Abstract
We demonstrated previously that 3-(5′-hydroxymethyl-2′-furyl)-1-benzylindazole (YC-1), an activator of soluble guanylate cyclase (sGC), induces cyclooxygenase-2 (COX-2) expression via cGMP- and p44/42 mitogen-activated protein kinase-dependent pathways in human pulmonary epithelial A549 cells. In this study, we explore the role of Ras, phosphoinositide-3-OH-kinase (PI3K), Akt, and transcription factor nuclear factor-κB (NF-κB) in YC-1–induced COX-2 expression in A549 cells. A Ras inhibitor (manumycin A), a PI3K inhibitor (wortmannin), an Akt inhibitor (1l-6-Hydroxymethyl-chiro-inositol2-[(R)-2-O-methyl-3-O-octadecylcarbonate]), and an NF-κB inhibitor [pyrrolidine dithiocarbamate (PDTC)] all reduced YC-1–induced COX-2 expression. The YC-1–induced increase in COX activity was also blocked by manumycin A, wortmannin, PDTC, and the dominant-negative mutants for Ras (RasN17), Akt (Akt DN), and IκBα (IκBαM). The YC-1–induced increase in Ras activity was inhibited by an sGC inhibitor [1H-(1,2,4)oxadiazolo[4,3-a]quinozalin-1-one (ODQ)], a protein kinase G (PKG) inhibitor [1-oxo-9.12-epoxy-1H-diindolo[1,2,3-fg:3′,2′,1′-kl]pyrrolo[3,4-I][1,6]benzodiazocine-10-carboxylic acid methyl ester (KT-5823)], and manumycin A. YC-1–induced Akt activation was also inhibited by ODQ, KT-5823, manumycin A, and wortmannin. YC-1 caused the formation of an NF-κB–specific DNA-protein complex and an increase in κB-luciferase activity. YC-1–induced κB-luciferase activity was inhibited by ODQ, KT-5823, manumycin A, wortmannin, an Akt inhibitor, PDTC, RasN17, Akt DN, and IκBαM. Likewise, YC-1–induced IKKα/β activation was inhibited by ODQ, KT-5823, manumycin A, wortmannin, and an Akt inhibitor. Furthermore, YC-1–induced COX-2 promoter activity was inhibited by manumycin A, RasN17, Akt DN, PDTC, and IκBαM. Taken together, these results indicate that YC-1 might activate the sGC/cGMP/PKG pathway to induce Ras and PI3K/Akt activation, which in turn initiates IKKα/β and NF-κB activation and finally induces COX-2 expression in A549 cells.
- Received January 16, 2004.
- Accepted June 2, 2004.
- The American Society for Pharmacology and Experimental Therapeutics
MolPharm articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|