Impact on growth and invasion of gastric cancer cell lines by silencing NEDD9

Background: Gastric adenocarcinoma is a predominant disease with latent attribute, high malignancy, and poor prognosis in People's Republic of China. Gastric cancer is the most common malignant tumor of the digestive tract. It has been suggested that abnormal expression of NEDD9 was associated with stage progression and metabolism of carcinomas. Some authors demonstrated that both messenger RNA (mRNA) and protein of NEDD9 were highly expressed in gastric cancer, and paired paracancerous atypical hyperplasia tissues were correlated with lymph node metastasis, tumor depth, and tumor-lymph node-metastasis (TNM) staging. In this study, we found that NEDD9 small interfering RNA (siRNA) can induce apoptosis and suppress proliferation, migration, and invasion of BGC823 cell lines. These findings suggested that NEDD9 siRNA might serve as a tumor suppressor by targeting NEDD9 in gastric cancer cell. It has been suggested that abnormal expression of NEDD9 was associated with carcinogenesis, and in the first part of the study, we found that NEDD9 was highly expressed in gastric cancer tissues; and it too was correlated with lymph node metastasis, tumor depth, and TNM staging. In this project, experiments were carried out to silence NEDD9 in BGC823 cell lines using NEDD9 siRNA, and the biological activity of BGC823 cells was observed after RNA interference. Methods: The target analysis of NEDD9 siRNA was forecast using online tools. In order to determine a more efficient NEDD9 siRNA, three pairs of NEDD9 siRNA primer were designed, synthesized, and then transfected into BGC823 cells. NEDD9-2 siRNA was finally adopted by detecting the quantitative real-time polymerase chain reaction (qRT-PCR). Cells were collected for detecting mRNA by qRT-PCR or protein by western blot analysis. Cell apoptosis was detected using flow cytometry, and the transwell invasion system was used for cell migration and invasion assays. The effect of NEDD9 siRNA in silencing the target gene in BGC823 cells was then assessed. Also, the impact of NEDD9-2 siRNA on cell proliferation, apoptosis, migration, and invasion were detected in BGC823 cell lines. Results: The relative quantity of expression of mRNA and protein showed a decrease in all cells transfected with siNEDD9-2 at different concentrations. The cell proliferation inhibition assay showed that the inhibition rate was significantly increased in all transfected cells compared with control groups. Cell apoptosis assay showed that the number of living cells were significantly reduced compared with control groups, and cell migration and invasion assay showed that siNEDD9 could inhibit BGC823 cell migration and invasion in vitro. Conclusion: NEDD9 siRNA could inhibit expression of NEDD9 and induce apoptosis, suppress proliferation, migration, and invasion of BGC823 cells, acting as a tumor suppressor in carcinogenesis of gastric cancer. These findings suggested that NEDD9 siRNA plays an important role in the proliferation, apoptosis, and invasion of BGC823 cells.