No abstract

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death throughout the world. Although hepatitis B or C viral infections are main risk factors for HCC, the molecular mechanisms leading to HCC formation have not been clarified. To reduce the mortality and improve the effectiveness of therapy, it is important to search for changes in tumor-specific biomarkers whose function may involve in disease progression and which may be useful as potential therapeutic targets. In this study, we employed two-dimensional difference gel electrophoresis (2D-DIGE) combined with nano flow liquid chromatography tandem mass spectrometry (nanoLC-MS/MS) to investigate differentially expressed proteins in HCC. For each of eight HCC patients, Cy3-labeled proteins isolated from tumor tissue were combined with Cy5-labeled proteins isolated from the surrounding nontumor tissue and separated by 2D gel electrophoresis along with a Cy2-labeled mixture of all tumor and nontumor samples as an internal standard. Thirty-four protein spots corresponding to 30 different proteins were identified by nanoLC-MS/MS as showing significant change (paired t-test, p< 0.05) in the level of expression between tumor and nontumor tissues. Sixteen proteins were up-regulated and 14 were down-regulated in HCC; they seem to play important roles in a variety of pathways including glycolysis, fatty acid transport and trafficking, amino acid metabolism, iron and xenobiotic metabolism, ethanol metabolism, cell cycle regulation, cytoskeleton, and stress. A remarkable finding is the up-regulation of 14-3-3gamma protein in HCC. 14-3-3 isoforms had been linked to carcinogenesis because they are involved in various cellular processes such as cell cycle regulation, apoptosis, proliferation, and differentiation. In conclusion, 2D-DIGE is an efficient strategy that enables us to identify differentially expressed proteins in HCC. Identification of potential biomarkers, such as the pinpointing of 14-3-3gamma in our findings, may provide further useful insights into the pathogenesis of HCC.

Although the significant risk factors for hepatocellular carcinoma (HCC) are well known from epidemiological studies, diagnosis of this disease at an early stage is difficult, and HCC remains one of the leading causes of cancer death worldwide. Thus, to identify any useful HCC-related biomarkers is still a need. We performed SELDI-TOF MS to identify differentially expressed proteins in HCC serum using weak cation exchange protein chips. Protein characterization was performed by 2-DE separation and nano flow LC-MS/MS. A total of 55 sera were collected from HCC patients and compared with those from 48 patients with chronic hepatitis and 9 healthy individuals. A candidate marker of about 8900 Da was detected as differentially expressed in patients with chronic hepatitis C and hepatitis C virus (HCV)-related HCC. We identified this differentially expressed protein as complement C3a. The expression of C3a in HCC sera was further validated by PS20 chip immunoassay and Western blotting. Complement C3a was found to be elevated in patients with chronic hepatitis C and HCV-related HCC. The combination of SELDI-TOF MS and 2-DE provides a solution to identify disease-associated serum biomarkers.

Malignant pleural effusion (MPE) obtained from lung adenocarcinoma may contain potentially useful biomarkers for detection of lung cancer. In this study, we used a removal system for high-abundance proteins followed by one-dimensional SDS-PAGE combined with nano-LC-MS/MS to generate a comprehensive MPE proteome data set with 482 nonredundant proteins. Next, we integrated the MPE proteome and secretome data sets from three adenocarcinoma cell lines, with a view to identifying potential PE biomarkers originating from malignant cells. Four potential candidates, alpha-2-HS-glycoprotein (AHSG), angiogenin, cystatin-C, and insulin-like growth factor-binding protein 2, (IGFBP2), were isolated for preclinical validation using ELISA. Both AHSG and IGFBP2 levels were increased in lung patients with MPE (n = 68), compared to those with nonmalignant pleural effusion (n = 119). Notably, the IGFBP2 level was higher in MPE, compared with that in benign diseases (bacteria pneumonia and tuberculosis pleuritis), and significantly associated with malignancy, regardless of the cancer type. Our data additionally support an extracellular function of IGFBP2 in migration in lung cancer cells. These findings collectively suggest that the adenocarcinoma MPE proteome provides a useful data set for malignancy biomarker research.