Abstract
Different hormonal therapies are used for estrogen receptor positive (ER+) breast cancers, being the third-generation of aromatase inhibitors (AIs), an effective alternative to the classical tamoxifen. AIs inhibit the enzyme aromatase, which is responsible for catalyzing the conversion of androgens to estrogens. In this study, it was evaluated the effects of several steroidal AIs, namely 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), on cell proliferation, cell cycle progression and cell death in an ER+ aromatase-overexpressing human breast cancer cell line (MCF-7aro). All AIs induced a decrease in cell proliferation and these anti-proliferative effects were due to a disruption in cell cycle progression and cell death, by apoptosis. AIs 1 and 16 caused cell cycle arrest in G0/G1, while AIs 12 and 13a induced an arrest in G2/M. Moreover, it was observed that these AIs induced apoptosis by different pathways, since AIs 1, 12 and 13a activated the apoptotic mitochondrial pathway, while AI 16 induced apoptosis through activation of caspase-8. These results are important for the elucidation of the cellular effects of steroidal AIs on breast cancer cells and will also highlight the importance of AIs as inducers of apoptosis in hormone-dependent breast cancers.
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Abbreviations
- MCF-7aro cells:
-
ER-positive aromatase-overexpressing breast cancer cell line
- ER:
-
Estrogen receptor
- SERM:
-
Selective ER modulator
- AIs:
-
Aromatase inhibitors
- DISC:
-
Death-inducing signaling complex
- 1 :
-
3β-hydroxyandrost-4-en-17-one
- 12 :
-
Androst-4-en-17-one
- 13a :
-
4α,5α-epoxyandrostan-17-one
- 16 :
-
5α-androst-2-en-17-one
- MEM:
-
Eagles’s minimum essential medium
- FBS:
-
Fetal bovine serum
- CFBS:
-
Pre-treated charcoal heat-inactivated fetal bovine serum
- T:
-
Testosterone
- PI:
-
Propidium iodide
- PS:
-
Phosphatidylserine
- ∆Ψm:
-
Mitochondrial transmembrane potential
- DiOC6(3):
-
3,3′-dihexyloxacarbocyanine iodide
- 7-AAD:
-
7-aminoactinomycin D
- STS:
-
Staurosporine
- CCCP:
-
Carbonyl cyanide m-chlorophenylhydrazone
- RLU:
-
Relative luminescence units
- ROS:
-
Intracellular reactive oxygen species
- DCFH2-DA:
-
2′,7′-dichlorodihydrofluorescein diacetate
- PMA:
-
Phorbol 12-myristate 13-acetate
- MFI:
-
Mean fluorescence intensity
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Acknowledgments
The authors are grateful to Fundação para a Ciência e Tecnologia (FCT) for the PhD grants attributed to Cristina Amaral (SFRH/BD/48190/2008) and Carla Varela (SFRH/BD/44872/2008). This work was funded by FEDER Funds through the Operational Competitiveness Program- COMPETE and by National Funds through FCT under the project FCOMP-01-0124-FEDER-020970 (PTDC/QUI-BIQ/120319/2010). We thank Dr. Shiuan Chen for kindly supplying MCF-7aro cells.
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The authors have no conflict of interest to declare.
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Amaral, C., Varela, C., Borges, M. et al. Steroidal aromatase inhibitors inhibit growth of hormone-dependent breast cancer cells by inducing cell cycle arrest and apoptosis. Apoptosis 18, 1426–1436 (2013). https://doi.org/10.1007/s10495-013-0879-6
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DOI: https://doi.org/10.1007/s10495-013-0879-6