title: Effects of steroidal aromatase inhibitors on sensitive and resistant breast cancer cells: aromatase inhibition and autophagy.
abstract: Several therapeutic approaches are used in estrogen receptor positive (ER(+)) breast cancers, being one of them the use of aromatase inhibitors (AIs). Although AIs demonstrate higher efficacy than tamoxifen, they can also exhibit de novo or acquired resistance after prolonged treatment. Recently, we have described the synthesis and biochemical evaluation of four steroidal AIs, 3β-hydroxyandrost-4-en-17-one (1), androst-4-en-17-one (12), 4α,5α-epoxyandrostan-17-one (13a) and 5α-androst-2-en-17-one (16), obtained from modifications in the A-ring of the aromatase substrate, androstenedione. In this study, it was investigated the biological effects of these AIs in different breast cancer cell lines, an ER(+) aromatase-overexpressing human breast cancer cell line (MCF-7aro cells), an estrogen-receptor negative (ER(-)) human breast cancer cell line (SK-BR-3 cells), and a late stage of acquired resistance cell line (LTEDaro cells). The effects of an autophagic inhibitor (3-methyladenine) plus AIs 1, 12, 13a or exemestane in LTEDaro cells were also studied to understand the involvement of autophagy in AI acquired resistance. Our results showed that these steroids inhibit aromatase of MCF-7aro cells and decrease cell viability in a dose- and time-dependent manner. The new AI 1 is the most potent inhibitor, although the AI 12 demonstrates to be the most effective in decreasing cell viability. Besides, and in advantage over exemestane, AIs 12 and 13a also reduced LTEDaro cells viability. The use of the autophagic inhibitor allowed AIs to diminish viability of LTEDaro cells, presenting a similar behavior to the sensitive cells. Thus, inhibition of autophagy may sensitize hormone-resistant cancer cells to anti-estrogen therapies.
authors: Laboratory of Biochemistry, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Rua Jorge Viterbo Ferreira, no 228, 4050-313 Porto, Portugal.
authors: Cristina
authors: C
authors: Amaral
authors: Carla
authors: C
authors: Varela
authors: Margarida
authors: M
authors: Azevedo
authors: Elisiário Tavares
authors: ET
authors: da Silva
authors: Fernanda M F
authors: FM
authors: Roleira
authors: Shiuan
authors: S
authors: Chen
authors: Georgina
authors: G
authors: Correia-da-Silva
authors: Natércia
authors: N
authors: Teixeira
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000731:Androstanes / Q000737:chemistry / Q000494:pharmacology; D047072:Aromatase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D001343:Autophagy / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D004965:Estrogen Antagonists / Q000494:pharmacology; D005260:Female; D006801:Humans; D061986:MCF-7 Cells; D009376:Neoplasms, Hormone-Dependent / Q000188:drug therapy / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism*; D013739:Testosterone / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000731:Androstanes; D047072:Aromatase Inhibitors; D004965:Estrogen Antagonists; D011960:Receptors, Estrogen; D013739:Testosterone; C025946:3-methyladenine; D019869:Phosphatidylinositol 3-Kinases; D000225:Adenine