Antioxidants reduce cyclooxygenase-2 expression, prostaglandin production, and proliferation in colorectal cancer cells.

Chinery R, Beauchamp RD, Shyr Y, Kirkland SC, Coffey RJ, Morrow JD
Cancer Res. 1998 58 (11): 2323-7

PMID: 9622066

Increased expression of cyclooxygenase (COX) and overproduction of prostaglandins (PGs) have been implicated in the development and progression of colorectal cancer (CRC). Recent observations suggest that reactive oxygen intermediates play a role in tumor cell growth regulation and expression of the inducible COX, COX-2. We therefore evaluated the effects of various antioxidants on COX expression and cellular growth in the human CRC cell line HCA-7. The antioxidants pyrrolidinedithiocarbamate (PDTC), N-acetylcysteine, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), and U74006 decreased PG production, intracellular redox status, and cellular growth in a concentration-dependent manner. The decrease in cellular growth was associated with the induction of apoptosis. Unlike the selective COX inhibitors 1-[(4-methylsulfonyl)phenyl]-3-trifluoromethyl-5-[(4-fluoro)phenyl]pyraz ole (SC 58125) and (2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide (NS 398) that inhibit COX-2 catalytic activity, these antioxidants decreased COX-2 expression at the transcriptional level. Combined treatment of HCA-7 cells with PDTC and SC 58125 resulted in an additive decrease in PG levels and anchorage-dependent and -independent growth. Furthermore, whereas antioxidants or SC 58125 reduced tumor growth in vivo, coadministration of PDTC and SC 58125 resulted in actual tumor regression. These results suggest that combined therapy with NSAIDs and antioxidants might be useful in the prevention and/or treatment of CRC.

MeSH Terms (19)

Animals Antioxidants Cell Division Colorectal Neoplasms Cyclooxygenase 2 Cyclooxygenase 2 Inhibitors Cyclooxygenase Inhibitors Humans Isoenzymes Male Membrane Proteins Mice Mice, Inbred BALB C Oxidation-Reduction Prostaglandin-Endoperoxide Synthases Prostaglandins Pyrazoles Transcription, Genetic Tumor Cells, Cultured

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