Effects of combined tamoxifen and short-term starvation on the gene expression profile of hormone receptor-positive breast cancer cells

Periodic fasting or modified fasting hold promise as strategies to enhance the activity of cancer treatments. We aimed at defining whether culture conditions that mimic the metabolic effects of fasting (1% serum and 0.5 g/L glucose) have an impact on the effects of tamoxifen, a broadly used selective estrogen receptor modulator, on the gene expression profile of MCF7 cells, a hormone receptor+ breast cancer cell line. MCF7 breast cancer cells were plated in 10 cm dishes in regular DMEM medium containing 10% FBS and 1.0 g/L glucose. 24 h later, the cell medium was removed and cells were incubated for 24h either in the same medium or in low-glucose (0.5 g/L) DMEM medium with 1 % FBS (short-term starvation conditions). 24h later, tamoxifen (5 uM) or vehicle were added to the culture medium. 24 h later, cells were used for RNA extraction and gene expression was assessed by Agilent gene expression microarrays. Direct comparisons were performed in order to obtain differential gene expression gene lists.