Circular RNA VRK1 correlates with favourable prognosis, inhibits cell proliferation but promotes apoptosis in breast cancer

OBJECTIVE: This study aimed to evaluate the correlation between the circular RNA VRK serine/threonine kinase 1 (circ‐VRK1) and the clinicopathological features and survival outcomes of breast cancer patients and determine its effects on breast cancer cell proliferation and apoptosis. METHODS: A total of 350 breast cancer tissues and 163 breast cancer adjacent tissues, as controls, were acquired from Specimen House. Circ‐VRK1 expression was measured using qPCR. The correlations between circ‐VRK1 expression and demographic characteristics, tumour features and overall survival were analysed. In vitro, the effects of circ‐VRK1 on breast cancer cell proliferation and apoptosis were measured by upregulating and downregulating circ‐VRK1 expression via plasmid transfection. RESULTS: Circ‐VRK1 was downregulated in breast cancer tissues compared with adjacent tissues and represented a good value in distinguishing breast cancer tissues from the adjacent tissues. Circ‐VRK1 was associated with smaller tumour size, reduced T stage and lower TNM stage, and circ‐VRK1 was also an independent predictor of better overall survival. According to the in vitro experiments, circ‐VRK1 expression was lower in breast cancer cell lines (including BT474, MDA‐MB‐453 and MDA‐MB‐231) than in a normal breast epithelial cell line (MCF10A), and circ‐VRK1 inhibited cell proliferation but promoted cell apoptosis in MDA‐MB‐231 cells. CONCLUSION: Circ‐VRK1 is downregulated in tumour tissues and associated with reduced tumour stage as well as better survival, and it inhibits cell proliferation but promotes cell apoptosis in breast cancer.