MicroRNA 519a-1 (miR-519a-1)

MicroRNA 519a-1 is a small, non-coding RNA belonging to the C19MC cluster, with critical regulatory activity in gene expression via post-transcriptional silencing mechanisms. It is implicated as an oncomir in several cancers, notably breast cancer, by promoting cell cycle progression, increasing cell viability, and conferring resistance to apoptotic stimuli such as tamoxifen exposure. miR-519a-1 achieves these effects by directly targeting and repressing tumor-suppressor genes—including PTEN, RB1, and CDKN1A (p21)—and further modulates pathways such as PI3K-Akt signaling and cell cycle control. In contrast, in other contexts such as ovarian cancer, miR-519a-1 may function as a tumor suppressor, inhibiting proliferation and promoting apoptosis by targeting STAT3. Its exact role varies depending on tissue context, tumor type, and cellular environment. Elevated levels of miR-519a-1 have been repeatedly associated with poor patient prognosis and drug resistance, especially in hormone receptor-positive breast cancer, making both its expression and its molecular network significant targets for therapeutic intervention and biomarker development. Drugs targeting miR-519a-1 (such as experimental antagomirs) are under investigation for overcoming chemotherapy resistance, but safety concerns arise from its broad regulatory actions and potential effects on normal cellular functions.

Other names

MIR519A1hsa-mir-519a-1MIRN519A-1MIRN519A1mir-519a-1

miRNA inhibitors (antagomirs) block miR-519a-1, thereby derepressing its target tumor-suppressor genes (PTEN, RB1, CDKN1A/p21), leading to resensitization to drugs like tamoxifen