Background: Mitochondriopathy has been recently rekindled as new cancer theory. We report on structural damage of breast-infiltrating ductal carcinoma (IDC) mitochondria characterised by reduced expression levels of the oxidative phosphorylation system (OXPHOS). Methods: Mitochondria from HMC-1 (human mammary carcinoma) and HMEC (human mammary epithelial cell) cultures, traced by Mitotracker, were assayed for OXPHOS expression levels using cryo-immunoelectron microscopy (CIEM) quantitative labelling and fluorescence immunolabelling on unfractionated HMC-1 and HEMC cells. Convolution degeneration was established by transmission electron microscopy (TEM). Twenty different cell sections for both HMC-1 and HEMC cells, including 65 and 72 mitochondria, respectively, were randomly recorded and quantitatively analyzed for the percentage of area occupied by intact cristae to provide a grading of mitochondrial damage (cristae loss index). Results: Depressed expression levels were detected for all HMC-1 OXPHOS complexes by CIEM. Normalized labelling density (HEMC/HMC-1), expressed as colloidal gold particles/mitochondrial area (ρ) provided the following values: 1.77 for the NADH-ubiquinone oxidoreductase complex I NDUFS3; 1.86 for the succinate- dehydrogenase complex II SDH-B protein; 1.63 for the ubiquinol cytochrome c reductase complex III UQCRC2; 4.88 and 1.58 for the cytochrome-oxidase complex IV (CO) subunit I and IV, respectively; 2.70 for the ATP-synthase complex V F1β protein. Fluorescence immunolabelling confirmed CIEM quantitative data. MitoTracker's co-staining showed altered membrane potential and permeability. Injury grading was categorised assigning three levels of morphological damage: i) severe, ii) moderate, iii) slight, corresponding to 0 % (6.2 % and 1.4 % for HMC-1 and HMEC, respectively), 1–50 % (21.5 % and 2.8 % for HMC-1 and HMEC, respectively) and 51–75 % (44.6 % and 15.3 % for HMC-1 and HMEC, respectively) of area occupied by intact cristae (p<0.0001, χ2Test). The entire HMC-1 mitochondrial damage resulted 3.7 times higher than that observed for HMEC cells (72.3HMC-1 %/19.5HMEC %). Conclusions: New phenotypic harm indexes for IDC cell mitochondria might provide new hallmarks in breast cancer cell biology. No significant financial relationships to disclose.
Development of phenotypic indexes for the description of morphological injury in breast cancer cell mitochondria
Putignani L;
2009-01-01
Abstract
Background: Mitochondriopathy has been recently rekindled as new cancer theory. We report on structural damage of breast-infiltrating ductal carcinoma (IDC) mitochondria characterised by reduced expression levels of the oxidative phosphorylation system (OXPHOS). Methods: Mitochondria from HMC-1 (human mammary carcinoma) and HMEC (human mammary epithelial cell) cultures, traced by Mitotracker, were assayed for OXPHOS expression levels using cryo-immunoelectron microscopy (CIEM) quantitative labelling and fluorescence immunolabelling on unfractionated HMC-1 and HEMC cells. Convolution degeneration was established by transmission electron microscopy (TEM). Twenty different cell sections for both HMC-1 and HEMC cells, including 65 and 72 mitochondria, respectively, were randomly recorded and quantitatively analyzed for the percentage of area occupied by intact cristae to provide a grading of mitochondrial damage (cristae loss index). Results: Depressed expression levels were detected for all HMC-1 OXPHOS complexes by CIEM. Normalized labelling density (HEMC/HMC-1), expressed as colloidal gold particles/mitochondrial area (ρ) provided the following values: 1.77 for the NADH-ubiquinone oxidoreductase complex I NDUFS3; 1.86 for the succinate- dehydrogenase complex II SDH-B protein; 1.63 for the ubiquinol cytochrome c reductase complex III UQCRC2; 4.88 and 1.58 for the cytochrome-oxidase complex IV (CO) subunit I and IV, respectively; 2.70 for the ATP-synthase complex V F1β protein. Fluorescence immunolabelling confirmed CIEM quantitative data. MitoTracker's co-staining showed altered membrane potential and permeability. Injury grading was categorised assigning three levels of morphological damage: i) severe, ii) moderate, iii) slight, corresponding to 0 % (6.2 % and 1.4 % for HMC-1 and HMEC, respectively), 1–50 % (21.5 % and 2.8 % for HMC-1 and HMEC, respectively) and 51–75 % (44.6 % and 15.3 % for HMC-1 and HMEC, respectively) of area occupied by intact cristae (p<0.0001, χ2Test). The entire HMC-1 mitochondrial damage resulted 3.7 times higher than that observed for HMEC cells (72.3HMC-1 %/19.5HMEC %). Conclusions: New phenotypic harm indexes for IDC cell mitochondria might provide new hallmarks in breast cancer cell biology. No significant financial relationships to disclose.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
