LncRNA MEG3 Suppresses Prostate Cancer Progression by Mediating Macrophage Polarization via the miR-148a-3p/ARRDC3 Signaling Axis.

Long-chain non-coding RNA (LncRNA) MEG3 significantly influences tumor microenvironment (TME) dynamics and macrophage polarization. However, its specific involvement in prostate cancer (PCa) progression remains unclear. MEG3 exhibited low expression in PCa, and immune infiltration analysis revealed a positive association with M1 macrophages infiltration and a negative association with M2 macrophages infiltration. Immunohistochemical analysis demonstrated increased MEG3 levels, corresponding with upregulated INOS (an M1 marker) and downregulated CD163 (an M2 marker). MEG3 expression was markedly elevated in LPS-induced M1 macrophages and notably reduced in IL-4-induced M2 macrophages. The overexpression of MEG3 significantly enhanced M1 macrophages polarization while suppressing M2 macrophages polarization. Using an online database and a dual luciferase reporter assay, miR-148a-3p was identified as a downstream target of MEG3. Reduced miR-148a-3p expression was observed in LPS-induced M1 macrophages, while an increase was noted in IL-4-induced M2 macrophages. Moreover, MEG3 overexpression's impact on macrophage polarization was nullified following miR-148a-3p mimic transfection. ARRDC3 was validated as a downstream target of miR-148a-3p. The upregulation of ARRDC3 triggered by MEG3 overexpression was effectively suppressed by miR-148a-3p mimics. Additionally, Knockdown of ARRDC3 effectively counteracted the MEG3 overexpression-induced increase in M1 macrophages polarization while simultaneously mitigating the reduction in M2 macrophages polarization. Collectively, MEG3 exhibits reduced expression in PCa and correlates with macrophage infiltration and polarization. Specifically, it drives M1 macrophages polarization while suppressing M2 macrophages polarization via the miR-148a-3p/ARRDC3 axis, thereby impeding tumor immune evasion and restricting PCa progression.