Inhibition by berberine of cyclooxygenase-2 transcriptional activity in human colon cancer cells.

The enzyme cyclooxygenase-2 (COX-2) is abundantly expressed in colon cancer cells and plays a key role in colon tumorigenesis. Compounds inhibiting COX-2 transcriptional activity have therefore potentially a chemopreventive property against colon tumor formation. An assay method for estimating COX-2 transcriptional activity in human colon cancer cells was established using a β-galactosidase reporter gene system, and examination was made of various medicinal herbs and their ingredients for an inhibitory effect on COX-2 transcriptional activity. We found that berberine, an isoquinoline alkaloid present in plants of the genera Berberis and Coptis, effectively inhibits COX-2 transcriptional activity in colon cancer cells in a dose- and time-dependent manner at concentrations higher than 0.3 μM. The present findings may further explain the mechanism of anti-inflammatory and anti-tumor promoting effects of berberine.