RESUMEN
Proteome analysis of human hepatocellular carcinoma tissues was conducted using two-dimensional difference gel electrophoresis coupled with mass spectrometry. Paired samples from the normal and tumor region of resected human liver were labeled with Cy3 and Cy5, respectively while the pooled standard sample was labeled with Cy2. After analysis by the DeCyder software, protein spots that exhibited at least a two-fold difference in intensity were excised for in-gel tryptic digestion and matrix-assisted laser desorption/ionization-time of flight mass spectrometry. A total of 6 and 42 proteins were successfully identified from the well- and poorly-differentiated samples, respectively. The majority of these proteins are related to detoxification/oxidative stress and metabolism. Three down-regulated metabolic enzymes, methionine adenosyltransferase, glycine N-methyltransferase, and betaine-homocysteine S-methyltransferase that are involved in the methylation cycle in the liver are of special interest. Their expression levels, especially, methionine adenosyltransferase, seemed to have a major influence on the level of S-adenosylmethionine (AdoMet), a vital intermediate metabolite required for the proper functioning of the liver. Recent work has shown that chronic deficiency in AdoMet in the liver results in spontaneous development of steatohepatitis and hepatocellular carcinoma, and hence the down-regulation of hepatic methionine adenosyltransferase in our hepatocellular carcinoma samples is in line with this observation. Moreover, when a comparison is made between the differentially expressed proteins from our human hepatocellular carcinoma samples and from the liver tissues of knockout mice deficient in methionine adenosyltransferase, there is a fairly good correlation between them.
Asunto(s)
Carcinoma Hepatocelular/química , Electroforesis en Gel Bidimensional , Neoplasias Hepáticas/química , Espectrometría de Masas , Proteoma/análisis , Carcinoma Hepatocelular/patología , Humanos , Procesamiento de Imagen Asistido por Computador , Neoplasias Hepáticas/patología , Tinción con Nitrato de Plata , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Tripsina/farmacologíaRESUMEN
Hepatocellular carcinoma (HCC or hepatoma) is the most common primary cancer of the liver. Persistent viral infection by the hepatic B or C virus is probably the most important cause of HCC worldwide. It is responsible for approximately one million deaths each year, predominantly in the underdeveloped and developing countries, but its incidence is also on the rise in the developed countries. For most patients suffering from HCC, long-term survival is rare, as they are presented late and are often unsuitable for curative treatment. Thus there is great interest to identify novel HCC diagnostic markers for early detection of the disease, and tumour specific associated proteins as potential therapeutic targets in the treatment of HCC. Proteome analyses of HCC cell lines and liver tumour tissues should facilitate the screening and discovery of these HCC proteins. The creation of a comprehensive HCC proteome database would be an important first step towards achieving this goal. This review presents an update of the two-dimensional electrophoresis proteome database of the cell line, HCC-M, which is also now freely accessible through the World Wide Web at http://proteome.btc.nus.edu.sg/hccm/.