Breast cancer is a debilitating disease that affects many women across the globe and it is a highly prevalent cancer among women in the US. Latest research shows that 1 in 8 women in the US will develop invasive breast in their lifetime. African American women are at higher risk of developing breast cancer than native white American population, as well as Asians and Hispanics. Advances in research and treatment have resulted in decreasing death rates from breast cancer since 1989. The risk of breast cancer has been heavily linked to having a family history of breast cancer, as well as carrying the mutated genes; BRCA1 and BRCA2.
Purpose of the study
Like all other cancers, dietary habits were often investigated and linked to breast cancer prevalence. Sugar is often considered as a major concern when it comes to increase in the incidence of this disease. Sugar, excess simple carbohydrates and processed foods can cause “insulin resistance” in the body leading to inflammation and subsequent fat storage resulting in obesity. Obesity has been linked to many types of cancers, and breast cancer is no exception.
Researchers at Marmara University in Istanbul, Turkey researched the link between breast cancer cells and sugar molecules, and whether breast cancer cells thrive in a high sugar environment and if ketones can be used as energy source for such cells.
Ketone bodies (ketones) are produced as a result of ketosis when carbohydrates are absent from a ketogenic diet. Cancer cells cannot use ketones as a source of energy and metabolism in their mitochondria. Cancer cells thrive on the process of glycolysis and when glucose (sugar) is absent and ketones are present glycolysis is inhibited thereby affecting the proliferation and survival of breast cancer cells. The study investigated the viability of cancer cells in the absence of glucose (sugar) and presence of ketone bodies acetoacetate AA and beta-hydroxybutyrate BHB. The study was conducted using breast cancer cells against human fibroblast cells as control group.
The cell viability was measured for 24 hours. Solutions of AA and BHB were added to the human breast cancer cells MCF-7 and the control group of human foreskin fibroblast cells HFF. Group 1 was marked as high glucose, group 2 as low glucose and group 3 as glucose free (no sugar). Cells were incubated with ketone bodies and cell viability was measured after 24 hours of incubation.
The aim was to measure cell viability in the absence of glucose (sugar) and presence of ketone bodies; AA and BHB were used as ketone bodies in this study. Past studies have shown that ketone metabolism in healthy whole cells may inhibit cancer cell growth by creating a less favorable redox environment for survival. It was thought that ketone bodies have properties that can disrupt the survival and proliferation of cancer cells.
In this study, normal cells showed decrease in viability in glucose free (no sugar) media. The introduction of ketone bodies showed a small increase in viability. But when the cancer cells were tested in glucose free media (no sugar), their viability decreased significantly. Importantly, the addition of ketone bodies to cancer cells did not improve their viability.
Breast cancer cells in a glucose-free (no sugar) media had a significant decrease in viability that could not be reversed by the addition of ketone bodies. This means that cells were not rescued by the addition of the ketone bodies AA or BHB. The implications are that breast cancer cells do not use ketone bodies as a primary energy source in place of sugar. The study states: “Thus our data support the hypothesis that, like other cancers of breast origin, MCF-7 cells lack the ability to use ketone bodies as an energy source.”
The study concludes that the results show a significant reduction in cell viability of MCF-7 breast cancer cells supporting the Warburg effect. However, the molecular mechanism of the changes needs to be further identified. The authors also believe that use of a ketogenic diet might create new therapeutic approaches in the treatment of different forms of cancer.
Effect of ketone bodies on viability of human breast cancer cells (MCF-7). Kaya, A., Yilmaz, AM, Yalcin, AS, Marmara Medical Journal 2018; 31: 57-60 DOI: 10.5472/marumj.430783