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The prevention and treatment of gastric cancer has been the focus and difficulty of medical research. We aimed to explore the mechanism of inhibiting migration and invasion of gastric cancer cells by methionine restriction (MR). The human gastric cancer cell lines AGS and MKN45 cultured with complete medium (CM) or medium without methionine were used for in vitro experiments. MKN45 cells were injected tail vein into BALB/c nude mice and then fed with normal diet or methionine diet for in vivo experiments. MR treatment decreased cell migration and invasion, increased E-cadherin expression, decreased N-cadherin and p-p65 expressions, and inhibited nuclear p65 translocation of AGS and MKN45 cells when compared with CM group. MR treatment increased IκBα protein expression and protein stability, and decreased IκBα protein ubiquitination level and TRIM47 expression. TRIM47 interacted with IκBα protein, and overexpression of TRIM47 reversed the regulatory effects of MR. TRIM47 promoted lung metastasis formation and partially attenuated the effect of MR on metastasis formation in vivo compared to normal diet group mice. MR reduces TRIM47 expression, leads to the degradation of IκBα, and then inhibits the translocation of nuclear p65 and the migration and invasion of gastric cancer cells. [ABSTRACT FROM AUTHOR]

Background/Aims: Targeted drug delivery vehicles with low immunogenicity and toxicity are needed for cancer therapy. Here, we prepare an active targeting drug carrier of low immunogenicity and toxicity for targeted therapy. Methods: Immature dendritic cells (imDCs) from BALB/c mice were used as donor cells of exosomes (Exos) that were transfected with the plasmids expressing fusion proteins of a tumor-targeting peptide known as internalizing RGD (iRGD) to construct a type of tumor-targeting iRGD-Exos and observe the interaction between these iRGD-Exos. Also, recombinant methioninase (rMETase) was loaded into the iRGD-Exos by electroporation to construct iRGD-Exos-rMETase and to assess the tumor-targeting function of the iRGD-Exos-rMETase. Finally, 30 BALB/c were randomly divided into five groups (n = 6), to observe tumor growth in vivo. Results: The iRGD-Exos-rMETase was 99.58 nm in diameter and presented a unique "goblet" structure under transmission electron microscopy (TEM), with the encapsulation efficiency (EE) of 19.05%. iRGD-Exos-rMETase group has the strongest tumor suppressive effect. Compared to the iRGD-Exos-rMETase group, rMETase group and the blank-Exos-rMETase group were less effective, while the PBS group and the iRGD-Exos group showed no inhibitory effect on tumor growth. After treatment, the iRGD-Exos-rMETase group had gastric tumors significantly smaller and lighter than the other groups (P < 0.05). Conclusion: The iRGD-Exos-rMETase is an effective antitumor therapy that delivers rMETase to tumor tissue using the iRGD-Exos. With its favorable inhibitory effect and tumor-targeting function, the iRGD-Exos-rMETase shows excellent potential value and exciting prospects in clinical applications. [ABSTRACT FROM AUTHOR]

Background: Mesenchymal stromal cells (MSCs) are multipotent and have great potential in cell therapy. Previously we reported the differentiation potential of human MSCs into hepatocytes in vitro and that these cells can rescue fulminant hepatic failure. However, the conventional static culture method neither maintains growth factors at an optimal level constantly nor removes cellular waste efficiently. In addition, not only is the duration of differentiating hepatocyte lineage cells from MSCs required to improve, but also the need for a large number of hepatocytes for cell therapy has not to date been addressed fully. The purpose of this study is to design and develop an innovative microfluidic device to overcome these shortcomings. Methods: We designed and fabricated a microfluidic device and a culture system for hepatic differentiation of MSCs using our protocol reported previously. The microfluidic device contains a large culture chamber with a stable uniform flow to allow homogeneous distribution and expansion as well as efficient induction of hepatic differentiation for MSCs. Results: The device enables real-time observation under light microscopy and exhibits a better differentiation efficiency for MSCs compared with conventional static culture. MSCs grown in the microfluidic device showed a higher level of hepatocyte marker gene expression under hepatic induction. Functional analysis of hepatic differentiation demonstrated significantly higher urea production in the microfluidic device after 21 days of hepatic differentiation. Conclusions: The microfluidic device allows the generation of a large number of MSCs and induces hepatic differentiation of MSCs efficiently. The device can be adapted for scale-up production of hepatic cells from MSCs for cellular therapy. [ABSTRACT FROM AUTHOR]

Background: Autophagy plays an important role in regulating cisplatin (CDDP) resistance in gastric cancer cells. However, the underlying mechanism of methioninase (METase) in the regulation of autophagy and CDDP resistance of gastric cancer cells is still not clear. Materials and methods: Western blot was used to detect the levels of autophagy-related proteins, multidrug-resistant 1 (MDR-1), and FoxM1 protein. LncRNA HULC was detected by qRT-PCR. Cell viability was detected using CCK-8 assay. The interaction between lncRNA HULC and FoxM1 was confirmed by RNA pull-down and RIP assay. Results: Lentiviral vector carrying METase (LV-METase) suppressed autophagy and CDDP resistance of drug-resistant gastric cancer cells. LncRNA HULC was significantly downregulated in drug-resistant gastric cancer cells transfected with LV-METase. Besides, we found that lncRNA HULC interacted with FoxM1. In addition, METase suppressed autophagy to reduce CDDP resistance of drug-resistant gastric cancer cells through regulating HULC/FoxM1, and interfering HULC suppressed autophagy to reduce CDDP resistance of drug-resistant gastric cancer cells through regulating FoxM1. Finally, interfering HULC inhibited tumor growth in vivo. Conclusion: METase suppressed autophagy to reduce CDDP resistance of drug-resistant gastric cancer cells through regulating HULC/FoxM1 pathway. [ABSTRACT FROM AUTHOR]

Gastric cancer metastasis is a major cause of poor prognosis. Our previous research showed that methionine restriction (MR) lowers the invasiveness and motility of gastric carcinoma. In this study, we investigated the particular mechanisms of MR on gastric carcinoma metastasis. In vitro, gastric carcinoma cells (AGS, SNU-5, MKN7, KATO III, SNU-1, and MKN45) were grown in an MR medium for 24 h. In vivo, BALB/c mice were given a methionine-free (Met−) diet. Transwell assays were used to investigate cell invasion and migration. The amounts of Krüppel like factor 10 (KLF10) and cystathionine β-synthase (CBS) were determined using quantitative real-time PCR and Western blot. To determine the relationship between KLF10 and CBS, chromatin immunoprecipitation and a dual-luciferase reporter experiment were used. Hematoxylin–eosin staining was used to detect lung metastasis. Liquid chromatography–mass spectrometry was used to determine cystathionine content. MR therapy had varying effects on the invasion and migration of gastric carcinoma cells AGS, SNU-5, MKN7, KATO III, SNU-1, and MKN45. KLF10 was highly expressed in AGS cells but poorly expressed in KATO III cells. KLF10 improved MR's ability to prevent gastric carcinoma cell invasion and migration. In addition, KLF10 may interact with CBS, facilitating transcription. Further detection revealed that inhibiting the KLF10/CBS-mediated trans -sulfur pathway lowered Met−'s inhibitory effect on lung metastasis development. KLF10 transcription activated CBS, accelerated the trans -sulfur pathway, and increased gastric carcinoma cells' susceptibility to MR. [Display omitted] [ABSTRACT FROM AUTHOR]

• LncRNA HCG18 is highly expressed in Exos derived from GC and exosomal lncRNA HCG18 facilitate M2 macrophage polarization. • Exosomal lncRNA HCG18 promotes M2 macrophage polarization by negatively regulating miR-875-3p in macrophages. • Overexpression of miR-875-3p in macrophages restrains M2 macrophage polarization by decreasing KLF4 expression. • GCCs-sh-HCG18-Exos restrain the tumor growth of GC induced by M2 macrophages. Gastric cancer (GC) derived exosomes (Exos) aggravate GC development by facilitating M2 macrophage polarization and long non-coding RNA (lncRNA) HCG18 was highly expressed in GC. This study aimed to investigate whether the exosomal lncRNA HCG18 regulated the M2 macrophage polarization in GC and the possible mechanism. The isolated GC cells (GCCs)-Exos were identified using transmission electron microscopy, Nanoparticle Tracking Analysis and Western blot. The GCCs-Exos function was verified by enzyme-linked immunosorbent assay and flow cytometry. Meanwhile, the exosomal lncRNA HCG18 function was determined using the in vitro assays. Furthermore, the underlying mechanism of the exosomal lncRNA HCG18 that regulated M2 macrophage polarization in GC was investigated using dual-luciferase reporter gene assay and RNA pull-down. After the validation of GCCs-Exos, the GCCs-Exos facilitated the M2 macrophage polarization. The in vitro assays confirmed that the exosomal lncRNA HCG18 positively regulated the M2 macrophage polarization. Mechanistically, lncRNA HCG18 bound to miR-875-3p, miR-875-3p bound to KLF4. Furthermore, GCCs-exosomal lncRNA HCG18 elevated the KLF4 expression by decreasing miR-875-3p in macrophages to facilitate M2 macrophage polarization, thus alleviating GC. The in vivo assays clarified that the GCCs-exosomal lncRNA HCG18 restrained the tumor growth of GC induced by M2 macrophages. GCCs-exosomal lncRNA HCG18 elevated KLF4 expression by decreasing miR-875-3p in macrophages to facilitate the M2 macrophage polarization. [ABSTRACT FROM AUTHOR]

Cancer stem cells are undifferentiated cancer cells that have self‐renewal ability, a high tumorigenic activity, and a multilineage differentiation potential. MicroRNAs play a critical role in regulating gene expression during carcinogenesis. Here, we investigated the role of miR‐7 and the mechanism by which it is dysregulated in gastric cancer stem cells (GCSCs). The stem cell marker, CD44, was used to sort GCSCs by fluorescence‐activated cell sorting. We found that CD44 (+) cells have higher invasiveness and form more number of sphere colonies than CD44 (−) cells. Quantitative real‐time polymerase chain reaction (PCR) revealed that the miR‐7‐5p expression was remarkably downregulated in GCSCs but was significantly increased in the methionine‐deprived medium. The downregulation of miR‐7‐5p results from the increased DNA methylation in the promoter region using the methylation‐specific PCR. Overexpression of miR‐7‐5p reduced the formation of colony and decreased the invasion of GCSCs through targeting Smo and Hes1 and subsequent repressing Notch and Hedgehog signaling pathways in vitro. Notably, upregulating miR‐7‐5p inhibited the growth of tumor in the xenograft model. Hence, these data demonstrated that miR‐7‐5p represses GCSC invasion through inhibition of Smo and Hes1, which provides a potential therapeutic target of gastric cancer treatment. [ABSTRACT FROM AUTHOR]

Abstract Background Gastric cancer (GC) severely threatens human life, and METase seemed to inhibit tumor growth. However, the potential mechanism underlying it is still unclear. Methods Both clinical tissues and cell lines were used in the present study. SNHG5 and miR-20a expressions were determined using real-time PCR. Western blot was performed to determine the expression of autophagy-related proteins. The interaction between miR-20a and SNHG5 was determined using luciferase reporter assay and RNA immunoprecipitation (RIP). Results The expression of SNHG5 was decreased in GC tissues and cell lines. Overexpressed METase significantly promoted cell apoptosis and autophagy, as well as the expression of SNHG5. SNHG5 directly regulated the expression of miR-20a. GC cells transfected with pcDNA-SNHG5 significantly promoted cell apoptosis and autophagy, while the co-transfected with miR-20a mimic dramatically reversed the effects of pcDNA-SNHG5. Overexpressed METase significantly promoted cell autophagy, which was abolished by down-regulated SNHG5. Conclusion Overexpressed METase promoted cell apoptosis and autophagy via up-regulating the expression of SNHG5 and down-regulating miR-20a in GC. [ABSTRACT FROM AUTHOR]

The occurrence of recurrence and metastasis after treatment is a major challenge in the treatment of gastric cancer. This study was based on the methionine (Met)-dependent characteristics of gastric cancer cells to explore the effect of Met deficiency on the occurrence and development of gastric cancer. Human gastric cancer cell lines MKN45 and AGS and nude mice model were used to explore how Met affects gastric cancer by regulating lncRNA PVT1. The levels of lncRNA PVT1 in gastric cancer cells and human gastric cancer xenografts of nude mice were down-regulated under the condition of Met deficiency. The cell viability and cell proliferation were declined after MKN45 and SGC-790 cells were cultured in Met-deficient medium. LncRNA PVT1 could affect BNIP3 promoter DNA methylation level through its interaction with DNMT1. Moreover, the silence of lncRNA PVT1 and the up-regulation of BNIP3 level inhibited the gastric cancer cell proliferation. Met deficiency could up-regulate BNIP3 expression by inhibiting the binding of lncRNA PVT1 to DNMT1, and activate mitophagy, thus inhibiting gastric cancer cell proliferation. Our study suggested that Met deficiency could down-regulate the expression of lncRNA PVT1, further demethylated the promoter of BNIP3, thus inhibiting the proliferation of gastric cancer cells by activating mitophagy. [Display omitted] [ABSTRACT FROM AUTHOR]