Circ_0032821 acts as an oncogene in cell proliferation, metastasis and autophagy in human gastric cancer cells in vitro and in vivo through activating MEK1/ERK1/2 signaling pathway

BACKGROUND: Circular RNA (circRNA) is increasingly attracting attention in gastric cancer (GC). Hsa_circ_0032821 (circ_0032821) has been declared to be upregulated in human GC tissues. However, the biological role of circ_0032821 remains undisclosed in GC cells. METHODS: Expression of circ_0032821 was measured by real-time quantitative PCR. Cell proliferation, autophagy, Epithelial-mesenchymal transition (EMT), migration, and invasion were evaluated by Cell counting kit-8 assay, western blotting or transwell assays. Expression of proliferating cell nuclear antigen (PCNA), Matrix metalloproteinase 2 (MMP2), MMP9, Light chain 3 (LC3), p62, total and phosphorylated Extracellular signal-regulated kinase 1/2 (ERK1/2) and Mitogen-activated protein kinase's kinase 1 (MEK1) was evaluated by western blotting. Xenograft tumor model was established to measure tumor growth in vivo. RESULTS: Circ_0032821 was significantly upregulated in human GC tumors and cells. Moreover, circ_0032821 might be a biomarker for the advanced Tumor node metastasis (TNM) stage, lymphoid node metastasis and poor prognosis in gastric cancer. Knockdown of circ_0032821 by transfection induced decrease of cell proliferation, EMT, migration and invasion, but increase of autophagy of AGS and HGC-27 cells in vitro, as well as induced tumor growth inhibition in vivo. Besides, overexpression of circ_0032821 by transfection functioned the opposite effects in human GC cells. Mechanically, the MEK1/ERK1/2 signaling pathway was activated when circ_0032821 upregulation, whereas inhibited when circ_0032821 silencing. CONCLUSION: Circ_0032821 expression induced cell proliferation, EMT, migration, invasion, and autophagy inhibition in human GC cells in vitro and in vivo through activating MEK1/ERK1/2 signaling pathway, suggesting circ_0032821 as an oncogenic role in GC.