Apoptotic activity of the marine diatom Cocconeis scutellum and eicosapentaenoic acid in BT20 cells

Abstract

Context: The marine diatoms Cocconeis scutellum Ehrenberg (Bacillariophyceae) are known to trigger apoptosis in the androgenic gland of the Mediterranean crustacean Hippolyte inermis Leach (Decapoda), affecting the shrimp’s sex reversal.

Objective: The aim of this study was to evaluate a possible apoptotic effect of extracts and fractions from these microalgae also on human tissues.

Materials and methods: The chemical profile of C. scutellum was determined by gas chromatography-mass spectrometry (GC-MS) and, afterwards, organic extracts and fractions from the diatoms were used to treat to breast cancer BT20 cells. Double labeling with annexin V-FITC and isotonic propidium iodide (PI) along with flow cytometry analysis enabled the evaluate of cell apoptosis and viability, whereas hypotonic PI staining was used to analyze the cell cycle in BT20 lines. The involvement of specific caspases was studied by Western blotting.

Results: Results demonstrated that the diethyl ether extract and, in particular, fraction 3, the richest fraction in eicosapentaenoic acid (EPA) from the diethyl ether extract, selectively induced apoptosis (up to 89.2% at 1 μg/well of fraction 3) and decreased viability in BT20 cells. The apoptotic effect was displayed in a concentration and time-dependent manner, by activating caspases-8 and 3, and arresting the progression of the cell cycle from S to G2-M phase. EPA alone showed similar apoptotic effects in BT20 cells.

Discussion and conclusion: The study demonstrates the apoptotic activity of C. scutellum diatoms on breast cancer cells and suggests their potential use as a source of apoptotic compounds.

Keywords::

• Apoptosis
• caspases
• polyunsaturated fatty acids

Acknowledgements

We are grateful to all the other participants of the project, Prof. A. Sagi and his research team (Ben-Gurion University, Beer Sheva, Israel), and Mr. S. Taboada (CEAB-CSIC, Blanes, Spain). Thanks also to Dr. A. Marín (Serveis Cientificotècnics, University of Barcelona) for performing GC-MS analyses, and Mrs. M.P. Pistillo for providing BT20 cells.

Declaration of interest

The study was supported by the European Project PHARMAPOX (FP6-2003-NEST-A/STREP 4800). The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.