Perp Expression in Oral Squamous Cell Carcinoma Cell-Lines

Objective: Cell-cell adhesion plays an important role during development and in maintenance of normal epithelial tissue architecture. Cell-cell junctions are the adhesive structures that allow epithelial cells to adhere to neighboring cells and function coordinately as a tissue. Desmosomes are a prominent cell adhesive junction in many epithelial tissues including the oral mucosa. The transmembrane core of the desmosome is comprised of the desmosomal cadherins, desmoglein and desmocollin. These transmembrane cadherins are liked to the keratin intermediate filament cytoskeleton via the desmosomal plaque proteins (plakoglobin, plakophilins and desmoplakin). Loss of desmosomal cell-cell adhesion is believed to be an early event in squamous cell carcinoma progression. Perp is a four-pass transmembrane protein recently shown to be localized to desmosomes in normal mouse epidermis. Methods: In our study we have begun to examine the role of Perp expression in desmosome assembly and stability in oral squamous cell carcinoma cell lines. We examined the expression of Perp protein in a panel of oral SCC cell lines by western blot analysis In addition, we retrovirally expressed Perp/GFP in SCC cell lines and examined desmosome assembly in these cells. Results: We determined that Perp expression was highest in cells which assemble robust desmosomes. In addition, Perp/GFP expressed in A431 cells resulted in altered desmocollin 2 incorporation into the desmosomal plaque was altered while desmoglein incorporation was unaffected. Conclusion: These data suggest that Perp may play an important role in desmosome assembly and stability in various epithelial tissues. Perp represents a novel marker for desmosomal adhesion and may serve as a regulator of cell-cell adhesion in the oral mucosa.