Biological and clinical implications of metastasis‐associated circular RNAs in oesophageal squamous cell carcinoma

Oesophageal squamous cell carcinoma (OSCC) is a prevalent malignancy with high morbidity and mortality as a result of early metastasis and poor prognosis. Metastasis is a multistep process, involving various signalling pathways. Circular RNAs (circRNAs) are a class of covalently closed noncoding RNAs, the aberrant expression of which is reported to be involved in several biological events, including cell transformation, proliferation, migration, invasion, apoptosis and metastasis. Several studies have reported interactions between circRNAs and metastasis‐associated signalling pathways. The abundance, stability and highly specific expression of candidate circRNAs make them potential biomarkers and therapeutic targets in OSCC. In this review article, we comprehensively describe metastasis‐related circRNAs and their interactions with epithelial–mesenchymal transition‐associated molecules. We also describe the molecular mechanisms and clinical relevance of circRNAs in OSCC progression and metastasis.