MicroRNA 891b (miR-891b)

MicroRNA 891b is a small, non-coding RNA molecule, extensively expressed in humans and encoded on the X chromosome. It functions as a post-transcriptional regulator, mainly by targeting mRNAs for translational inhibition or destabilization. In pancreatic ductal adenocarcinoma, miR-891b inhibits cancer cell proliferation by directly targeting the Cbl-b gene, resulting in activation of the Smad3/p21 tumor suppressor axis. Its expression level correlates with patient prognosis in PDAC, making it a promising biomarker and molecular target in oncology research. There is currently no documented pharmaceutical targeting miR-891b directly, but manipulation of its downstream molecular pathways has demonstrated inhibition of tumor cell growth.

Other names

hsa-mir-891bMIRN891BMIR891Bhsa-mir-891b (miRBase nomenclature)

Drugs targeting the effects of miR-891b act via inhibition or activation of its downstream signaling—e.g., SB431542 inhibits the TGF-β receptor pathway that is activated by miR-891b overexpression. miR-891b itself acts by binding to the 3'UTR of target mRNAs (such as Cbl-b), leading to decreased expression of the protein and subsequent downstream biological effects.