TY - JOUR T1 - Hypersensitivity and Growth Adaptation of Oestrogen-deprived MCF-7 Human Breast Cancer Cells JF - Anticancer Research JO - Anticancer Res SP - 99 LP - 105 VL - 34 IS - 1 AU - PHILIPPA D. DARBRE Y1 - 2014/01/01 UR - http://ar.iiarjournals.org/content/34/1/99.abstract N2 - Background: Efficacy of endocrine therapy is compromised when human breast cancer cells circumvent imposed growth inhibition. The model of long-term oestrogen-deprived MCF-7 human breast cancer cells has suggested the mechanism results from hypersensitivity to low levels of residual oestrogen. Materials and Methods: MCF-7 cells were maintained for up to 30 weeks in phenol-red-free medium and charcoal-stripped serum with 10−8 M 17β-oestradiol and 10 μg/ml insulin (stock 1), 10−8 M 17β-oestradiol (stock 2), 10 μg/ml insulin (stock 3) or no addition (stock 4). Results: Loss of growth response to oestrogen was observed only in stock 4 cells. Long-term maintenance with insulin in the absence of oestradiol (stock 3) resulted in raised oestrogen receptor-alpha (ERα) levels (measured by western immunoblotting) and development of hypersensitivity (assayed by oestrogen-responsive reporter gene induction and dose response to oestradiol for proliferation under serum-free conditions), but with no loss of growth response to oestrogen. Conclusion: Hypersensitivity can develop without any growth adaptation and therefore is not a prerequisite for loss of growth response in MCF-7 cells. ER -