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Previous studies have shown that secreted protein acidic and rich in cysteine (SPARC) proteins can inhibit the development of cancer cells in various ways, such as by inhibiting angiogenesis and inhibiting cell proliferation. In fact, SPARC proteins may have an effect on the chemoresistance of gastric cancer cells to 5-Fluorouracil (5-FU), which needs further research in the future. Therefore, the purpose of this study was to explore the relationship between SPARC proteins and the chemosensitivity of gastric cancer cells to 5-FU. In vitro, after SPARC protein levels were regulated by plasmid, siRNA and human recombinant SPARC protein transfection in MGC-803, SGC-7901 and BGC-823 cells, we detected epithelial-mesenchymal transition (EMT), apoptosis markers and cell viability after 5-FU treatment. In vivo, we implanted BGC-823 cells with stable SPARC overexpression into nude mice. Tumour size was measured to assess the effect of SPARC protein on tumour formation and 5-FU chemosensitivity. In SGC-7901 and BGC-823 cells, both endogenous and exogenous upregulation of SPARC protein levels decreased cell viability, destroyed cytoskeletal F-actin, inhibited cell migration, and downregulated a series of transcription factors to inhibit cell EMT; it also upregulated cell apoptosis-related proteins to promote cell apoptosis. However, we obtained opposite results in SPARC knockdown MGC-803 cells. In vivo, compared with the control group, the group engrafted with BGC-823 cells stably overexpressing SPARC had a significant smaller tumour size. After 5-FU treatment, the new tumour gradually decreased in size. Our results show that the SPARC protein could enhance 5-FU chemosensitivity in gastric cancer cell lines by inhibiting EMT and promoting cell apoptosis.

Increased xCT and transsulfuration pathway has been associated with metabolic reprogramming of colorectal cancer. However, the correlation between these 2 events and the underlying molecular mechanism remains obscure. xCT expression was determined in tissue microarrays of colorectal cancer. RNA sequencing and functional assays in vitro was adopted to delineate the involvement of transsulfuration pathway in the proper function of xCT in maintaining the chemoresistant phenotype. The synthetic lethality of blocking xCT and the transsulfuration pathway was investigated both in vitro and in vivo. The up-regulation of the transsulfuration pathway after inhibiting xCT in colon cancer cells was evident and exogenous H2S partially reversed the loss of chemoresistance phenotype after inhibiting xCT. Mechanistically, CTH derived H2S increased the stability of xCT through persulfidation of OTU domain-containing ubiquitin aldehyde-binding protein 1 at cysteine 91. AOAA and Erastin resulted in synthetic lethality both in vitro and in vivo, which was mediated through increased ferroptosis and apoptosis. Our findings suggest that a reciprocal regulation exists between xCT and the transsulfuration pathway, which is a targetable metabolic vulnerability. Mechanistically, CTH derived H2S increased the stability of xCT through persulfidation of OTU domain-containing ubiquitin aldehyde-binding protein 1 at cysteine 91.

Background. Colorectal cancer (CRC) is the second most common cause of cancer death in the United States and the third most common cancer globally. The incidence of CRC tends to be younger, and we urgently need a reliable prognostic assessment strategy. Methods. Protein expression profile and clinical information of 390 CRC patients/samples were downloaded from the TCPA and TCGA database, respectively. The Kaplan-Meier, Cox regression, and Pearson correlation analysis were applied in this study. Results. Based on the TCPA and TCGA database, we screened 6 hub proteins and first constructed protein risk signature, all of which were significantly associated with CRC patients’ overall survival (OS). The risk score was an independent prognostic factor and significantly related with the size of the tumor in situ (T). 6 hub proteins were differentially expressed in cancer and normal tissues and in different CRC stages, which were validated at the ONCOMINE database. Next, 40 coexpressed proteins of 6 hub proteins were extracted from the TCPA database. In the protein-protein interaction (PPI) network, HER1, HER2, and CTNNB1 were at the center. Function enrichment analysis illustrated that 46 proteins were mainly involved in the EGFR (HER1) tyrosine kinase inhibitor resistance pathway. Conclusion. Studies indicated that 6 hub proteins might be considered as new targets for CRC therapies, and the protein risk signature can be used to predict the OS of CRC patients.

Since the theory of seed and soil was put forward, people have increasingly recognized that the tumour microenvironment is an important regulator of tumour progression and therapeutic response. Among them, M2-type macrophages (M2, as the major macrophage subtype in the tumour foci) have important promoting effects on various biological behaviours. Secreted protein acidic and rich in cysteine (SPARC) is an important anti-tumour component in the microenvironment of gastric cancer. This study shows that macrophages are an important source of the SPARC and that SPARC overexpression in M2 can reduce M2-mediated promoting proliferation, migration and anti-apoptotic effects in gastric cancer. Additionally, the AKT/mTOR signalling pathways may participate in the malignant process.

Background: As the third confirmed gaseous transmitter, the role of hydrogen sulfide (H2S) in the pathogenesis of multiple types of cancer has been attracting increasing attention. Increased expression of cystathionine β-synthase (CBS) and H2S in colon cancer tissue samples has been validated and tumor-derived H2S, mainly produced by CBS, stimulates bioenergetics, cell proliferation, and angiogenesis in colon cancer. Recently, the therapeutic manipulation of H2S has been proposed as a promising anticancer approach. However, the effect of aminooxyacetic acid (AOAA), which has been widely used as an inhibitor of CBS dependent synthesis of H2S, on the chemotherapeutic effect of oxaliplatin (OXA) and the underlying mechanisms remain to be illustrated. Methods: We examined the expression of CBS in human colorectal cancer specimens and matched normal mucosa by immunohistochemistry. The effect of AOAA on the sensitivity of colon cancer cells to OXA and the level of apoptosis induced by caspase cascade was investigated in both HCT116 and HT29 cell lines utilizing CCK-8 assays, flow cytometry analysis and western blot analysis. The endogenous levels of reactive oxygen species (ROS) were detected fluorescently by DCF-DA, and glutathione (GSH) levels were measured by a Total GSH Detection Kit. Tumor bearing xenograft mouse models and in vivo imaging systems were further used to investigate the effect of AOAA in vivo and immunohistochemistry (IHC) and TUNEL analysis were performed. Results: In the current study, we confirmed CBS, the main target of AOAA, is overexpressed in human colorectal cancer by immunohistochemistry. The inhibitory effect of AOAA on the synthesis of H2S was validated utilizing fluorescent probe and specific electrode. AOAA significantly reduced the IC50 values of OXA in both colon cancer cell lines. Co-incubation with AOAA elicited increased apoptosis induced by OXA, featured by increased activation of caspase cascade. Besides, AOAA further increased the levels of ROS induced by OXA and attenuated the synthesis of glutathione (GSH), which is a vital antioxidant. Besides, the results of in vivo imaging and following IHC and TUNEL analysis were in accordance with cellular experiments, indicating that AOAA sensitizes colon cancer cells to OXA via exaggerating intrinsic apoptosis. Conclusion: The results suggested that CBS is overexpressed in colorectal cancer tissues and AOAA sensitizes colon cancer cells to OXA via exaggerating apoptosis both in vitro and in vivo. Decreasing the endogenous level of GSH and consequently impaired detoxification of ROS might be one of the mechanisms underlying the effect of AOAA.

BackgroundGlobally, stomach adenocarcinoma (STAD)’s high morbidity and mortality should arouse our urgent attention. How long can STAD patients survive after surgery and whether novel immunotherapy is effective are questions that our clinicians cannot escape.MethodsVarious R packages, GSEA software, Metascape, STRING, Cytoscape, Venn diagram, TIMER2.0 website, TCGA, and GEO databases were used in our study.ResultsIn the TCGA and GEO, macrophage abundance of STAD tissues was significantly higher than that of adjacent tissues and was an independent prognostic factor, significantly related to the overall survival (OS) of STAD patients. Between the high- and low- macrophage abundance, we conducted differential expression, univariate and multivariate Cox analysis, and obtained 12 candidate genes, and finally constructed a 3-gene signature. Both low macrophage abundance group and group D had higher TMB and PD-L1 expression. Furthermore, top 5 common gene-mutated STAD tissues had lower macrophage abundance. Macrophage abundance and 3 key genes expression were also lower in the Epstein-Barr Virus (EBV) and HM-indel STAD subtypes and significantly correlated with the tumor microenvironment score. The functional enrichment and ssGSEA revealed 2 signatures were similar and closely related to BOQUEST_STEM_CELL_UP, including genes up-regulated in proliferative stromal stem cells. Hsa-miR-335-5p simultaneously regulated 3 key genes and significantly related to the expression of PD-L1, CD8A and PDCD1.Conclusionmacrophage abundance and 3-gene signature could simultaneously predict the OS and immunotherapy efficacy, and both 2 signatures had remarkable similarities. Hsa-miR-335-5p and BOQUEST_STEM_CELL_UP might be novel immunotherapy targets.

The activated form of vitamin D3, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], regulates numerous cellular processes, including inhibition of cancer progression. IL-1β has been reported to facilitate cancer development, especially by inducing an epithelial-to-mesenchymal transition (EMT) in several malignant tumors. However, the underlying mechanism of 1,25(OH)2D3 and IL-1β in colorectal cancer (CRC) still remains largely unknown. To fill in this knowledge gap, we measured cell proliferation and invasion by CCK-8 and Transwell assays after stimulation with 1,25(OH)2D3 and IL-1β. E-cadherin and vimentin were chosen as markers of EMT measured by immunofluorescence, quantitative real-time PCR (qRT-PCR), and Western blot. The expression and function of the vitamin D receptor (VDR) was evaluated by Western blot and luciferase reporter assay. qRT-PCR and RNA-FISH were performed to detect the expression and location of lncTCF7 in vitro. The binding sites of VDR in the lncTCF7 promoter were confirmed by a chromatin immunoprecipitation assay. Based on the above experiments, we found that 1,25(OH)2D3 attenuates IL-1β-induced increased proliferation and invasion in colorectal cancer through enhancing VDR, which inhibits the expression of lncTCF7 by directly binding to its promoter region.

Bacterial flagella are nanomachines that drive bacteria motility and taxis in response to environmental changes. Whether flagella are permanent cell structures and, if not, the circumstances and timing of their production and loss during the bacterial life cycle remain poorly understood. Here we used the single polar flagellum of Vibrio alginolyticus as our model and implementing in vivo fluorescence imaging revealed that the percentage of flagellated bacteria (PFB) in a population varies substantially across different growth phases. In the early-exponential phase, the PFB increases rapidly through the widespread production of flagella. In the mid-exponential phase, the PFB peaks at around 76% and the partitioning of flagella between the daughter cells are 1:1 and strictly at the old poles. After entering the stationary phase, the PFB starts to decline, mainly because daughter cells stop making new flagella after cell division. Interestingly, we observed that bacteria can actively abandon flagella after prolonged stationary culturing, though cell division has long been suspended. Further experimental investigations confirmed that flagella were ejected in V. alginolyticus, starting from breakage in the rod. Our results highlight the dynamic production and loss of flagella during the bacterial life cycle. IMPORTANCE: Flagella motility is critical for many bacterial species. The bacterial flagellum is made up of about 20 different types of proteins in its final structure and can be self-assembled. The current understanding of the lifetime and durability of bacterial flagella is very limited. In the present study, we monitored Vibrio alginolyticus flagellar assembly and loss by in vivo fluorescence labeling, and found that the percentage of flagellated bacteria varies substantially across different growth phases. The production of flagella was synchronized with cell growth but stopped when cells entered the stationary phase. Surprisingly, we observed that bacteria can actively abandon flagella after prolonged stationary culturing, as well as in the low glucose buffering medium. We then confirmed the ejection of flagella in V. alginolyticus started with breakage of the rod. Our results highlight the dynamic production and loss of flagella during the bacterial life cycle.

Aims The present study investigated the effect of Escherichia coli Nissle 1917 (EcN) on irinotecan-induced intestinal barrier dysfunction and gut microbial dysbiosis in a mouse model and in the human colonic cells lines Caco-2. Materials and methods Male BALB/c mice received irinotecan intraperitoneal injection with or without EcN administration intragastrically. Body weight, diarrhea severity, intestinal permeability and histopathological analysis of ileum epithelia of mice from different groups were assessed. The expression and localization of tight junction proteins were examined using western blot and immunofluorescence. Gut microbiota structure and diversity were measured with 16 S rRNA sequencing. Caco-2 monolayers were incubated with EcN culture supernatant (EcNsup) or SN-38 and the monolayer barrier function was assessed by transepithelial electrical resistance (TER) and FITC-dextran 4000 Da (FD-4) flux. Key findings Pretreatment with EcN significantly attenuated irinotecan-induced weight loss and diarrhea in mice. In addition, EcN inhibited the increased intestinal permeability and decreased Claudin-1 expression in irinotecan-treated mice. Furthermore, irinotecan treatment decreased the diversity of gut microbiota and increased the relative abundance of Proteobacteria compared to control group. EcN administration ameliorated the gut microbiota dysbiosis. In Caco-2 monolayers, EcNsup ameliorated the decreased TER and increased FD-4 flux elicited by SN-38. Moreover, EcNsup attenuated SN-38-induced altered localization and distribution of Claudin-1 in Caco-2 monolayers. Significance Our results indicated that the administration of EcN protected against irinotecan-induced intestinal injury by regulating intestinal barrier function and gut microbiota.

Escherichia coli Nissle 1917 (EcN), a kind of probiotic, has been reported to have a protective effect on the intestinal barrier function and can ameliorate certain gastrointestinal disorders. In this study, the potential protective effect of EcN on the intestinal barrier function in a septic mouse model induced by cecal ligation and puncture (CLP) operation was investigated. FITC-Dextran 4,000 Da (FD-4) flux and the expression levels of tight junction (TJ) proteins were measured to evaluate the protective effect of EcN on the intestinal barrier function. Then, Caco-2 monolayers were utilized to further investigate the protective effect of the EcN supernatant (EcNsup) on the barrier dysfunction induced by TNF-α and IFN-γ in vitro; the plasma level of both the cytokines increased significantly during sepsis. Transepithelial electrical resistance (TEER) and FD-4 transmembrane flux were measured, and the localization of ZO-1 and Occludin was investigated by immunofluorescence. The expression of MLCK and the phosphorylation of MLC were detected by western blot. The activation of NF-κB was explored by immunofluorescence, and CHIP assays were performed to investigate the conjunction of NF-κB with the promoter of MLCK. The results indicated that EcN protected the intestinal barrier function in sepsis by ameliorating the altered expression and localization of TJ proteins and inhibiting the NF-κB-mediated activation of the MLCK-P-MLC signaling pathway which might be one of the mechanisms underlying the effect of EcN.

Background Cancer-associated fibroblasts (CAFs) play important roles in tumor progression. However, the behaviors of activated CAFs in gastric cancer remain to be determined. The aim of the present study was to investigate the correlations between activated gastric CAFs and the prognosis of patients with gastric cancer, and to determine the effects of activated CAFs on the malignant phenotype and 5-fluorouracil resistance in this cancer. Methods Ninety-five patients with primary gastric cancer were enrolled in this study. Activation states of gastric CAFs were evaluated by immunohistochemistry. A modified method for the primary culture of gastric CAFs was employed. Types of CAFs and activation states were identified by immunocytochemical and immunofluorescent staining. Cell co-culture and gastric CAF conditioned medium transfer models were established to investigate the paracrine effects of activated CAFs on the migration and invasion of gastric cell lines. The half maximal inhibitory concentration of 5-fluorouracil and levels of cell apoptosis were examined using cell viability assay and flow cytometry, respectively. Protein expression levels of associated molecules were measured by Western blotting. Results Kaplan–Meier survival curves showed that activated gastric CAFs identified via fibroblast activation protein were significantly related to poorer cumulative survival in gastric cancer patients. Five strains of CAFs were successfully cultured via the modified culture method, and three gastric CAFs strains were identified as activated gastric CAFs. The migration and invasion abilities of gastric cells were significantly enhanced in both the co-culture group and the conditioned medium group. The half maximal inhibitory concentration for 5-fluorouracil in BGC-823 cells was elevated after treatment with conditioned medium, and early apoptosis was inhibited. Additionally, an obvious elevation of epithelial–mesenchymal transition level was observed in the conditioned medium group. Conclusions Activated gastric CAFs correlate with a poor prognosis of cancer patients and may contribute to the malignant phenotype and the development of resistance to 5-fluorouracil via paracrine action in gastric cancer. Gastric CAFs with a specific activation state might be used as a tumor biomarker within the microenvironment for prognosis and as a new therapeutic target for chemoresistant gastric cancer. Electronic supplementary material The online version of this article (10.1186/s12935-018-0599-7) contains supplementary material, which is available to authorized users.