Role of various non-coding RNAs in EMT, cancer, and metastasis: Recent trends and future perspective

Epithelial-to-mesenchymal transition (EMT) is a key cellular process involved in the various biological processes ranging from embryonic development, wound healing, and cancer metastasis. EMT is the key player in cancer progression to a metastatic state. The transformed tumor cells acquire the migratory property and invade surrounding tissues, which ultimately leads to cancer metastasis via EMT. Epithelial cells undergo certain phenotypic changes to acquire mesenchymal status. At a molecular level, this transition process is elicited by several signaling cascades that include cytokines and a group of transcription factors like Twist, snail, and Zeb1/2. Emerging evidence suggests that various non-coding RNAs (ncRNAs) play a significant role in modulating EMT-associated transcription factors (EMT-TFs) and molecular signaling at the transcriptional and post-transcriptional level and thus, regulating the EMT process. Various noncoding-RNAs like miRNAs, piRNAs, tsRNAs, lncRNAs, T-UCRs, CircRNAs, eRNAs, snoRNAs can either promote or can inhibit the process of EMT and thus modulates cancer progression. Here we review the recent research advances in delineating the role of various non-coding RNAs in the EMT, cancer, and metastasis process as well as their potential roles as biomarkers and therapeutic targets.