Comparison of dienogest effects upon 3,3′–diindolylmethane supplementation in models of endometriosis and clinical cases

Abstract Dienogest (DNG) administration is a well-established treatment for endometriosis but bleeding irregularities remain its main disadvantage. Changes in diet, mainly to vegetable consumption, are beneficial in the treatment of estrogen-related pathologies but their use for endometriosis has been poorly studied. In this study, addition of the phytochemical 3,3′-diindolylmethane (DIM) to DNG therapy has been investigated in in vitro and ex vivo models for endometriosis and in a small cohort of women with endometriosis. Endometrial Ishikawa cells were treated with DNG or DIM at dosages from 10 −10  M to 10 −5  M for up to 72 h. Cell proliferation was measured by assessing BrdU incorporation. Endometrial tissue from women with endometriosis and controls was incubated with DNG or a combination of DNG and DIM. Tissue viability was determined using a modified colorimetric MTS assay. 17β-estradiol secretion was quantified by an electro-chemiluminescence immunoassay. Finally, DNG as monotherapy or in combination with DIM was randomly administered to women with endometriosis (n = 8) over 3 months. Bleeding patterns and associated pelvic pain were assessed by Visual Analogue Scale (VAS). DNG and DIM significantly reduced cell proliferation in Ishikawa cells. Ex vivo, DIM reduced viability and estradiol secretion specifically in endometriotic but not in normal endometrial tissue. This effect was enhanced by combination with DNG. Endometriosis associated pelvic pain was significantly reduced in patients taking the DNG-DIM combination therapy compared to those taking DNG alone. Bleeding pattern (number and duration of episodes) was significantly improved by addition of DIM to the DNG treatment. In conclusion, addition of DIM enhances effects of DNG ex vivo and may ameliorate bleeding patterns in endometriosis patients.