MiR-31 is a representative example as it can not only enhance tumor development and progression in pancreatic cancer, colorectal cancer and so on, but also inhibit tumorigenesis and induce apoptosis in ovarian cancer, prostate cancer and etc.
Cigarette smoke induces expression of miR-31 targeting several antagonists of cancer stem cell signaling in normal respiratory epithelia and lung cancer cells. miR-31 functions as an oncomir during human pulmonary carcinogenesis.
miR-31(*) is a functional miRNA involving in regulating RhoA, and the activity of miR-31(*)'s activity seems to counteract the functions of miR-31 during OSCC tumorigenesis.