The effect of fish-oil derived eicosapentaenoic acid on cell proliferation and caspase-3 activity in human colorectal cancer cell line

Background: Using natural compounds with low toxicity on normal cells and high efficacy on malignant cells is highly appreciated for treatment of colorectal cancer (CRC). In the present study, the effect of fish-oil derived eicosapentaenoic acid (EPA) on the cell number, cell proliferation rate and caspase-3 enzyme activity in LS174T human colorectal cancer cell line was investigated. Methods: This experimental study was performed in cell culture lab, Institute of Biotechnology, affiliated to the Urmia University, Urmia, Iran from April to September 2017. LS174T colorectal cancer cells at a density of 5×105 cells per well were cultured in RPMI-1640 medium supplemented with 10% fetal bovine serum (FBS) and kept at 37 °C in a humidified incubator with 5% CO2 for 24 hours. Thereafter, the cells were treated with 50, 100, 150 and 200 μmol EPA for 48 hours and cell numbers were counted using neobauer chamber and caspase-3 activities were measured by performing the caspase-3 colorimetric assay (Abcam, Cambridge, MA, USA). Furthermore, 5×103 LS174T colorectal cancer cells were cultured and treated with the above-mentioned EPA concentrations for 24, 48 and 72 hours, after which cell proliferation rate was evaluated by WST-1 proliferation assay (Roche Diagnostics, Mannheim, Germany). Results: Treatment of LS174T colorectal cancer cells with 50, 100, 150 and 200 μmol EPA decreased the number of cells in a dose-dependent manner. We also found that treatment of malignant cells with increasing EPA concentrations (50 to 200 μmol) significantly decreased cell proliferation in a dose and time dependent manner. After a 72 hours treatment of LS174T cells with 200 μmol EPA, cell proliferation was calculated to be 30.3% compared to untreated control cells. Following 48 hours treatment, caspase-3 activity increased with increasing EPA concentrations in which at 200 μmol EPA, caspase-3 activity increased by 3.4 fold compared to untreated control cells. Conclusion: Fish-oil derived eicosapentaenoic acid as a safe compound decreases the number of colorectal cancer cells and their proliferation rate and activates caspase-3 enzyme, as an executor protein in apoptosis