microRNA 557 (miR-557)

microRNA 557 (miR-557) is a small non-coding RNA molecule consisting of approximately 19–22 nucleotides that regulates gene expression post-transcriptionally by binding to the 3'-untranslated region (3'-UTR) of target mRNAs, leading to mRNA degradation or translation repression. miR-557 is widely downregulated in various human cancers, including pancreatic, breast, gastric, and liver cancers. In pancreatic cancer, miR-557 functions as a tumor suppressor by inhibiting cellular proliferation, migration, and invasion, and promoting apoptosis. Mechanistically, miR-557 directly targets the epidermal growth factor receptor (EGFR) mRNA, reducing its protein expression. miR-557 is also involved in the regulation of other oncogenic pathways, such as IGF1 and mTOR signaling, in different cancer types. Outside of oncology, overexpression of miR-557 in mammalian cell lines has been shown to enhance recombinant protein production, indicating its pleiotropic regulatory effects. No approved drugs are currently known to target or mimic miR-557 directly, but it remains a promising research candidate for RNA-based cancer therapies[1][3]. **Notes** - miR-557 is not a receptor, enzyme, or transporter, but acts as a regulatory microRNA influencing a variety of disease processes through gene silencing. - It is considered a *therapeutic target* in cancer biology due to its documented tumor suppressor activity[1]. - No approved diagnostic or therapeutic agents specifically targeting miR-557 are listed; it is a potential biomarker for pancreatic and other cancers[1]. - There is no evidence the entry is incorrect or misnamed; aliases are well-attested in the literature[1][3].

Other names

hsa-miR-557MIRN557MIR557hsa-mir-557

Silencing target mRNA translation (e.g., EGFR), mRNA degradation (via 3'-UTR binding)