Characterization of the Human Cervical Mucous Proteome

Abstract

INTRODUCTION: Cervical cancer is among the most common cancers in women worldwide. Discovery of biomarkers for the early detection of cervical cancer would improve current screening practices and reduce the burden of disease. OBJECTIVE: In this study, we report characterization of the human cervical mucous proteome as the first step towards protein biomarker discovery. METHODS: The protein composition was characterized using one- and two-dimensional gel electrophoresis, and liquid chromatography coupled with mass spectrometry. We chose to use this combination of traditional biochemical techniques and proteomics to allow a more comprehensive analysis. RESULTS AND CONCLUSION: A total of 107 unique proteins were identified, with plasma proteins being most abundant. These proteins represented the major functional categories of metabolism, immune response, and cellular transport. Removal of high molecular weight abundant proteins by immunoaffinity purification did not significantly increase the number of protein spots resolved. We also analyzed phosphorylated and glycosylated proteins by fluorescent post-staining procedures. The profiling of cervical mucous proteins and their post-translational modifications can be used to further our understanding of the cervical mucous proteome.

Fig. 1

Gel electrophoresis of the proteins extracted from cervical mucous. a 2-DE gel image (Coomassie staining); b 2-DE gel after depletion (SYPRO Ruby staining); and c 1-DE gel image (Coomassie staining). Only spots representing identified proteins are labeled on gel images

Fig. 2

Total number of proteins identified using three different strategies for protein fractionation

Fig. 3

Functional annotation of proteins identified in cervical mucous

Fig. 4

2-DE gel images of cervical mucous proteins stained for phosphoproteins and glycoproteins. a Staining with Pro-Q Emerald for detection of glycosylated proteins; b Staining with Pro-Q diamond for detection of phosphorylated proteins. The enlarged area (bottom left) was compared with the corresponding region in the total protein image stained with SYPRO Ruby fluorescent dye (bottom right). The relative intensities of four labeled spots representing S-100 A9 protein are listed in parenthesis