microRNA-449b (miR-449b)

microRNA-449b (miR-449b) is a small, non-coding RNA (~22 nucleotides) that belongs to the miR-449 family, operating primarily through post-transcriptional regulation of gene expression. As part of a cluster with miR-449a/c, miR-449b plays a tumor suppressor role by inhibiting cell proliferation and promoting cell cycle arrest and apoptosis—mainly through direct inhibition of key oncogenic regulators such as CDK6, CDC25A, and MYCN[1][2][3]. It also has essential roles in developmental processes, notably in brain formation, ciliogenesis, and spermatogenesis, with redundancy shared with the related miR-34b/c cluster[5][6]. Dysregulation and epigenetic repression of the miR-449 family, especially miR-449b, have been implicated in a variety of cancers, including triple-negative breast cancer, and its expression levels are relevant as diagnostic and prognostic biomarkers in these settings[4]. The pathway activity of miR-449b is interlinked with feedback loops regulating histone deacetylases (HDAC1, SIRT1) and fatty acid metabolism (ACSL4/ABCG2 axis), underpinning its importance in cell fate and therapeutic response[4]. There are currently no approved drugs that directly target miR-449b, but molecules modulating its expression (such as epigenetic drugs) or regulated pathways may have significant clinical relevance.

Other names

hsa-miR-449bmiR-449b-5pMIR449Bmir-449bhsa-mir-449bMIRN449B

Regulation of cancer-associated pathways by post-transcriptional repression of gene targets (e.g. CDK6, CDC25A, MYCN, BCL-2). Modulation of chemosensitivity by controlling expression of genes involved in drug resistance (e.g. ACSL4, ABCG2).