MicroRNA 221-5p (miR-221-5p)

MicroRNA 221–5p is a short non-coding RNA molecule, part of the microRNA family that regulates gene expression post-transcriptionally by binding complementary sequences on target messenger RNAs. It is transcribed from a cluster with its paralogue miR‑222 on chromosome X. MiR‑221–5p has been extensively studied as an oncogenic microRNA, promoting tumor growth by downregulating tumor suppressors such as CD117 and DIRAS3; it also modulates processes like angiogenesis, epithelial-to-mesenchymal transition (EMT), cell proliferation/migration/invasion across various cancers including liver, prostate, breast, lung, thyroid carcinomas among others. Its dysregulation has diagnostic/prognostic value—e.g., non-invasive colorectal cancer screening—and it represents an emerging therapeutic target using antisense technologies. However, its pleiotropic effects pose safety concerns when considering systemic inhibition.

Other names

miR-221MIR221microRNA 221miR-221/222 cluster

Antisense inhibition of miR‑221 leads to derepression of its mRNA targets—restoring tumor suppressor gene expression or reducing oncogene activity. Modulation affects cell cycle genes, apoptosis regulators, angiogenesis factors.