A novel method to detect intracellular metabolite alterations in MCF-7 cells by doxorubicin induced cell death

Abstract

Metabolic reprogramming within cancer cells is suggested as a potential barrier to chemotherapy. Additionally, metabolic tumor heterogeneity is one of factor behind discernible hallmarks such as drug resistance, relapse of tumor and the formation of secondary tumors. In this paper, cell based assays including PI/annexin V staining and immunoblot assay were performed to show the apoptotic cell death in MCF-7 cells treated with DOX. Further, MCF-7 cells were lysed in hypotonic buffer and whole cell lysate was purified by a novel and specifically designed metabolite (100 to 1000 Da) fractionation system as vertical tube gel electrophoresis (VTGE). Further, purified intracellular metabolites were subjected to identification by LC-HRMS technique. The authors show the presence of cleaved PARP 1 in MCF-7 cells treated with DOX. Concomitantly, data show the absence of active caspase 3 in MCF-7 cells. Novel findings are to identify key intracellular metabolites assisted by VTGE system that include lipid (CDP-DG, phytosphingosine, dodecanamide), non-lipid (N-acetyl-D-glucosamine, N1-acetylspermidine and gamma-L-glutamyl-L-cysteine) and tripeptide metabolites in MCF-7 cells treated by DOX. Interestingly, the authors report a first evidence of doxorubicinone, an aglycone form of DOX in MCF-7 cells that is potentially linked to the mechanism of cell death in MCF-7 cells. This paper reports on novel methods and processes that involve VTGE system based purification of hypotonically lysed novel intracellular metabolites of MCF-7 cells treated by DOX. Here, these identified intracellular metabolites corroborate to caspase 3 independent and mitochondria induced apoptotic cell death in MCF-7 cells.\n\nSIGNIFICANCE STATEMENTMetabolic reprogramming in cancer cells is implicated in various tumor hallmarks. Interestingly, thousands of research have addressed the molecular basis of drug treatment and resistance in chemotherapy. But, there is a significant gap in the precise methodologies and approaches in addressing intracellular metabolite alterations. This paper reports on a novel approach that helped reveal new findings on intracellular metabolite changes in case of doxorubicin (DOX) induced cell death in MCF-7 cells. This paper highlights the additional insights on debatable findings available in literature in the contexts of DOX induced cell death mechanisms. In this paper, novel and specifically designed vertical tube gel electrophoresis (VTGE) system is claimed to purify intracellular metabolites and this method is compatible with other biological system.