MIR300: MIR300 is an intergenic miRNA belonging to the DLK1-DIO3 genomic region located on human chromosome 14 (14q32) [PMC8151247]. It has been found to play a role in chronic myelogenous leukemia (CML) stemness and the persistence of drug-resistant quiescent leukemic stem cells [PMC8269304] [PMC7960773]. MIR300-induced loss of cyclin D2/cyclin-dependent kinase 6 (CDK6) contributes to its antiproliferative activity in CML stemness [PMC8269304]. Upregulation of MIR300 in malignant cells, including through extracellular vesicles transfer from bone marrow MSCs, impairs leukemic cell proliferation [PMC7960773]. MIR300 expression is maintained in CML LSCs and affects CCND2 and CDK6, leading to cell cycle arrest and quiescence [PMC8151247] [PMC7998932]. BCR-ABL1 downregulates MIR300 in CML progenitors to protect them from apoptosis and cell cycle arrest [PMC8151247] [PMC7998932]. MIR300 has been found to target BRD7, and its overexpression can antagonize the promotive effect of MIR300 on cell growth and invasion [PMC7006413]. The TUG1/miR-300/PP2A signaling pathway is important for both CML development and treatment, as modulation of MIR300 or PP2A-activating treatment can trigger LSC apoptosis [PMC8684082]. Overall, MIR300 plays a crucial role in CML stemness, quiescence, apoptosis, and proliferation through its interaction with various target genes.