Ketogenic diets have the potential to lower glucose availability to cancer cells. However, the effect that the resulting increase in ketone bodies has on cancer cells is not fully understood. The present study explored the effect of β-hydroxybutyrate (BHB) on glucose-deprived MCF-7 and T47D breast cancer cells. Cell proliferation was decreased in response to lower glucose conditions, which could not be rescued consistently by 10 or 25 mM BHB supplementation. In addition, gene expression levels were altered when cells were glucose deprived. Reducing glucose availability of cancer cells to 225 mg/l for 4 days significantly decreased the expression of 113 genes and increased the expression of 100 genes in MCF-7 breast cancer cells, and significantly decreased the expression of 425 genes and increased the expression of 447 genes in T47D breast cancer cells. Pathway enrichment analysis demonstrated that glucose deprivation decreased activity of the Hippo-Yap cell signaling pathway in MCF-7 breast cancer cells, whereas it increased the expression of genes in the NRF2-pathaway and genes regulating ferroptosis in T47D breast cancer cells. Treatment of glucose-deprived cells with 10 or 25 mM BHB significantly changed the expression of 14 genes in MCF-7 breast cancer cells and 40 genes in T47D breast cancer cells. No significant pathway enrichment was detected when glucose-deprived cells were treated with BHB. Both cell lines expressed the enzymes (OXCT1/2, BDH1 and ACAT1/2) responsible for metabolizing BHB to acetyl-CoA, yet expression of these enzymes was not altered by either glucose deprivation or BHB treatment. In the publicly available The Cancer Genome Atlas (TCGA), increased expression of ketone body-catabolizing enzymes was observed in various types of cancer based on mRNA expression z-scores. Increased expression of BDH1 and ACAT1 significantly decreased overall survival of patients with breast cancer in TCGA studies, while decreased OXCT1 expression non-significantly decreased overall survival. In conclusion, neither MCF-7 nor T47D breast cancer cells were affected by BHB during glucose deprivation; however, screening of tumors for activation of ketone body-metabolizing enzymes may be able to identify patients that will benefit from ketogenic diet interventions.

Ketogenic diets have the potential to lower glucose availability to cancer cells. The effect that the resulting increase in ketone bodies has on cancer cells is not fully understood. Here we explored the effect of beta-hydroxybutyrate (BHB) on glucose deprived MCF-7 and T47D breast cancer cells. Cell proliferation was decreased with lower glucose conditions which could not be rescued by either 10 mM or 25 mM BHB supplementation. Gene expression changes were altered when cells were glucose deprived. Smaller changes were observed when gene expression changes were compared between glucose deprived cells and those treated with BHB. Pathway enrichment analysis demonstrated that glucose deprivation decreased activity of the Hippo-Yap cell signaling pathway in MCF-7 breast cancer cells, while it increased expression of genes of the NRF2-pathawy and genes regulating ferroptosis in T47D breast cancer cells. No significant pathway enrichment was found when glucose deprived cells were treated with BHB. Both cell lines expressed the enzymes (OXCT1/2, BDH1, ACAT1/2) responsible for metabolizing BHB to acetyl-CoA, yet expression of these enzymes does not change with either glucose deprivation or BHB treatment. In the publicly available Cancer Genome Atlas increased expression compared to healthy tissue of enzymes responsible for metabolizing BHB to acetyl-CoA was also observed, however only a small subset of patients showed alterations in these enzymes. This alteration was linked to a significant decrease in overall survival. In conclusion, neither MCF-7 nor T47D breast cancer cells were affected by BHB during glucose deprivation, however screening of the patient’s tumor for activation of ketone bodies metabolizing enzymes may be indicated to identify who will benefit from ketogenic diet interventions. Citation Format: Rylee Maldonado, Chloe Adrienna Talana, Kahealani Uehara, Michael Weichhaus. Breast cancer cell metabolism: Effect of beta-hydroxybutyrate on glucose deprived breast cancer cells [abstract]. In: Abstracts: AACR Special Virtual Conference on Epigenetics and Metabolism; October 15-16, 2020; 2020 Oct 15-16. Philadelphia (PA): AACR; Cancer Res 2020;80(23 Suppl):Abstract nr PO-057.