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Query: UMLS:C0006142 (breast cancer)
 160,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We found that Adriamycin increased the pentose phosphate shunt activity in both Adriamycin-sensitive (WT) and Adriamycin-resistant (ADRR) human breast cancer MCF-7 cells. In contrast, hydrogen peroxide and cumene hydroperoxide markedly stimulated pentose-shunt activity in ADRR but only moderately increased the activity in WT cells. Furthermore, the altered oxidation-reduction regulation is associated with changes intrinsic to the key enzymes of the pentose-shunt pathway, glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase and with glutathione peroxidase. We found the Vmax values for glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were 50- and 4-fold lower, respectively, in ADRR than WT cells and the Kms of NADP+ were 10-fold lower in ADRR than WT. The activity of glutathione reductase in ADRR is 42% of that in WT. In spite of these changes, the response of the cells to both hydrogen peroxide and organic peroxide is not limited by either the capacity of the pentose shunt or glutathione reductase, but is determined by the activity of glutathione peroxidase and a glutathione transferase which possess peroxidase activity. The kinetic properties of the glucose-6-phosphate dehydrogenase in ADRR may, however, seriously limit the activity of cytochrome P-450 reductase, a major enzyme of Adriamycin conversion to a free radical.
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PMID:Adriamycin resistance in human tumor cells associated with marked alteration in the regulation of the hexose monophosphate shunt and its response to oxidant stress. 366 3

Selective estrogen receptor (ER) modulators are highly successful breast cancer therapies, but they are not effective in patients with ER negative and selective estrogen receptor modulator (SERM)-resistant tumors. Understanding the mechanisms of estrogen-stimulated proliferation may provide a route to design estrogen-independent therapies that would be effective in these patients. In this study, metabolic flux analysis was used to determine the intracellular fluxes that are significantly affected by estradiol stimulation in MCF-7 breast cancer cells. Intracellular fluxes were calculated from nuclear magnetic resonance (NMR)-generated isotope enrichment data and extracellular metabolite fluxes, using a specific flux analysis algorithm. The metabolic pathway model used by the algorithm includes glycolysis, the tricarboxylic acid cycle (TCA cycle), the pentose phosphate pathway, glutamine catabolism, pyruvate carboxylase, and malic enzyme. The pathway model also incorporates mitochondrial compartmentalization and reversible trans-mitochondrial membrane reactions to more accurately describe the role of mitochondria in cancer cell proliferation. Flux results indicate that estradiol significantly increases carbon flow through the pentose phosphate pathway and increases glutamine consumption. In addition, intra-mitochondrial malic enzyme was found to be inactive and the malate-aspartate shuttle (MAS) was only minimally active. The inactivity of these enzymes indicates that glutamine is not oxidized within mitochondria, but is consumed primarily to provide biosynthetic precursors. The excretion of glutamine carbons from the mitochondria has the secondary effect of limiting nicotinamide adenine dinucleotide (NADH) recycle, resulting in NADH buildup in the cytosol and the excretion of lactate. The observed dependence of breast cancer cells on pentose phosphate pathway activity and glutamine consumption for estradiol-stimulated biosynthesis suggests that these pathways may be targets for estrogen-independent breast cancer therapies.
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PMID:Estradiol stimulates the biosynthetic pathways of breast cancer cells: detection by metabolic flux analysis. 1690 60

Brain metastases are among the most feared complications in breast cancer, as no therapy exists that prevents or eliminates breast cancer spreading to the brain. New therapeutic strategies depend on specific knowledge of tumor cell properties that allow breast cancer cell growth within the brain tissue. To provide information in this direction, we established a human breast cancer cell model for brain metastasis based on circulating tumor cells from a breast cancer patient and variants of these cells derived from bone or brain lesions in immunodeficient mice. The brain-derived cells showed an increased potential for brain metastasis in vivo and exhibited a unique protein expression profile identified by large-scale proteomic analysis. This protein profile is consistent with either a selection of predisposed cells or bioenergetic adaptation of the tumor cells to the unique energy metabolism of the brain. Increased expression of enzymes involved in glycolysis, tricarboxylic acid cycle, and oxidative phosphorylation pathways suggests that the brain metastatic cells derive energy from glucose oxidation. The cells further showed enhanced activation of the pentose phosphate pathway and the glutathione system, which can minimize production of reactive oxygen species resulting from an enhanced oxidative metabolism. These changes promoted resistance of brain metastatic cells to drugs that affect the cellular redox balance. Importantly, the metabolic alterations are associated with strongly enhanced tumor cell survival and proliferation in the brain microenvironment. Thus, our data support the hypothesis that predisposition or adaptation of the tumor cell energy metabolism is a key element in breast cancer brain metastasis, and raise the possibility of targeting the functional differentiation in breast cancer brain lesions as a novel therapeutic strategy.
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PMID:Adaptation of energy metabolism in breast cancer brain metastases. 1730 85

Malignant tumors degrade glucose to lactate even in the presence of oxygen via the pentose phosphate pathway (ppp). The non-oxidative part of the ppp is controlled by thiamine-dependant transketolase enzyme reactions. Overexpression of the transketolase-like-1-gene (TKTL1) in urothelial and colorectal cancer is associated with poor patient outcome. We analyzed the expression of the TKTL1 protein in a retrospective institution-based patient cohort with invasive breast cancer by immunohistochemical analysis of 124 paraffin-embedded breast cancer tissues. Our study revealed TKTL1 expression in 86% of breast cancer specimens with 45% showing high expression levels. In contrast, only 29% of corresponding non-neoplastic breast tissues were TKTL1 immunopositive, including 9% with high expression levels. High expression levels of TKTL1 correlated significantly to Her2/neu overexpression (p=0.015). However, TKTL1 expression failed to reach statistical significance for other common prognostic parameters. In contrast to recent data for e.g. colorectal cancer TKTL1 overexpression did not correlate to patient outcome and survival. However, in the context of novel insights into TKTL1-related tumor metabolism and the high proportion of TKTL1 overexpressing breast cancers, this enzyme represents a potential candidate for targeted inhibition of tumor growth in this tumor entity.
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PMID:Transketolase protein TKTL1 overexpression: A potential biomarker and therapeutic target in breast cancer. 1734 25

There is a growing belief that the metabolic program of breast tumor cells could be a therapeutic target. Yet, without detailed information on central carbon metabolism in breast tumors it is impossible to know which metabolic pathways to target, and how their inhibition might influence different stages of breast tumor progression. Here we perform the first comprehensive profiling of central metabolism in the MCF10 model of mammary carcinoma, where the steps of breast tumor progression (transformation, tumorigenicity and metastasis) can all be examined in the context of the same genetic background. The metabolism of [U-(13)C]-glucose by a series of progressively more aggressive MCF10 cell lines was tracked by 2D NMR and mass spectrometry. From this analysis the flux of carbon through distinct metabolic reactions was quantified by isotopomer modeling. The results indicate widespread changes to central metabolism upon cellular transformation including increased carbon flux through the pentose phosphate pathway (PPP), the TCA cycle, as well as increased synthesis of glutamate, glutathione and fatty acids (including elongation and desaturation). The de novo synthesis of glycine increased upon transformation as well as at each subsequent step of breast tumor cell progression. Interestingly, the major metabolic shift in metastatic cells is a large increase in the de novo synthesis of proline. This work provides the first comprehensive view of changes to central metabolism as a result of breast tumor progression.
Breast Cancer Res Treat 2008 Jul
PMID:Central carbon metabolism in the progression of mammary carcinoma. 1787 59

In several tumors the transketolase activity, controlled inter alia by enzymes of the pentose phosphate pathway which is an alternative, energy generating reaction-cascade to glycolysis, has been correlated with proliferation. The increase of thiamine-dependent transketolase enzyme reactions is induced especially through upregulated transketolase-like enzyme 1 (TKTL1)-activity; that shows TKTL1 to be a causative enzyme for tumors enhanced, anaerobic glucose degradation. We investigated TKTL1-expression in 88 human, formalin-fixed non-small cell lung cancer tissues and 24 carcinomas of the breast by immunohistochemical stainings applying a 0 to 3 staining-score system (3 = strongest expression). For means of validation we additionally stained 40 NSCLC fixed and paraffin-embedded utilizing the HOPE-technique; showing comparable results to the formalin-fixed, paraffin-embedded specimens (not shown). Potential correlations with age, sex, TNM-classification parameters and tumor grading as well as tumor transcription factor 1 (TTF1) and surfactant protein A (SPA) expression were investigated. 40.9% of the analyzed lung tumors expressed TKTL1 weakly (Score 1), 38.6% moderately (score 2) and 17.1% strongly (score 3). 3 tumors were diagnosed TKTL1-negative (3.4%; score 0). All breast cancer specimen stainings were positive and scored 1: 32%; scored 2: 36%; scored 3: 32%. Alveolar macrophages and Alveolar Epithelial Cells Type II were also found to be TKTL1-positive.None of the listed clinical parameters could be found to show a significant correlation to TKTL1 signal appearance. Although we describe the expression of TKTL1 in lung cancers, we need to state that up till now there is no scientific indication for any treatment regimens based upon these findings.
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PMID:TKTL1 is overexpressed in a large portion of non-small cell lung cancer specimens. 1870 18

Breast cancer is the most common cancer type for women in the western world. Despite decades of research, the molecular processes associated with breast cancer progression are still inadequately defined. Here, we focus on the systematic alteration of metabolism by using the state of the art metabolomic profiling techniques to investigate the changes of 157 metabolites during the progression of normal mouse mammary epithelial cells to an isogenic series of mammary tumor cell lines with increasing metastatic potentials. Our results suggest a two-step metabolic progression hypothesis during the acquisition of tumorigenic and metastatic abilities. Metabolite changes accompanying tumor progression are identified in the intracellular and secreted forms in several pathways, including glycolysis, the tricarboxylic acid cycle, the pentose phosphate pathway, fatty acid and nucleotide biosynthesis, and the GSH-dependent antioxidative pathway. These results suggest possible biomarkers of breast cancer progression as well as opportunities of interrupting tumor progression through the targeting of metabolic pathways.
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PMID:Metabolomic changes accompanying transformation and acquisition of metastatic potential in a syngeneic mouse mammary tumor model. 2013 83

In contrast to normal cells, cancer cells avidly take up glucose and metabolize it to lactate even when oxygen is abundant, a phenomenon referred to as the Warburg effect. This fundamental alteration in glucose metabolism in cancer cells enables their specific detection by positron emission tomography (PET) following i.v. injection of the glucose analogue (18)F-fluorodeoxy-glucose ((18)FDG). However, this useful imaging technique is limited by the fact that not all cancers avidly take up FDG. To identify molecular determinants of (18)FDG retention, we interrogated the transcriptomes of human-cancer cell lines and primary tumors for metabolic pathways associated with (18)FDG radiotracer uptake. From ninety-five metabolic pathways that were interrogated, the glycolysis, and several glycolysis-related pathways (pentose phosphate, carbon fixation, aminoacyl-tRNA biosynthesis, one-carbon-pool by folate) showed the greatest transcriptional enrichment. This "FDG signature" predicted FDG uptake in breast cancer cell lines and overlapped with established gene expression signatures for the "basal-like" breast cancer subtype and MYC-induced tumorigenesis in mice. Human breast cancers with nuclear MYC staining and high RNA expression of MYC target genes showed high (18)FDG-PET uptake (P < 0.005). Presence of the FDG signature was similarly associated with MYC gene copy gain, increased MYC transcript levels, and elevated expression of metabolic MYC target genes in a human breast cancer genomic dataset. Together, our findings link clinical observations of glucose uptake with a pathologic and molecular subtype of human breast cancer. Furthermore, they suggest related approaches to derive molecular determinants of radiotracer retention for other PET-imaging probes.
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PMID:18F-fluorodeoxy-glucose positron emission tomography marks MYC-overexpressing human basal-like breast cancers. 2164 75

To investigate the quantitative response of energy metabolic pathways in human MCF-7 breast cancer cells to hypoxia, glucose deprivation, and estradiol stimulation, we developed a targeted proteomics assay for accurate quantification of protein expression in glycolysis/gluconeogenesis, TCA cycle, and pentose phosphate pathways. Cell growth conditions were selected to roughly mimic the exposure of cells in the cancer tissue to the intermittent hypoxia, glucose deprivation, and hormonal stimulation. Targeted proteomics assay allowed for reproducible quantification of 76 proteins in four different growth conditions after 24 and 48 h of perturbation. Differential expression of a number of control and metabolic pathway proteins in response to the change of growth conditions was found. Elevated expression of the majority of glycolytic enzymes was observed in hypoxia. Cancer cells, as opposed to near-normal MCF-10A cells, exhibited significantly increased expression of key energy metabolic pathway enzymes (FBP1, IDH2, and G6PD) that are known to redirect cellular metabolism and increase carbon flux through the pentose phosphate pathway. Our quantitative proteomic protocol is based on a mass spectrometry-compatible acid-labile detergent and is described in detail. Optimized parameters of a multiplex selected reaction monitoring (SRM) assay for 76 proteins, 134 proteotypic peptides, and 401 transitions are included and can be downloaded and used with any SRM-compatible mass spectrometer. The presented workflow is an integrated tool for hypothesis-driven studies of mammalian cells as well as functional studies of proteins, and can greatly complement experimental methods in systems biology, metabolic engineering, and metabolic transformation of cancer cells.
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PMID:Quantitative analysis of energy metabolic pathways in MCF-7 breast cancer cells by selected reaction monitoring assay. 2253 6

Metabolic reprogramming that alters the utilization of glucose including the "Warburg effect" is critical in the development of a tumorigenic phenotype. However, the effects of the Harvey-ras (H-ras) oncogene on cellular energy metabolism during mammary carcinogenesis are not known. The purpose of this study was to determine the effect of H-ras transformation on glucose metabolism using the untransformed MCF10A and H-ras oncogene transfected (MCF10A-ras) human breast epithelial cells, a model for early breast cancer progression. We measured the metabolite fluxes at the cell membrane by a selective micro-biosensor, [(13)C6 ]glucose flux by (13)C-mass isotopomer distribution analysis of media metabolites, intracellular metabolite levels by NMR, and gene expression of glucose metabolism enzymes by quantitative PCR. Results from these studies indicated that MCF10A-ras cells exhibited enhanced glycolytic activity and lactate production, decreased glucose flux through the tricarboxylic acid (TCA) cycle, as well as an increase in the utilization of glucose in the pentose phosphate pathway (PPP). These results provide evidence for a role of H-ras oncogene in the metabolic reprogramming of MCF10A cells during early mammary carcinogenesis.
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PMID:Altered glucose metabolism in Harvey-ras transformed MCF10A cells. 2400 Jan 46


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