Targeted Proteins Reveal Cathepsin D as a Novel Biomarker in Differentiating Hepatocellular Carcinoma from Cirrhosis and Other Liver Cancers

Objective: Hepatocellular carcinoma (HCC) represents a global health concern, particularly in Southeast Asia where hepatitis B virus (HBV) infection is common. In this study, we applied tissue-based proteomics to identify novel serological proteins for HCC and validated their performance in serum specimens. Methods: In a discovery set, liver tissue specimens of HBV-related HCC, intrahepatic cholangiocarcinoma (iCCA) and colorectal cancer with liver metastasis (CRLM) were analyzed using mass spectrometry (LTQ-Orbitrap-XL). A subset of proteins that showed highly expressed in HCC were then confirmed by Western blotting. Additionally, clinical significance of selected candidate proteins was tested in serum samples of 80 patients with HBV-related HCC, 50 patients with HBV-related liver cirrhosis and 30 healthy controls. Results: Based on LTQ-Orbitrap-XL mass spectrometer, various differentially expressed proteins (DEPs) between tumor and adjacent non-tumor tissues were identified. These included 77 DEPs for HCC, 77 DEPs for iCCA and 55 DEPs for CRLM. Among selected candidate proteins, annexin A2 and cathepsin D were confirmed to be overexpressed in HCC tissue by Western blot analysis. In a validate cohort, serum cathepsin D level, but not annexin A2, was significantly higher in HCC compared with the non-HCC groups. Serum cathepsin D level was also positively correlated with tumor size and tumor stage. Additionally, the combined assay of serum cathepsin D and alpha-fetoprotein had a high sensitivity in detecting early HCC (83%) and intermediate/advanced HCC (96%). Moreover, patients with low serum cathepsin D (<305 ng/mL) displayed significantly better overall survival than those whose serum levels were high (≥305 ng/mL). Conclusions: Proteomics and subsequent validation revealed cathepsin D as a novel biomarker for HCC. Apart from its diagnostic role, serum cathepsin D might also serve as a prognostic biomarker of HCC. Additional large-scale studies are needed to verify our finding

A database of naturally occurring human urinary peptides and proteins for use in clinical applications

Owing to its availability, ease of collection and correlation with (patho-) physiology, urine is an attractive source for clinical proteomics. However, the lack of comparable datasets from large cohorts has greatly hindered development in this field. Here we report the establishment of a high resolution proteome database of naturally occurring human urinary peptides and proteins - ranging from 800-17,000 Da - from over 3,600 individual samples using capillary electrophoresis coupled to mass spectrometry, yielding an average of 1,500 peptides per sample. All processed data were deposited in an SQL database, currently containing 5,010 relevant unique urinary peptides that serve as classifiers for diagnosis and monitoring of diseases, including kidney and vascular diseases. Of these, 352 have been sequenced to date. To demonstrate the applicability of this database, two examples of disease diagnosis were provided: For renal damage diagnosis, patients with a specific renal disease were identified with high specificity and sensitivity in a blinded cohort of 131 individuals. We further show definition of biomarkers specific for immunosuppression and complications after transplantation (Kaposi's sarcoma). Due to its high information content, this database will be a powerful tool for the validation of biomarkers for both renal and non-renal diseases

Proteomics in Dengue Virus Infection: Host Response in Human Endothelial Cells

This mini-review highlights important findings obtained from a series of our recent proteomic studies of human endothelial cells in response to dengue virus infection, which remains common in tropical/subtropical countries. These findings shed light onto mechanisms of vascular leakage, which is a fatal complication of this disease

Study of Diabetic Nephropathy in the Proteomic Era

Diabetic nephropathy (DN) remains a major complication of diabetes leading to end-stage renal disease (ESRD). The number of diabetic patients with ESRD who require renal replacement therapy has been increasing, implicating unsuccessful prevention of dia-betic renal complication. This unfavorable outcome reflects insufficient knowledge on pathogenic mechanisms of DN and its detection at late stage. Currently, microalbuminu-ria is used for diagnosis of DN. However, some patients with microalbuminuria have advanced renal pathological changes indicating that microalbuminuria is not the perfect marker for early detection of DN and a better biomarker is urgently needed. Recently, particularly after the completion of the Human Genome Project, proteomics (systematic analysis of proteins for their identity, quantity and function) has been recognized as an emerging subdiscipline of modern sciences. During the past decade, proteomics has been widely applied to several areas of biomedical research, including the investigation of DN. This chapter summarizes recent progress of proteomics applied to DN with ulti-mate goals to better understand its pathogenic mechanisms and to search for novel bio