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Background/Aims: Gastric cancer (GC) is the most common gastrointestinal malignancy, causing cancer-related deaths in East Asia. MicroRNAs (miRNAs) are small non-coding RNAs aberrantly expressed in human tumors. In this study, we aim to investigate the roles of miR-204 in the epithelial to mesenchymal transition (EMT)-associated chemosensitivity. Methods: The expression of miR-204 was detected in clinical tumor samples and GC cell lines by real time PCR. Tumor cell’s growth, invasion, and migration were measured by MTT assay, wound healing assay, and transwell invasion assay, respectively. Western blot method was used to detect the protein levels of indicated genes. Luciferase reporter assay was performed to validate the target gene of miR-204. The in vivo role of miR-204 was measured using a xenograft mouse model of GC. Results: By comparing the expressions of miR-204 in human gastric tumors and their adjacent normal tissues, it was disclosed that miR-204 was significantly downregulated in gastric tumors. Moreover, miR-204 was downregulated in multiple GC cell lines compared with normal gastric epithelial cells. Overexpression of miR-204 suppressed GC cells’ proliferation, invasion, and migration. It is noteworthy that 5-FU treatments induced miR-204 expression and suppressed TGF-β pathway. By establishment of 5-FU resistant GC cell line, it was revealed that miR-204 was significantly downregulated in 5-FU resistant GC cells, representing mesenchymal features with downregulation of epithelial marker, while mesenchymal markers were upregulated. We identified TGFBR2 as a direct target of miR-204 by Western blot method and luciferase assay in GC cells and tumor samples as well. In addition, overexpression of miR-204 sensitized GC cells to 5-FU in vitro. Xenograft experiments demonstrated that the combination of miR-204 and 5-FU efficiently inhibited tumor growth and improved survival rate of mice as well. Eventually, we illustrated the restoration of TGFBR2 in miR-204 overexpression GC cells, which recovered resistance to 5-FU treatments compared with miR-204 overexpression GC cells. Conclusion: This study describes a miRNA-based therapeutic strategy against 5-FU resistance in GC, contributing to the development of anti-chemoresistance therapeutic agents.

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Cancer cells usually utilize glucose as a carbon source for aerobic glycolysis, which is named as ``Warburg effect''. Recent studies have shown that MicroRNAs (miRNAs), a class of short and non-coding RNAs, play a role in the regulation of metabolic reprograming in cancer cells. In the present study, we report that miR-181b negatively regulates glycolysis in gastric cancer cells. Over-expression of miR-181b mimics reduces the glucose uptake and lactate production, while increasing the cellular ATP levels in NCI-N87 and MGC80-3 cells. At the molecular level, miR-181b directly inhibits the expression level of hexokinase 2 (HK2), a key enzyme that catalyzes the first step of glycolysis, through targeting its 3'-untranslated region. In addition, miR-181b represses cell proliferation and migration and is dramatically down-regulated in human gastric cancers. Therefore, our data disclose a novel function of miR-181b in reprogramming the metabolic process in gastric cancer.

Autophagy is an intracellular degradation pathway that delivers organelles or protein to the lysosome and has been recently implicated in the resistance of gastric cancer to chemotherapy. This study aimed to investigate whether blocking autophagy is a new approach for the treatment of chemoresistant gastric cancer. SGC-7901 gastric cancer cell line was treated with 5-fluorouracil (5-FU) or/and autophagy inhibitor bafilomycin A1. Cell viability and growth were evaluated by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) and clonogenic assay. Apoptosis was evaluated by flow cytometry. Cell migratory and invasive ability were evaluated by migration and invasion assays. Autophagy was evaluated by scanning electron microscopic, acridine orange staining, and Western blot analysis. We observed that 5-FU induced autophagy in SGC-7901 cells. Bafilomycin A1 decreased the viability and clone formation, inhibited the invasive and migratory ability, and increased the apoptosis of SGC-7901 cells. Taken together, our data suggest that chemotherapy-induced autophagy contributes to gastric cancer chemoresistance, and the inhibition of autophagy is a promising strategy for gastric cancer therapy.

In this article, we will give a complete classification of simple C * -algebras which can be written as inductive limits of algebras of the form A n ¼ È kn i¼1 M ½n;i ðCðX n;i ÞÞ, where X n;i are arbitrary variable one-dimensional compact metrizable spaces. The results unify and generalize the previous results for the case X n;i ¼ S 1 and for the case of X n;i being trees. We obtain our classification results by reducing the case of general one-dimensional spaces to the case of circles. The techniques in this paper play important roles in the study of the case of higher-dimensional spaces.