Efficacy of Several Candidate Protein Biomarkers in the Differentiation of Vaginal from Buccal Epithelial Cells*

Abstract

Currently, there is no accurate method to differentiate vaginal epithelial cells from buccal epithelial cells in biological samples typically encountered in forensic casework. This study tested the expression of a selection of candidate proteins in buccal and vaginal epithelial cells. We investigated six candidate biomarkers, such as loricrin, vimentin, stratifin, cytokeratin 4, cytokeratin 13, small proline-rich protein 2, and involucrin, using Western blot analysis on whole protein extracts and immunohistochemistry (IHC) on intact cells in an attempt to identify cell-specific markers that would differentiate these cells by microscopy. Involucrin, loricrin, and stratifin showed differential expression during Western blot analysis and were carried through to IHC. Although proteins unique to vaginal epithelial cells and buccal epithelial cells were not identified from among the proteins tested, the increased expression levels of two proteins, loricrin and stratifin in vaginal cells, when compared to buccal cells, do provide encouraging results in the search for epithelial cell-specific markers.