A macrocircular ellagitannin, oenothein B, suppresses mouse mammary tumor gene expression via inhibition of poly(ADP-ribose) glycohydrolase.

Oenothein B, a macrocircular dimeric ellagitannin, was found to be a potent and specific inhibitor of poly(ADP-ribose) glycohydrolase. Oenothein B suppressed glucocorticoid-sensitive mouse mammary tumor virus (MMTV) transcription in 34I cells. This suppression was accompanied by inhibition of glucocorticoid-induced endogeneous de-poly(ADP-ribosyl)ation of high mobility group (HMG) 14 and 17 proteins. These results suggest that de-poly(ADP-ribosyl)ation of these proteins may be closely connected with the events initiating glucocorticoid-sensitive MMTV gene transcription.