Prostaglandin-endoperoxide synthase 2

Overview

Prostaglandin-endoperoxide synthase 2, encoded by the PTGS2 gene and commonly referred to as cyclooxygenase-2 (COX-2), is a bifunctional enzyme that catalyzes two sequential steps in the biosynthesis of prostaglandins from arachidonic acid: the cyclooxygenase reaction (converting arachidonic acid to prostaglandin G2) and the peroxidase reaction (reducing PGG2 to prostaglandin H2, or PGH2). PGH2 is then converted by downstream synthases into bioactive prostanoids including prostaglandin E2 (PGE2), thromboxanes, and prostacyclins. Unlike its constitutively expressed isoform COX-1 (PTGS1), COX-2 is an inducible enzyme whose expression is tightly regulated by pro-inflammatory stimuli, growth factors, cytokines such as interleukin-1 beta and interleukin-6, and transcription factors including nuclear factor kappa B (NF-κB) and MAPK signaling cascades. Its expression is normally low or absent in most tissues under homeostatic conditions but is rapidly upregulated in response to inflammatory, mitogenic, or oncogenic signals.

The pharmacological importance of PTGS2 is substantial. Non-steroidal anti-inflammatory drugs (NSAIDs) exert their analgesic and anti-inflammatory effects largely through inhibition of COX enzymes, and selective COX-2 inhibitors (coxibs)—including celecoxib, etoricoxib, and meloxicam—were developed to provide anti-inflammatory efficacy while reducing the gastrointestinal side effects associated with non-selective COX inhibition. Beyond inflammation and pain, PTGS2 is upregulated in a broad spectrum of cancers, where it promotes tumor growth, angiogenesis, immune evasion, and metastasis, partly through production of PGE2. This breadth of pathological relevance has established PTGS2 as one of the most extensively studied therapeutic targets in biomedicine.

Focus of Latest Publications

Recent publications have continued to position prostaglandin-endoperoxide synthase 2 (PTGS2/COX-2) as a central inflammatory and disease-modifying target across diverse therapeutic areas. Several studies focused on identifying natural products or synthetic small molecules with COX-2 inhibitory activity, often combining experimental screening with molecular docking or network pharmacology. For example, phenylpropanoids from Dendropanax proteus root extract were shown to inhibit COX-2 and reduce COX-2 and prostaglandin E2 expression in TNF-α-stimulated MH7A cells, supporting their potential in rheumatoid arthritis. Similarly, compounds from Curcumae Rhizoma were linked to attenuation of COX-2-mediated neuroinflammation in ischemic stroke, while Convolvulus oxyphyllus extracts and their selenium nanoparticle formulations downregulated COX2 expression in anti-inflammatory assays. Other recent work identified COX-2 as a key target in plant-derived or food-derived candidates, including avenanthramide C, garlic-derived peptides, and 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone, with computational and experimental data supporting anti-inflammatory or metabolic benefits.

COX-2 has also been explored in the context of rational drug design and multitarget inhibitor development. New polyhydroxylated bis-chalcones, pyrimidine derivatives, thiadiazole derivatives, and zingerone-1,2,3-triazole hybrids were synthesized and evaluated as COX-2-selective or COX-2-containing multitarget agents, with docking studies used to explain potency and selectivity. In these studies, the compounds generally showed favorable COX-2 binding and, in some cases, broader anti-inflammatory or anticancer profiles. One pyrimidine derivative demonstrated stronger COX-2 inhibition than celecoxib and Diclofenac sodium, while also suppressing 5-LOX, IL-6, and reactive oxygen species. A chalcone-paracetamol hybrid was reported to inhibit COX-2 alongside EGFR and VEGFR-2, and a dual COX-2/HDAC6 inhibitor series was developed for Alzheimer’s disease, with one lead compound reducing inflammatory mediators including COX-2, IL-1β, IL-6, and TNF-α.

Beyond direct inhibition, PTGS2 was incorporated into more advanced therapeutic strategies. A COX-2 PROTAC nanodrug was designed to degrade intracellular COX-2 via the ubiquitin-proteasome system, while also repolarizing macrophages toward an anti-inflammatory phenotype and improving cartilage repair in osteoarthritis models. In oncology, COX-2 was targeted in combination approaches such as a dual c-Met/COX-2 inhibitor for gastric and colorectal cancers, a COX-2-targeting hydrogel with meloxicam for postoperative recurrence prevention, and a kaempferitrin-based strategy to potentiate trastuzumab efficacy in HER2-positive gastric cancer by inhibiting COX-2 and ERK signaling. COX-2 was also implicated in tumor ecosystem regulation in nanoparticle-based delivery systems and in studies of environmental carcinogens, where PTGS2 emerged among high-affinity targets.

Additional publications reinforced the broad relevance of PTGS2 in inflammatory and immune-related disease networks. In Clostridioides difficile infection, Ptgs2 was identified among core host-response genes associated with toxin-driven inflammatory programs. In asthma, PTGS2 was upregulated downstream of the Fra2/LCN2 axis during PM2.5-induced macrophage ferroptosis. In ulcerative colitis and chronic kidney disease, PTGS2 appeared within arachidonic acid metabolism-centered mechanisms, including formula-based interventions that modulated COX-2 alongside other enzymes. Collectively, these studies highlight PTGS2/COX-2 as a recurring target in recent work spanning natural products, synthetic chemistry, nanomedicine, and multi-omics-guided disease mechanism studies.

Key Publications

• NEWJul Fluorescent labeled enzyme immobilized on chitosan-coated magnetic microspheres for potential cyclooxygenase-2 inhibitors screening accompanied with molecular modeling and in situ cell imaging. (Mikrochimica acta, 2026, PMID 42393368): "...to specifically screen and evaluate the activity of potential COX-2 inhibitors derived from Yaobitong capsules (YBTC)."
• NEWJun A COX-2 PROTAC Nanodrug for osteoarthritis therapy via enhancing cartilage repair and reprogramming macrophage polarization. (Journal of controlled release : official journal of the Controlled Release Society, 2026, PMID 42365877): "Inhibition of cyclooxygenase-2 (COX-2) represents a promising approach for OA management, but its application is limited by drug-related side effects."
• NEWJun Neuroprotective efficacy of Curcumae Rhizoma against ischemic stroke via attenuation of COX-2-mediated neuroinflammation: a systematic study predicting thrombin inhibition and highlighting alexandrin and hederagenin. (Metabolic brain disease, 2026, PMID 42301551): "Molecular docking revealed that alexandrin and hederagenin exhibited potent binding affinities for COX-2 and thrombin."
• Jun Integrating machine learning and WGCNA to identify core candidate genes and decipher immune-related molecular networks in TcdA/TcdB-associated CDI. (Antonie van Leeuwenhoek, 2026, PMID 42230843): "Machine learning algorithms further narrowed these to nine core genes: Areg, Ptgs2, Cd40, Tlr7, Aif1, Cxcl10, Il6, Cybb, and Nos2."
• May Targeting the Fra2/LCN2 axis attenuates PM2.5-aggravated asthma by suppressing M2 macrophage ferroptosis. (Redox biology, 2026, PMID 42214888): "The Fra2/LCN2 axis activation triggers ferroptosis via coordinated downregulation of FTH1 and upregulation of ACSL4 and PTGS2."
• Jun Multi-target mechanisms of 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone from Syzygium nervosum DC. flower buds in alleviating obesity and metabolic complications: An integrated study combining network pharmacology and experimental validation. (European journal of pharmacology, 2026, PMID 42140514): "Analysis identified 92 common targets, with IL-6, IL1B, TNF, MMP9, and PTGS2 confirmed as core targets."
• May Biogenic selenium extract-mediated and total Convolvulus oxyphyllus extracts suppress IL6 and COX2 expression: insights from LC-MS metabolite profiling and molecular docking. (Scientific reports, 2026, PMID 42128884): "Total alcohol extract and extract-mediated Se-NPs of C. oxyphyllus were evaluated for their ability to modulate IL6 and COX2 expression using quantitative real-time PCR (qRT-PCR)."
• Jun Protection of skin from UVB-induced photoaging: Antioxidant and anti-inflammatory effects of avenanthramide C from oat sprout extract via suppression of MAPK pathways. (Journal of photochemistry and photobiology. B, Biology, 2026, PMID 42102478): "AVN C also suppressed the production of inflammatory mediators, including COX-2, IL-1β, and TNF-α, through the inhibition of nuclear factor-kappa B (NF-κB) and upstream MAPK signaling."
• May Meloxicam-1-d-MT Dual-Drug Hydrogel Serves as an Immunomodulator to Reverse Tumor Postoperative Recurrence and Metastasis. (ACS applied materials & interfaces, 2026, PMID 42081317): "Here, we design and construct an in situ injectable therapeutic hydrogel encapsulating 1-methyl-d-tryptophan (1-d-MT), a small-molecule competitive inhibitor of indoleamine 2,3-dioxygenase, and meloxicam, a selective inhibitor of cyclooxygenase-2 (Ge1MT/Mel hydrogel) to prevent postoperative tumor metastasis and relapse."
• May Celecoxib Mitigates Paclitaxel-Induced Peripheral Neuropathy Through Modulation of the COX-2/PGE2 Pathway in Rats. (FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 2026, PMID 42048120): "Celecoxib also downregulated paclitaxel-induced upregulation of COX-2, PGE2, and MHC in these tissues."