CircRNAs and lung cancer: Biomarkers and master regulators.

CircRNAs are a class of competitive, endogenous, non-coding RNAs with closed-loop structures. High-throughput sequencing indicates that circRNAs are ubiquitously expressed in many eukaryotes. Biological functions of circRNAs include interaction with proteins and regulation of gene transcription, translation, and miRNA sponge activity. These functions suggest that circRNAs may be useful as novel biomarkers for disease diagnosis and prognosis. Lung cancer is known worldwide as the most common malignant tumor. It is also the main cause of cancer-related death. In recent years, it has become increasingly evident that circRNAs are involved in the proliferation, migration, and invasion of lung cancer cells. Differentially expressed circRNAs may be used as non-invasive diagnostic and prognostic markers for lung cancer. Therefore, they are considered a research hotspot for lung cancer studies. This article is a systematic review of mechanisms underlying the action, diagnosis, clinical aspects, and drug resistance of circRNAs in lung cancer.