Thymoquinone Upregulates microRNA-199a-3p and Downregulates COX-2 Expression and PGE2 Production via Deactivation of p38/ERK/JNK-MAPKs and p65/p50-NF-κB Signaling in Human Lung Cancer Cells

Chronic inflammation driven by Cyclooxygenase-2 (COX-2) overexpression plays a key role in lung cancer (LC) progression, making it a critical therapeutic target. This study explores thymoquinone (TQ), a potent bioactive phytochemical derived from Nigella sativa, known for its anti-inflammatory and anti-cancer effects, focusing on its ability to suppress lipopolysaccharide (LPS)-induced COX-2 expression via microRNA hsa-miR-199a-3p modulation in LC cells. Using A549 and SHP-77 LC cells, we tested the effect of TQ under LPS stimulation and miRNA inhibition. Advanced techniques like TaqMan qPCR, luciferase reporter gene constructs, and anti-miRNA transfection confirmed that miR-199a-3p directly silences COX-2. Western blot and ELISA assays revealed that TQ dramatically reduces COX-2 protein and PGE2 levels by boosting miRNA-199a-3p. Importantly, TQ also blocked MAPK (p38, JNK, ERK) and NF-κB activation, even when miR-199a-3p was suppressed, proving its multi-targeted action beyond miRNA regulation. These findings reveal a novel anti-inflammatory mechanism, where TQ curbs COX-2-driven inflammation by enhancing miR-199a-3p, simultaneously shutting down pro-cancer MAPK/NF-κB signaling pathways. Given the strong link between chronic inflammation and LC aggressiveness, this study positions TQ as a promising therapeutic candidate, especially for inflammation-mediated lung cancer progression. Its dual ability to modulate miRNA and key signaling cascades makes it a compelling option for future LC treatment strategies.