Differential expression proteomics of human colon cancer

Abstract

The focus of this study was to use differential protein expression to investigate operative pathways in early stages of human colon cancer. Colorectal cancer represents an ideal model system to study the development and progression of human tumors, and the proteomic approach avoids overlooking posttranslational modifications not detected by microarray analyses and the limited correlation between transcript and protein levels. Colon cancer samples, confined to the intestinal wall, were analyzed by expression proteomics and compared with matched samples from normal colon tissue. Samples were processed by two-dimensional gel electrophoresis, and spots differentially expressed and consistent across all patients were identified by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry analyses and by Western blot analyses. After differentially expressed proteins and their metabolic pathways were analyzed, the following main conclusions were achieved for tumor tissue: 1) a shift from beta-oxidation, as the main source of energy, to anaerobic glycolysis was observed owed to the alteration of nuclear- versus mitochondrial-encoded proteins and other proteins related to fatty acid and carbohydrate metabolism; 2) lower capacity for Na(+) and K(+) cycling; and 3) operativity of the apoptosis pathway, especially the mitochondrial one. This study of the human colon cancer proteome represents a step toward a better understanding of the metabolomics of colon cancer at early stages confined to the intestinal wall.

Quantitative Metabolome Profiling of Colon and Stomach Cancer Microenvironment by Capillary Electrophoresis Time-of-Flight Mass Spectrometry

“…This clearly indicates a high dependence of cancer cells on anaerobic breakdown of pyruvate. In particular, high lactate dehydrogenase 5 activity and resulting effective conversion of pyruvate to lactate have been identified in colon cancer (24,25). Active glycolysis also increases the cytosolic NADH/NAD + ratio and thereby accelerates the activity of lactate dehydrogenase (26).…”

Causes and Consequences of Increased Glucose Metabolism of Cancers

“…Mitochondrial impairment is often seen in clear cell renal carcinomas (86). In colorectal cancers, transcriptome and proteome analyses have observed that expression of glycolytic and tricarboxylic acid cycle proteins were inversely proportional (87)(88)(89). Also, in breast cancer, the metabolic proteome undergoes a pronounced shift toward an enhanced glycolytic phenotype concurrent with a profound reduction in the F1-ATPase levels with a classification sensitivity of approximately 97% to overall and disease-free survival (90).…”

Discovery and Scoring of Protein Interaction Subnetworks Discriminative of Late Stage Human Colon Cancer

“…Using the DeCyder software, spots were matched on an intragel basis with differential image analysis (DIA) (5) and on an intergel basis with biological variation analysis (BVA) to assess biological variation (6). Significant spots (⌬fold dependent on statistical power) were selected for robotic excision (7) and digested by trypsin (8), and the peptides were separated by reverse-phase (RP) chromatography and detected by tandem mass spectrometry (9). MS 2 spectra were searched using SEQUEST (10), and identified proteins were imported to MetaCore to search for relevant networks (11).…”