Revision of commonly accepted Warburg mechanism of cancer development. Redox-sensitive mitochondrial cytochromes in breast and brain cancers by Raman imaging

Abstract

AbstractBackgroundWe studied oncogenic processes that characterize human breast cancer (infiltrating ductal carcinoma (IDC)) and human brain tumors: glioma, astrocytoma and medulloblastoma based on the quantification of cytochrome redox status by exploiting the resonance-enhancement effect of Raman scattering.MethodsWe used Raman imaging to monitor changes in the redox state of the mitochondrial cytochromes in ex vivo human brain and breast tissues surgically resected specimens of human tissues and in vitro human brain cells of normal astrocytes (NHA), astrocytoma (CRL-1718), glioblastoma (U87-MG) and medulloblastoma (Daoy), and human breast cells of normal cells (MCF 10A), slightly malignant cells (MCF7) and highly aggressive cells (MDA-MB-231) by means of Raman microspectroscopy at 532 nm.ResultsWe visualized localization of cytochromes by Raman imaging in the major organelles in cancer cells. We demonstrated that the “redox state Raman marker” of the ferric low spin heme in cytochrome c at 1584 cm−1 can serve as a sensitive indicator of cancer aggressiveness. We compared concentration of reduced cytochrome c and the grade of cancer aggressiveness in cancer tissues and single cells and specific organelles in cells: nucleous, mitochondrium, lipid droplets, cytoplasm, and membrane.ConclusionsWe found that the concentration of reduced cytochrome c becomes abnormally high in human brain tumors and breast cancers in human tissues. Our results suggest that the mechanisms controlling the electron transport chain are spectacularly deregulated in cancers and indicate that electron transport, organized in terms of electronegativity, is inhibited between complex III and cytochrome c for isolated cells in vitro and between cytochrome c and complex IV in brain and breast tissues. The results provide evidence that the extracellular matrix and interactions with cell microenvironment play an important role in the mechanisms controlling the electron transport chain by cytochrome c. Our results reveal the universality of Raman vibrational characteristics of mitochondrial cytochromes in metabolic regulation in cancers that arise from epithelial breast cells and brain glial cells.