Susumu Joyama

Synovial sarcoma is a stem cell malignancy.

Synovial sarcoma (SS) is a malignant soft tissue tumor characterized by its unique t(X;18)(p11;q11) chromosomal translocation leading to the formation of the SS18‐SSX fusion gene. The resulting fusion protein product is considered to play as an aberrant transcription factor and transform target cells by perturbing their gene expression program. However, the cellular origin of SS is highly debated. We herein established two novel human SS cell lines, named Yamato‐SS and Aska‐SS, and investigated their biological properties. We found the self‐renewal ability of these cells to generate sarcospheres, to form tumors in serial xenotransplantation and reconstitute the tumor phenotypes without fractionation by any surface markers. Both SS cells as well as clinical tissue specimens from 15 patients expressed the marker genes‐associated stem cell identity, Oct3/4, Nanog, and Sox2. We also found that both SS cells displayed limited differentiation potentials for mesenchymal lineages into osteocytes and chondrocytes albeit with the expression of early mesenchymal and hematopoietic lineage genes. Upon SS18‐SSX silencing with sequence‐specific siRNAs, these SS cells exhibited morphological transition from spherical growth in suspension to adherent growth in monolayer, additional expression of later mesenchymal and hematopoietic lineage genes, and broader differentiation potentials into osteocytes, chondrocytes, adipocytes, and macrophages in appropriate differentiation cocktails. Collectively, these data suggest that a human multipotent mesenchymal stem cell can serve as a cell of origin for SS and SS is a stem cell malignancy resulting from dysregulation of self‐renewal and differentiation capacities driven by SS18‐SSX fusion protein. STEM CELLS 2010;28:1119–1131

Extraskeletal mesenchymal chondrosarcoma: an imaging review of ten new patients.

ObjectiveExtraskeletal mesenchymal chondrosarcoma (EMC) is a rare soft-tissue tumor that most arises in young adults. Because of its rarity, few imaging studies have been reported to date. The purpose of this study was to elucidate the imaging features of this tumor.DesignWe conducted a multi-institutional study in cooperation with five referral cancer centers in Japan. Imaging findings of ten new EMC cases, including conventional radiography, computed tomography (CT), and magnetic resonance imaging (MRI), performed at each institute, were reviewed along with clinical features.PatientsTen patients with EMC, who had been treated at each hospital from 1990 to 2001, participated in this study.Results and conclusionsSoft-tissue masses with well-demarcated, dense and granular calcification were most frequently observed on plain radiographs and CT scans. T2-weighted MR images most clearly depicted a two-component structure composed of calcified and uncalcified areas, and enhanced MRI showed inhomogeneous enhancement in both areas. Although the sensitivity and specificity of these findings are unknown, they might be characteristic and have diagnostic value for this rare tumor.

Interleukin-6/soluble interleukin-6 receptor signaling attenuates proliferation and invasion, and induces morphological changes of a newly established pleomorphic malignant fibrous histiocytoma cell line.

Pleomorphic malignant fibrous histiocytoma (MFH) is occasionally associated with inflammatory paraneoplastic syndrome (PNS). Recently, we reported that interleukin (IL)-6, one of the candidate cytokines, which induces such systemic inflammatory reaction, may be a tumor-associated factor involved in the pathogenesis and its clinical manifestations of MFH. In the local microenvironment, tumor-induced inflammatory reaction may play a role favoring tumor progression. To clarify the biological relevance of IL-6 in MFH, we established a human MFH cell line, named MIPS-2, derived from a resected specimen of a patient presenting with PNS. In this patient, the serum IL-6 level ran parallel to the disease course: elevated serum IL-6 concentration normalized immediately after radical surgery, and re-elevation occurred on tumor recurrence. MIPS-2 presented pleomorphic appearance, severe nuclear abnormalities with prominent nucleoli, and tumorigenesis in nude mice. MIPS-2 expressed IL-6, IL-6 receptor (IL-6R), and glycoprotein 130 (gp130) but lacked the soluble form of IL-6R (sIL-6R), as determined by flow cytometry and reverse transcriptase-polymerase chain reaction analyses. Stimulation of MIPS-2 with IL-6 combined with exogenous sIL-6R induced phosphorylation of both signal transducer and activator of transcription 3 (STAT3) and mitogen-activated protein kinase (MAPK), decreased cell proliferation, attenuated invasion, and induced morphological changes. Collectively, these data suggested that the IL-6/sIL-6R signaling pathway plays a pivotal role for proliferation, invasion, and morphology of MFH via STAT3 and MAPK pathway as autocrine and/or paracrine manner, and proposed the therapeutic potential for the use of both anti-growth factor and proinflammatory cytokine-targeting strategies to combat devastating MFH.

Monoclonal antibody to parathyroid hormone-related protein induces differentiation and apoptosis of chondrosarcoma cells.

We investigated the effects of treatment with anti-parathyroid hormone-related protein (1-34) monoclonal murine antibody (anti-PTHrP MoAb) on apoptosis and the differentiation of chondrosarcoma HTB-94 cells. Treatment with anti-PTHrP MoAb accelerated apoptosis of HTB-94 cells in a dose-dependent manner, and anti-PTHrP MoAb also promoted the chondrogenic differentiation of HTB-94 cells. The induction of apoptosis by anti-PTHrP MoAb via imbalance of Bcl-2/Bax ratio and activation of caspase-3 may provide a mechanistic explanation for its potential antitumor effects. Our results suggest the possibility that anti-PTHrP MoAb may be beneficial as a new treatment for chondrosarcoma.

Frequent expression of smooth muscle markers in malignant fibrous histiocytoma of bone

Background/Aims: Malignant fibrous histiocytoma (MFH) of bone, a relatively rare primary malignant bone tumour, is a distinct clinicopathological entity as opposed to MFH derived from soft tissue. Although the true histogenesis of this condition is still controversial, a considerable number of cases of MFH in soft tissue show positive immunohistochemical reactivity for muscle markers such as desmin, common muscle actin (HHF35), and α smooth muscle actin (SMA), suggesting that MFH cells are myofibroblastic in nature. Methods: This study investigated immunoreactivity for several different muscle markers in 19 cases of MFH of bone together with reverse transcription polymerase chain reaction (RT-PCR) analysis on frozen tissue samples that were available in four cases, and compared the data with those found in 11 cases of osteosarcoma and 11 cases of soft tissue MFH treated over the same period. Results: Immunohistochemistry revealed that MFH of bone showed relatively frequent expression of smooth muscle markers, including calponin (nine cases), α-SMA (nine cases), and SM22α (18 cases), and this was confirmed by RT-PCR analysis. However, only one, two, and three cases of MFH of bone showed positive staining for desmin, MyoD1, and HHF35, respectively. Similarly, 11 osteosarcoma cases were relatively frequently positive for α-SMA (five cases), calponin (four cases), and SM22α (seven cases), and less frequently positive for desmin (one case), MyoD1 (none), and HHF35 (none). In contrast, very few MFH of soft tissue cases (n = 11) showed positive reactivity for all of these muscle markers. It has recently been reported that human bone marrow stromal cells also express various kinds of smooth muscle markers including α-SMA and calponin. Conclusions: These results suggested that MFH of bone may derive from mesenchymal stromal cells in bone marrow and has a more myofibroblastic differentiation than soft tissue MFH.

Involvement of BMP‐2 signaling in a cartilage cap in osteochondroma

This study describes the distributions of bone morphogenetic protein (BMP)‐2 as well as mRNAs for BMP receptor type IB (BMPRIB), collagen types II (Col II) and III (Col III) in a growing “cartilage cap” of osteochondroma. In situ hybridization and immunohistochemical study were performed using histological sections obtained during surgery. BMP‐2 was detected in mesenchymal cells in the outer fibrous layer and chondrocytes in the inner cartilaginous matrix, positive for Col III and Col II, respectively. BMPRIB mRNA was distributed in chondrocytes. This is the first study to provide observational evidence of the involvement of BMP‐2 signaling in the pathogenesis of cartilage cap of osteochondroma, and suggests the role of BMP‐2 in the growth of cartilage cap in osteochondroma.

Eleven Cases of Cardiac Metastases from Soft-tissue Sarcomas

OBJECTIVE Cardiac metastasis is a highly life-threatening condition because it leads to cardiac failure. However, it is difficult to diagnose because its precise clinical features are unknown. Here, we report 11 cases of cardiac metastasis from soft-tissue sarcoma, and discuss its diagnosis and treatment. METHODS Of 641 patients with soft-tissue sarcoma treated in our institute between 1996 and 2009, we retrospectively reviewed the medical records of 11 patients whose cardiac metastases were diagnosed while they were alive. RESULTS The most common primary tumor was leiomyosarcoma (n= 5), followed by clear cell sarcoma (n= 2). In all cases, metastases to other organs, including lungs (n= 10), soft tissues (n= 5) and bones (n= 4) were found along with cardiac metastases. Cardiac metastasis was diagnosed by echocardiography in six cases and by computed tomography in four cases. In four patients, cardiac metastasis was not detected by chest computed tomography as follow-up to lung metastases and echocardiography was required to make the diagnosis. Although five patients complained of exertional dyspnea, four were asymptomatic. Seven cases were treated with radiotherapy. No patient had surgery for their cardiac metastasis. The median survival of patients who received radiation therapy was 10.5 months; that of those who did not was 3.5 months. CONCLUSIONS Cardiac metastasis is often asymptomatic. Echocardiography is better than computed tomography for diagnosing cardiac metastasis, and should be considered in all patients presenting with soft-tissue metastases. Owing to the highly life-threatening nature of cardiac metastases and the possibility of soft-tissue dissemination, treatment with radiation therapy is recommended immediately on diagnosis.

Quantification of SSX mRNA Expression in Human Bone and Soft Tissue Tumors Using Nucleic Acid Sequence-Based Amplification

The SSX family proteins have been considered new members of the cancer/testis antigens because of the restricted expression in testis among normal tissues and the activation in a wide range of cancers. Thus, they would be potential molecular targets for immunotherapeutic strategies. We have developed a competitive nucleic acid sequence-based amplification (NASBA) assay to analyze SSX mRNA expression in 211 bone and soft tissue tumors. The copy numbers of SSX mRNA per mug of total RNA in tumor tissues were widely distributed, ranging logarithmically from 0.6 to 6.6. We found that malignant tumors showed significantly higher expression of SSX mRNA than benign tumors (P < 0.0001). Further, SSX mRNA expression in stage III tumors was significantly higher than that in stage I or II tumors (P < 0.005). This NASBA assay was also more sensitive compared to immunohistochemistry using newly affinity-purified polyclonal antibody against SSX. Collectively, these results suggest that the SSX quantitative NASBA assay could provide useful information to select eligible patients for SSX-specific cancer vaccines.

Myxoid liposarcoma with adipocytic maturation: detection of TLS/CHOP fusion gene transcript.

This report describes a 49-year-old woman with a well-circumscribed nodule of liposarcoma. The patient noticed a soft, slowly growing mass at the right sural region. Both axial computed tomography and magnetic resonance imaging revealed a soft tissue tumor consisting of nonfatty lesion measuring 5 × 3 × 3 cm circumscribed by a 1-cm thickened fatty area. Histologically, the tumor was made of 2 distinct components: the inner component of the tumor was a classic myxoid liposarcoma with numerous lipoblasts; the outer component was a lipoma-like lesion consisting of mature adipocytes without atypical nuclei. Immunohistochemically, MDM2 overexpression was observed and p53 immunophenotype was negative in both components. Molecular analysis revealed that type 1 TLS/ CHOP fusion gene transcript, characteristic of myxoid/round cell liposarcoma, was detected in both areas.

Surgery With Vascular Reconstruction for Soft-Tissue Sarcomas in the Inguinal Region: Oncologic and Functional Outcomes

BACKGROUND Treatment of soft-tissue sarcomas involving the inguinal region remains challenging because of difficulties in achieving wide surgical margins due to anatomical features. The study aimed to analyze the oncologic and functional outcomes of wide resection with vascular reconstruction for inguinal soft-tissue sarcomas. METHODS Three men and seven women were treated for inguinal soft-tissue sarcomas by wide surgical resection with vascular reconstruction. RESULTS Arteries and veins were replaced in nine patients, and artery replacement alone was carried out in one patient. Femoral nerve resections were performed in six patients. One patient and five patients developed local recurrence and distant metastases, respectively. Limb salvage was achieved in 9 of 10 patients (90%). Six patients and one patient developed vascular (arterial graft occlusion [n = 1], lymphedema [n = 5]) and nonvascular (hematoma [n = 1]) complications, respectively. Five-year arterial primary patency was 77%. Five-year disease-free and overall survival rates were 45% and 77%, respectively. Functional outcome scores at latest follow-up averaged 87.5% for Musculoskeletal Tumor Society 1993. CONCLUSIONS En-bloc resection of major critical structures along with tumor and vascular reconstructions using synthetic grafts is a feasible option in limb salvage surgery for inguinal soft-tissue sarcomas.