal cells promotes recruitment of numerous reactive multinucleated osteoclast-like giant cells, causing lacunar bone resorption. Preferential treatment is curettage with local adjuvants such as phenol, alcohol or liquid nitrogen. The remaining cavity may be filled with bone graft or polymethylmethacrylate (PMMA) bone cement; benefits of the latter are a lower risk of recurrence, possibility of direct weight bearing and early radiographic detection of recurrences. Reported recurrence rates are comparable for the different local adjuvants (27-31%). Factors increasing the local recurrence risk include soft tissue extension and anatomically difficult localisations such as the sacrum. When joint salvage is impossible, en-bloc resection and endoprosthetic joint replacement may be performed. Local tumour control on the one hand and maintenance of a functional native joint and quality of life on the other hand are the main pillars of surgical treatment for this disease. Current knowledge and development in the fields of imaging, functional biology and systemic therapy are forcing us into a paradigm shift from a purely surgical approach towards a multidisciplinary approach. Systemic therapy with denosumab (RANKL inhibitor) or zoledronic acid (bisphosphonates) blocks, respectively inhibits, bone resorption by osteoclast-like giant cells. After use of zoledronic acid, stabilisation of local and metastatic disease has been reported, although the level of evidence is low. Denosumab is more extensively studied in two prospective trials, and appears effective for the optimisation of surgical treatment. Denosumab should be considered in the standard multidisciplinary treatment of advanced GCTB (e.g. cortical destruction, soft tissue extension, joint involvement or sacral localisation) to facilitate surgery at a later stage, and thereby aiming at immediate local control. Even though several questions concerning optimal treatment dose, duration and interval and drug safety remain unanswered, denosumab is among the most effective drug therapies in oncology.

Fibrosarcoma development 15 years after curettage and bone grafting of giant cell tumor of bone

Malignant transformation of conventional giant cell tumor of bone is rare and usually occurs with irradiation. This article describes a case of malignant transformation of a giant cell tumor 15 years after initial curettage and bone graft. A 35-year-old man was admitted to the hospital with a recurrent giant cell tumor of the distal femur. On presentation, the patient reported the insidious onset of a dull aching pain in the distal part of the left thigh 4 months prior to admission. Radiographs revealed a destructive lesion in the left distal femur. Needle biopsy revealed recurrence of giant cell tumor with suspected malignant transformation. The patient underwent en bloc resection of the distal femur with adequately wide margins and reconstruction of the knee joint with a prosthesis. Pathological findings showed malignant transformation of a giant cell tumor to high-grade spindle cell sarcoma. Immunohistochemistry showed diffuse and strong p53 expression. A diagnosis of secondary fibrosarcoma was made after discussion. Unfortunately, the tumor proved to be highly resistant to the chemotherapy, and the patient died of multiple lung metastases 14 months after the diagnosis of malignant transformation. What has to be stressed in this case is that any late recurrence must be approached considering the possibility of a secondary induced primary tumor. Because of the rarity of this disease, the effective therapeutic strategy for fibrosarcoma secondary to giant cell tumor is lacking. In addition, identification of the p53 mutation may help in diagnosing cases of potential malignant transformation of giant cell tumor.

The clinical approach toward giant cell tumor of bone

We provide an overview of imaging, histopathology, genetics, and multidisciplinary treatment of giant cell tumor of bone (GCTB), an intermediate, locally aggressive but rarely metastasizing tumor. Overexpression of receptor activator of nuclear factor κB ligand (RANKL) by mononuclear neoplastic stromal cells promotes recruitment of numerous reactive multinucleated giant cells. Conventional radiographs show a typical eccentric lytic lesion, mostly located in the meta-epiphyseal area of long bones. GCTB may also arise in the axial skeleton and very occasionally in the small bones of hands and feet. Magnetic resonance imaging is necessary to evaluate the extent of GCTB within bone and surrounding soft tissues to plan a surgical approach. Curettage with local adjuvants is the preferred treatment. Recurrence rates after curettage with phenol and polymethylmethacrylate (PMMA; 8%-27%) or cryosurgery and PMMA (0%-20%) are comparable. Resection is indicated when joint salvage is not feasible (e.g., intra-articular fracture with soft tissue component). Denosumab (RANKL inhibitor) blocks and bisphosphonates inhibit GCTB-derived osteoclast resorption. With bisphosphonates, stabilization of local and metastatic disease has been reported, although level of evidence was low. Denosumab has been studied to a larger extent and seems to be effective in facilitating intralesional surgery after therapy. Denosumab was recently registered for unresectable disease. Moderate-dose radiotherapy (40-55 Gy) is restricted to rare cases in which surgery would lead to unacceptable morbidity and RANKL inhibitors are contraindicated or unavailable.

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.

A case of secondary malignant giant-cell tumor of bone with p53 mutation after long-term follow-up

A 46-year-old man was admitted to the hospital with a recurrent giant-cell tumor of the distal femur. This was his fourth recurrence, and it had occurred 16 years after his last treatment. The resected recurrent tumor was histologically determined to be a conventional giant-cell tumor. However, a single lung metastatic lesion and local recurrence were noticed 6 months after the resection, both of which were surgically excised. The lung lesion was histologically determined to be an implantation of giant-cell tumor, whereas the local recurrent lesion contained a clearly separated fibrosarcomatous area within the conventional giant-cell tumor. Immunohistochemistry showed diffuse and strong p53 expression in the fibrosarcomatous area. Direct sequencing revealed a p53 mutation in the sarcomatous area and a recessive mutant signal in the conventional area. The lung lesion also contained the same p53 mutation. Identification of the p53 mutation may help in diagnosing potential malignant transformation of giant-cell tumor.

P53 expression as a prognostic marker in giant cell tumor of bone: a pilot study

P53 is the best known tumor suppressor gene. If p53 is mutated, the ability of the cell to sense and repair DNA defects is lost. Failure of this mechanism increases the risk of malignant transformation and tumorigenesis. P53 overexpression is implicated in many carcinomas. P53 alterations appear to be frequent in bone and soft tissue sarcoma and have a strong negative impact on survival in various subtypes of sarcoma like Ewing's sarcoma, synovial sarcoma, and myxoid liposarcoma. There is also evidence in the literature that p53 may be implicated in bone giant cell tumor behavior. The goal of this pilot retrospective study was to detect p53 mutation in giant cell tumor of bone and correlate it with clinical outcome. We analyzed the presence of p53 mutation in 39 patients with giant cell tumor of bone by means of immunohistochemical staining; 8 tumors expressed mutated p53 protein. Seven of them recurred locally (P<.001) and 2 metastasized to the lung (P<.05). In multivariate analysis/subgroup analysis, local recurrence was still strongly correlated, while metastasis had a weaker correlation. Our findings suggest that p53 mutation in giant cell tumor of bone can be useful in predicting tumor behavior, especially in regard to local recurrence. Limitations of this study include the retrospective data collection, the limited number of patients, and the multifactorial nature of the disease; tumor grade, surgical margins, use of adjuvant therapy, and thoroughness of excision may influence the therapeutic outcome. Despite these limitations, this correlation should be further investigated with larger clinical studies. P53 may be used as a marker for the biologic behavior of giant cell tumor of bone.

Identification of differentially expressed genes in the high and low metastatic human ovarian cancer cell lines and analyses of their chromosomal localizations and functions

Oligonucleotide microarrays were used to study the differences of gene expressions in high (H) and low (L) metastatic ovarian cancer cell lines and in normal ovarian tissues (C). Bioinformatics was used to identify novel genes and their functions as well as chromosomal localizations. A total of 409 genes were differentially expressed between the high and low metastatic ovarian cancer cell lines. Of them, 271 genes were up regulated (Signal Log Ratio[SLR] > or = 1), and 138 genes were down regulated (SLR < or = -1). Except one gene whose location was unknown, all these genes were localized randomly on all the chromosomes, with a majority of them localized to Chromosomes 1, 6, 2, 17, 3, 5 and 11. Chromosome 1 contained, 43 of them (10.7%), the most for a single chromosome. A total of 264 genes (64.7%) were localized on the short arm of the chromosome (q). Functional classification showed that the 104 (25.4%) genes coding for enzymes and enzyme regulators made up the largest functional group, followed by signal transduction activity genes (43, 10.5%), nucleic acid binding activity genes (42, 10.3%), and proteins binding activity genes (34, 8.3%). These four groups accounted for 54.5% of all the differentially expressed genes. In addition, the functions of 76 genes (18.6%) were unknown. Tumor metastasis is the result of a number of genes acting in concert. The four functional groups of genes classified among these genes and their abnormalities would be the focus of further studies on ovarian cancer metastasis.

Liver transplantation for hepatocellular carcinoma: extension of indications based on molecular markers

BACKGROUND/AIMS

Liver transplantation usually cures hepatocellular carcinoma when the Milan selection criteria are applied, whereas there is substantial risk of posttransplant recurrence with tumors beyond these criteria. This study uses molecular data to identify a subgroup of patients who, despite having hepatocellular carcinoma beyond Milan criteria, have favorable outcomes.

METHODS

Allelic imbalance of 18 microsatellites was analyzed in 70 consecutive patients (35 within Milan, 35 beyond Milan criteria) transplanted for hepatocellular carcinoma of whom 24 had recurrence and 46 survived at least 5 years recurrence-free. Fractional allelic imbalance (the fraction of significant microsatellites that demonstrated allelic imbalance) and relevant clinical/pathological variables were tested for correlation with time to recurrence.

RESULTS

Allelic imbalance in 9/18 microsatellites correlated with recurrence. Fractional allelic imbalance > 0.27 and macrovascular invasion were independent predictors of recurrence in patients with tumors beyond Milan criteria; the probability of recurrence at 5 years was 85% with fractional allelic imbalance > or = 0.27 vs. 10% when < 0.27 (p=0.0002). An algorithm including Milan criteria and fractional allelic imbalance status is 89% accurate in predicting tumor recurrence after transplantation.

CONCLUSION

Analysis of allelic imbalance of 9 microsatellites identifies a subgroup of patients who, despite having hepatocellular carcinoma beyond Milan criteria, have a low risk of posttransplant recurrence.

Telomere biology in giant cell tumour of bone

Giant cell tumour of bone (GCTB) is a benign bone tumour known for the unpredictable clinical behaviour of recurrences and, in rare instances, distant metastases. It consists of uniformly distributed osteoclastic giant cells in a background of mononuclear rounded and spindle-shaped cells. Cytogenetically, telomeric associations are the most common chromosomal aberrations, which, however, are normally almost exclusively found in high-grade malignancies. GCTB has often been regarded as a polyclonal tumour, but more recently a recurrent specific aberration was reported, which suggests a possible role for disturbed telomere maintenance. Here we further investigate telomere maintenance in GCTB using 19 samples from 19 patients. A combination of immunofluorescence and FISH was performed, applying antibodies directed against promyelocytic leukaemia body-related antigen and hTERT and using telomere peptide nucleic acid probes. The TRAP assay and telomere restriction fragment length analysis were performed for functional detection of telomerase activity and alternative telomere lengthening. Both osteoclastic giant cells and mononuclear cells showed positivity for hTERT and promyelocytic leukaemia body-related antigen. In most mononuclear cells, co-expression was present. The TRAP assay demonstrated heterogeneous telomerase activity, while telomere restriction fragment length analysis showed non-heterogeneous telomere lengths, indicating the absence of alternative telomere lengthening. Confocal microscopy showed stereometric co-localization of nucleolin with promyelocytic leukaemia body-related antigen in association with telomeres in the spindle-shaped cells. hTERT was more diffusely distributed throughout the nucleus. Our results show that GCTB demonstrates remarkable telomere maintenance of activated telomerase and inactivated alternative telomere lengthening in the presence of normal mean telomere restriction fragment lengths. These findings strongly suggest that these aggregates, while activating telomerase, are part of a structural telomere protective-capping mechanism rather than of a telomere-lengthening mechanism. Telomere maintenance could be considered an important key factor in the pathogenesis of GCTB.

Pulmonary metastasis of giant cell tumor of the bone diagnosed by fine-needle aspiration biopsy

Giant cell tumor is a benign but locally aggressive tumor that primarily affects the epiphyses of long bones of young adults. Pulmonary metastases in giant cell tumor are rare (about 1-9%). Here, we report a case of metastatic pulmonary giant cell tumor in a patient who had a previous history of giant cell tumor of the distal femur with multiple recurrences. The diagnosis of pulmonary metastasis was achieved by cytologic evaluation with concurrent immunohistochemical studies in material obtained by fine-needle aspiration biopsy. The aspirate smears contained clustered and dispersed mononuclear and osteoclast-like giant cells that had bland nuclei with inconspicuous nucleoli. All multinucleated cells showed immunoreactivity to KP-1 antibody, a histiocytic marker (not lineage specific) and only a subset of mononuclear cells (30%) stained with this marker. Twenty percent of the mononuclear cells also displayed increased Ki-67 and p53 protein expression. The pulmonary metastasis was similar morphologically and immunophenotypically to the recurrent giant cell tumor of the bone.

Comparison of allelic losses in chondroblastoma and primary chondrosarcoma of bone and correlation with fluorescence in situ hybridization analysis

Chondroblastoma (CBL) is a benign neoplasm of bone for which the genomic characteristics remain unclear. We compared the status of allelic losses of CBL with that seen in a set of chondrosarcomas (CS) to determine whether differences in their natural history and behavior are also reflected genetically. Eleven cases of CBL and 10 cases of CS of different grades were included. Tumors were subjected to microdissection and polymerase chain reaction using 17 markers located near genes on chromosomes 5, 9, 11, 13, 17, and 19. The selected chromosomes are known to be involved in several mesenchymal neoplasms. Fluorescence in situ hybridization was also performed on tumors displaying allelic losses, with dual-color probes for 9p, 17p, and 13q. Fractional allelic losses per gene ranged from 18.2% to 63.7% in CBLs and from 28.6% to 66.7% in CSs. Loss of heterozygosity (LOH) of 5q, 9p, 11p, 13q, and 19q occurred in both CBLs and CSs. Loss of heterozygosity of 17p (p53 locus) occurred in 7 of 11 CBLs and in only 1 case of recurrent CS. The pattern of allelic loss was similar in low-grade CSs and CBLs. Loci with LOH in both tumor types suggest possible involvement of the genes p53, RB1, CDKN2/p16, ERC, and XRCC in tumorigenesis. Overall correlation between LOH and fluorescence in situ hybridization results was 90% with 17p13, 80% with 9p, and 60% with 13q. The role of p53 in CBL is uncertain; however, given the benign behavior of this tumor, it is probably unrelated to tumor progression.

Analysis of chromosomal imbalances in an elderly woman with a giant cell tumour

Giant cell tumour (GCT) remains one of the most obscure and intensely studied bone tumours. In an effort to resolve questions regarding the genesis and clinical outcome of GCT, advances have been made recently in the identification of chromosomal abnormalities implicated in the tumour. Fusion of telomeres is very frequent in GCT, and this process may be associated with chromosome instability and tumour development. However, little emphasis has been placed on chromosomal imbalances in the molecular characterization of this disease. Here, we report the case of an 83-year-old woman diagnosed with GCT where local recurrence was observed after 11 months of the resection. Cytogenetic studies of the GCT showed a modal number of 46 chromosomes with telomeric associations on 11p and dicentric chromosomes. Moreover, clonal abnormalities, such as del(17p) and losses of chromosomes 4, 13 and 18 and gains on chromosome 7, were also detected. Interestingly, comparative genomic hybridisation (CGH) analysis revealed chromosomal imbalances with gains on chromosomes 1p31-q44, 6q12-q23 and 12q15-q22. Thus, the use of CGH expanded the information obtained by conventional cytogenetics and demonstrated that chromosomal imbalances were associated with the recurrence of the GCT.

Giant cell tumors of the bone: Molecular profiling and expression analysis of Ephrin A1 receptor, Claudin 7, CD52, FGFR3 and AMFR

Giant cell tumors (GCTs) of the bone are osteolytic neoplasms with variable degrees of aggressiveness. The aim of this study was the molecular characterization of GCT tissue. We established gene expression profiles and discovered a number of genes that have not been described in GCTs before. RNA was prepared from 7 cryopreserved GCTs (primary tumors n = 5, relapses n = 2) and was hybridized to Affymetrix HG U133A microarrays. Paraffin-embedded samples were used for immunohistochemical validation (primary tumors n = 16, relapses n = 6). Gene ontology revealed that the majority of genes, found to be differentially expressed between primary and recurrent GCTs, were associated with receptor tyrosine kinase activity. We selected one upregulated gene (Claudin 7) and four downregulated genes (CD52, Ephrin A1 receptor, autocrine motility factor receptor [AMFR] and fibroblast growth factor receptor 3 [FGFR3] for further analysis using immunohistochemistry. Immunohistochemical analysis of CD52, AMFR, and Ephrin A1 receptor revealed expression profiles concordant with the microarray data, also with regard to differences between primary tumors and relapses.