{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nMicroRNA‐519a (MIR519A1) has emerged as a key modulator of gene expression by targeting specific mRNAs to regulate protein synthesis and cellular proliferation. In several carcinoma cell lines, for example, MIR519A1 directly represses the translation of HuR— a critical RNA‐binding protein that stabilizes and modulates mRNAs involved in cell growth—resulting in decreased HuR protein levels and reduced cell proliferation. This regulation occurs without altering HuR mRNA abundance but by impairing its translation, ultimately affecting the expression of HuR‐dependent genes."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn contrast, context‐dependent roles have been reported in other tumor types. In hepatocellular carcinoma, elevated levels of MIR519A1 are associated with larger tumor size, advanced disease stage, and enhanced cell cycle progression; here, MIR519A1 directly targets phosphatase and tensin homolog (PTEN), thereby modulating the PI3K/AKT signaling pathway to promote tumor growth. Similarly, in estrogen receptor–positive breast cancer, overexpression of MIR519A1 contributes to tamoxifen resistance by coordinately downregulating a network of key tumor suppressor genes that regulate PI3K signaling and cell cycle progression. Aberrant expression of this miRNA has also been noted in laryngeal squamous cell carcinoma, suggesting a broader involvement in tumorigenesis."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "2", "end_ref": "4"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nFurthermore, in non‐small cell lung cancer, MIR519A1 appears to function as a tumor suppressor by targeting the ephrinA2 receptor (EphA2), thereby enhancing radiosensitivity and inhibiting cell proliferation and migration. Related studies in esophageal squamous cell carcinoma also support a tumor-suppressive role for this miRNA. In addition, altered expression of MIR519A1 in placental tissues has been implicated in pathological conditions such as preeclampsia, where its differential expression correlates with adverse clinical features."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "5", "end_ref": "7"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Kotb Abdelmohsen, Subramanya Srikantan, Yuki Kuwano, et al. 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