DNA-hypomethylating agent, 5'-azacytidine, induces cyclooxygenase-2 expression via the PI3-kinase/Akt and extracellular signal-regulated kinase-1/2 pathways in human HT1080 fibrosarcoma cells.

Abstract

The cytosine analogue 5'-azacytidine (5'-aza) induces DNA hypomethylation by inhibiting DNA methyltransferase. In clinical trials, 5'-aza is widely used in epigenetic anticancer treatments. Accumulated evidence shows that cyclooxygenase-2 (COX-2) is overexpressed in various cancers, indicating that it may play a critical role in carcinogenesis. However, few studies have been performed to explore the molecular mechanism underlying the increased COX-2 expression. Therefore, we tested the hypothesis that 5'-aza regulates COX-2 expression and prostaglandin E2 (PGE2) production. The human fibrosarcoma cell line HT1080, was treated with various concentrations of 5'-aza for different time periods. Protein expressions of COX-2, DNA (cytosine-5)-methyltransferase 1 (DNMT1), pAkt, Akt, extracellular signal-regulated kinase (ERK), and phosphorylated ERK (pERK) were determined using western blot analysis, and COX-2 mRNA expression was determined using RT-PCR. PGE2 production was evaluated using the PGE2 assay kit. The localization and expression of COX-2 were determined using immunofluorescence staining. Treatment with 5'-aza induces protein and mRNA expression of COX-2. We also observed that 5'-aza-induced COX-2 expression and PGE2 production were inhibited by S-adenosylmethionine (SAM), a methyl donor. Treatment with 5'-aza phosphorylates PI3-kinase/Akt and ERK-1/2; inhibition of these pathways by LY294002, an inhibitor of PI3-kinase/Akt, or PD98059, an inhibitor of ERK-1/2, respectively, prevents 5'-aza-induced COX-2 expression and PGE2 production. Overall, these observations indicate that the hypomethylating agent 5'-aza modulates COX-2 expression via the PI3-kinase/Akt and ERK-1/2 pathways in human HT1080 fibrosarcoma cells.

• Authors: Seon-Mi Yu, Song-Ja Kim
• Journal: International journal of oncology (Int J Oncol) Vol. 47 Issue 4 Pg. 1469-75 (Oct 2015) ISSN: 1791-2423 [Electronic] Greece
• PMID: 26238650 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antimetabolites, Antineoplastic
• Cyclooxygenase 2
• Phosphatidylinositol 3-Kinases
• Proto-Oncogene Proteins c-akt
• Dinoprostone
• Azacitidine

Topics

• Antimetabolites, Antineoplastic (pharmacology)
• Azacitidine (pharmacology)
• Blotting, Western
• Cell Line, Tumor
• Cyclooxygenase 2 (biosynthesis)
• Dinoprostone (biosynthesis)
• Fibrosarcoma (enzymology, pathology)
• Fluorescent Antibody Technique
• Humans
• MAP Kinase Signaling System (drug effects)
• Phosphatidylinositol 3-Kinases (metabolism)
• Proto-Oncogene Proteins c-akt (metabolism)
• Reverse Transcriptase Polymerase Chain Reaction
• Signal Transduction (drug effects)