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BackgroundOver the last two or three decades, the pace of development of treatments for osteosarcoma tends has been slow. Novel effective therapies for osteosarcoma are still lacking. Previously, we reported that tumor-suppressing STF cDNA 3 (TSSC3) functions as an imprinted tumor suppressor gene in osteosarcoma; however, the underlying mechanism by which TSSC3 suppresses the tumorigenesis and metastasis remain unclear.MethodsWe investigated the dynamic expression patterns of TSSC3 and autophagy-related proteins (autophagy related 5 (ATG5) and P62) in 33 human benign bone tumors and 58 osteosarcoma tissues using immunohistochemistry. We further investigated the correlations between TSSC3 and autophagy in osteosarcoma using western blotting and transmission electronic microscopy. CCK-8, Edu, and clone formation assays; wound healing and Transwell assays; PCR; immunohistochemistry; immunofluorescence; and western blotting were used to investigated the responses in TSSC3-overexpressing osteosarcoma cell lines, and in xenografts and metastasis in vivo models, with or without autophagy deficiency caused by chloroquine or ATG5 silencing.ResultsWe found that ATG5 expression correlated positively with TSSC3 expression in human osteosarcoma tissues. We demonstrated that TSSC3 was an independent prognostic marker for overall survival in osteosarcoma, and positive ATG5 expression associated with positive TSSC3 expression suggested a favorable prognosis for patients. Then, we showed that TSSC3 overexpression enhanced autophagy via inactivating the Src-mediated PI3K/Akt/mTOR pathway in osteosarcoma. Further results suggested autophagy contributed to TSSC3-induced suppression of tumorigenesis and metastasis in osteosarcoma in vitro and in vivo models.ConclusionsOur findings highlighted, for the first time, the importance of autophagy as an underlying mechanism in TSSC3-induced antitumor effects in osteosarcoma. We also revealed that TSSC3-associated positive ATG5 expression might be a potential predictor of favorable prognosis in patients with osteosarcoma.Electronic supplementary materialThe online version of this article (10.1186/s13046-018-0856-6) contains supplementary material, which is available to authorized users.

Enhancer of zeste homolog 2 (EZH2)-mediated trimethylation of histone 3 lysine 27 (H3K27Me3) is critical for immune regulation. However, evidence is lacking to address the effect of EZH2 enzyme’s activity on intestinal immune responses during inflammatory bowel disease (IBD). Here we report that suppressing EZH2 activity ameliorates experimental intestinal inflammation and delayed the onset of colitis-associated cancer. In addition, we identified an increased number of functional MDSCs in the colons, which are essential for EZH2 inhibitor activity. Moreover, inhibition of EZH2 activity promotes the generation of MDSCs from hematopoietic progenitor cells in vitro, demonstrating a previously unappreciated role for EZH2 in the development of MDSCs. Together, these findings suggest the feasibility of EZH2 inhibitor clinical trials for the control of IBD. In addition, this study identifies MDSC-promoting effects of EZH2 inhibitors that may be undesirable in other therapeutic contexts and should be addressed in a clinical trial setting.

Background The endoglycosidase heparanase which degrades heparan sulfate proteoglycans, exerts a pro-inflammatory mediator in various inflammatory disorders. However, the function and underlying mechanism of heparanase in acute pancreatitis remain poorly understood. Here, we investigated the interplay between heparanase and the gut microbiota in the development of acute pancreatitis. Methods Acute pancreatitis was induced in wild-type and heparanase-transgenic mice by administration of caerulein. The differences in gut microbiota were analyzed by 16S ribosomal RNA sequencing. Antibiotic cocktail experiment, fecal microbiota transplantation, and cohousing experiments were used to assess the role of gut microbiota. Results As compared with wild-type mice, acute pancreatitis was exacerbated in heparanase-transgenic mice. Moreover, the gut microbiota differed between heparanase-transgenic and wild-type mice. Heparanase exacerbated acute pancreatitis in a gut microbiota-dependent manner. Specially, the commensal Parabacteroides contributed most to distinguish the differences between wild-type and heparanase-transgenic mice. Administration of Parabacteroides alleviated acute pancreatitis in wild-type and heparanase-transgenic mice. In addition, Parabacteroides produced acetate to alleviate heparanase-exacerbated acute pancreatitis through reducing neutrophil infiltration. Conclusions The gut–pancreas axis played an important role in the development of acute pancreatitis and the acetate produced by Parabacteroides may be beneficial for acute pancreatitis treatment.

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