The Effect of Seal Oil on Paclitaxel Induced Cytotoxicity and Apoptosis in Breast Carcinoma MCF-7 and MDA-MB-231 Cell Lines

Abstract

Some studies have suggested that ω-3 polyunsaturated fatty acids (PUFAs) have an inhibitory effect on the growth of cancer cells and therefore have the potential to increase the efficacy of cancer chemotherapeutic drugs. Considering that ω-3 PUFAs are present abundantly in harp seal oil, we investigated the effect of seal oil on the cytotoxicity and apoptosis induced by paclitaxel in 2 breast cancer cell lines, MCF-7 and MDA-MB-231, respectively. Cytotoxicity evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay revealed that the concentration of paclitaxel that is required for 50% inhibition of cell growth in the presence of seal oil was significantly lower than that of paclitaxel alone. Apoptosis assessment based on morphological changes and DNA fragmentation results indicated that more cells treated with paclitaxel in combination with seal oil underwent apoptosis than with paclitaxel alone. Western blot analysis showed that the expression of B cell lymphoma-2 (Bcl-2) protein, an apoptosis inhibitory protein, in both cell lines was decreased more significant by paclitaxel in combination with seal oil than by paclitaxel alone. In addition, seal oil alone was found to induce apoptosis in both cell lines tested, which appeared to be due to the increased intracellular lipid peroxides produced. It is therefore concluded that paclitaxel in combination with seal oil demonstrated enhanced cytotoxicity and apoptosis in MCF-7 and MDA-MB-231 cells compared to paclitaxel alone, and the use of seal oil may be beneficial in the treatment of breast cancer.

Acknowledgments and Notes

We would like to thank Ms. Jieying Xiong, Division of Basic Sciences, Faculty of Medicine, Memorial University of Newfoundland, for her technical support. This research was supported by the Canadian Institutes of Health Research. Hu Liu was a recipient of the Rx&D-HRF/CIHR Career Award in Health Sciences funded by the Health Research Foundation of Canada's Research Based Pharmaceutical Companies (Rx&D) and CIHR (1999–2004).

Notes

^a Abbreviation is as follows: IC_50,inhibitory concentration at 50%. Results represent mean ± SD from 4 separate experiments. Statistical analysis was performed using the Student t-test.

∗Statistically significant at P < 0.05.

∗∗Statistically significant at P < 0.01 compared to paclitaxel alone in the same cell line.

^a Results represent mean ± SD from 4 separate experiments. Statistical analysis was done using the Student t-test.

∗Statistically significant at P < 0.05 and

∗∗Statistically significant at P < 0.01 compared to control.

^a Results represent mean ± SD from 4 separate experiments. Statistical analysis was done using the Student t-test.

∗∗Statistically significant at P < 0.01 compared to control in the same cell line.

^a Data represent mean ± SD from 3 separate experiments. Statistical analysis was performed using the Student t-test.

∗Statistically significant at P < 0.05 in comparison with control in the same cell line.