Beta-catenin nuclear expression correlates with cyclin D1 expression in primary and metastatic synovial sarcoma: a tissue microarray study

Advances of SS18-SSX fusion gene in synovial sarcoma: Emerging novel functions and therapeutic potentials

Synovial sarcoma is a rare type of soft tissue sarcoma that primarily affects adolescents and young adults, featured by aggressive behavior and a high potential for metastasis. Genetically, synovial sarcoma is defined by the fusion oncogene SS18-SSX arising from the translocation of t(X;18)(p11;q11). SS18-SSX fusion gene is the major driver of the oncogenic event in synovial sarcoma. SS18-SSX fusion protein, while not containing any DNA-binding motifs, binds to the SWI/SNF (BAF) complex, a major epigenetic regulator, leading to the disruption of gene expression which results in tumor initiation and progression. Emerging studies on the molecular mechanisms of SS18-SSX associated signaling pathway hold promise for developments in diagnosis and treatments. Advanced diagnostic methods facilitate early and precise detection of the tumor, enabling disease monitoring and prognostic improvements. Treatment of synovial sarcoma typically comprises local surgery, radiotherapy and chemotherapy, while novel managements such as immunotherapy, targeted therapies and epigenetic modifiers are explored. This review focuses on the recent studies of SS18-SSX fusion gene, epigenetic landscape, signaling pathways, diagnostic techniques, and relevant therapeutic advances, aiming to inhibit the oncogenic processes and improve outcomes for patients with synovial sarcoma.

Biological and therapeutic insights from animal modeling of fusion-driven pediatric soft tissue sarcomas

Survival for children with cancer has primarily improved over the past decades due to refinements in surgery, radiation and chemotherapy. Although these general therapies are sometimes curative, the cancer often recurs, resulting in poor outcomes for patients. Fusion-driven pediatric soft tissue sarcomas are genetically defined by chromosomal translocations that create a chimeric oncogene. This distinctive, almost 'monogenic', genetic feature supports the generation of animal models to study the respective diseases in vivo. This Review focuses on a subset of fusion-driven pediatric soft tissue sarcomas that have transgenic animal tumor models, which includes fusion-positive and infantile rhabdomyosarcoma, synovial sarcoma, undifferentiated small round cell sarcoma, alveolar soft part sarcoma and clear cell sarcoma. Studies using the animal models of these sarcomas have highlighted that pediatric cancers require a specific cellular state or developmental stage to drive tumorigenesis, as the fusion oncogenes cause different outcomes depending on their lineage and timing of expression. Therefore, understanding these context-specific activities could identify targetable activities and mechanisms critical for tumorigenesis. Broadly, these cancers show dependencies on chromatin regulators to support oncogenic gene expression and co-opting of developmental pathways. Comparative analyses across lineages and tumor models will further provide biological and therapeutic insights to improve outcomes for these children.

Hippo Signaling in the Endometrium

The uterus is essential for embryo implantation and fetal development. During the estrous cycle, the uterine endometrium undergoes dramatic remodeling to prepare for pregnancy. Angiogenesis is an essential biological process in endometrial remodeling. Steroid hormones regulate the series of events that occur during such remodeling. Researchers have investigated the potential factors, including angiofactors, involved in endometrial remodeling. The Hippo signaling pathway discovered in the 21st century, plays important roles in various cellular functions, including cell proliferation and cell death. However, its role in the endometrium remains unclear. In this review, we describe the female reproductive system and its association with the Hippo signaling pathway, as well as novel Hippo pathway genes and potential target genes.

The role of SYT-SSX fusion gene in tumorigenesis of synovial sarcoma

Synovial sarcoma (SS) is an aggressive malignancy of an unknown tissue origin that is characterized by biphasic differentiation. A possible basis of the pathogenesis of SS is pathognomonic t(X;18) (p11.2; q11.2) translocation, leading to the formation and expression of the SYT-SSX fusion gene. More than a quarter of the patients die of SS metastasis within 5 years after the diagnosis, but the pathogenic factors are unknown. Therefore, there is an urgent need to explore the pathogenesis, invasion, metastasis, and clinical treatment options for SS, especially molecular-targeted drug therapy. Recent studies have shown that the SYT-SSX fusion gene associated with SS may be regulated by different signaling pathways, microRNAs, and other molecules, which may produce stem cell characteristics or promote epithelial-mesenchymal transition, resulting in SS invasion and metastasis. This review article aims to show the relationship between the SYT-SSX fusion gene and the related pathway molecules as well as other molecules involved from different perspectives, which may provide a deeper and clearer understanding of the SYT-SSX fusion gene function. Therefore, this review may provide a more innovative and broader perspective of the current research, treatment options, and prognosis assessment of SS.

Hematolymphoid Neoplasms Rarely Mimic Undifferentiated Pleomorphic Sarcoma of Soft Tissue

CONTEXT.—

Undifferentiated pleomorphic sarcoma (UPS) of soft tissue is defined as a sarcoma with no recognizable line of differentiation. During the past few decades, advances in ancillary studies and review of prior UPS diagnoses have narrowed the category of UPS by excluding more-specific malignancies. However, few of those studies have specifically targeted pleomorphic hematolymphoid neoplasms.

OBJECTIVE.—

To determine what fraction of UPS cases are misclassified pleomorphic hematolymphoid neoplasms, such as anaplastic large cell lymphoma, diffuse large B-cell lymphoma, histiocytic sarcoma (HS), myeloid sarcoma, and follicular dendritic cell sarcoma.

DESIGN.—

Sixty-one UPS cases were screened by tissue microarray and an immunostain panel with subsequent analysis on whole block sections for suspicious cases.

RESULTS.—

Five of 61 tumors (8%) were suggestive of HS based on the screening panel and were further evaluated with additional immunostains (PU.1, CD45, CD163) using whole sections. The 5 candidate HS cases were only focally positive for at most one stain with most staining in smaller, less-pleomorphic cells. Ultimately, no UPS met criteria for anaplastic large cell lymphoma, diffuse large B-cell lymphoma, myeloid sarcoma, follicular dendritic cell sarcoma, or HS.

CONCLUSIONS.—

Our results suggest that a UPS of somatic soft tissue is unlikely to represent a misclassified hematopoietic malignancy. Exclusion of HS is most challenging, but immunostaining for PU.1, a nuclear transcription factor, may be easier to interpret in this context.

Myxoinflammatory fibroblastic sarcoma: an immunohistochemical and molecular genetic study of 73 cases

Myxoinflammatory fibroblastic sarcoma (MIFS) is a rare, low-grade soft tissue neoplasm preferentially arising in the extremities of young to middle-aged adults characterized histologically by a variegated appearance and absence of a distinctive immunophenotype. Herein we have evaluated a series of 73 cases of MIFS to define potential features and markers that may facilitate diagnosis. An immunohistochemical study with a large panel of antibodies showed strong positivity of the tumor cells for bcl-1 (94.5%), FXIIIa (89%), CD10 (80%), and D2-40 (56%). FISH and array comparative genomic hybridization (aCGH) were performed in a large subset of cases to investigate the utility for detecting the TGFBR3 and OGA t(1;10) rearrangement and BRAF abnormalities. Using a combination of FISH and/or aCGH, t(1;10) was detected in only 3 of 54 cases (5.5%). The aCGH study also demonstrated amplification of VGLL3 on chromosome 3 that was detected in 8 of 20 cases (40%). BRAF alterations were observed by FISH in 4 of 70 cases (5.7%) and correlated with gain of chromosome 3p12 (VGLL3). A novel fusion transcript involving exon 6 of ZNF335 and exon 10 of BRAF was identified in one case. Demonstration of amplification of VGLL3 on chromosome 3 in combination with expression of bcl-1 and FXIIIa may help support the diagnosis, however, due to their low specificity these markers are not sufficient for a definitive diagnosis in the absence of the appropriate clinical-pathological context. Until a more robust genetic or immunohistochemical signature is identified, the diagnosis of MIFS rests on its characteristic clinicopathological features.

Reduced expression of odd-skipped related transcription factor 1 promotes proliferation and invasion of breast cancer cells and indicates poor patient prognosis

Odd-skipped related transcription factor 1 (OSR1) serves an important role in the development of the intermediate mesoderm; however, its expression in cancer remains unknown. The present study aimed to explore the expression and role of OSR1 in breast cancer development. Immunohistochemistry was performed to detect OSR1 expression in breast cancer tissue and western blot analysis was used to evaluate the expression of OSR1 and related proteins, including β-catenin, c-Myc and cyclin D1. OSR1 expression was increased following transfection of MCF7 cells with OSR1 overexpression vector (MCF7-OSR1) and reduced by transfecting MDA-MB-231 cells with small interfering (si)RNA targeting OSR1 (MDA-MB-231-siOSR1). Cell proliferation and Matrigel™ invasion assays were used to investigate the effects of OSR1 on the proliferation and invasion of breast cancer cells. OSR1 was downregulated in breast cancer tissue compared with that in normal breast tissue and associated with lymph node metastases and estrogen receptor (ER) expression. Furthermore, reduced expression of OSR1 was associated with poor patient prognosis. Overexpression of OSR1 inhibited the proliferation and invasion of breast cancer cells. Western blot analysis of MCF7-OSR1 cells demonstrated that compared with that in the control cells, the expression of E-cadherin was increased, whereas that of key epithelial-mesenchymal transition (EMT) proteins, N-cadherin and Snail, was decreased. In addition, overexpression of OSR1 significantly decreased the expression level of β-catenin and Wnt target genes, such as c-Myc and cyclin D1, compared with that in the control cells. These expression patterns were reversed in the MDA-MB-231-siOSR1 cells. The results of the present study suggested that OSR1 downregulates the activity of the Wnt signaling pathway and EMT, which inhibits the proliferative and invasive abilities of breast cancer cells.

Significance of H3K27me3 loss in the diagnosis of malignant peripheral nerve sheath tumors

The diagnosis of malignant peripheral nerve sheath tumors can be challenging and other spindle cell sarcomas commonly enter in the differential diagnosis. Loss of trimethylation at lysine 27 of histone-H3 (H3K27me3) by immunohistochemistry was recently described in malignant peripheral nerve sheath tumors. However, its specificity remains controversial. We therefore studied 82 synovial sarcomas, 39 malignant peripheral nerve sheath tumors, and 10 fibrosarcomatous dermatofibrosarcoma protuberans for H3K27me3 loss by immunohistochemistry. The diagnoses were based on morphology, immunophenotype, and genetics based on WHO classification. H3K27me3 immunohistochemistry was scored by two pathologists based on fraction of cells with nuclear staining (score 0 to 3+). Loss of H3K27me3 (score 0) was seen in 44% of malignant peripheral nerve sheath tumors and 9% of synovial sarcomas yielding positive and negative predictive values of 71% and 77%, respectively. Loss of H3K27me3 was seen in 10% of fibrosarcomatous dermatofibrosarcoma protuberans, yielding positive and negative predictive values of 94 and 29% in the differential diagnosis of malignant peripheral nerve sheath tumor versus fibrosarcomatous dermatofibrosarcoma protuberans. Partial loss (score 1-2) was common in all three tumor types. Among malignant peripheral nerve sheath tumors, there was no significant association between H3K27me3 loss and gender, tumor site, or size, and progression-free or overall survival. Patients with tumors with H3K27me3 loss were younger than those with tumors with retained H3K27me3 expression (P=0.011). H3K27me3 expression was lost in 50 and 31% of sporadic and Neurofibromatosis-associated malignant peripheral nerve sheath tumors, respectively (P=0.25).Complete H3K27me3 loss is a moderately sensitive and relatively specific marker for the diagnosis of malignant peripheral nerve sheath tumor when the differential diagnosis includes synovial sarcoma and fibrosarcomatous dermatofibrosarcoma protuberans. Partial loss has limited diagnostic utility. H3K27me3 status does not show significant association with clinical outcome in malignant peripheral nerve sheath tumors.

Targeting Cyclin-Dependent Kinases in Synovial Sarcoma: Palbociclib as a Potential Treatment for Synovial Sarcoma Patients

Background

In synovial sarcomas alterations in the cyclin D1-CDK4/6-Rb axis have been described. Also, β-catenin, a cyclin D1 regulator, is often overexpressed. Additionally, studies have shown that the t(X;18) translocation influences tumor behavior partly through cyclin D1 activation. We investigated how alterations in the cyclin D1-CDK4/6-Rb axis impact prognosis and studied effects of targeting this axis with the CDK4/6 inhibitor palbociclib.

Methods

Synovial sarcoma samples (n = 43) were immunohistochemically stained for β-catenin, cyclin D1, p16, p21, p27, Rb, and phospho-Rb. Fluorescent in situ hybridization (FISH) was performed to detect CCND1 amplification or translocation. In 4 synovial sarcoma cell lines sensitivity to palbociclib was investigated using cell viability assays, and effects on the sensitive cell lines were evaluated on protein level and by cell cycle arrest.

Results

Expression of nuclear phospho-Rb and nuclear β-catenin in the patient samples was associated with poor survival. FISH showed a sporadic translocation of CCND1 in a subset of tumors. An 8-fold CCND1 amplification was found in 1 cell line, but not in the patient samples investigated. Palbociclib effectively inhibited Rb-phosphorylation in 3 cell lines, resulting in an induction of a G1 arrest and proliferation block.

Conclusions

In this series nuclear phospho-Rb and nuclear β-catenin expression were negative prognostic factors. In vitro data suggest that palbociclib may be a potential treatment for a subset of synovial sarcoma patients. Whether this effect can be enhanced by combination treatment deserves further preclinical investigations.

Electronic supplementary material

The online version of this article (doi:10.1245/s10434-016-5341-x) contains supplementary material, which is available to authorized users.

Nuclear β-Catenin Expression is Frequent in Sinonasal Hemangiopericytoma and Its Mimics

Sinonasal hemangiopericytoma (HPC) is a tumor showing pericytic myoid differentiation and which arises in the nasal cavity and paranasal sinuses. CTNNB1 mutations appear to be a consistent aberration in sinonasal HPC, and nuclear expression of β-catenin has been reported. Our aim was to evaluate the frequency of β-catenin expression in sinonasal HPC and its histologic mimics in the upper aerodigestive tract. Cases were retrieved from the surgical pathology and consultation files. Immunohistochemical staining for β-catenin was performed on 50 soft tissue tumors arising in the sinonasal tract or oral cavity, and nuclear staining was recorded semiquantitatively by extent and intensity. Nuclear reactivity for β-catenin was present in 19/20 cases of sinonasal HPC; 17 showed moderate-to-strong multifocal or diffuse staining, and 2 had moderate focal nuclear reactivity. All solitary fibrous tumors (SFT) (10/10) showed focal-to-multifocal nuclear staining, varying from weak to strong in intensity. Most cases of synovial sarcoma (9/10) showed nuclear β-catenin expression in the spindle cell component, ranging from focal-weak to strong-multifocal. No cases of myopericytoma (0/10) showed any nuclear β-catenin expression. β-catenin expression is prevalent in sinonasal HPC, but is also frequent in SFT and synovial sarcoma. Our findings indicate that β-catenin is not a useful diagnostic tool in the evaluation of spindle cell tumors with a prominent hemangiopericytoma-like vasculature in the sinonasal tract and oral cavity, and that definitive diagnosis relies on the use of a broader immunohistochemical panel.

Down-Regulation of AKT Signalling by Ursolic Acid Induces Intrinsic Apoptosis and Sensitization to Doxorubicin in Soft Tissue Sarcoma

Several important biological activities have been attributed to the pentacyclic triterpene ursolic acid (UA), being its antitumoral effect extensively studied in human adenocarcinomas. In this work, we focused on the efficacy and molecular mechanisms involved in the antitumoral effects of UA, as single agent or combined with doxorubicin (DXR), in human soft tissue sarcoma cells. UA (5-50 μM) strongly inhibited (up to 80%) the viability of STS cells at 24 h and its proliferation in soft agar, with higher concentrations increasing apoptotic death up to 30%. UA treatment (6-9 h) strongly blocked the survival AKT/GSK3β/β-catenin signalling pathway, which led to a concomitant reduction of the anti-apoptotic proteins c-Myc and p21, altogether resulting in the activation of intrinsic apoptosis. Interestingly, UA at low concentrations (10-15 μM) enhanced the antitumoral effects of DXR by up to 2-fold, while in parallel inhibiting DXR-induced AKT activation and p21 expression, two proteins implicated in antitumoral drug resistance and cell survival. In conclusion, UA is able to induce intrinsic apoptosis in human STS cells and also to sensitize these cells to DXR by blocking the AKT signalling pathway. Therefore, UA may have beneficial effects, if used as nutraceutical adjuvant during standard chemotherapy treatment of STS.

Biphenotypic sinonasal sarcoma: an expanded immunoprofile including consistent nuclear β-catenin positivity and absence of SOX10 expression

Biphenotypic sinonasal sarcoma (BSNS) is a recently recognized low-grade sarcoma that exhibits both neural and myogenic differentiation. This unique dual phenotype stems from recurrent rearrangements in PAX3, a transcription factor that promotes commitment along both lineages. While identification of PAX3 rearrangements by fluorescence in situ hybridization (FISH) can confirm a BSNS diagnosis, this assay is not widely available. This study evaluates whether an expanded immunohistochemical panel can facilitate recognition of BSNS without molecular analysis. Eleven cases of BSNS were identified from the surgical pathology archives of two academic medical centers. In 8 cases, the diagnosis was confirmed by FISH using custom probes for PAX3. In 3 cases, FISH failed but histologic and immunophenotypic findings were diagnostic for BSNS. All 11 BSNS (100%) were at least focally positive for S100 as well as calponin and/or smooth muscle actin. In addition, 10 (91%) of 11 expressed nuclear β-catenin, 8 (80%) of 10 expressed factor XIIIa, 4 (36%) of 11 expressed desmin, and 3 (30%) of 10 expressed myogenin. All 11 tumors were negative for SOX10. While no single marker resolves immunohistochemical overlap between BSNS and its histologic mimickers such as nerve sheath tumors, an extended immunohistochemical panel that includes β-catenin and SOX10 helps to support the diagnosis of BSNS without the need for gene rearrangement studies.

The fusion protein SS18-SSX1 employs core Wnt pathway transcription factors to induce a partial Wnt signature in synovial sarcoma

Expression of the SS18/SYT-SSX fusion protein is believed to underlie the pathogenesis of synovial sarcoma (SS). Recent evidence suggests that deregulation of the Wnt pathway may play an important role in SS but the mechanisms whereby SS18-SSX might affect Wnt signaling remain to be elucidated. Here, we show that SS18/SSX tightly regulates the elevated expression of the key Wnt target AXIN2 in primary SS. SS18-SSX is shown to interact with TCF/LEF, TLE and HDAC but not β-catenin in vivo and to induce Wnt target gene expression by forming a complex containing promoter-bound TCF/LEF and HDAC but lacking β-catenin. Our observations provide a tumor-specific mechanistic basis for Wnt target gene induction in SS that can occur in the absence of Wnt ligand stimulation.

CTNNB1 (β-Catenin)-altered Neoplasia: A Review Focusing on Soft Tissue Neoplasms and Parenchymal Lesions of Uncertain Histogenesis

β-catenin (CTNNB1) is a key regulatory molecule of the Wnt signaling pathway, which is important for tissue homeostasis and regulation of cell proliferation, differentiation, and function. Abnormal stabilization and nuclear accumulation of β-catenin as a consequence of missense mutations or alternative molecular mechanisms occurs at a high frequency in a variety of epithelial cancers. In mesenchymal neoplasia, the role of β-catenin has been traditionally considered limited to desmoid-type fibromatosis. However, the spectrum of β-catenin-driven (β-catenin-altered) neoplasia of mesenchymal origin has been steadily widening to include, in addition to desmoid tumors, a variety of benign and intermediate-biology neoplasms of soft tissue (intranodal palisaded myofibroblastoma), head and neck (juvenile nasopharyngeal angiofibroma and sinonasal hemangiopericytoma/glomangiopericytoma), and ovarian (microcystic stromal tumor) origin. In addition, several old and newly reported distinctive site-specific β-catenin-driven parenchymal neoplasms of uncertain histogenesis have been well characterized in recent studies, including solid-pseudopapillary neoplasm of the pancreas and its recently described ovarian counterpart, sclerosing hemangioma of lung and calcifying nested stromal-epithelial tumor of the liver. This review addresses the most relevant pathobiological and differential diagnostic aspects of β-catenin-altered neoplasms with emphasis on site-specific histologic and biological variations. In addition, the morphologic overlap and analogy as well as distinctness between these uncommon tumors will be presented and discussed. Furthermore, a note is made on association of some of these lesions with hereditary tumor syndromes, in particular with the familial adenomatous polyposis coli.

Synovial sarcoma: recent discoveries as a roadmap to new avenues for therapy

Oncogenesis in synovial sarcoma is driven by the chromosomal translocation t(X,18; p11,q11), which generates an in-frame fusion of the SWI/SNF subunit SS18 to the C-terminal repression domains of SSX1 or SSX2. Proteomic studies have identified an integral role of SS18-SSX in the SWI/SNF complex, and provide new evidence for mistargeting of polycomb repression in synovial sarcoma. Two recent in vivo studies are highlighted, providing additional support for the importance of WNT signaling in synovial sarcoma: One used a conditional mouse model in which knockout of β-catenin prevents tumor formation, and the other used a small-molecule inhibitor of β-catenin in xenograft models.

SIGNIFICANCE

Synovial sarcoma appears to arise from still poorly characterized immature mesenchymal progenitor cells through the action of its primary oncogenic driver, the SS18-SSX fusion gene, which encodes a multifaceted disruptor of epigenetic control. The effects of SS18-SSX on polycomb-mediated gene repression and SWI/SNF chromatin remodeling have recently come into focus and may offer new insights into the basic function of these processes. A central role for deregulation of WNT-β-catenin signaling in synovial sarcoma has also been strengthened by recent in vivo studies. These new insights into the the biology of synovial sarcoma are guiding novel preclinical and clinical studies in this aggressive cancer.

Jordan R. Fibro-osseous lesions of the craniofacial bones: β-catenin immunohistochemical analysis and CTNNB1 and APC mutation analysis

The canonical Wnt/β-catenin pathway is involved in the formation of craniofacial skeleton and oral tissues. Aberrant nuclear localization of β-catenin protein has been described in several human diseases including a subset of odontogenic tumors thereby suggesting an important role in tumor development. Fibro-osseous lesions of the craniofacial skeleton comprise several neoplastic, and reactive mesenchymal proliferations in which β-catenin status is unknown. To study this, we immunostained 171 fibro-osseous lesions for β-catenin protein and, for lesions with nuclear positivity, sequenced exon 3 of the CTNNB1 gene and exon 15 of the APC gene. Nuclear β-catenin immunostaining was detected in 34 (20 %) tumors with no correlation between nuclear positivity and either age, gender, or tissue decalcification status (p = 0.2, 0.17, 0.12, respectively). Absent nuclear β-catenin in fibrous dysplasia was the only diagnostically significant finding (p = 0.0034). A single point mutation at Asp56 of CTNNB1 was identified in one case of ossifying fibroma. A second ossifying fibroma and one desmoplastic fibroma demonstrated point mutations (Glu1317 and Glu1536, respectively [corrected] ) in the APC gene. These findings show that apart from fibrous dysplasia where nuclear β-catenin is rare, nuclear β-catenin staining has limited utility in discriminating among the craniofacial fibro-osseous lesions. The molecular mechanisms underlying nuclear β-catenin accumulation in the positive tumors is unlikely to be mediated by CTNNB1 exon 3 or APC exon 15 mutations in most cases.

Diagnostic utility of SOX10 to distinguish malignant peripheral nerve sheath tumor from synovial sarcoma, including intraneural synovial sarcoma

Synovial sarcoma and malignant peripheral nerve sheath tumor pose a significant diagnostic challenge given similar histomorphology. The distinction is further complicated by similar immunophenotype and especially by occasional synovial sarcomas that present as intraneural tumors. Although the presence of a t(X;18) rearrangement or expression of TLE1 can help confirm the diagnosis of synovial sarcoma, negative results for these tests are not diagnostic of malignant peripheral nerve sheath tumor. The SOX10 transcription factor, a putative marker of neural crest differentiation, may have diagnostic utility in this differential, but immunohistochemical data are limited. The goal of the present study was to determine the diagnostic utility of SOX10 to discriminate between synovial sarcoma and malignant peripheral nerve sheath tumor. Forty-eight cases of malignant peripheral nerve sheath tumor, all from patients with documented neurofibromatosis, and 97 cases of genetically confirmed synovial sarcoma, including 4 intraneural synovial sarcomas, were immunohistochemically stained for SOX10. The stain was scored for intensity and fraction of cells staining. Thirty-two of 48 malignant peripheral nerve sheath tumors (67%) were SOX10-positive. The majority of malignant peripheral nerve sheath tumors showed ≥2+ staining, but staining did not correlate with grade. By contrast, only 7/97 (7%) synovial sarcomas were SOX10-positive. Only three synovial sarcomas showed ≥2+ staining but, importantly, two of these were intraneural synovial sarcoma. Therefore, SOX10 is a specific (93%), albeit not very sensitive (67%), diagnostic marker to support a diagnosis of malignant peripheral nerve sheath tumor over synovial sarcoma. Furthermore, the stain needs to be interpreted with caution in intraneural tumors in order to avoid a potential diagnostic pitfall. It remains to be determined whether SOX10-positive cells in intraneural synovial sarcoma represent entrapped Schwann cells, synovial sarcoma cells or both.

Truncated SSX protein suppresses synovial sarcoma cell proliferation by inhibiting the localization of SS18-SSX fusion protein

Synovial sarcoma is a relatively rare high-grade soft tissue sarcoma that often develops in the limbs of young people and induces the lung and the lymph node metastasis resulting in poor prognosis. In patients with synovial sarcoma, specific chromosomal translocation of t(X; 18) (p11.2;q11.2) is observed, and SS18-SSX fusion protein expressed by this translocation is reported to be associated with pathogenesis. However, role of the fusion protein in the pathogenesis of synovial sarcoma has not yet been completely clarified. In this study, we focused on the localization patterns of SS18-SSX fusion protein. We constructed expression plasmids coding for the full length SS18-SSX, the truncated SS18 moiety (tSS18) and the truncated SSX moiety (tSSX) of SS18-SSX, tagged with fluorescent proteins. These plasmids were transfected in synovial sarcoma SYO-1 cells and we observed the expression of these proteins using a fluorescence microscope. The SS18-SSX fusion protein showed a characteristic speckle pattern in the nucleus. However, when SS18-SSX was co-expressed with tSSX, localization of SS18-SSX changed from speckle patterns to the diffused pattern similar to the localization pattern of tSSX and SSX. Furthermore, cell proliferation and colony formation of synovial sarcoma SYO-1 and YaFuSS cells were suppressed by exogenous tSSX expression. Our results suggest that the characteristic speckle localization pattern of SS18-SSX is strongly involved in the tumorigenesis through the SSX moiety of the SS18-SSX fusion protein. These findings could be applied to further understand the pathogenic mechanisms, and towards the development of molecular targeting approach for synovial sarcoma.

CyclinD1, a prominent prognostic marker for endometrial diseases

Purpose

Alteration of CyclinD1 was suggested to relate with development of endometrial carcinogenesis before, however CyclinD1 expression is not well defined in endometrial hyperplasia lesions. We checked the relationship between its expression and clinic-pathological variables of endometrial lesions to explore the possibility for CyclinD1 as a potential diagnostic and prognostic marker.

Methods

Cyclin D1 immunohistochemical analysis (IHC) was used to evaluate 201 fixed, paraffin-embedded endometrial samples which included simple hyperplasia (n = 27), atypical complex hyperplasia (ACH) (n = 41), endometrioid carcinoma (n = 103), endometrial serous carcinoma (ESC) (n = 21) and clear cell carcinoma (CCC) (n = 9). A breast cancer with known CyclinD1 expression was selected as a positive control in each immunohistochemistry run. We also performed follow-up study to estimate patients’ prognosis.

Results

CyclinD1 was significantly overexpressed in atypical complex hyperplasia (ACH), endometrioid carcinoma and clear cell carcinoma (CCC). The positive signaling of CyclinD1 was showed less than 40% in simple hyperplasia and endometrial serous carcinoma (ESC). The high expression of CyclinD1 was observed in metastasis carcinoma group more significantly than non-metastasis carcinoma group. Kaplan Meier analysis demonstrated that patients with high CyclinD1 expression had an obviously poor prognosis than patients without CyclinD1 staining (p < 0.05). Moreover, according to multivariate Cox regression analysis, CyclinD1 expression, as crucial as metastasis, was a risk marker for overall survival rate.

Conclusion

CyclinD1 exhibited a promising potential to predict the prognosis of patients with endometrial carcinoma. However, the statistical analysis demonstrated that CyclinD1 exhibited a poor ability to differentiate neoplastic lesions from non-neoplastic lesions; thus, the application of CyclinD1 only is not so credible for differentiation between benign and malignant lesions.

Virtual slides

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1871063048950173.

Targeting the Wnt pathway in synovial sarcoma models

Synovial sarcoma is an aggressive soft-tissue malignancy of children and young adults, with no effective systemic therapies. Its specific oncogene, SYT-SSX (SS18-SSX), drives sarcoma initiation and development. The exact mechanism of SYT-SSX oncogenic function remains unknown. In an SYT-SSX2 transgenic model, we show that a constitutive Wnt/β-catenin signal is aberrantly activated by SYT-SSX2, and inhibition of Wnt signaling through the genetic loss of β-catenin blocks synovial sarcoma tumor formation. In a combination of cell-based and synovial sarcoma tumor xenograft models, we show that inhibition of the Wnt cascade through coreceptor blockade and the use of small-molecule CK1α activators arrests synovial sarcoma tumor growth. We find that upregulation of the Wnt/β-catenin cascade by SYT-SSX2 correlates with its nuclear reprogramming function. These studies reveal the central role of Wnt/β-catenin signaling in SYT-SSX2-induced sarcoma genesis, and open new venues for the development of effective synovial sarcoma curative agents.

SIGNIFICANCE

Synovial sarcoma is an aggressive soft-tissue cancer that afflicts children and young adults, and for which there is no effective treatment. The current studies provide critical insight into our understanding of the pathogenesis of SYT–SSX-dependent synovial sarcoma and pave the way for the development of effective therapeutic agents for the treatment of the disease in humans.

Cyclin D1 as a diagnostic immunomarker for endometrial stromal sarcoma with YWHAE-FAM22 rearrangement

Endometrial stromal sarcoma (ESS) characterized by YWHAE-FAM22 genetic fusion is histologically higher grade and clinically more aggressive than ESS with JAZF1-SUZ12 or equivalent genetic rearrangements, hence it is clinically important to recognize this subset of ESS. To identify diagnostic immunomarkers for this biologically defined ESS subset, we compared gene expression profiles between YWHAE-FAM22 ESS and JAZF1-rearranged ESS. These studies showed consistent upregulation of cyclin D1 in YWHAE-FAM22 ESS compared with JAZF1-SUZ12 ESS. Immunohistochemically, the high-grade round cell component of all 12 YWHAE-FAM22 ESS demonstrated diffuse (≥70%) moderate to strong nuclear cyclin D1 staining, and this diffuse positivity was not seen in 34 ESSs with JAZF1 and equivalent genetic rearrangements or in 21 low-grade ESS with no demonstrable genetic rearrangements. In a series of 243 non-ESS pure uterine mesenchymal and mixed epithelial-mesenchymal tumors, only 2 of 8 undifferentiated endometrial sarcomas with nuclear uniformity and 1 of 80 uterine leiomyosarcomas demonstrate diffuse cyclin D1 immunoreactivity. Both cyclin D1-positive undifferentiated endometrial sarcomas showed diffuse strong CD10 staining, which is consistently absent in the high-grade round cell component of YWHAE-FAM22 ESS. The low-grade spindle cell component of YWHAE-FAM22 ESS showed a spatially heterogenous cyclin D1 staining pattern that was weaker and less diffuse overall. Our findings indicate that cyclin D1 is a sensitive and specific diagnostic immunomarker for YWHAE-FAM22 ESS. When evaluating high-grade uterine sarcomas, cyclin D1 can be included in the immunohistochemical panel as an indicator of YWHAE-FAM22 ESS.

Regulators of skeletal development: a cluster analysis of 206 bone tumors reveals diagnostically useful markers

The molecules Indian hedgehog (IHH), SP7 (also known as osterix), sex-determining region Y-box 9 (SOX9), runt-related transcription factor 2 (RUNX2) and TWIST1 regulate the normal differentiation of osteo- and chondrogenic cells from precursors during skeletal development and remodeling. The aberrant function of the same molecules has been implicated in the pathogenesis of bone tumors. Preliminary studies suggest that antibodies against these molecules have practical, diagnostic or prognostic utility in tumors. However, a comprehensive analysis of the expression of these molecules in a large, diverse set of bone tumors has yet to be reported. The goals of this study were to compare the immunohistochemical profiles of IHH, SP7, SOX9, RUNX2 and TWIST1 among bone tumors and to determine the optimum panel for diagnostic utility. Tissue microarrays prepared from 206 undecalcified tumors (71 osteosarcomas, 26 osteoblastomas/osteoid osteomas, 50 giant cell tumors, 5 chondromyxoid fibromas and 54 chondroblastomas) were stained with antibodies to IHH, SP7, SOX9, RUNX2 and TWIST1. The stains were scored for intensity (0-3+) and distribution. The results were analyzed by cluster analysis. Optimum antibody panels for diagnostic sensitivity and specificity were calculated. Analysis revealed six main clusters that corresponded well to tumor types and suggested a close relationship between the stromal cells of giant cell tumor and the osteoblasts of osteosarcoma. The expression profile of chondromyxoid fibroma and chondroblastoma also suggested related differentiation. The distribution of osteoblastomas and osteoid osteomas was more heterogeneous. RUNX2, SOX9 and TWIST1 represented the most sensitive and specific immunohistochemical panel to distinguish among these diagnoses with the limitation that no result could discriminate between chondroblastoma and chondromyxoid fibroma. IHH and SP7 did not yield additional utility.

Soft tissue tumors of uncertain origin

Many soft tissue tumors of childhood lack obvious differentiation toward a defined mesenchymal tissue type or have a phenotype that does not correspond to any defined normal tissue. These challenging tumors are currently regarded as neoplasms of uncertain differentiation. Nonetheless, there have been great strides in the understanding of their pathologic and genetic features and biologic underpinnings. The application of new genetic information to the pathologic diagnosis among this group of tumors is an emerging area in diagnostic pediatric pathology. This article reviews the clinicopathologic features of tumors of uncertain and/or miscellaneous origin, with an emphasis on the unique aspects of these neoplasms in children and adolescents, use of diagnostic adjuncts, and differential diagnosis.

Downstream and intermediate interactions of synovial sarcoma-associated fusion oncoproteins and their implication for targeted therapy

Synovial sarcoma (SS), an aggressive type of soft tissue tumor, occurs mostly in adolescents and young adults. The origin and molecular mechanism of the development of SS remain only partially known. Over 90% of SS cases are characterized by the t(X;18)(p11.2;q11.2) translocation, which results mainly in the formation of SS18-SSX1 or SS18-SSX2 fusion genes. In recent years, several reports describing direct and indirect interactions of SS18-SSX1/SSX2 oncoproteins have been published. These reports suggest that the fusion proteins particularly affect the cell growth, cell proliferation, TP53 pathway, and chromatin remodeling mechanisms, contributing to SS oncogenesis. Additional research efforts are required to fully explore the protein-protein interactions of SS18-SSX oncoproteins and the pathways that are regulated by these partnerships for the development of effective targeted therapy.

Molecular characterization of synovial sarcoma in children and adolescents: evidence of akt activation

Synovial sarcoma (SS) is the most frequent nonrhabdomyosarcomatous soft tissue sarcoma encountered in adolescents and young adults, and despite advances in the treatment of local disease, metastases remain the main cause of death. The aim of this study was to characterize a single-center series of pediatric SS molecularly to seek any biomarkers or pathways that might make suitable targets for new agents. Seventeen cases of pediatric SS showing the SYT-SSX fusion transcript were screened immunohistochemically, biochemically, molecularly, and cytogenetically (depending on the available material) to investigate any expression/activation of epidermal growth factor receptor, platelet-derived growth factor receptor alpha (PDGFRalpha), PDGFRbeta, Akt, and deregulated Wnt pathway. The most relevant outcome was the finding of activated epidermal growth factor receptor, PDGFRalpha, and PDGFRbeta, which activated Akt in both the monophasic and biphasic histologic subtypes. Consistently, Akt activation was completely abolished in an SS cell line assay when stimulated by PDGF-AA and treated with the phosphatidylinositol 3-kinase inhibitor LY294002. Our results also showed the nuclear localization of beta-catenin and cyclin D1 gene products in monophasic SS and the movement of beta-catenin into the cytoplasm in the glandular component of the biphasic subtype. Although they need to be confirmed in larger series, these preliminary data suggest that therapeutic strategies including specific inhibitors of the phosphatidylinositol 3-kinase/Akt pathway might be exploited in SS.

Similarity in genetic alterations between paired well-differentiated and dedifferentiated components of dedifferentiated liposarcoma

Liposarcoma represents a unique model insofar as some well-differentiated liposarcomas progress to non-lipogenic, so-called 'dedifferentiated,' forms. The well-differentiated and dedifferentiated family of liposarcomas demonstrates amplification of the chromosome subregion 12q13-q15 with resultant amplification of the MDM2 and CDK4 genes. However, the specific genetic changes that distinguish between well-differentiated and dedifferentiated liposarcomas are less well understood. To study the genetic changes in dedifferentiated liposarcomas, paired well-differentiated and dedifferentiated components of 29 tumors were analyzed separately by array-based comparative genomic hybridization. A bacterial artificial chromosome array at approximately 1-Mb resolution was used. The genetic changes were compared with clinical presentation, grade of the dedifferentiated component and overexpression of MDM2 and CDK4. Most tumors (n=21, 72%) were retroperitoneal, with both components present at initial diagnosis (n=25, 86%). Eight tumors (28%) were classified as low-grade dedifferentiation. In four cases (14%), a well-differentiated liposarcoma preceded the presentation of the dedifferentiated tumor by 1-5 years. 12q13-q15 was amplified in all tumors. Using unsupervised hierarchical clustering of copy-number changes, all but two tumors showed close similarities between well-differentiated and dedifferentiated components, and segregated as pairs. Dedifferentiated components had more total amplifications (P=0.008) and a trend for gain at 19q13.2, but no genetic changes were significant in distinguishing between the two components. High-level amplifications of 1p21-32 (n=7, 24%), 1q21-23 (n=9, 31%), 6q23-24 (n=6, 21%) and 12q24 (n=3, 10%) were common, but none significantly correlated with differentiation. Presentation and grade correlated with the frequency of changes at a number of genetic loci (P<0.001), whereas CDK4 immunostaining showed negative correlation with 12q13.13 amplification. The genotypic similarity, at the limit of the array's resolution, between components implies that most genetic changes precede phenotypic 'progression,' early in tumorigenesis. The relationship between genetic changes and presentation or grade may reflect differences in factors that control genomic instability or the background genotype of the tumor.

A phase II study of gefitinib for patients with advanced HER-1 expressing synovial sarcoma refractory to doxorubicin-containing regimens

RATIONALE

Advanced synovial sarcomas (SyS) refractory to doxorubicin and ifosfamide are highly resistant to the currently available cytotoxic agents. Based on a report showing a specific overexpression of HER-1 in SyS, we investigated an HER-1 inhibitor, gefitinib, in refractory SyS.

SUBJECTS AND METHODS

To establish the efficacy and safety of gefitinib in HER-1 - positive SyS refractory to one or two lines of doxorubicin- and ifosfamide-based chemotherapy, a phase II study was conducted from December 2002 to October 2005 by 12 centers of the European Organization for Research and Treatment of Cancer Soft Tissue and Bone Sarcoma Group. Gefitinib was given at a 500-mg/day oral dose until progression or intolerance.

RESULTS

Forty-eight patients were included (46 eligible). All patients had previously received chemotherapy for metastatic disease, with a median number of two lines (range, 1-4). The most frequent metastatic sites were the lungs (n = 44, 92%), lymph nodes (n = 11, 23%), and soft tissues (n = 10, 21%). The median duration of treatment was 43 days (range, 13-315). Treatment was interrupted in five patients (10%). Treatment was halted for progression in 45 (94%) patients. The best response was stable disease in 10 patients (21%). Disease progression occurred in 32 patients (70%), with a median time to disease progression of 6 weeks. Progression-free survival at 4 and 6 months was 21% and 6%, respectively.

CONCLUSION

The results show that gefitinib monotherapy in advanced SyS refractory to conventional chemotherapy did not demonstrate sufficient activity to warrant further investigation in this setting. This may suggest that HER-1 is not a critical protein in tumor progression in this disease.

Immunostaining for peroxisome proliferator gamma distinguishes dedifferentiated liposarcoma from other retroperitoneal sarcomas

Dedifferentiated liposarcoma can be readily diagnosed by the juxtaposition of a well-differentiated liposarcoma to a nonlipogenic sarcoma. However, if the lipogenic component is not abundant due to surgical sampling or small biopsy, dedifferentiated liposarcoma can be difficult to distinguish from other poorly different sarcomas. Peroxisome proliferator-activated receptor gamma (PPAR-gamma) is a nuclear hormone receptor that plays a critical role in adipocyte differentiation. Prior studies have not only demonstrated PPAR-gamma mRNA in various subtypes of liposarcoma but have also shown that adipocyte differentiation can be induced in some liposarcomas by a PPAR-gamma agonist. In the present study, we investigated whether immunostaining for PPAR-gamma can be used to distinguish dedifferentiated liposarcoma from other retroperitoneal sarcomas. We examined a series of 40 dedifferentiated liposarcoma and compared the staining for PPAR-gamma to a series of 24 retroperitoneal sarcomas that lacked lipogenic differentiation. A monoclonal antibody against PPAR-gamma was used to stain formalin-fixed paraffin-embedded tissue. Specific nuclear immunostaining was present in 37/40 (93%) of the dedifferentiated liposarcoma and 6/24 (25%) of the other sarcomas (two leiomyosarcomas and four undifferentiated sarcomas). Interestingly, immunostaining for CDK4 and/or MDM2 was identified in three of the four PPAR-gamma-positive undifferentiated sarcomas, raising the possibility that these may represent dedifferentiated liposarcoma. This is the first study demonstrating the utility of PPAR-gamma immunohistochemistry in the diagnosis of dedifferentiated liposarcoma in tissue sections. Although not completely specific, the presence of PPAR-gamma staining, in combination with histologic findings and other markers, can aid in the diagnosis of dedifferentiated liposarcoma, particularly on small biopsies that may not sample the well-differentiated component.

Distribution and prognostic significance of human telomerase reverse transcriptase (hTERT) expression in giant-cell tumor of bone

Giant-cell tumor of bone is considered a benign, locally aggressive and rarely metastasizing neoplasm of bone. Specific microscopic or radiographic findings that reliably predict behavior have remained elusive. However, recent evidence suggests that activity of the telomerase enzyme complex correlates with recurrence in giant-cell tumor, although the subset of cells with telomerase activity in these heterogeneous tumors has not been defined. In the present study, we investigated whether immunostaining for human telomerase reverse transcriptase, a component of the telomerase complex, correlates with outcome in giant-cell tumor and the distribution of telomerase reverse transcriptase staining in these tumors. We analyzed 58 cases of giant-cell tumor for the presence and pattern of telomerase reverse transcriptase immunostaining, presence of soft tissue involvement and the type of initial surgery, and correlated these findings with recurrence-free survival and metastasis-free survival. Specific staining with telomerase reverse transcriptase was present in 20 out of 58 tumors (35%) in the nuclei of mononuclear cells and, occasionally, osteoclast-like giant cells. Furthermore, positive telomerase reverse transcriptase immunohistochemistry correlated with recurrence-free survival (P=0.02), whereas the presence of soft tissue extension (P=0.3) and the type of initial surgery (P=0.2) did not. Only soft-tissue extension significantly correlated with metastasis-free survival (P=0.003). Therefore, telomerase reverse transcriptase expression may predict recurrence in giant-cell tumor insofar as positive immunostaining correlates with shorter recurrence-free survival and may be a useful prognostic marker to stratify patients to more aggressive treatment protocols.