Cancer Gastric Chemoprevention: Isolation of Gastric Tumor-Initiating Cells

Bone morphogenetic protein and activin membrane-bound inhibitor overexpression inhibits gastric tumor cell invasion via the transforming growth factor-β/epithelial-mesenchymal transition signaling pathway

Gastric carcinoma is one of the most common human malignancies and remains the second leading cause of cancer-associated mortality worldwide. Gastric carcinoma is characterized by early-stage metastasis and is typically diagnosed in the advanced stage. Previous results have indicated that bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) overexpression has been demonstrated to inhibit growth and metastasis of gastric cancer cells. However, the molecular mechanisms of the BAMBI-mediated signaling pathway in the progression of gastric cancer are poorly understood. In the present study, to assess whether BAMBI overexpression inhibited the growth and aggressiveness of gastric carcinoma cells through regulation of transforming growth factor (TGF)-β/epithelial-mesenchymal transition (EMT) signaling pathway, the growth and metastasis of gastric carcinoma cells were analyzed following BAMBI overexpression and knockdown in vitro and in vivo. Molecular changes in the TGF-β/EMT signaling pathway were studied in gastric carcinoma cells following BAMBI overexpression and knockdown. DNA methylation of the gene regions encoding the TGF-β/EMT signaling pathway was investigated in gastric carcinoma cells. Tumor growth in tumor-bearing mice was analyzed after mice were subjected to endogenous overexpression of BAMBI. Results indicated that BAMBI overexpression significantly inhibited gastric carcinoma cell growth and aggressiveness, whereas knockdown of BAMBI significantly promoted its growth and metastasis compared with the control (P<0.01). The TGF-β/EMT signaling pathway was downregulated in BAMBI-overexpressed gastric carcinoma cells; however, signaling was promoted following BAMBI knockdown. In addition, it was observed that BAMBI overexpression significantly downregulated the DNA methylation of the gene regions encoding the TGF-β/EMT signaling pathway (P<0.01). Furthermore, RNA interference-mediated BAMBI overexpression also promoted apoptosis in gastric cancer cells and significantly inhibited growth of gastric tumors in murine xenografts (P<0.01). In conclusion, the present findings suggest that BAMBI overexpression inhibited the TGF-β/EMT signaling pathway and suppressed the invasiveness of gastric tumors, suggesting BAMBI may be a potential target for the treatment of gastric carcinoma via regulation of the TGF-β/EMT signaling pathway.

3-Phosphoinositide Dependent Protein Kinase-1 (PDK-1) Promotes Migration and Invasion in Gastric Cancer Cells Through Activating the NF-κB Pathway

Gastric cancer (GC) is one of the most common cancers and the second leading cause of cancer deaths in the world. Many factors have been reported regarding the progression and development of GC. In this study, we aimed to investigate the correlation of 3-phosphoinositide dependent protein kinase-1 (PDK-1) with cell viability, migration, and invasion of GC. The expression of PDK-1 was measured in different GC cell lines. Thereafter, the expression of PDK-1 was interfered by small hairpin RNA (shRNA) and then incubated with or without the inhibitor of nuclear factor-κB (NF-κB) pyrrolidine dithiocarbamate (PDTC). We then investigated the effects of PDK-1 aberrant expression on GC cell viability, migration, invasion, and the epithelial-mesenchymal transition (EMT) progress. The results showed that PDK-1 was highly expressed in GC cells, and PDK-1 promoted cell viability, migration, invasion, and EMT in GC. Moreover, we confirmed that PDK-1 activated the phosphatidylinositol 3-hydroxy kinase (PI3K)/AKT and NF-κB signaling pathways. However, administration of PDTC reversed the effects of overexpression of PDK-1 on cell migration and invasion. All these findings suggest that PDK-1 may be involved in progression of GC and could be a new therapeutic target for this disease.