Phase transition and remodeling complex assembly are important for SS18-SSX oncogenic activity in synovial sarcomas.

Oncoprotein SS18-SSX is a hallmark of synovial sarcomas. However, as a part of the SS18-SSX fusion protein, SS18's function remains unclear. Here, we depict the structures of both human SS18/BRG1 and yeast SNF11/SNF2 subcomplexes. Both subcomplexes assemble into heterodimers that share a similar conformation, suggesting that SNF11 might be a homologue of SS18 in chromatin remodeling complexes. Importantly, our study shows that the self-association of the intrinsically disordered region, QPGY domain, leads to liquid-liquid phase separation (LLPS) of SS18 or SS18-SSX and the subsequent recruitment of BRG1 into phase-separated condensates. Moreover, our results show that the tyrosine residues in the QPGY domain play a decisive role in the LLPS of SS18 or SS18-SSX. Perturbations of either SS18-SSX LLPS or SS18-SSX's binding to BRG1 impair NIH3T3 cell transformation by SS18-SSX. Our data demonstrate that both LLPS and assembling into chromatin remodelers contribute to the oncogenic activity of SS18-SSX in synovial sarcomas.

[Animal experimentation of reimplantation of hypertonic saline-induced devitalized bone].

OBJECTIVE: To observe the healing process and the change of biomechanical properties of hypertonic saline-induced devitalized bone segment, so as to provide fundamental theory for clinical treatment. METHODS: A model of New Zealand rabbit ulnar segments devitalized by hypertonic saline was established and then reimplanted in situ. The ulnar specimens were taken for examination of X-rays, light microscope and three-point-bend test at the end of 3, 6, 12, and 24 weeks postoperatively. RESULTS: The devitalized bone healed at the end of 12 weeks in the X-ray film. The histological examination showed that osteoblast multiplied and secreted osteoid gradually. The maximal breaking load of the devitalized bone continuously increased and reached the top at the end of 24 weeks [control group (206.25±16.64) N vs. devitalized group (196.88±8.24) N, P>0.05]. CONCLUSION: The devitalized bone healed through intramembranous and endochondral ossification, and the endochondral ossification predominated; the biomechanical strength of devitalized bone continually increased as time lasted.

(-)-Epigallocatechin-3-gallate induces apoptosis and suppresses proliferation by inhibiting the human Indian Hedgehog pathway in human chondrosarcoma cells.

PURPOSE: Chondrosarcoma is a soft tissue sarcoma with a poor prognosis that is unresponsive to conventional chemotherapy. The regulatory mechanisms for the rapid proliferation of chondrosarcoma cells and the particular aggressiveness of this sarcoma remain poorly understood. In this study, we investigate the effect of epigallocatechin-3-gallate (EGCG) on growth and apoptosis of chondrosarcoma cells. METHODS: The chondrosarcoma cell lines, SW1353 and CRL-7891, were cultured with and without EGCG. The MTT assay was used to test the cytotoxicity of EGCG. Flow cytometry and DAPI staining were used to observe cell apoptosis caused by EGCG. To explore the effect of EGCG on the Indian Hedgehog signaling pathway and apoptosis-related proteins, RT-PCR and Western blotting were used to detect the expression of PTCH and Gli-1 in the Indian Hedgehog signaling pathway. Meanwhile, expression of Bcl-2, Bax, and caspase-3 were also evaluated by Western blot analysis. RESULTS: EGCG effectively inhibited cellular proliferation and induced apoptosis of SW1353 and CRL-7891. EGCG inhibited the human Indian Hedgehog pathway, down-regulated PTCH and Gli-1 levels, and induced apoptosis as confirmed by DAPI staining followed by flow cytometry. Protein expression levels of caspase-3 were unchanged in response to EGCG treatment in chondrosarcoma cells; however, the expression levels of Bcl-2 were significantly decreased and the levels of Bax were significantly increased. CONCLUSIONS: Our findings demonstrate that EGCG is effective for growth inhibition of a chondrosarcoma cell lines in vitro, and suggest that EGCG may be a new therapeutic option for patients with chondrosarcoma.

[Lethal effects of nanoliposome encapsulated cisplatin on Saos-2 cells and its distribution in nude mice bearing human].

OBJECTIVE: To investigate the killing effect of nanoliposome encapsulated cisplatin (NLE-CDDP) on human osteosarcoma cell line Saos-2 and explore the distribution of platinum (Pt) in tumor-bearing mice. METHODS: Saos-2 cells were cultured at different concentrations of NLE-CDDP. MTT assay, inverted microscopic observation and flow cytometry assay(FCM)were used to observe the antiproliferative effect of NLE-CDDP on the human osteosarcoma cells. Antitumor effect of NLE-CDDP was determined using the xenografts models of human osteosarcoma cell Saos-2 in nude mice. The Pt concentration in the tissues of tumor-transplanted mice was determined by atomic spectrophotometer. RESULTS: When treated at different concentrations of NLE-CDDP for 24-96 hours, the survival rate of Saos-2 cells decreased significantly(P<0.05). At the same time point, the inhibitory effect of NLE-CDDP was stronger than that of CDDP;Degeneration and necrosis of Saos-2 cells increased; the apoptosis increased and the S phase reduced. This study demonstrated that NLE-CDDP had obvious anti-tumor activity. Within 1 hour of injection, in NLE-CDDP group plasma platinum concentration was 4.4-fold that in CDDP group; 2 hours later, platinum was not detected in the blood of CDDP group; 24 hours later, platinum still could be detected in NLE-CDDP group at 2.76 mumol/L. During the first hour after injection of NLE-CDDP, the platinum content of the kidney was 50% less than that of CDDP group. Platinum in NLE-CDDP group showed rapid higher accumulation in the liver, spleen and tumor compared with CDDP group, and within 24 hours platinum reached the peak concentration in the spleen. CONCLUSION: The antitumor efficacy of NLE-CDDP on Saos-2 tumor is higher than that CDDP alone, and its mechanism is delaying rapid clearance from circulation.

Sorafenib induces growth inhibition and apoptosis in human synovial sarcoma cells via inhibiting the RAF/MEK/ERK signaling pathway.

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.

[Comparison and analysis of different dendritic cell-based immunotherapeutic strategies for Ewing sarcoma: in vitro and in vivo induction on SCID mouse models].

OBJECTIVE: To compare the efficacy of different immunotherapeutic strategies of loading dendritic cells (DCs) with the antigen of the Ewing sarcoma in vitro and in vivo. METHODS: DCs were either electrofused with the whole Ewing sarcoma cells A673, pulsed with lysates of the tumor cell or modified with the characteristic EWS/FLI1 gene. Then we assessed the capacity of the stimulated cytoxicity T lymphocyte (CTLs) by the parameter of the interferon-gamma (IFN-gamma) secreted and the cytotoxicity to the A673. In vivo experiment, the human IgG serum concentrations of the SCID mice were measured to determine the mouse human immune system reconstitution, and the growths of the inoculated tumor were measured to assess the anti-tumor effect. RESULTS: The data revealed that various DC-based strategies could induce specific immune responses to the tumor, with the hybrids showing superiority to the other strategies while there were no significant differences between the sets of the gene modified DCs and non-manipulated DCs in the cytotoxicity assay to A673 cells. Moreover, there were no significant differences among the sets of the gene modified DCs, lysate pulsed DCs and non-manipulated in vivo anti-tumor effect about the tumor volume on the SCID mice. CONCLUSION: The Ewing sarcoma had good responses to the DC-based immunotherapy and based on this experiment, we could also conclude that the product of electrofusion may be an optimal strategy for immunotherapy of Ewing sarcoma.