What is the miR-200 family and how does miR-141 fit in?

The miR-200 family is a cluster of five related microRNAs (miR-200a, miR-200b, miR-200c, miR-141, and miR-429) that share significant sequence similarity and largely overlapping target gene sets. They are best known for regulating the epithelial-to-mesenchymal transition (EMT) — a process by which epithelial cells (which form organ surfaces and glands) acquire invasive, mesenchymal properties. In normal biology, miR-200 family members enforce the epithelial state by suppressing ZEB1 and ZEB2 transcription factors. In cancer, the role of miR-200 family members is context-dependent: in some cancers they are downregulated (loss of epithelial identity enables metastasis), while in others (including prostate cancer and some colorectal cancers) specific members like miR-141-3p are overexpressed and promote cancer cell survival through other mechanisms. The Yenos validation found miR-141-3p to be the most accurate individual marker at 97.3%.