The miR-21/PTEN/Akt signaling pathway is involved in the anti-tumoral effects of zoledronic acid in human breast cancer cell lines

• Published in: Naunyn-Schmiedeberg's archives of pharmacology 2016-05, Vol.389 (5), p.529-538
• Main Authors: Fragni, M., Bonini, S. A., Bettinsoli, P., Bodei, S., Generali, D., Bottini, A., Spano, P. F., Memo, M., Sigala, S.
• Format: Article
• Language: English
• Subjects: Antineoplastic Agents - pharmacology; Apoptosis - drug effects; Biomedical and Life Sciences; Biomedicine; Breast Neoplasms - metabolism; Cell Cycle - drug effects; Cell Line, Tumor; Cell Survival - drug effects; Diphosphonates - pharmacology; Female; Humans; Imidazoles - pharmacology; MicroRNAs - metabolism; Neurosciences; Original Article; Pharmacology/Toxicology; Proto-Oncogene Proteins c-akt - metabolism; PTEN Phosphohydrolase - metabolism; Signal Transduction - drug effects
• ISSN: 0028-1298; 1432-1912
• DOI: 10.1007/s00210-016-1224-8

Preclinical data indicate a direct anti-tumor effect of zoledronic acid (ZA) outside the skeleton, but its molecular mechanism is still not completely clarified. The aim of this study was to investigate the anti-cancer effects of ZA in human breast cancer cell lines, suggesting that they may in part be mediated via the miR-21/PTEN/Akt signaling pathway. The effect of ZA on cell viability was measured by MTT assay, and cell death induction was analyzed using either a double AO/EtBr staining and M30 ELISA assay. A Proteome Profiler Human Apoptosis Array was executed to evaluate the molecular basis of ZA-induced apoptosis. Cell cycle analysis was executed by flow cytometry. The effect of ZA on miR-21 expression was quantified by qRT-PCR, and the amount of PTEN protein and its targets were analyzed by Western blot. ZA inhibited cell growth in a concentration- and time-dependent manner, through the activation of cell death pathways and arrest of cell cycle progression. ZA downregulated the expression of miR-21, resulting in dephosphorilation of Akt and Bad and in a significant increase of p21 and p27 proteins expression. These results were observed also in MDA-MB-231 cells, commonly used as an experimental model of bone metastasis of breast cancer. This study revealed, for the first time, an involvement of the miR-21/PTEN/Akt signaling pathway in the mechanism of ZA anti-cancer actions in breast cancer cells. We would like to underline that this pathway is present both in the hormone responsive BC cell line (MCF-7) as well as in a triple negative cell line (MDA-MB-231). Taken together these results reinforce the use of ZA in clinical practice, suggesting the role of miR-21 as a possible mediator of its therapeutic efficacy.