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Evidence-Based Complementary and Alternative Medicine
Volume 2015, Article ID 908493, 9 pages
http://dx.doi.org/10.1155/2015/908493
Research Article

Oleuropein-Enriched Olive Leaf Extract Affects Calcium Dynamics and Impairs Viability of Malignant Mesothelioma Cells

1Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Via De Marini 6, 16149 Genova, Italy
2Dipartimento di Scienze e Innovazione Tecnologica (DISIT), Università del Piemonte Orientale, Viale Teresa Michel 11, 15121 Alessandria, Italy
3Dipartimento di Scienze della Terra dell’Ambiente e della Vita (DISTAV), Università degli Studi di Genova, Corso Europa 26, 16132 Genova, Italy

Received 14 September 2015; Revised 3 November 2015; Accepted 11 November 2015

Academic Editor: I-Min Liu

Copyright © 2015 Carla Marchetti et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Malignant mesothelioma is a poor prognosis cancer in urgent need of alternative therapies. Oleuropein, the major phenolic of olive tree (Olea europaea L.), is believed to have therapeutic potentials for various diseases, including tumors. We obtained an oleuropein-enriched fraction, consisting of 60% w/w oleuropein, from olive leaves, and assessed its effects on intracellular Ca2+ and cell viability in mesothelioma cells. Effects of the oleuropein-enriched fraction on Ca2+ dynamics and cell viability were studied in the REN mesothelioma cell line, using fura-2 microspectrofluorimetry and MTT assay, respectively. Fura-2-loaded cells, transiently exposed to the oleuropein-enriched fraction, showed dose-dependent transient elevations of cytosolic Ca2+ concentration (). Application of standard oleuropein and hydroxytyrosol, and of the inhibitor of low-voltage T-type Ca2+ channels NNC-55-0396, suggested that the effect is mainly due to oleuropein acting through its hydroxytyrosol moiety on T-type Ca2+ channels. The oleuropein-enriched fraction and standard oleuropein displayed a significant antiproliferative effect, as measured on REN cells by MTT cell viability assay, with IC50 of 22 μg/mL oleuropein. Data suggest that our oleuropein-enriched fraction from olive leaf extract could have pharmacological application in malignant mesothelioma anticancer therapy, possibly by targeting T-type Ca2+ channels and thereby dysregulating intracellular Ca2+ dynamics.