An update on long intergenic noncoding RNA p21: a regulatory molecule with various significant functions in cancer

Long intergenic noncoding RNA p21 was mapped on the human chromosome 6p21.2. Accordingly, it was firstly described by promoting the p53-dependent apoptosis in the mouse. Also, it is a new lncRNA playing some vital roles in the cell cycle, apoptosis, cell proliferation, tumorigenesis, invasion, metastasis, and angiogenesis. In this regard, it was shown that, lincRNA-p21 regulates these biological processes involved in carcinogenesis through various signaling pathways including Notch signaling, JAK2/STAT3, and AKT/mTOR pathways. Another mechanism by that lincRNA-p21 can affect these processes is a cross-talk with different miRNAs. In vitro and in vivo studies revealed dysregulation of lincRNA-p21 in various human cancers. In addition, emerging evidence demonstrated that, lincRNA-p21 can be considered as a potential prognostic and therapeutic biomarker in cancers. Also, lincRNA-p21 enhances the response to radiotherapy for colorectal cancer. However, the molecular mechanisms of lincRNA-p21 in carcinogenesis have not been fully elucidated so far. So, this review summarizes the function of lincRNA-p21, as a tumor suppressor factor in different biological processes implicated in cancers.