Effect of miR-206 Derived from Bone Marrow Mesenchymal Stem Cells (BMSCs) on CD8 Expression in Gastric Cancer

The BMSCs are one of the components of tumor micro-environment and participate in tumor evolution. Our study aimed to discuss the effect of exosome derived from BMSC on gastric cancer cells. Tumor and para-tumor tissues were isolated to measure miR-206 level by RT-PCR. Gastric cancer cell behaviors were analyzed using MTT assay and scratch test. Gastric cancer model was established and treated TIGIT inhibitor to assess its role in the tumor growth in vivo. The miR-206 in exosome from BMSCs in cancer tissue was detected. CD8 expression excreted by DC could be induced after miR-206 treatment possibly through regulating the signaling pathway of TIGIT/PVR. Inhibition of TIGIT decreased tumor growth, development and reversed tumor phenotype. In conclusion, miR-206 derived from BMSCs induces CD8 expression in gastric cancer through regulating the signaling pathway of TIGIT/PVR, indicating that it might be a novel target for the treatment of gastric cancer.

Stromal Cell-Derived Factor-1α (SDF-1α) Promotes Growth and Migration of Bone Marrow Stromal Cells (BMSCs) and Gastric Cancer Cells Through Phosphatidylinositol 3-Kinase/AKT (PI3K/Akt) Pathway

SDF-1α activity is closely related to information transmission and cell migration when contributing to lymphatic metastasis in various tumors. Herein, we explored the interaction among SDF-1α, CXCR4 and PI3K/Akt signaling pathway in gastric cancer (GC) and their roles in this disorder. Human GC cells KATO-III and BMSCs were co-cultured without contact. GC cells were transfected with SDF-1α, CXCR4 inhibitor, and PI3K inhibitor. After examining the efficiency of transfection, cell migration was evaluated using Transwell chamber, and expression SDF-1α, CD133, and CXCR4 was determined by RT-qPCR. With transfection rate of 98%, the number of migrated cells reduced upon inhibition of CXCR4 and PI3K. Luciferase activity in 565 nm are high than CXCR4 inhibition group. (p < 0.05). Likewise, up-regulation of SDF-1α increased the expression of SDF-1 (0.825±0.061), CD133 (0.875±0.058), CXCR4 (0.801±0.052), and Akt (0.852±0.062), compared to the blank group, CXCR4 inhibition group and PI3K inhibition group (p < 0.05). Down-regulation of CXCR4 and PI3K, however, decreased the expression insignificantly (p > 0.05). Collectively, up-regulation of SDF-1α activates CXCR4 signaling pathway of BMSCs and stimulates its downstream PI3K/Akt signaling pathway and and increases the expression of CD133, thereby promoting malignant behaviors of GC cells.

Bone Marrow Mesenchymal Stem Cell (BMSC)-Derived Exosomal miR-168-5p Inhibits Proliferation and Chemotherapy Resistance in Gastric Cancer by Downregulation of Cyclin D1 and P Glycoprotein

miR-168-5p is indicated as an upstream effector of the tumor suppressor signal pathway in ovarian cancer and bladder cancer, but the role in gastric cancer (GC) remains unknown. This study aims to reveal the expression and significance of miR-168-5p in GC. RT-qPCR analysis was used to detect the expression of miR-168-5p in GC tissues and plasma, and the relationship of miR-168-5p and CCND1 was evaluated. GC cells were co-cultured with BMSCs or transfected with miR-168-5p mimic. CCK-8 assay and flow cytometry were conducted to assess the effect of miR-168-5p in GC and the interaction between BMSCs and cancer cell progression. Animal experiment was established to explore the in vivo effect of miR-168-5p. miR-168-5p is poorly expressed in gastric cancer cells and the plasma of patients with gastric cancer. BMSC co-culture is similar to miR-168-5p mimic induced miR-168-5p expression increase. miR-168-5p overexpression decreased the proliferative, invasive and migratory capacities of GC cells, and promoted apoptosis. Mechanically, miR-168-5p targeted and decreased the expression of CCND1. Additionally, the low miR-168-5p expression in GC was closely related to poor prognosis and malignant transformation. BMSC exosomes carrying miR-168-5p suppress cell progression in GC when inhibiting the expression of CCND1 and P glycoprotein, which indicates potential diagnostic and prognostic value of miR-168-5p and helps the development of miR-168-5p-based treatment for drug-resistant GC.

The Role of miR-4256/HOXC8 Signaling Axis in the Gastric Cancer Progression: Evidence From lncRNA-miRNA-mRNA Network Analysis

Gastric cancer is a deadly human malignancy and the molecular mechanisms underlying gastric cancer pathophysiology are very complicated. Thus, further investigations are warranted to decipher the underlying molecular mechanisms. With the development of high-throughput screening and bioinformatics, gene expression profiles with large scale have been performed in gastric cancer. In the present study, we mined The Cancer Genome Atlas (TCGA) database and analyzed the gene expression profiles between gastric cancer tissues and normal gastric tissues. A series of differentially expressed lncRNAs, miRNAs and mRNAs between gastric cancer tissues and normal gastric tissues were identified. Based on the differentially expressed genes, we constructed miRNA-mRNA network, lncRNA-mRNA network and transcriptional factors-mRNA-miRNA-lncRNA network. Furthermore, the Kaplan survival analysis showed that high expression levels of EVX1, GBX2, GCM1, HOXC8, HOXC9, HOXC10, HOXC11, HOXC12 and HOXC13 were all significantly correlated with shorter overall survival of the patients with gastric cancer. On the other hand, low expression level of HOXA13 was associated with shorter overall survival of patients with gastric cancer. Among these hub genes, we performed the in vitro functional studies of HOXC8 in the gastric cancer cells. Knockdown of HOXC8 and overexpression of miR-4256 both significantly repressed the gastric cancer cell proliferation and migration, and miR-4256 repressed the expression of HOXC8 via targeting its 3’ untranslated region in gastric cancer cells. Collectively, our results revealed that a complex interaction networks of differentially expressed genes in gastric cancer, and further functional studies indicated that miR-4256/HOXC8 may be an important axis in regulating gastric cancer progression.

Revealing the Role of lncRNA CCDC144NL-AS1 and LINC01614 in Gastric Cancer via Integrative Bioinformatics Analysis and Experimental Validation

Long non-coding RNAs (lncRNAs) are key regulators in the pathophysiology of gastric cancer, and lncRNAs have been regarded as potential biomarkers and therapeutic targets for gastric cancer. The present study performed the WGCNA analysis of the GSE70880 dataset and aimed to identify novel lncRNAs associated with gastric cancer progression. Based on the WGCNA, the lncRNAs and mRNA co-expression network were constructed. A total of four modules were identified and the eigengenes in different modules were involved in various key signaling pathways. Furthermore, the co-expression networks were constructed between the lncRNAs and mRNA; this leads to the identification of 6 modules, which participated in various cellular pathways. The survival analysis showed that high expression of CCDC144NL antisense RNA 1 (CCDC144NL-AS1) and LINC01614 was positively correlated with the poor prognosis of patients with gastric cancer. The in vitro validation results showed that CCDC144NL-AS1 and LINC01614 were both up-regulated in the gastric cancer cells. Silence of CCDC144NL-AS1 and LINC01614 both significantly suppressed the cell proliferation and migration of gastric cancer cells, and also promoted the chemosensitivity of gastric cancer cells to 5-fluorouracil. Collectively, our results suggested that the newly identified two lncRNAs (CCDC144NL-AS1 and LINC01614) may act as oncogenes in gastric cancer.

The scaffolding protein Flot2 regulates cytoneme-based transport of Wnt3 in gastric cancer

The Wnt/β-catenin signalling pathway regulates multiple cellular processes during development and many diseases, including cell proliferation, migration, and differentiation. Despite their hydrophobic nature, Wnt proteins exert their function over long distances to induce paracrine signalling. Recent studies have identified several factors involved in Wnt secretion, however, our understanding of how Wnt ligands are transported between cells to interact with their cognate receptors is still debated. Here, we demonstrate that gastric cancer cells utilise cytonemes to transport Wnt3 intercellularly to promote proliferation. Furthermore, we identify the membrane-bound scaffolding protein Flotillin-2 (Flot2), frequently overexpressed in gastric cancer, as a regulator of these cytonemes. Together with the Wnt co-receptor and cytoneme initiator Ror2, Flot2 determines the number and length of Wnt3 cytonemes in gastric cancer. Finally, we show that Flot2 is necessary for Wnt8a cytonemes during zebrafish embryogenesis, suggesting a conserved mechanism for Flot2-mediated Wnt transport on cytonemes in development and disease.

Downregulation of CCKBR Expression Inhibits the Proliferation of Gastric Cancer Cells, Revealing a Potential Target for Immunotoxin Therapy

Background Increased CCKBR expression density or frequency has been reported in many neoplasms. Objective We aimed to investigate whether CCKBR drives the growth of gastric cancer (GC) and its potential as a therapeutic target of immunotoxins. Methods A lentiviral interference system was used to generate CCKBR-knockdown gastric cancer cells. Cell Counting Kit-8 and clonogenic assays were used to evaluate cell proliferation. Wound-healing and cell invasion assays were performed to evaluate cell mobility. Cell cycle was analyzed by flow cytometry. Tumor growth in vivo was investigated using a heterologous tumor transplantation model in nude mice. In addition, we generated the immunotoxin FQ17P and evaluated the combining capacity and tumor cytotoxicity of FQ17P in vitro. Results Stable downregulation of CCKBR expression resulted in reduced proliferation, migration and invasion of BGC-823 and SGC-7901 cells. The impact of CCKBR on gastric cancer cells was further verified through CCKBR overexpression studies. Downregulation of CCKBR expression also inhibited the growth of gastric tumors in vivo. Furthermore, FQ17P killed CCKBR-overexpressing GC cells by specifically binding to CCKBR on the tumor cell surface. Conclusion The CCKBR protein drives the growth, migration, and invasion of gastric cancer cells, and it might be a promising target for immunotoxin therapy based on its aberrant expression, functional binding interactions with gastrin, and subsequent internalization.

RhoGDI2-Mediated Rac1 Recruitment to Filamin A Enhances Rac1 Activity and Promotes Invasive Abilities of Gastric Cancer Cells

Rho GDP dissociation inhibitor 2 (RhoGDI2), a regulator of Rho family GTPase, has been known to promote tumor growth and malignant progression in gastric cancer. We previously showed that RhoGDI2 positively regulates Rac1 activity and Rac1 activation is critical for RhoGDI2-induced gastric cancer cell invasion. In this study, to identify the precise molecular mechanism by which RhoGDI2 activates Rac1 activity, we performed two-hybrid screenings using yeast and found that RhoGDI2 plays an important role in the interaction between Rac1, Filamin A and Rac1 activation in gastric cancer cells. Moreover, we found that Filamin A is required for Rac1 activation and the invasive ability of gastric cancer cells. Depletion of Filamin A expression markedly reduced Rac1 activity in RhoGDI2-expressing gastric cancer cells. The migration and invasion ability of RhoGDI2-expressing gastric cancer cells also substantially decreased when Filamin A expression was depleted. Furthermore, we found that Trio, a Rac1-specific guanine nucleotide exchange factor (GEF), is critical for Rac1 activation and the invasive ability of gastric cancer cells. Therefore, we conclude that RhoGDI2 increases Rac1 activity by recruiting Rac1 to Filamin A and enhancing the interaction between Rac1 and Trio, which is critical for the invasive ability of gastric cancer cells.