MIR3609: MIR3609 is a downregulated miRNA that has been identified as a potential biomarker for patients with locally advanced breast cancer [PMC9818474]. In kalirin–GEF1–inhibited cells, the miRNA precursors MIR181A2 and MIR3609 were found to be downregulated, which may explain the upregulation of miR-181 and miR-3609 targets [PMC8017594]. MIR3609 has been shown to improve the immune response in breast cancer by blocking the programmed death-ligand 1 immune checkpoint [PMC7527443]. Specifically, MIR3609 can bind to the 3′ UTR region of PD-L1 and suppress PD-L1 expression, thereby sensitizing breast cancer cells to doxorubicin [PMC9713762]. Functional analysis of downregulated miRNAs, including miR-24-2-5p, MIR3609, and miR-664b-3p, revealed that their target genes are involved in positive regulation processes such as cell morphogenesis, nervous system development, and neuron differentiation [PMC9727336]. Additionally, upregulation of MIR3609 has been shown to sensitize breast cancer cells to Adriamycin [PMC9727336]. Overall, these findings highlight the potential role of MIR3609 in breast cancer progression and treatment response.