Silencing of Long Non-coding RNA HOTAIR Suppresses Reverses Epithelial-Mesenchymal Transition in AGS Gastric Cancer Cell Line by Downregulation of Fibronectin 1 and Claudin-4

Background: Gastric cancer is the second reason for cancer mortality worldwide, with a high capacity for metastasis. Long non-coding RNAs (lncRNAs) are recently described as lengthy transcripts with no open reading frame. The lncRNAs play an important role in critical cellular and molecular pathways, including cell cycle, growth, differentiation, and apoptosis. Therefore, it is not surprising that abnormal expression of lncRNAs may be involved in human cancers. The HOX antisense intergenic RNA (HOTAIR) is a highly cited lncRNAs whose altered expression has been reported in a variety of human cancers such as gastric cancer. Epithelial to mesenchymal transition (EMT) is a cellular route in which an epithelial phenotype of the cells can be changed into the mesenchymal state. The signaling pathways involved in EMT are related to cancer metastasis and recurrence of gastric cancer. Methods: The present study was aimed to investigate the effect of HOTAIR gene silencing on expression levels of fibronectin 1 (FN1) and claudin-4 (CLDN4) genes, two important markers of EMT, in AGS cellular model of gastric cancer. The AGS cells were exposed to the HOTAIR-specific siRNA for 48 hours. The extracted RNAs were subjected to complementary DNA synthesis and real-time PCR. Data were analyzed using 2^−ΔΔCt method. Cells with no siRNA treatment were considered the control set. The P-value 0.05 was considered statistically significant. Results: The observed data showed that the expression levels of two EMT markers FN1 and CLDN4, were significantly decreased after HOTAIR silencing. Conclusions: This study demonstrates that HOTAIR can regulate the EMT signaling pathway through critical EMT factors like FN1 and CLDN4 transcripts. However, a long way remains to apply this finding in therapeutic approach, and further experiments are needed.