Human T47D-ERβ breast cancer cells with tetracycline-dependent ERβ expression reflect ERα/ERβ ratios in rat and human breast tissue

Deconjugation of soy isoflavone glucuronides needed for estrogenic activity

“…Fig. 4 presents the dose-dependent increase in proliferation of T47D-ERb cells with an ERa/ERb ratio mimicking the ERa/ERb ratio in normal rat and human breast tissue by addition of 100 nM tetracycline (Evers et al, 2013). Again, low concentrations of the SIF reduced the proliferation as compared to E2, and at high concentrations the maximum proliferation induced by the aglycones is higher than that of E2 ( Fig.…”

“…These cells were also grown in a 1:1 mixture of F12 and DMEM (31331-028) supplemented with 5% FCS plus 100 ng tetracycline/ ml. With this amount of tetracycline the ERa/ERb ratio becomes comparable with that of normal human breast tissue based on Western blot analysis carried out by Evers et al (2013). The cells were reselected (with 0.5 lg/ml puromycin) every 10 passages (about 3 weeks) to prevent loss of ERb and its related expression of enhanced green fluorescent protein (EGFP) activity (Sotoca et al, 2008).…”

“…The T47D-ERb cells with tetracycline dependent inhibition of expression of ERb allowed mimicking the ERa/ERb ratio of normal rat and human breast tissue (Evers et al, 2013). The cell proliferation assay was performed using the method described by Sotoca et al (2010).…”

“…In estrogen sensitive tissues, the estrogenic responses are mediated by estrogen receptors (ERs) of which an alpha and beta form exist. The relative occurrence of ERa and ERb is tissue dependent, for example, ERa is predominant in the mammary gland, epididymis, testis, uterus, kidney and pituitary gland whereas more ERb than ERa is present in the prostate, bladder and lungs (Evers et al, 2013;Kuiper et al, 1997;Pearce and Jordan, 2004;Pfaffl et al, 2001). In certain types of breast cancer, the ERa/ERb ratio is significantly increased compared to healthy tissue (Bardin et al, 2004a;Leygue et al, 1998), mainly due to a decrease of the ERb levels (Lazennec et al, 2001;Rutherford et al, 2000).…”

“…However, in the reported in vitro studies, no attention was paid to use ERa and ERb ratios reflecting the ratios present in specific estrogen sensitive tissues. In the present study an in vitro cell model was used where in T47D-ERb breast cancer cells the genetically enhanced ERb levels could be suppressed by tetracycline to achieve an ERa/ERb ratio which according to Evers et al (2013) is similar to that in normal human breast tissue. This is important, given that due to differences in ERa/ERb ratios, the effect of estrogen active compounds on inhibition or stimulation of cell proliferation can vary significantly between different estrogen sensitive tissues and cell models.…”