cyclin-d1 and Sarcoma--Synovial

Soft tissue sarcomas (STSs) are a rare cancer type. Almost half are unresponsive to multi-pronged treatment and might therefore benefit from biologically targeted therapy. An emerging target is glycogen synthase kinase (GSK)3β, which is implicated in various diseases including cancer. Here, we investigated the expression, activity and putative pathological role of GSK3β in synovial sarcoma and fibrosarcoma, comprising the majority of STS that are encountered in orthopedics. Expression of the active form of GSK3β (tyrosine 216-phosphorylated) was higher in synovial sarcoma (SYO-1, HS-SY-II, SW982) and in fibrosarcoma (HT1080) tumor cell lines than in untransformed fibroblast (NHDF) cells that are assumed to be the normal mesenchymal counterpart cells. Inhibition of GSK3β activity by pharmacological agents (AR-A014418, SB-216763) or of its expression by RNA interference suppressed the proliferation of sarcoma cells and their invasion of collagen gel, as well as inducing their apoptosis. These effects were associated with G0/G1-phase cell cycle arrest and decreased expression of cyclin D1, cyclin-dependent kinase (CDK)4 and matrix metalloproteinase 2. Intraperitoneal injection of the GSK3β inhibitors attenuated the growth of SYO-1 and HT1080 xenografts in athymic mice without obvious detrimental effects. It also mitigated cell proliferation and induced apoptosis in the tumors of mice. This study indicates that increased activity of GSK3β in synovial sarcoma and fibrosarcoma sustains tumor proliferation and invasion through the cyclin D1/CDK4-mediated pathway and enhanced extracellular matrix degradation. Our results provide a biological basis for GSK3β as a new and promising therapeutic target for these STS types.

Topics: Animals; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cyclin D1; Cyclin-Dependent Kinase 4; Fibrosarcoma; Gene Expression Regulation, Neoplastic; Glycogen Synthase Kinase 3 beta; Humans; Indoles; Injections, Intraperitoneal; Maleimides; Mice; Phosphorylation; RNA Interference; Sarcoma, Synovial; Thiazoles; Up-Regulation; Urea; Xenograft Model Antitumor Assays

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.. 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.. 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.. 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.

Topics: Adolescent; Antineoplastic Agents; beta Catenin; Cell Line, Tumor; Cell Proliferation; Cyclin D1; Cyclin-Dependent Kinase 4; Cyclin-Dependent Kinase 6; Cyclin-Dependent Kinase Inhibitor p16; Cyclin-Dependent Kinase Inhibitor p21; Cyclin-Dependent Kinase Inhibitor p27; Female; G1 Phase Cell Cycle Checkpoints; Humans; Immunohistochemistry; Male; Phosphorylation; Piperazines; Pyridines; Retinoblastoma Protein; Sarcoma, Synovial; Survival Rate; Young Adult

Synovial sarcoma (SS) is a highly aggressive soft tissue sarcoma that causes death in more than half of the affected patients. An immunohistochemical and molecular study of the BCL2, MKI67, and CCND1 genes (expressing the BCL2, KI-67, and cyclin D1 proteins, respectively) was performed to determine the expression profiles in correlation with mRNA levels, and to assess the possible utility of these genes as a potential target for the treatment. Cyclin D1 staining was identified in 18 of 30 cases (60%), and CCND1 mRNA was overexpressed in 15 of 32 cases (47%). KI-67 nuclear immunoreactivity was found in 14 of 29 cases (48%), and MKI67 mRNA was overexpressed in 12 of 32 cases (37.5%). The high level of MKI67 mRNA was observed predominantly in monophasic SS. BCL2, a negative regulator of apoptosis, was expressed in all 32 cases. The intensity of the BCL2 protein expression correlated well with the mRNA level (P<0.0001). The high level of BCL2 mRNA correlated with a high level of CCND1 mRNA, but not with MKI67 mRNA level. Despite advances in therapy of sarcomas, the prognosis of patients with SS remains unfavorable, and a search for an improved therapy approach remains necessary. The strong immunopositivity of BCL2 in SS correlates well with a high level of BCL2 mRNA. Treatment with antisense BCL2 (G3139) may therefore represent an appropriate alternative therapy for patients with BCL2-positive synovial sarcomas.

Topics: Adolescent; Adult; Aged; Analysis of Variance; Cell Nucleus; Child; Child, Preschool; Cyclin D1; Female; Humans; Immunohistochemistry; Infant; Ki-67 Antigen; Male; Middle Aged; Proto-Oncogene Proteins c-bcl-2; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; RNA, Neoplasm; Sarcoma, Synovial; Soft Tissue Neoplasms; Statistics, Nonparametric

Synovial sarcoma is a soft tissue sarcoma with poor prognosis and lack of response to conventional cytotoxic chemotherapy. The regulatory mechanisms for the rapid proliferation of synovial sarcoma cells and the particular aggressiveness of this sarcoma remain poorly understood. Mitogen-activated protein kinase (MAPK) cascades have been shown to play important roles in synovial sarcoma survival. Sorafenib (Nexavar, BAY 43-9006), a potent recombinant activated factor (RAF) inhibitor, inhibits the MAPK signaling pathway both in vitro and in vivo. In this study, we examined the inhibitory proliferation effects of sorafenib in synovial sarcoma growth and evaluated whether sorafenib modulates MAPK and tumor apoptosis cascades in human synovial sarcoma cell lines SW982 and HS-SY-II. Our results indicated that sorafenib effectively inhibited cellular proliferation and induces apoptosis of these two cells. Sorafenib inhibited the phosphorylation of MEK and ERK, downregulated cyclin D1 and Rb levels, caused G(1) arrest and S phase decrease, and induced apoptosis as confirmed by flow cytometry and the TUNEL assay. Furthermore, Bcl-xl and Mcl-1 levels significantly decreased, whereas expression levels of the proteins bcl-2 and bax were unchanged in response to sorafenib treatment in SW982 and HS-SY-II cells. In conclusion, our findings demonstrate that sorafenib is effective for growth inhibition of synovial sarcoma cell lines in vitro and suggest that sorafenib may be a new therapeutic option for patients with synovial sarcoma.

Topics: Antineoplastic Agents; Apoptosis; bcl-X Protein; Benzenesulfonates; Blotting, Western; Cell Line, Tumor; Cell Proliferation; Cyclin D1; Dose-Response Relationship, Drug; Extracellular Signal-Regulated MAP Kinases; Flow Cytometry; G1 Phase; Humans; In Situ Nick-End Labeling; Mitogen-Activated Protein Kinases; Myeloid Cell Leukemia Sequence 1 Protein; Niacinamide; Phenylurea Compounds; Phosphorylation; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins c-bcl-2; Pyridines; raf Kinases; Retinoblastoma Protein; S Phase; Sarcoma, Synovial; Signal Transduction; Sorafenib

Localization of beta-catenin in the cell is a key determinant in its decision to function as a critical mediator of cell adhesion at the surface or a transcription activator in the nucleus. SYT-SSX2 is the fusion product of the chromosomal translocation, t(X;18)(p11.2;q11.2), which occurs in synovial sarcoma, a soft tissue tumor. SYT-SSX2 is known to associate with chromatin remodeling complexes and is proposed to be involved in controlling gene expression. We report that SYT-SSX2 plays a direct role in beta-catenin regulation. When expressed in mammalian cells, SYT-SSX2-induced beta-catenin recruitment to the nucleus. Interestingly, known target genes of canonical Wnt were not activated as a result of SYT-SSX2 expression, nor was the nuclear localization of beta-catenin due to one of the signaling pathways normally implicated in this event. beta-Catenin accumulation in the nucleus led to the formation of a transcriptionally active nuclear complex that contained SYT-SSX2 and beta-catenin. More importantly, depletion of SYT-SSX2 in primary synovial sarcoma cells resulted in loss of nuclear beta-catenin signal and a significant decrease in its signaling activity. These results unravel a novel pathway in the control of beta-catenin cellular transport and strongly suggest that SYT-SSX2 contributes to tumor development, in part through beta-catenin signaling.

Topics: Active Transport, Cell Nucleus; Animals; beta Catenin; Cell Nucleus; Cyclin D1; E1A-Associated p300 Protein; Enzyme Inhibitors; Humans; Mice; Multiprotein Complexes; Oncogene Proteins, Fusion; Sarcoma, Synovial; Signal Transduction; Tumor Cells, Cultured

Nuclear beta-catenin staining in soft tissue sarcomas (STSs) has been shown to correlate with tumor progression as assessed by proliferative activity or poor prognosis. Frequent activation of Wnt signaling pathway has been also shown in synovial sarcoma (SS), suggesting a specific role of this pathway in SS. We examined roles of nuclear beta-catenin staining within soft tissue sarcomas. Immunohistochemical detection of nuclear beta-catenin accumulation correlated with cyclin D1 overexpression in spindle cell and pleomorphic sarcomas (P = .037), and the expression of these proteins evenly distributed throughout each section. In some cases, strong beta-catenin nuclear staining was observed in highly pleomorphic and mitotic cells. Furthermore, tumors with nuclear beta-catenin accumulation showed statistically significant increasing cyclin D1 mRNA expression level compared with those without (P = .023). Cyclin D1 mRNA expression levels were statistically higher in tumors with cyclin D1 overexpression than in tumors without (P = .037), suggesting that cyclin D1 overexpression is due to transcriptional activation. However, these correlations could not be detected in SS. In biphasic SS, beta-catenin nuclear staining was observed in spindle cells, whereas cyclin D1 nuclear staining was seen in glandular areas where beta-catenin kept membranous expression. Mutations in exon 3 of the beta-catenin gene and in the mutation cluster region of adenomatous polyposis coli gene were absent in this series of cases. Thus, cyclin D1 could be considered as one of the targets of the nuclear beta-catenin in spindle cell and pleomorphic sarcomas. A possible association between beta-catenin accumulation and spindle cell morphogenesis may exist in SS.

Topics: beta Catenin; Cell Nucleus; Cyclin D1; Humans; Immunohistochemistry; RNA, Messenger; Sarcoma; Sarcoma, Synovial; Tissue Distribution

The association between aberrant (nuclear) beta-catenin expression and cyclin D1 accumulation has been demonstrated in diverse neoplasms. In synovial sarcoma (SS), aberrant beta-catenin expression has prognostic relevance, but the association with cyclin D1 has not been established. The SYT-SSX fusion protein, unique to SS, may independently increase cyclin D1.. To determine whether nuclear beta-catenin is associated with cyclin D1 overexpression in SS and whether primary and metastatic SS differ in the expression of these markers.. We incorporated 82 tumors initially diagnosed as SS into a tissue array. Fluorescence in situ hybridization with custom probes was used to select t(X;18) positive tumors. Clinical data, tumor type and outcome were tabulated. The tumors were tested for the association between nuclear beta-catenin and cyclin D1 immunostaining. Primary and metastatic tumors were compared.. Fifty-one tumors (41 primary and 10 metastatic) from 43 patients demonstrated t(X;18). Cyclin D1 staining was identified in 21 (59%) primary and 8 (80%) metastatic tumors, respectively, and nuclear beta-catenin in 24 (41%) primary and 7 (70%) metastatic tumors, respectively. No significant difference was noted between primary and metastatic tumors with respect to the above markers. The presence of nuclear beta-catenin showed a significant association with cyclin D1 expression (P < .001). A small number of cyclin D1 cases were negative for nuclear beta-catenin but positive for phosphorylated Akt.. Increased cyclin D1 in SS may be driven by abnormally expressed beta-catenin, similar to other neoplasms. The pattern of expression of these markers is established early during tumorigenesis.

Topics: Adolescent; Adult; Aged; beta Catenin; Biomarkers, Tumor; Cell Nucleus; Chromosomes, Human, Pair 18; Chromosomes, Human, X; Cyclin D1; Extremities; Female; Humans; Immunoenzyme Techniques; In Situ Hybridization, Fluorescence; Male; Middle Aged; Sarcoma, Synovial; Soft Tissue Neoplasms; Survival Rate; Tissue Array Analysis; Translocation, Genetic

A recent large multi-centre study convincingly confirmed previous observations that the SYT-SSX1 fusion type, compared to SYT-SSX2, of synovial sarcoma is associated with a worse clinical outcome. Apart from the clinical impact, this fact also suggests (1) that the SYT-SSX fusion gene may influence molecular mechanisms involved in tumour growth and progression; and (2) that the SYT-SSX1 fusion type has a stronger influence on these mechanisms than SYT-SSX2. The nature of the underlying mechanisms is, however, still unknown. In this study we made use of the SYT-SSX1 vs SYT-SSX2 concept to investigate whether major, tumour relevant, and growth regulatory proteins (e.g. cyclins and cyclin-dependent kinases) may be involved. Using Western blotting analysis on 74 fresh, fusion variant-typed, tumour samples from localized synovial sarcoma, we found a significant correlation between SYT-SSX1 and high expression of cyclin A (P=0.003) and D1 (P=0.025). Our data suggest that SYT-SSX may influence the cell cycle machinery, and that the more aggressive phenotype of the SYT-SSX1 variant is due to an accelerated tumour cell proliferation.

Topics: Cell Cycle; Chromosomes, Human, Pair 18; Cyclin A; Cyclin D1; Humans; Oncogene Proteins, Fusion; Proto-Oncogene Proteins c-bcl-2; Sarcoma, Synovial; Translocation, Genetic; X Chromosome

The SYT-SSX fusion gene has been implicated in the malignant tumor cell growth of synovial sarcoma, but the underlying molecular mechanisms are still poorly understood. Here we demonstrate that SYT-SSX is critical for the protein level of cyclin D1 in synovial sarcoma cells. Antisense oligonucleotides to SYT-SSX mRNA rapidly and drastically decreased cyclin D1 and subsequently inhibited cell growth. This effect is specific for SYT-SSX, without involving the wild-type genes SYT or SSX. The decrease in cyclin D1 expression, which occurred shortly after inhibition of SYT-SSX expression, was found to be primarily dependent on an increased degradation of the cyclin D1 protein, as assessed by pulse-chase experiments using [(35)S]methionine. Furthermore, transfection of mouse fibroblasts with SYT-SSX cDNA increased the stability of cyclin D1. Because treatment with a proteasome inhibitor restored cyclin D1 expression, it seems like SYT-SSX interferes with ubiquitin-dependent degradation of cyclin D1. However, SYT-SSX-regulated cyclin D1 expression was proven to be independent of the glycogen synthetase kinase-3beta pathway. Taken together, our study provides evidence that SYT-SSX stabilizes cyclin D1 and is critical for cyclin D1 expression in synovial sarcoma cells. SYT-SSX-dependent expression of cyclin D1 may be an important mechanism in the development and progression of synovial sarcoma and also raises the possibility for targeted therapy.

Topics: 3T3 Cells; Animals; Cell Division; Chromosomes, Human, Pair 18; Cyclin D1; Down-Regulation; Humans; Mice; Oligonucleotides, Antisense; Oncogene Proteins, Fusion; Phosphatidylinositol 3-Kinases; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Sarcoma, Synovial; Transfection; Translocation, Genetic; Tumor Cells, Cultured; X Chromosome