Synovial Sarcoma: Advances in Diagnosis and Treatment Identification of New Biologic Targets to Improve Multimodal Therapy

Exclusion of HDAC1/2 complexes by oncogenic nuclear condensates

Nuclear condensates have been shown to regulate cell fate control, but its role in oncogenic transformation remains largely unknown. Here we show acquisition of oncogenic potential by nuclear condensate remodeling. The proto-oncogene SS18 and its oncogenic fusion SS18-SSX1 can both form condensates, but with drastically different properties and impact on 3D genome architecture. The oncogenic condensates, not wild type ones, readily exclude HDAC1 and 2 complexes, thus, allowing aberrant accumulation of H3K27ac on chromatin loci, leading to oncogenic expression of key target genes. These results provide the first case for condensate remodeling as a transforming event to generate oncogene and such condensates can be targeted for therapy. One sentence summary: Expulsion of HDACs complexes leads to oncogenic transformation.

Synovial sarcoma of the viscera (lung and jejunum): a case report

We report the case of a woman nearing 70 years old who was admitted to the hospital with a complaint of "epigastric distension for 1 month". Her main signs and symptoms were progressive abdominal distension and occasional abdominal pain. Computed tomography suggested an abdominal mass. She had a surgical history of synovial sarcoma (SS) of the lungs. After admission, she was diagnosed with jejunal SS following a puncture biopsy and laparoscopic surgery. This disease usually occurs in the soft tissues of the limbs, and it is extremely rare for SS to originate in the jejunum. The morphologic heterogeneity of SS overlaps with other tumors and makes the diagnosis particularly difficult. Imaging studies usually lack specificity; however, measuring multiple immunohistochemical markers can greatly assist in the diagnosis and differential diagnosis of SS. This case not only enriches our understanding of SS and describes a rare site of origin, but also emphasizes the importance and challenges of achieving an accurate diagnosis. Immunohistochemical and molecular biological testing have important roles in the definitive diagnosis, highlighting the need for precise and innovative diagnostic and therapeutic approaches in SS.

SOFT TISSUE SARCOMA - SANTA CASA DE SÃO PAULO EXPERIENCE FROM 2006 TO 2019

Objective

To conduct an epidemiologic review, analyzing treatment, evolution, and survival of soft tissue sarcomas.

Methods

Retrospective study based on medical records of patient with STS treated by the Orthopedic Oncology Group at the Santa Casa de São Paulo, from 2006 to 2019. Data from 121 patients were analyzed according to age, sex, histological type, tumor location, treatment, previous surgery in a non-specialized service, local recurrences, lung metastases, and survival analysis.

Results

The most frequent location was the thigh. Patients who underwent surgery with a non-specialized group had higher rates of local recurrence and those with pulmonary metastasis had a lower survival rate.

Conclusion

STS can occur at any age and the prevalence of the histological type depends on the patients' age group. Level of Evidence II, Prognostic Study.

Treatment patterns and outcomes in patients with metastatic synovial sarcoma in France, Germany, Italy, Spain and the United Kingdom

Aim: Describing the treatment patterns, outcomes by line of treatment (LOT), and healthcare resource utilization (HCRU) in patients with metastatic synovial sarcoma (mSS). Patients & methods: In this descriptive, non-interventional, retrospective cohort study, physicians from five European countries reported on patients with recent pharmacological treatment for mSS. Results: Among 296 patients with mSS, 86.1, 38.9 and 8.4% received 1 LOT (1L), 2 LOTs (2L) and 3+ LOTs (L3+), respectively. Common regimens were doxorubicin/ifosfamide-based (37.4%) for 1L and trabectedin-based for 2L (29.7%). For 1L, median time to next treatment was 13.1 and 6.0 months for living and deceased patients, respectively. Median OS was 22.0, 6.0 and 4.9 months in all patients, 2L and 3L, respectively. HCRU data showed median one inpatient hospital admission, 3 days in hospital and four outpatient visits yearly. Conclusion: This large-scale study documents high unmet needs in patients previously treated for mSS and for more effective therapies.

The clinicopathological spectrum of sclerosing epithelioid fibrosarcoma: report of an additional series with review of the literature

We present a case series of sclerosing epithelioid fibrosarcoma (SEF) to further characterise its clinical and pathological features. Twenty-one patients with SEF were included in this study. There were 12 males and nine females (range 25-63 years; median 38 years). Tumours were located in the kidney (n=5), thigh (n=3), chest wall (n=3), head and neck (n=2), bone (n=2), abdominal wall (n=1), psoas major (n=1), retroperitoneum (n=1), omentum (n=1), popliteal space (n=1) and lung (n=1). Tumour sizes ranged from 2.5 to 16 cm (median 7 cm). Microscopically, epithelioid tumour cells were arranged in nests and cords and embedded in a dense sclerotic stroma. Some tumours showed myxoid areas, fibroma-like areas, acinar growth patterns and haemangiopericytoma-like appearance. A few tumour cells presented a rhabdomyoid shape. Calcification, ossification, cystic and necrosis were observed in some cases. The diagnosis was confirmed by immunoreactivity for MUC4, and by further fluorescence in situ hybridisation (FISH) or next generation sequencing (NGS) analysis. Clinical follow-up was available for 16 cases (median, 24 months; range 6-62 months). Seven patients developed metastases to lung (n=3), bone (n=3), brain (n=2) and back (n=1). Four patients developed a local recurrence. Three patients died of disease. Overall survival (OS) of SEF was related to patient age (p=0.001) and progression-free survival (PFS) was related to tumour size (p=0.046). In addition to soft tissue, SEF is more likely to involve the viscera and the abdominal cavity and has morphological variants. Familiarity with its distinctive clinical and pathological features helps avoid misdiagnosis.

Relapsed Synovial Sarcoma: Treatment Options

OPINION STATEMENT

Synovial sarcoma (SS) is a fusion-driven subtype of sarcoma that is a more chemo-sensitive subtype of soft tissue sarcoma. While chemotherapy options are currently standard of care, our fundamental understanding of the biology of SS is driving new therapies. We will review the current standard of care, as well as the current therapies showing promise in a clinical trial. It is our hope that by encouraging participation in clinical trials, the fundamental therapies available for SS will change the current treatment paradigm.

Targeting cyclin-dependent kinases in sarcoma treatment: Current perspectives and future directions

Effective treatment of advanced/metastatic bone and soft tissue sarcomas still represents an unmet medical need. Recent advances in targeted therapies have highlighted the potential of cyclin-dependent kinases (CDK) inhibitors in several cancer types, including sarcomas. CDKs are master regulators of the cell cycle; their dysregulation is listed among the "hallmarks of cancer" and sarcomas are no exception to the rule. In this review, we report both the molecular basis, and the potential therapeutic implications for the use of CDK inhibitors in sarcoma treatment. What is more, we describe and discuss the possibility and biological rationale for combination therapies with conventional treatments, target therapy and immunotherapy, highlighting potential avenues for future research to integrate CDK inhibition in sarcoma treatment.

Modification of m5C regulators in sarcoma can guide different immune infiltrations as well as immunotherapy

Background

Recent studies have found that 5-methylcytosine (m5C) modulators are associated with the prognosis and treatment of cancer. However, the relevance of m5C modulators in sarcoma prognosis and the tumour microenvironment is unclear.

Methods

We selected 15 m5C regulators and performed unsupervised clustering to identify m5C modification patterns and differentially expressed genes associated with the m5C phenotype in The Cancer Genome Atlas (TCGA) sarcomas. The extent of immune cell infiltration in different clustering groups was explored using single-sample gene set enrichment analysis and estimation algorithms. A principal component analysis algorithm-based m5C scoring protocol was performed to assess the m5C modification patterns of individual tumors.

Results

We identified two distinct m5C modification patterns in the TCGA sarcoma cohort, which possess different clinical outcomes and biological processes. Tumour microenvironment analysis revealed two groups of immune infiltration patterns highly consistent with m5C modification patterns, classified as immune inflammatory and immune desert types. We constructed m5C scores and found that high m5C scores were closely associated with leiomyosarcoma and other subtypes, and were associated with poorer prognosis, lower PD-L1 expression, and poorer immunotherapy outcomes. The best application was validated against the m5C database.

Conclusion

We constructed an m5C score for sarcoma based on the TCGA database and identified a poorer prognosis in the high m5c score group. The stability and good prognostic predictive power of the m5C score was verified by an external database. We found that sarcomas in the low m5C score group may have a better response to immunotherapy.

A deep belief network-based clinical decision system for patients with osteosarcoma

Osteosarcoma was the most frequent type of malignant primary bone tumor with a poor survival rate mainly occurring in children and adolescents. For precision treatment, an accurate individualized prognosis for Osteosarcoma patients is highly desired. In recent years, many machine learning-based approaches have been used to predict distant metastasis and overall survival based on available individual information. In this study, we compared the performance of the deep belief networks (DBN) algorithm with six other machine learning algorithms, including Random Forest, XGBoost, Decision Tree, Gradient Boosting Machine, Logistic Regression, and Naive Bayes Classifier, to predict lung metastasis for Osteosarcoma patients. Therefore the DBN-based lung metastasis prediction model was integrated as a parameter into the Cox proportional hazards model to predict the overall survival of Osteosarcoma patients. The accuracy, precision, recall, and F1 score of the DBN algorithm were 0.917/0.888, 0.896/0.643, 0.956/0.900, and 0.925/0.750 in the training/validation sets, respectively, which were better than the other six machine-learning algorithms. For the performance of the DBN survival Cox model, the areas under the curve (AUCs) for the 1-, 3- and 5-year survival in the training set were 0.851, 0.806 and 0.793, respectively, indicating good discrimination, and the calibration curves showed good agreement between the prediction and actual observations. The DBN survival Cox model also demonstrated promising performance in the validation set. In addition, a nomogram integrating the DBN output was designed as a tool to aid clinical decision-making.

miRNAs as Biomarkers and Possible Therapeutic Strategies in Synovial Sarcoma

Synovial sarcoma (SS) is an epithelial-differentiated malignant stromal tumor that has the highest incidence in young people and can occur almost anywhere in the body. Many noncoding RNAs are involved in the occurrence, development, or pathogenesis of SS. In particular, the role of MicroRNAs (miRNAs) in SS is receiving increasing attention. MiRNA is a noncoding RNA abundant in cells and extracellular serums. Increasing evidence suggests that miRNA has played a significant role in the incidence and development of tumors in recent years, including sarcomas. Previous studies show that various sarcomas have their unique miRNA expression patterns and that various miRNA expression profiles can illustrate the classes of miRNAs that may elicit cancer-relevant activities in specific sarcoma subtypes. Furthermore, SS has been reported to have the most number of differentially expressed miRNAs, which indicated that miRNA is linked to SS. In fact, according to many publications, miRNAs have been shown to have a role in the development and appearance of SS in recent years, according to many publications. Since many studies showing that various miRNAs have a role in the development and appearance of SS in recent years have not been systematically summarized, we summarize the recent studies on the relationship between miRNA and SS in this review. For example, miR-494 promotes the development of SS via modulating cytokine gene expression. The role of miR-494-3p as a tumor suppressor is most likely linked to the CXCR4 (C-X-C chemokine receptor 4) regulator, although the exact mechanism is unknown. Our review aims to reveal in detail the potential biological value and clinical significance of miRNAs for SS and the potential clinical value brought by the association between SS and miRNAs.

Transmission of synovial sarcoma from a single multi-organ donor to three transplant recipients: case report

Background

Transmission of malignancy is a notable problem that cannot always be absolutely predicted at the time of transplantation. In particular, donor-derived transmission of synovial sarcoma in solid-organ transplantation is a rare but catastrophic event.

Case presentation

We are the first to report three cases of synovial sarcoma transmitted from a single multi-organ donor in China. The donor died of respiratory failure caused by an intrathoracic tumor, which was diagnosed as benign at the time of donation. All three recipients developed synovial sarcoma 3–13 months after transplantation; all three cases were confirmed to be donor transmitted. The liver transplant recipient died of tumor metastasis after partial-allograft hepatectomy. The two renal-transplant recipients survived after comprehensive therapy, including allograft nephrectomy, withdrawal of immunosuppressants and targeted therapy with anlotinib.

Conclusions

This report highlights the importance of detailed donor assessment, close follow-up and timely treatment of unexpected donor-transmitted malignancy. Although pathology is the most important evidence for the exclusion of donors for malignant potential, it should be combined with tumor type, tumor size and speed of growth. Organs from donors with malignant potential should be discarded. Allograft nephrectomy should be considered after confirmation of renal-allograft synovial sarcoma. Anlotinib for synovial sarcoma seems to be effective and well tolerated during long-term follow-up.

Synovial sarcoma of the spinal canal and paraspinal muscle and retroperitoneum: a case with extensive calcification

INTRODUCTION

Synovial sarcoma (SS) is a rare mesenchymal malignant tumor. SS of the spine or retroperitoneum is an extremely rare site. Approximately 30% cases show focal calcifications on radiographs and computed tomography (CT) images, while extensive calcification rarely occurs. We presented a case of SS involving the spinal canal and paraspinal muscle and retroperitoneum, which showed extensive calcification on CT.

CLINICAL PRESENTATION

The present report describes the case of a 13-year-old girl suffering from a tumor in the spinal canal and paraspinal muscle and retroperitoneum with extensive calcification on CT. The patient underwent lumbar and retroperitoneal giant tumor resection, lumbar decompression, and spinal tumor resection with a small tumor remnant remaining in the paravertebral region. Histological examination and genetic testing after surgery confirmed synovial sarcoma. After surgery, the patient refused local radiotherapy but agreed to receive chemotherapy. After 4 months of follow-up, her condition was basically stable, and the pain in her left lower limb disappeared. The residual tumor was not increased.

CONCLUSION

Extensive calcification of SS is rare. The possibility of synovial sarcoma should be considered in those who show extensive calcification in the spinal canal and paraspinal muscle and retroperitoneum on CT. For cases that cannot be completely resected, adjuvant chemotherapy can control the residual tumor in the short term. In addition, the long-term effects need to be observed.

Primary Intraosseous Synovial Sarcoma in the Mandible

Synovial sarcoma (SS) is a rare malignant mesenchymal tumor that mainly occurs in body extremities, being uncommon in the head and neck region. In the present study, we described a case of primary intraosseous SS arising in the mandible of a 22-year-old young male. The patient reported a painful swelling on the left side of the mandible for the last 7 months. Imaging exams showed the presence of an expansive and multilocular radiolucent lesion, extending from the left condyle to the mandibular body. The clinic diagnostic hypotheses were ameloblastoma or malignant neoplasm. Histologically, the lesion was characterized by a proliferation of spindle cells exhibiting vesicular nuclei and evident nucleolus. Neoplastic cells were positive for AE1/AE3, cytokeratin 7, vimentin, CD-99, and TLE-1 and negative for CD-34, S-100, SMA, and HHF-35. A combination of clinical, histologic, and immunohistochemical characteristics supported the diagnosis of SS. The patient was referred for treatment, and preoperative exams did not reveal any other tumor foci in the body of the patient. The final diagnosis was of a primary intraosseous SS of the mandible.

Liquid Biopsy: A New Translational Diagnostic and Monitoring Tool for Musculoskeletal Tumors

Soft tissue and bone sarcomas represent a group of aggressive neoplasms often accompanied by dismal patient prognosis, especially when distant metastases are present. Moreover, effective treatment can pose a challenge, as recurrences are frequent and almost half of patients present with advanced disease. Researchers have unveiled the molecular abnormalities implicated in sarcomas' carcinogenesis, paving the way for novel treatment strategies based on each individual tumor's characteristics. Therefore, the development of new techniques aiding in early disease detection and tumor molecular profiling is imperative. Liquid biopsy refers to the sampling and analysis of patients' fluids, such as blood, to identify tumor biomarkers, through a variety of methods, including qRT-PCR, qPCR, droplet digital PCR, magnetic microbeads and digital PCR. Assessment of circulating tumor cells (CTCs), circulating free DNA (ctDNA), micro RNAs (miRs), long non-coding RNAs (lncRNAs), exosomes and exosome-associated proteins can yield a plethora of information on tumor molecular signature, histologic type and disease stage. In addition, the minimal invasiveness of the procedure renders possible its wide application in the clinical setting, and, therefore, the early detection of the presence of tumors. In this review of the literature, we gathered information on biomarkers assessed through liquid biopsy in soft tissue and bone sarcoma patients and we present the information they can yield for each individual tumor type.

The Biology of Synovial Sarcoma: State-of-the-Art and Future Perspectives

New molecular insights are being achieved in synovial sarcoma (SS) that can provide new potential diagnostic and prognostic markers as well as therapeutic targets. In particular, the advancement of research on epigenomics and gene regulation is promising. The concrete hypothesis that the pathogenesis of SS might mainly depend on the disruption of the balance of the complex interaction between epigenomic regulatory complexes and the consequences on gene expression opens interesting new perspectives. The standard of care for primary SS is wide surgical resection combined with radiation in selected cases. The role of chemotherapy is still under refinement and can be considered in patients at high risk of metastasis or in those with advanced disease. Cytotoxic chemotherapy (anthracyclines, ifosfamide, trabectedin, and pazopanib) is the treatment of choice, despite several possible side effects. Many possible drug-able targets have been identified. However, the impact of these strategies in improving SS outcome is still limited, thus making current and future research strongly needed to improve the survival of patients with SS.

Selinexor and the Selective Inhibition of Nuclear Export: A New Perspective on the Treatment of Sarcomas and Other Solid and Non-Solid Tumors

Nucleocytoplasmic transport has been found dysregulated in many types of cancer and is often described as a poor prognostic factor. Specifically, Exportin-1 (XPO1) has been found overexpressed in many tumors and has become an attractive target in molecular oncology and therapeutics development. The selective inhibitor of nuclear export, Selinexor, is one of the most scientifically interesting drugs that targets XPO1 in clinical development. In this review, we summarized the most relevant preclinical and clinical results achieved for non-solid tumors, sarcomas, and other kind of solid tumors.

Identification of Potential Genomic Alterations and the circRNA-miRNA-mRNA Regulatory Network in Primary and Recurrent Synovial Sarcomas

Introduction: Synovial sarcoma (SS) is one of the most invasive soft tissue sarcomas, prone to recurrence and metastasis, and the efficacy of surgical treatment and chemotherapy for SS remains poor. Therefore, the diagnosis and treatment of SS remain a significant challenge. This study aimed to analyze the mutated genes of primary SS (PSS) and recurrent SS (RSS), discover whether these sarcomas exhibit some potential mutated genes, and then predict associated microRNAs (miRNA) and circular RNAs (circRNA) by analyzing the mutated genes. We focused on the regulation mechanism of the circRNA-miRNA-mutated hub gene in PSS and RSS.

Methods: We performed a comprehensive genomic analysis of four pairs of formalin-fixed paraffin-embedded samples of PSS and RSS, using Illumina human exon microarrays. The gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) function, and pathway enrichment of the mutated genes were analyzed, and the protein-protein interaction (PPI) network was forecast using String software 11.0. The hub genes were then obtained using the Molecular Complex Detection (MCODE) plug-in for Cytoscape 3.7.2 and were used to analyze overall survival (OS) using the Gene Expression Profiling Interactive Analysis (GEPIA) database. The corresponding miRNAs were obtained from the miRDB 5.0 and TargetScan 7.2 databases. The corresponding circRNAs of the hub genes were found through the miRNAs from these databases: Circbank, CircInteractome, and StarBase v2.0. Thereafter we set up a competing endogenous RNA (ceRNA) network with circRNA-miRNA and miRNA-messenger RNA (mRNA) pairs.

Results: Using the chi-squared test, 391 mutated genes were screened using a significance level of p-values < 0.01 from the four pairs of PSS and RSS samples. A GO pathway analysis of 391 mutated genes demonstrated that differential expression mRNAs (DEmRNAs) might be bound up with the “positive regulation of neurogenesis,” “cell growth,” “axon part,” “cell−substrate junction,” or “protein phosphatase binding” of SS. The PPI network was constructed using 391 mutated genes, and 53 hub genes were identified (p < 0.05). Eight variant hub genes were discovered to be statistically significant using the OS analysis (p < 0.05). The circRNA-miRNA-mRNA (ceRNA) network was constructed, and it identified two circRNAs (hsa_circ_0070557 and hsa_circ_0070558), 10 miRNAs (hsa-let-7a-3p, hsa-let-7b-3p, hsa-let-7f-1-3p, hsa-let-7f-2-3p, hsa-mir-1244, hsa-mir-1197, hsa-mir-124-3p, hsa-mir-1249-5p, hsa-mir-1253, and hsa-mir-1271-5p) and five hub genes (CENPE, ENPP3, GPR18, MDC1, and PLOD2).

Conclusion: This study screened novel biological markers and investigated the differentiated circRNA-miRNA-mutated hub gene axis, which may play a pivotal role in the nosogenesis of PSS and RSS. Some circRNAs may be deemed new diagnostic or therapeutic targets that could be conducive to the future clinical treatment of SS.

Primary Synovial Sarcoma of the Orbit: A Case Report and Update on Diagnostic Techniques

Synovial sarcoma is a malignant mesenchymal tumor that most commonly occurs in the deep soft tissue of the extremities in adolescents and young adults. Primary periocular synovial sarcoma is extremely rare with only 11 previously reported cases. We describe a 23-year-old woman who presented with a 1-year history of painful, progressive right upper eyelid swelling. She was subsequently found to have a superomedial orbital mass on CT scan. Pathologic evaluation revealed a spindle cell neoplasm with SS18 (SYT) rearrangement by fluorescence in situ hybridization studies, consistent with a monophasic synovial sarcoma. This case describes the clinical, radiographic, histopathologic, and molecular cytogenetic features of this rare orbital neoplasm, with an emphasis on the emerging diagnostic techniques and novel therapies.

A rare case of synovial sarcoma with lung, heart and adrenal gland metastasis: a caution for patients and clinicians

A 68-year-old man presented to the Urology Clinic, West China Hospital, Chengdu, with a suspected right adrenal gland mass that had persisted for two months. He had no associated lumbodynia, dizziness or palpitation. Abdominal computed tomography (CT) revealed an uneven density and contrast-enhanced oval-like mass with smooth edges in the right adrenal gland. Laparoscopic right adrenal gland resection followed by histopathology confirmed a diagnosis of metastatic synovial sarcoma. The patient had a history of synovial sarcoma on the right upper leg 3 years previously that was surgically treated, but he had not undergone further treatment. Approximately 1.5 years later, he had undergone surgery for heart and lung metastasis from the synovial sarcoma of the thigh. At 5 months following laparoscopic right adrenal gland resection, abdominal CT showed a significant sign of right adrenal recurrence, and targeted therapy of 12 mg oral anlotinib, daily, was initiated. This relatively rare but alarming case highlights the importance of patient understanding and compliance to treatment.

Synovial sarcoma of the transverse colon metastatic to the chest wall after 3 years of follow-up

We report a fifth case of a transverse colon primary synovial sarcoma. A 31-year-old man with history of grade I obesity presented to an outpatient clinic reporting 6 months of intermittent colicky abdominal pain associated with haematochezia and rectal bleeding. Colonoscopy reported a partially obstructive intraluminal tumour lesion located in the transverse colon. There was no evidence of metastatic disease in the extension studies, so the patient was admitted to the hospital for a laparoscopic subtotal colectomy. Histopathology demonstrated intermediate-grade synovial sarcoma. At the third year of follow-up, the patient presented metastases on the chest wall, which required extensive resection and complementary oncological management.

Whole-exon sequencing insights into pancreatic synovial sarcoma: a case report

More than 30 cases of synovial sarcoma are sequenced on all organs of cBioPortal database, but it has not yet been reported before. Here, we reported a case of a 66-year-old male patient with an upper abdominal pain for half a month and a previous history of oral cancer. During this hospitalization, the patient underwent laparoscopic exploration followed by open pancreaticoduodenectomy. The histopathological diagnosis was pancreatic synovial sarcoma (PSS), and we further performed whole exome sequencing for this patient. We found that there are many copy number variations (CNV) of exon gene in all the 24 chromosomes, of which chr1, chr2, chr4 have the most exon gene amplification and chr21, chr22, chrY have the most exon gene deletion. Besides, GO (Gene Ontology) analysis showed that many driver-genes are related to chromosome or chromatin organization while KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis demonstrated that many driver-genes are enriched in the cancer-related pathways. Furthermore, we found mutations or CNV of the five vital driver-genes in the results of sequencing, including arid1a, arid1b, tp53, cdkn2a and asxl1. Of them, arid1a and arid1b in exon 1 are both in-frame mutations. By exploring the pathogenic genes of PSS, we have found some vital gene mutations and better understood the pathogenesis to promote the targeted treatment of primary PSS.

Is immunotherapy in the future of therapeutic management of sarcomas?

Sarcomas are rare, ubiquitous and heterogeneous tumors usually treated with surgery, chemotherapy, target therapy, and radiotherapy. However, 25-50% of patients experience local relapses and/or distant metastases after chemotherapy with an overall survival about 12-18 months. Recently, immuno-therapy has revolutionized the cancer treatments with initial indications for non-small cell lung cancer (NSCLC) and melanoma (immune-checkpoint inhibitors).Here, we provide a narrative review on the topic as well as a critical description of the currently available trials on immunotherapy treatments in patients with sarcoma. Given the promising results obtained with anti-PD-1 monoclonal antibodies (pembrolizumab and nivolumab) and CAR-T cells, we strongly believe that these new immunotherapeutic approaches, along with an innovative characterization of tumor genetics, will provide an exciting opportunity to ameliorate the therapeutic management of sarcomas.

Potential application of genomic profiling for the diagnosis and treatment of patients with sarcoma

Sarcomas represent a heterogeneous group of mesenchymal malignancies arising at various locations in the soft tissue and bone. Though a rare disease, sarcoma affects ~200,000 patients worldwide every year. The prognosis of patients with sarcoma is poor, and targeted therapy options are limited; therefore, accurate diagnosis and classification are essential for effective treatment. Sarcoma samples were acquired from 199 patients, in which TP53 (39.70%, 79/199), CDKN2A (19.10%, 38/199), CDKN2B (15.08%, 30/199), KIT (14.07%, 28/199), ATRX (10.05%, 20/199) and RB1 (10.05%, 20/199) were identified as the most commonly mutated genes (>10% incidence). Among 64 soft-tissue sarcomas that were unclassified by immunohistochemistry, 15 (23.44%, 15/64) were subsequently classified using next-generation sequencing (NGS). For the most part, the sarcoma subtypes were evenly distributed between male and female patients, while a significant association with sex was detected in leiomyosarcomas. Statistical analysis showed that osteosarcoma, Ewing's sarcoma, gastrointestinal stromal tumors and liposarcoma were all significantly associated with the patient age, and that angiosarcoma was significantly associated with high tumor mutational burden. Furthermore, serially mutated genes associated with myxofibrosarcoma, gastrointestinal stromal tumor, osteosarcoma, liposarcoma, leiomyosarcoma, synovial sarcoma and Ewing's sarcoma were identified, as well as neurotrophic tropomyosin-related kinase (NTRK) fusions of IRF2BP2-NTRK1, MEF2A-NTRK3 and ITFG1-NTRK3. Collectively, the results of the present study suggest that NGS-targeting provides potential new biomarkers for sarcoma diagnosis, and may guide more precise therapeutic strategies for patients with bone and soft-tissue sarcomas.

Synovial sarcoma of the hand-wrist: a case report and review of the literature

Background

Synovial sarcomas are infrequent malignant tumors occurring mostly in adolescents and young adults. The occurrence of synovial sarcoma in the hand-wrist area is rare (4 to 8.5% of all synovial sarcomas in different studies).

Case presentation

This report documents an uncommon case of synovial sarcoma occurring in the hand-wrist of a 69-year-old Caucasian woman. She was subsequently treated with surgical excision and radiotherapy without recurrence after follow up.

Conclusions

This paper aims to characterize the demographic, pathologic, and clinical features with a literature review. The present literature review confirms that hand-wrist synovial sarcomas are more frequent among males and subjects 10 to 40 years old. Most cases in this location are usually not larger than 5 cm in size. The five-year survival rate is higher than that reported in a previous review on hand synovial sarcomas, and this suggests an improved survival in recent decades.

Gene Fusions in Ocular Adnexal Tumors

PURPOSE

To highlight the increasing importance of gene fusions in the diagnosis, prognosis, and therapy of ocular adnexal tumors.

DESIGN

Perspective.

METHODS

A focused review of gene fusions, their pathogenic mechanism, and gene fusion detection methods in lacrimal gland and primary orbital and ocular adnexal soft tissue tumors; reappraisal of diagnostic, prognostic, and therapeutic approach to ocular adnexal tumors in light of emerging molecular genetic data.

RESULTS

The widespread implementation of fluorescence in situ hybridization and next-generation sequencing methods in pathology practice has led to identification of recurrent gene rearrangements and fusions in a variety of tumors. As a result, molecular genetic methods have become the gold standard for diagnosis of tumors with overlapping histology and immunophenotype, such as small round blue cell tumors. Identification of canonic gene fusions has led to development of sensitive and specific immunohistochemical markers, such as STAT6 in solitary fibrous tumor. In addition to diagnostic accuracy, gene fusions have prognostic implications, such as unfavorable prognosis of PAX3-FOXO1 fusion in alveolar rhabdomyosarcoma. Finally, recognition of gene fusions as a driving mechanism in neoplasia has led to development of U.S. Food and Drug Administration-approved targeted therapies, such as TRK inhibitors for NTRK fusion-positive cancers.

CONCLUSION

The discovery of recurrent gene fusions in various tumors, including those involving ocular adnexa, has led to a deeper insight into the molecular mechanisms of these neoplasms, revolutionizing our approach to their diagnosis, prognostication, and therapy.

Synovial sarcoma of the spine in the lumbar vertebral body: A rare case report

RATIONALE

Synovial sarcoma (SS) is a soft tissue neoplasm that rarely occurs in the vertebral body and should be considered in the differential diagnosis in patients with SS and vertebral lesions. SS often presents as a painless mass in the spine, which may undergo slow enlargement, resulting in sustained symptoms of neurologic deficit and pain. Due to the difficulty in differentiating between SS from other soft tissue tumors and metastatic tumors, careful histological confirmation is required for definite diagnosis. Furthermore, due to its malignancy, the appropriate treatment procedure for SS should be carefully considered.

PATIENT CONCERNS

A 56-year-old female patient had low back pain. Radiological examination revealed bony erosion of the L-2 vertebral body, and no soft tissue mass around the lumbar spine.

DIAGNOSIS

Histopathological and immunohistochemical examination revealed SS.

INTERVENTIONS

The initial treatment of posterior laminectomy decompression and percutaneous vertebro plasty (PVP) was performed, however, this initial treatment course was inappropriate, but she eventually underwent L-2 complete resection and internal fixation. After the second surgery, she was treated by external beam radiation therapy.

OUTCOMES

operation radiotherapy was finally performed. No local recurrence in L-2 vertebral body or distant metastasis was found at 1-year follow up postoperation; the neurologic symptom gradually relieved, and no other symptom was noted. And no local recurrence in L-2 vertebral body and distant metastasis was found in 1 year follow up postoperation.

LESSONS

Solitary spinal SS is extremely rare. Early surgery for total resection and adjuvant radiotherapy/chemotherapy should be emphasized.

Identification of Subtype-Specific Metastasis-Related Genetic Signatures in Sarcoma

Background: Sarcomas are heterogeneous rare malignancies constituting approximately 1% of all solid cancers in adults and including more than 70 histological and molecular subtypes with different pathological and clinical development characteristics.

Method: We identified prognostic biomarkers of sarcomas by integrating clinical information and RNA-seq data from TCGA and GEO databases. In addition, results obtained from cell cycle, cell migration, and invasion assays were used to assess the capacity for Tanespimycin to inhibit the proliferation and metastasis of sarcoma.

Results: Sarcoma samples (N = 536) were divided into four pathological subtypes including DL (dedifferentiated liposarcoma), LMS (leiomyosarcoma), UPS (undifferentiated pleomorphic sarcomas), and MFS (myxofibrosarcoma). RNA-seq expression profile data from the TCGA dataset were used to analyze differentially expressed genes (DEGs) within metastatic and non-metastatic samples of these four sarcoma pathological subtypes with DEGs defined as metastatic-related signatures (MRS). Prognostic analysis of MRS identified a group of genes significantly associated with prognosis in three pathological subtypes: DL, LMS, and UPS. ISG15, NUP50, PTTG1, SERPINE1, and TSR1 were found to be more likely associated with adverse prognosis. We also identified Tanespimycin as a drug exerting inhibitory effects on metastatic LMS subtype and therefore can serve a potential treatment for this type of sarcoma.

Conclusions: These results provide new insights into the pathogenesis, diagnosis, treatment, and prognosis of sarcomas and provide new directions for further study of sarcoma.

Synovial Sarcoma: A Complex Disease with Multifaceted Signaling and Epigenetic Landscapes

PURPOSE OF REVIEW

Aside from a characteristic SS18-SSX translocation identified in almost all cases, no genetic anomalies have been reliably isolated yet to drive the pathogenesis of synovial sarcoma. In the following review, we explore the structural units of wild-type SS18 and SSX, particularly as they relate to the transcriptional alterations and cellular pathway changes imposed by SS18-SSX.

RECENT FINDINGS

Native SS18 and SSX contribute recognizable domains to the SS18-SSX chimeric proteins, which inflict transcriptional and epigenetic changes through selective protein interactions involving the SWI/SNF and Polycomb chromatin remodeling complexes. Multiple oncogenic and developmental pathways become altered, collectively reprogramming the cellular origin of synovial sarcoma and promoting its malignant transformation. Synovial sarcoma is characterized by complex epigenetic and signaling landscapes. Identifying the operational pathways and concomitant genetic changes induced by SS18-SSX fusions could help develop tailored therapeutic strategies to ultimately improve disease control and patient survivorship.

Skp2 depletion reduces tumor-initiating properties and promotes apoptosis in synovial sarcoma

Synovial sarcoma (SS) is an aggressive soft-tissue cancer with a poor prognosis and a propensity for local recurrence and distant metastasis. In this study, we investigated whether S phase kinase-associated protein (Skp2) plays an oncogenic role in tumor initiation, progression, and metastasis of SS. Our study revealed that Skp2 is frequently overexpressed in SS specimens and SS18-SSX transgenic mouse tumors, as well as correlated with clinical stages. Next, we identified that genetic depletion of Skp2 reduced mesenchymal and stemness markers, and inhibited the invasive and proliferative capacities of SS cell lines. Furthermore, Skp2 depletion markedly suppressed the growth of SS xenografts tumors. Treatment of SS cell lines with the skp2 inhibitor flavokawain A (FKA) reduced Skp2 expression in a dose-dependent manner and resulted in cell cycle arrest and apoptosis. FKA also suppressed the invasion and tumor-initiating properties in SS, similar to the effects of Skp2 knockdown. In addition, a combination of FKA and conventional chemotherapy showed a synergistic therapeutic efficacy. Taken together, our results suggest that Skp2 plays an essential role in the biology of SS by promoting the mesenchymal state and cancer stemness. Given that chemotherapy resistance is often associated with cancer stemness, strategies of combining Skp2 inhibitors with conventional chemotherapy in SS may be desirable.

Urgent distal pancreatectomy for intraperitoneal hemorrhage due to the spontaneous rupture of a pancreatic metastatic tumor from synovial sarcoma: a case report

Background

Synovial sarcoma is a soft tissue malignancy that frequently affects the extremities, adjacent to the large joints. Synovial sarcoma has a high rate of distant metastasis; however, pancreatic metastasis is extremely rare, and to our knowledge, there has been no report of bleeding due to spontaneous tumor rupture. This study reports the case of a patient with synovial sarcoma pancreatic metastasis causing tumor rupture and bleeding, which was successfully managed with emergent distal pancreatectomy.

Case presentation

A 27-year-old woman underwent extensive resection of the primary tumor and partial lung resection after chemotherapy for left femoral synovial sarcoma and multiple lung metastases 4 years prior. During the follow-up, a 35-mm tumor was noted in the pancreatic tail on abdominal computed tomography (CT), and no other distant metastases were detected via positron emission tomography CT. Laparoscopic distal pancreatectomy was scheduled for pancreatic metastasis of synovial sarcoma. However, before the scheduled pancreatectomy could be conducted, the patient visited the emergency department because of abdominal pain that occurred after consuming a small amount of alcohol, and CT showed ascites with high CT values and leakage of contrast media. She was diagnosed with intra-abdominal hemorrhage due to a ruptured metastatic pancreatic tumor, and an emergency operation was performed. In total, 1500 mL of blood was evacuated from the abdomen, and the bleeding pancreatic tail tumor was resected. Histopathological findings revealed synovial sarcoma metastasis and a ruptured tumor capsule, and tumor cells were observed in the hematoma. After discharge on postoperative day 18, the patient was carefully monitored and confirmed to be in relapse-free survival, without chemotherapy, at 6 months post-surgery.

Conclusions

While the rate of tumor growth varies depending on the grade of the tumor, the possibility of rupture should be considered even in metastatic pancreatic tumors. In the case of pancreatic tumor rupture with stable circulation, radiological evaluation for oncology is necessary, and primary resection may be compatible with resectable cases.

Genetic aberrations and molecular biology of cardiac sarcoma

Cardiac tumors are rare and complex entities. Early assessment and differentiation between non-neoplastic and neoplastic masses, be they benign or malignant, is essential for guiding diagnosis, determining prognosis, and planning therapy. Cardiac sarcomas represent the most frequent primary malignant histotype. They could have manifold presentations so that the diagnosis is often belated. Moreover, considering their rarity and the limitation due to the cardiac location itself, the optimal multimodal management of patients affected by primary cardiac sarcomas still remains highly difficult and outcome dismal. Therefore, there is an urgent need to improve these results mainly focusing on more adequate tools for prompt diagnosis and exploring new and more effective therapies. Knowledge about the molecular landscape and pathogenesis of cardiac sarcoma is even more limited due to the rarity of this disease. In this sense, the molecular characterization of heart tumors could unfold potentially novel, druggable targets. In this review, we focused on genetic aberrations and molecular biology of cardiac sarcomas, collecting the scarce information available and resuming all the molecular findings discovered in each tumor subtype, with the aim to get further insights on mechanisms involved in tumor growth and to possibly highlight specific molecular profiles that can be used as diagnostic tests and unveil new clinically actionable targets in this tricky and challenging disease.

CDKs in Sarcoma: Mediators of Disease and Emerging Therapeutic Targets

Sarcomas represent one of the most challenging tumor types to treat due to their diverse nature and our incomplete understanding of their underlying biology. Recent work suggests cyclin-dependent kinase (CDK) pathway activation is a powerful driver of sarcomagenesis. CDK proteins participate in numerous cellular processes required for normal cell function, but their dysregulation is a hallmark of many pathologies including cancer. The contributions and significance of aberrant CDK activity to sarcoma development, however, is only partly understood. Here, we describe what is known about CDK-related alterations in the most common subtypes of sarcoma and highlight areas that warrant further investigation. As disruptions in CDK pathways appear in most, if not all, subtypes of sarcoma, we discuss the history and value of pharmacologically targeting CDKs to combat these tumors. The goals of this review are to (1) assess the prevalence and importance of CDK pathway alterations in sarcomas, (2) highlight the gap in knowledge for certain CDKs in these tumors, and (3) provide insight into studies focused on CDK inhibition for sarcoma treatment. Overall, growing evidence demonstrates a crucial role for activated CDKs in sarcoma development and as important targets for sarcoma therapy.

Cellular immunotherapy: a clinical state-of-the-art of a new paradigm for cancer treatment

Cancer immunotherapy has opened a new chapter in Medical Oncology. Many novel therapies are under clinical testing and some have already been approved and implemented in cancer treatment protocols. In particular, cellular immunotherapies take advantage of the antitumor capabilities of the immune system. From dendritic cell-based vaccines to treatments centered on genetically engineered T cells, this form of personalized cancer therapy has taken the field by storm. They commonly share the ex vivo genetic modification of the patient's immune cells to generate or induce tumor antigen-specific immune responses. The latest clinical trials and translational research have shed light on its clinical effectiveness as well as on the mechanisms behind targeting specific antigens or unique tumor alterations. This review gives an overview of the clinical developments in immune cell-based technologies predominantly for solid tumors and on how the latest discoveries are being incorporated within the standard of care.

Current Approaches for Personalized Therapy of Soft Tissue Sarcomas

Soft tissue sarcomas (STS) are a highly heterogeneous group of cancers of mesenchymal origin with diverse morphologies and clinical behaviors. While surgical resection is the standard treatment for primary STS, advanced and metastatic STS patients are not eligible for surgery. Systemic treatments, including standard chemotherapy and newer chemical agents, still play the most relevant role in the management of the disease. Discovery of specific genetic alterations in distinct STS subtypes allowed better understanding of mechanisms driving their pathogenesis and treatment optimization. This review focuses on the available targeted drugs or drug combinations based on genetic aberration involved in STS development including chromosomal translocations, oncogenic mutations, gene amplifications, and their perspectives in STS treatment. Furthermore, in this review, we discuss the possible use of chemotherapy sensitivity and resistance assays (CSRA) for the adjustment of treatment for individual patients. In summary, current trends in personalized management of advanced and metastatic STS are based on combination of both genetic testing and CSRA.

Systemic therapy in pediatric-type soft-tissue sarcoma

Soft-tissue sarcoma (sts) is rare and represents approximately 7% of cancers in children and in adolescents less than 20 years of age. Rhabdomyosarcoma (rms) is most prevalent in children less than 10 years of age and peaks again during adolescence (16-19 years of age). Multi-agent chemotherapy constitutes the mainstay of treatment for rms. In other non-rhabdomyosarcoma soft-tissue tumours, such as synovial sarcoma, evidence for routine use of chemotherapy is less robust, and alternative treatment options, including targeted agents and immunotherapy, are being explored. In this review, we focus on chemotherapy for pediatric-type rms and discuss the advances and challenges in systemic treatment for select non-rhabdomyosarcoma soft-tissue tumours in children and adolescents. We support an increasingly cooperative approach for treating pediatric and adult sts.

Diagnostic Value of TLE1 in Synovial Sarcoma: A Systematic Review and Meta-Analysis

Background

Synovial sarcoma can present morphologically in multiple forms, including biphasic and monophasic subtypes. As a result, the histological diagnosis can sometimes be challenging. Transducin-Like Enhancer 1 (TLE1) is a transcriptional corepressor that normally is involved in embryogenesis and hematopoiesis but is also expressed in certain tumors. This systematic review examines the potential role of TLE1 as a diagnostic biomarker for the synovial sarcoma. Materials and Methods. A literature review and meta-analysis were conducted using the electronic databases Pubmed, the Cochrane Library, and Google Scholar. Thirteen studies met our eligibility criteria and were selected for in-depth analysis.

Results

The mean sensitivity and specificity of TLE1 in detecting synovial sarcoma were 94% (95% CI 91%-97%) and 81% (95% CI 72%-91%), respectively, when all studies were aggregated together. The mean positive predictive value (PPV) of TLE1 was 75% (95% CI 62%-87%), whereas the negative predictive value (NPV) was 96% (95% CI 93%-98%).

Conclusion

TLE1 is a sensitive and specific marker for synovial sarcoma that can aid in its diagnosis. Due to its involvement in several relevant signaling pathways, TLE1 might have direct relevance to the pathophysiology of the disease.

Precision Medicine in Soft Tissue Sarcoma Treatment

Soft tissue sarcoma (STS) is a rare component of malignant diseases. STS includes various histological subtypes, and there are some important differences among the different histological subtypes regarding the mutation profile and sensitivity to antitumor agents. Many clinical trials of STS incorporating many different histological subtypes in various populations have been conducted; it is difficult to compare the findings and make conclusions about clinical efficacy. Targeted therapies focusing on specific histological subtypes and precision therapy focusing on the specific genetic mutation(s) of each STS patient are being investigated. Since STS patients are a small population, new clinical trial designs are required to evaluate and establish new targeted therapies for each histological subtype that has a limited number of patients, and preclinical investigations are needed to detect targetable mutations. Now that cancer genome profiling is used in clinical practice, it is urgently necessary to connect the genome profiling data obtained in clinical settings to the optimal clinical treatment strategies. Herein we review the development and challenges of precision therapy in the management of STS patients.

Novel SS18-NEDD4 gene fusion in a primary renal synovial sarcoma

We report a primary renal synovial sarcoma with a novel gene fusion and unusual morphology. The patient was a 35-year-old female who was found to have a 5 cm hypocellular, myxoid spindle cell renal neoplasm that subtly permeated amongst native renal tubules. The tumor cells showed elongated hyperchromatic nuclei with ill-defined pale cytoplasm, lacking significant mitotic activity or necrosis. Based on its deceptively bland morphology, the differential diagnosis included mainly benign entities, such as metanephric stromal tumor, mixed epithelial stromal tumor (MEST), and myxoid peripheral nerve sheath tumors. A definitive diagnosis of synovial sarcoma was made only subsequently to RNA-sequencing, which revealed a novel SS18-NEDD4 gene fusion. These results were further confirmed by fluorescence in situ hybridization using custom design break-apart probes for both genes. This case illustrates the utility of targeted RNA-sequencing in the classification of challenging tumors with deceptive morphology and identification of novel gene fusion variants. Apart from the canonical SS18-SSX fusion, this is only the second alternative gene fusion variant described in synovial sarcoma to date, in addition to two cases harboring the SS18L1-SSX1 fusion.

Primary renal synovial sarcoma: A case report

BACKGROUND

Synovial sarcoma, a rare mesenchymal tumor type with unclear histological origin and direction of differentiation, accounts for 6%–10% of soft tissue tumors. It is mainly located near the joints and tendons of the limbs, and occurs primarily in children or young adults. Primary renal synovial sarcoma (PRSS) is very rare, accounting for approximately 1% of synovial sarcomas. It is a spindle cell tumor type affecting mesenchymal tissue, and has morphological, genetic, and clinical characteristics, and a certain degree of epithelial differentiation. It is highly malignant and has the fourth highest incidence among soft tissue sarcomas. Here, we report a case of PRSS and share some valuable information about the disease.

CASE SUMMARY

A 54-year-old male patient was admitted to the hospital for a space-occupying lesion in the right kidney for 2 d upon ultrasound examination. The patient had no cold or fever; no frequency, urgency or pain of urination; and no other discomfort. The results of a hemogram, blood biochemistry, and tumor markers were in the normal range. The patient was examined by computed tomography (CT), which indicated the presence of a soft tissue density shadow with a diameter of approximately 6.8 cm in the right renal pelvis area, showing uneven enhancement. Ultrasound indicated a cystic solid mass of approximately 6.8 cm × 6.5 cm in the right kidney, with an unclear boundary and irregular shape. Meanwhile, color Doppler flow imaging showed dotted blood flow signals in the periphery and interior. Contrast-enhanced ultrasound (CEUS) showed "slow in and fast out" hyperenhancement of the right renal mass after contrast agent injection. The postoperative pathological diagnosis was (right kidney) synovial sarcoma. Despite postoperative adjuvant chemotherapy, tumor recurrence was detected two years later.

CONCLUSION

PRSS is a rare malignant tumor. To date, no characteristic imaging findings have been observed. The diagnosis is confirmed primarily through postoperative pathological immunohistochemistry and SS18 (SYT) gene detection. In this case, CEUS was used preoperatively. We found that PRSS has the characteristic of "slow in and fast out" hyperenhancement, and its particular characteristics have diagnostic value. Postoperative adjuvant chemotherapy is not very effective.

TP53 in bone and soft tissue sarcomas

Genomic and functional study of existing and emerging sarcoma targets, such as fusion proteins, chromosomal aberrations, reduced tumor suppressor activity, and oncogenic drivers, is broadening our understanding of sarcomagenesis. Among these mechanisms, the tumor suppressor p53 (TP53) plays significant roles in the suppression of bone and soft tissue sarcoma progression. Although mutations in TP53 were thought to be relatively low in sarcomas, modern techniques including whole-genome sequencing have recently illuminated unappreciated alterations in TP53 in osteosarcoma. In addition, oncogenic gain-of-function activities of missense mutant p53 (mutp53) have been reported in sarcomas. Moreover, new targeting strategies for TP53 have been discovered: restoration of wild-type p53 (wtp53) activity through inhibition of TP53 negative regulators, reactivation of the wtp53 activity from mutp53, depletion of mutp53, and targeting of vulnerabilities in cells with TP53 deletions or mutations. These discoveries enable development of novel therapeutic strategies for therapy-resistant sarcomas. We have outlined nine bone and soft tissue sarcomas for which TP53 plays a crucial tumor suppressive role. These include osteosarcoma, Ewing sarcoma, chondrosarcoma, rhabdomyosarcoma (RMS), leiomyosarcoma (LMS), synovial sarcoma, liposarcoma (LPS), angiosarcoma, and undifferentiated pleomorphic sarcoma (UPS).

Diagnostic Imaging and Management of Common Intra-articular and Peri-articular Soft Tissue Tumors and Tumorlike Conditions of the Knee

Intra-articular (IA) and peri-articular (PA) tumors of the knee are frequently encountered by orthopaedic surgeons. Nonetheless, due to the possibility of great morbidity and potential mortality, it is important to recognize and differentiate between benign and malignant lesions in a timely manner. Therefore, the purpose of this article is to provide a concise, practical, and updated review of commonly encountered IA and PA tumors including intratendinous gout, synovial chondromatosis, schwannoma, pigmented villonodular synovitis, and synovial sarcoma, and a detailed description of differentiating features to include various imaging modalities.

Proteomic signatures corresponding to the SS18/SSX fusion gene in synovial sarcoma

Synovial sarcoma (SS) is a malignant soft tissue lesion and most commonly arises in young adults. Chromosomal translocation t(X;18)(p11;q11) results in the formation of SS18/SSX by gene fusion of the SS18 gene on chromosome 18 to either SSX1, SSX2, or SSX4 gene located on chromosome X, which is detected in more than 95% of SSs. Although multiple lines of evidence suggest that the SS18/SSX fusion is the oncogene in this tumor, the protein expression profiles associated with SS18/SSX have yet to be elucidated. In this study, we conducted proteomic studies using SS18/SSX knockdown in three SS cell lines to identify the regulated proteins associated with SS18/SSX in SS. Isobaric tags for relative and absolute quantitation (i-TRAQ) analyses identified approximate 1700–2,000 proteins regulated by the SS18/SSX fusion in each SS cell line. We also analyzed the three profiles to identify proteins that were similarly altered in all 3 cell lines and found 17 consistently upregulated and 18 consistently downregulated proteins, including TAGLN and ACTN4. In addition, network analyses identified several critical pathways including RUNX2 and SMARCA4. RUNX2 and SMARCA4 had the highest ranking in these identified pathways. In addition, we found that expression of TAGLN inhibited cell viability in SS cell lines. Our data suggest that the differentiation and cell growth of SS may be enhanced by the identified proteins induced by SS18/SSX. We believe that the findings obtained in the present functional analyses will help to improve our understanding of the relationship between SS18/SSX and malignant behavior in SS.