Microarray Analysis of Breast Cancer Gene Expression Profiling in Response to 2-Deoxyglucose, Metformin, and Glucose Starvation

Abstract

Background: Breast cancer (BC) is the most frequently diagnosed cancer in women. Altering glucose metabolism and its effects on cancer progression and treatment resistance is an emerging interest in BC research. For instance, combining chemotherapy with glucose-lowering drugs (2-deoxyglucose (2-DG), metformin) or glucose starvation (GS) has shown better outcomes than with chemotherapy alone. However, the genes and molecular mechanisms that govern the action of these glucose deprivation conditions have not been fully elucidated. Here, we compared the effect of glucose deprivation (2-DG, metformin, GS) on MDA-MB-231 and MCF-7 BC cell lines using microarray analysis to establish a database of differentially expressed genes and enrichment pathways, in order to investigate the beneficial effect of glucose-lowering treatments on the vulnerability of BC cells.Methods: MDA-MB-231 and MCF-7 cells were treated with 20 mM metformin or 4 mM 2-DG for 48 hours. GS was performed by gradually decreasing the concentration of glucose in the culture medium to 0 g/L with fetal bovine serum over 1 week. Expression profiling was carried out using Affymetrix Human Clariom S microarrays. Differentially expressed genes were obtained from the Transcriptome Analysis Console and enriched using DAVID and R packages.Results: Our results showed that MDA-MB-231 cells were more responsive to glucose deprivation than MCF-7 cells. Endoplasmic reticulum stress response and cell cycle inhibition were detected after all three glucose deprivations in MDA-MB-231 cells and only under the metformin and GS conditions in MCF-7 cells. Induction of apoptosis and inhibition of DNA replication were observed with all three treatments in MDA-MB-231 cells and metformin-treated MCF-7 cells. Upregulation of cellular response to reactive oxygen species and inhibition of DNA repair mechanisms resulted after metformin and GS administration in MDA-MB-231 cell lines and metformin-treated MCF-7 cells. Autophagy was induced after 2-DG treatment in MDA-MB-231 cells and after metformin in MCF-7 cells. Finally, enhanced cell-cell adhesion and inhibition of DNA methylation and cholesterol biosynthesis were observed with GS only in MDA-MB-231 cells. Conclusion: GS had the greatest effect on breast cancer cells compared to 2-DG and metformin. Our results suggest that the combination of metformin and GS should weaken both cell lines and makes them more vulnerable to conventional chemotherapy.