In molecular biology mir-143 microRNA is a short RNA molecule. MicroRNAs function to regulate the expression levels of other genes by a several mechanisms. mir–143 is highly conserved in vertebrates. mir-143 is thought be involved in cardiac morphogenesis but has also been implicated in cancer.
Changes in mir-143 expression have frequently been implicated in cancer. However the exact nature of this relationship is not fully understood. The up-regulation of mir-143 was observed in a hepatocellular carcinoma model during tumor metastasis through repression of FNDC38. However decreased expression of mir-143 and 145 have been observed in cancer samples. Expression was shown to be decreased in a range of cancer stages, including in very early samples. This suggests that they are involved in tumorgenesis.