Biomarker detection in urinary proteome of prostate cancer by nanoflow LC-MS/MS

INTRODUCTION: Urinary proteomics provides a wealth of information in the identification of protein markers associated with various diseases such as in carcinoma. With the increasing incidence of prostate cancer and the lack of sensitivity and specificity of prostate specific antigen, the simultaneous identification of an alternative protein biomarker through urinary proteomics is encouraging. Urine, which has similar proteins with serum, makes it an ideal alternative biofluid wherein the collection is easy and non-invasive.METHODS: Urinary proteins were separated by gradient SDS-PAGE followed by in-gel digestion and organic/buffer peptide extraction. The protein biomarkers in prostate cancer patients and control subjects were identified via LC-MS/MS and submitted to Protein Prospector where the peptide fragmentation of sequence was analyzed and compared with the SwissProt database.RESULTS: A panel of three protein biomarkers for the early detection of prostate cancer were identified: transthyretin, hemoglobin subunit alpha and hemoglobin sububit beta. The presence of these three biomarkers is associated with high Gleason scores and TNM stages but not with PSA level. Uromodulin and mannan binding lectin serine protease cancer from BPH. The study also revealed the divergence of the urinary proteome of the cancer patients from the urinary proteome of the control with BPH suggesting the fundamental differences in benign and malignant growth of the prostate epithelial cells. Another highlight of the study was the identification of oxidation of pro63 of transthyretin in patient 3. The proposed role of the post translational modification in pro63 of transthyretinin in the mechanism of prostate carcinogenesis remains to be defined and warrants further study.CONCLUSION: Our study was able to establish the homology of urine proteome among the controls and its divergence from the patients afflicted with prostate cancer by simultaneously comparing their urine proteomes leading to the identification of a distinct panel of biomarkers, namely, transthyretin, hemoglobin subunit alpha and hemoglobin subunit beta. Uromodulin and mannan binding lectin serine protease 2 are the additional biomarkers that can distinguish prostate cancer from BPH. Due to limitations in the number of controls and patients, only preliminary findings and their significance were shown. These findings need to be confirmed in future investigations using larger sample size for both the controls and the patients.

Concordance of hepatitis C virus subtyping by non-structural 5A and non-structural 5B sequencing

The non-structural 5B (NS5B) gene is the target region to identify hepatitis C virus (HCV) subtypes. However, it is not always possible to amplify this region because of inherently high sequence variability. Nucleotide sequences of the non-structural 5A (NS5A) and NS5B genes and its concordance were determined from patients infected with HCV genotype 1 (HCV-1). Among the 30 HCV-1 samples, 7 (23%) were identified as subtype 1a and 23 (77%) were identified as 1b by NS5A sequencing. Sequence analysis of the NS5B showed that 13 (43%) were identified as 1a and 17 (57%) were identified as 1b. Out of the 13 samples identified as 1a by NS5B, 6 (46%) were correctly identified by NS5A. Of the 17 samples identified as 1b by NS5B, 16 (94%) were correctly identified by NS5A. The presence of glutamic acid (E) or aspartic acid (D) at position 2225 in the NS5A differentiates 1a from 1b subtypes, respectively. This study showed that the NS5A sequencing can identify HCV-1a and 1b subtypes with predictive values of 86% and 70% of cases, respectively. The overall concordance with NS5B was 73%. NS5B sequence analysis remains to be the reference method to identify HCV-1 subtypes. NS5A sequencing may be used to complement NS5B sequencing in case the NS5B gene cannot be successfully amplified.