Antiproliferative Effects of Vitamin D, DHA and 5‐ Fluorourocil on Breast Cancer

It is well documented that both vitamin D and DHA have antiproliferative effects on a variety of human cancer cells, including breast cancer. Research also shows that a combination approach to cancer treatment is often more effective than any one treatment alone. The purpose of our research was to determine whether the combination of vitamin D (calcitriol) and DHA would slow the progression of human MCF‐7 breast cancer cells more than when they were added alone. We also sought to determine whether these compounds would increase the sensitivity of cells to the antimetabolite chemotherapy drug, 5‐Fluorourocil which is commonly used in the treatment of breast cancer. If either calcitriol or DHA are able to enhance the effects of a chemoptherapeutic agent, it could translate into a lower drug requirement for the patient. This would be beneficial due to the undesirable side effects patients typically experience when taking cytotoxic drugs. In this study, human mammary epithelial cells, MCF‐7s, were treated with 25μM DHA, 100 nM calcitriol, and 15μM 5‐Fluorourocil alone and in multiple combinations for 48 hrs. Cells were then assessed for viability using a fluorescence assay. At 100 nM, calcitriol was ineffective in slowing cell growth. In contrast, both 5‐Fluorourocil and DHA slowed growth significantly. Combining calcitriol and DHA treatments did not improve cell outcome more than treating cells separately. Interestingly, DHA was just as effective as 5‐Fluorourocil in limiting cell growth. Combining cell treatments did not appear to be any more effective than treating cells with only one compound. These results suggest that DHA alone may be just as efficacious as 5‐Fluorourocil in slowing breast cancer progression and may thus offer a dietary approach to breast cancer treatment. This research is supported by the Office of Graduate Research, Central Washington University.