Sphingosine 1-phosphate counteracts the effects of interleukin-1ß in human chondrocytes.

OBJECTIVE: The lipid mediator sphingosine 1-phosphate (S1P) is found in the synovial fluid of osteoarthritis (OA) patients. S1P protects bovine cartilage by counteracting the effects of interleukin-1ß (IL-1ß). This study was undertaken to examine the interaction of S1P and IL-1ß in human OA chondrocytes. METHODS: Human cartilage was obtained from patients undergoing total knee joint replacement. Chondrocytes were cultured in monolayer and treated with IL-1ß and S1P. Expression of S1P receptor subtypes and genes involved in cartilage degradation was evaluated using real-time polymerase chain reaction, immunohistochemistry, and Western blotting. S1P signaling was evaluated using inhibitors of S1P receptors and small interfering RNA (siRNA) knockdown of the S1P2 receptor. Phosphorylation of MAP kinases and NF-κB in response to IL-1ß and S1P was detected by Western blotting. RESULTS: S1P2 was identified as the most prevalent S1P receptor subtype in human OA cartilage and chondrocytes in vitro. S1P reduced expression of inducible nitric oxide synthase (iNOS) in IL-1ß-treated chondrocytes. Reduction of ADAMTS-4 and matrix metalloproteinase 13 expression by S1P correlated with S1P2 expression. Pharmacologic inhibition of the S1P2 receptor, but not the S1P1 and S1P3 receptors, abrogated the inhibition of iNOS expression. Similar results were observed using siRNA knockdown. S1P signaling inhibited IL-1ß-induced phosphorylation of p38 MAPK. CONCLUSION: In human chondrocytes, S1P reduces the induction of catabolic genes in the presence of IL-1ß. Activation of the S1P2 receptor counteracts the detrimental phosphorylation of p38 MAPK by IL-1ß.

The immunosuppressant FTY720 (fingolimod) enhances glycosaminoglycan depletion in articular cartilage.

BACKGROUND: FTY720 (Fingolimod) is a novel immunosuppressive drug investigated in clinical trials for organ transplantation and multiple sclerosis. It acts as a functional sphingosine-1-phosphate (S1P) receptor antagonist, thereby inhibiting the egress of lymphocytes from secondary lymphoid organs. As S1P is able to prevent IL-1beta induced cartilage degradation, we examined the direct impact of FTY720 on cytokine induced cartilage destruction. METHODS: Bovine chondrocytes were treated with the bioactive phosphorylated form of FTY720 (FTY720-P) in combination with IL-1beta or TNF-alpha. Expression of MMP-1,-3.-13, iNOS and ADAMTS-4,-5 and COX-2 was evaluated using quantitative real-time PCR and western blot. Glycosaminoglycan depletion from cartilage explants was determined using a 1,9-dimethylene blue assay and safranin O staining. RESULTS: FTY720-P significantly reduced IL-1beta and TNF-alpha induced expression of iNOS. In contrast FTY720-P increased MMP-3 and ADAMTS-5 mRNA expression. Furthermore depletion of glycosaminoglycan from cartilage explants by IL-1beta and TNF-alpha was significantly enhanced by FTY720-P in an MMP-3 dependent manner. CONCLUSIONS: Our results suggest that FTY720 may enhance cartilage degradation in pro-inflammatory environment.

Histone deacetylase inhibitor vorinostat suppresses the growth of uterine sarcomas in vitro and in vivo.

BACKGROUND: Uterine sarcomas are very rare malignancies with no approved chemotherapy protocols. Histone deacetylase (HDAC) inhibitors belong to the most promising groups of compounds for molecular targeting therapy. Here, we described the antitumor effects of suberoylanilide hydroxamic acid (SAHA; vorinostat) on MES-SA uterine sarcoma cells in vitro and in vivo. We investigated effects of vorinostat on growth and colony forming ability by using uterine sarcoma MES-SA cells. We analyzed the influence of vorinostat on expression of different HDACs, p21(WAF1) and activation of apoptosis. Finally, we examined the antitumor effects of vorinostat on uterine sarcoma in vivo. RESULTS: Vorinostat efficiently suppressed MES-SA cell growth at a low dosage (3 microM) already after 24 hours treatment. Decrease of cell survival was even more pronounced after prolonged treatment and reached 9% and 2% after 48 and 72 hours of treatment, respectively. Colony forming capability of MES-SA cells treated with 3 microM vorinostat for 24 and 48 hours was significantly diminished and blocked after 72 hours. HDACs class I (HDAC2 and 3) as well as class II (HDAC7) were preferentially affected by this treatment. Vorinostat significantly increased p21(WAF1) expression and apoptosis. Nude mice injected with 5 x 106 MES-SA cells were treated for 21 days with vorinostat (50 mg/kg/day) and, in comparison to placebo group, a tumor growth reduction of more than 50% was observed. Results obtained by light- and electron-microscopy suggested pronounced activation of apoptosis in tumors isolated from vorinostat-treated mice. CONCLUSIONS: Our data strongly indicate the high therapeutic potential of vorinostat in uterine sarcomas.

Valproate inhibition of histone deacetylase 2 affects differentiation and decreases proliferation of endometrial stromal sarcoma cells.

Covalent modifications of histone proteins, in particular deacetylation of lysine residues, are important for the regulation of gene transcription both in normal and malignant cells. These processes are controlled by histone acetyltransferases and histone deacetylases (HDAC) and have up to now not been described in solid mesenchymal tumors. The present study shows differences in the HDAC1 and HDAC2 expression in endometrial stromal sarcomas (ESS) and a cognate cell line (ESS-1) compared with nonneoplastic endometrial stroma. We show for the first time that HDAC2 expression is consistently increased in ESS. In contrast, HDAC1 expression is generally lower than HDAC2 both in nonneoplastic stroma and in ESS, suggesting that these two proteins, although closely related, are regulated in different ways. In vitro experiments with an ESS cell line showed that valproate, an inhibitor of the class I HDACs, led to significant HDAC2 decrease and to cell differentiation. HDAC2 inhibition in ESS-1 cells caused significant changes in the cell cycle by inhibiting G1-S transition and influencing expression of p21WAF1 and cyclin D1. Moreover, in ESS-1 cells, increased expression of the p21WAF1 was associated with reduction of HDAC2 expression after transfection with small interfering RNA directed against HDAC2. Our results suggest that HDAC2 might be considered as potential drug target in the therapy of ESS and that HDAC inhibitors should be further evaluated in clinical trials in ESS.

JAZF1/JJAZ1 gene fusion in endometrial stromal sarcomas: molecular analysis by reverse transcriptase-polymerase chain reaction optimized for paraffin-embedded tissue.

Endometrial stromal tumors are rare uterine neoplasms including benign stromal nodules, low-grade endometrial stromal sarcomas (ESS), and undifferentiated endometrial sarcomas (UES), the latter representing the most aggressive form. Morphological characteristics and cytogenetic abnormalities are heterogeneous, making diagnosis difficult. Recently, a gene fusion on chromosome 7 that includes two zinc-finger genes (JAZF1 and JJAZ1) has been discovered in these tumors. Hitherto only 31 cases, described by three different research groups, have shown JAZF1/JJAZ1 fusion in approximately 50% of all analyzed low-grade ESSs whereas it is less frequent in UESs. In this study we analyzed 20 ESS and 2 UES cases using two-step reverse transcriptase-polymerase chain reaction optimized for formalin-fixed, paraffin-embedded tissue. In our subset of samples, the JAZF1/JJAZ1 fusion transcript occurred in 80% of analyzed ESS cases and in none of two UES cases. In comparison to published data, our results identified the JAZF1/JJAZ1 gene fusion more frequently in endometrial stromal tumors than hitherto presumed. This cytogenetic abnormality was not present in normal endometria, leiomyomas, or leiomyosarcomas or in lung, gastric, or hepatic carcinomas, indicating its specificity for endometrial stromal tumors. In combination with other established methods, accurate reverse transcriptase-polymerase chain reaction analysis of JAZF1/JJAZ1 gene fusion may be useful in diagnosing difficult or unusual ESS/UES cases.

Chromosomal alterations in low-grade endometrial stromal sarcoma and undifferentiated endometrial sarcoma as detected by comparative genomic hybridization.

OBJECTIVE: Endometrial stromal sarcomas (ESS) are very rare neoplasms constituting less than 0.5% of all malignant uterine tumors. The aim of the present study was to characterize the karyotypic abnormalities in these malignant mesenchymal tumors and to find specific chromosomal aberrations with eventual correlation with histologic grades. METHODS: Twelve cases of endometrial stromal sarcomas consisting of nine low-grade ESS and three undifferentiated endometrial sarcomas (UES) were investigated by comparative genomic hybridization (CGH). RESULTS: Ten of the twelve cases (83.3%) displayed chromosomal gains or losses. Deletions occurred more frequently than gains (63.4% versus 36.6%). In low-grade ESS, gains on 1, 6q, 9q, 16p, 19, 20q, 22q and losses on 2, 4q, 6, 7, 11q, 13q, 15q, 16q, 20p, X were detected. CGH with UES exhibited gains on 2q, 4q, 6q, 7p, 9q, 20q and losses on 3q, 10p, 14q. One low-grade ESS and one UES did not reveal any chromosomal aberration. CONCLUSIONS: Chromosomal aberrations in endometrial sarcomas are heterogeneous and do not clearly correlate with the histologic grades. There is no increased accumulation of aberrations from low-grade ESS to UES. Despite the karyotypic variations, chromosomal deletion on 7p was the most common finding (55.6%) in low-grade ESS and may play a role in tumor development and progression.

Allelic imbalances in endometrial stromal neoplasms: frequent genetic alterations in the nontumorous normal-appearing endometrial and myometrial tissues.

OBJECTIVES: Endometrial stromal sarcoma (ESS) is among the rarest primary malignant tumors of the uterus. The aim of this study was to examine the possibility of loss of heterozygosity (LOH) and microsatellite instability (MIS) in different tissue components of ESS. METHODS AND MATERIALS: Using PCR, we examined DNA extracts from microdissected tissues of 27 uterus samples containing malignant stromal cells of ESS (20 low grade and 3 high grade sarcomas), benign tumor cells of endometrial stromal nodules (ESN, 4 cases) as well as tumor-free myometrial and endometrial tissues close to and distant from the tumors. Normal cervical tissues (epithelial cells, stroma cells) were also microdissected and analyzed. Fifteen polymorphic DNA markers (chromosomes 2p, 3p, 5q, 10q, 11q, 13q, and 17p) were tested to identify possible genetic alterations. Samples from 10 women with prolapsed uteri without any histopathologic abnormalities were also selected as controls. RESULTS: While no genetic alterations could be identified in 12 (44.5%) ESS cases, 15 (55.5%) revealed LOH with at least one polymorphic DNA marker. LOH were found in 3 (100%) high-grade sarcomas, 10 (50%) low-grade ESS, and 2 (50%) benign ESN. Although LOH was found more often in the neoplastic stromal cells, several cases showed concurrent and independent LOH in the tumor-free myometrial or endometrial tissues either close to or distant from the tumors. The most common genetic abnormality (LOH) was observed at PTEN, a tumor suppressor gene located on chromosome 10q. No tumor was associated with microsatellite instability (MSI). The control group without any histologic abnormalities did not show LOH or MSI. CONCLUSIONS: The frequent occurrence of LOH and the lack of MSI suggest that loss of function(s) of tumor suppressor genes and not mismatch repair deficiency plays a key role in the pathogenesis of endometrial stromal neoplasms. The concurrent and independent occurrence of LOH in the stromal tumor cells and the tumor-free and normal-appearing myometrial and endometrial tissues strongly support the concept of genetic alterations in microenvironmental tissues and the interaction(s) between different tissue components in the development and progression of endometrial stromal neoplasms.

Inverse correlation of secreted frizzled-related protein 4 and beta-catenin expression in endometrial stromal sarcomas.

Endometrial stromal sarcomas are rare uterine tumours. Whereas the histology and immunohistochemistry of these tumours are well documented, almost nothing is known about the molecular mechanisms involved in their pathogenesis. To characterize the genes altered in these malignancies, a genome-wide cDNA library was generated by suppression subtractive hybridization and a set of differentially expressed clones was isolated. These were then used to produce custom-spotted cDNA arrays. Genes deregulated in endometrial stromal sarcomas were identified by cDNA array hybridization and were confirmed by quantitative real-time PCR analyses and in situ hybridization. Following cDNA array analysis, more than 300 genes deregulated in endometrial stromal sarcoma were selected and sequenced. Among the most significantly deregulated genes were those of secreted frizzled-related proteins (SFRPs), in particular secreted frizzled-related protein 4 (SFRP4). SFRPs are putative modulators of the Wnt-signalling pathway and play a role in different cellular events including cell proliferation. Compared with normal endometrium, the expression of SFRP4 was decreased in both low-grade endometrial stromal sarcoma (ESS; n = 10) and undifferentiated endometrial sarcoma (UES; n = 4), being lower in the latter more aggressive form. These results were verified on paraffin wax-embedded tissue by quantitative real-time PCR analysis and in situ hybridization. Furthermore, the expression of beta-catenin, an important component of the Wnt-signalling pathway, was regulated in an opposite manner to SFRP4, being particularly increased in undifferentiated sarcomas. The activation of the Wnt-signalling pathway was additionally supported by the immunohistochemical demonstration that beta-catenin was translocated to the nucleus in UES. SFRP4 may therefore be a putative tumour suppressor involved in deregulation of the Wnt pathway and in the pathogenesis of ESS and UES.