Ber-EP4 immunoreactivity depends on the germ layer origin and maturity of the squamous epithelium

To map the expression of Ber-EP4 in well-differentiated squamous epithelia, metaplastic squamous epithelia and dysplastic squamous epithelia of different origins.

Squamous epithelium of different origin was stained using a standard immunohistochemistry method applied to paraffin sections. We found that normal squamous epithelium of the oral cavity, oesophagus, uterine cervix, vagina, anal canal, and branchial cysts are Ber-Ep4-negative, as are the mature squamous metaplasia of bronchial mucosa, urinary bladder mucosa and uterine cervical mucosa. In contrast, immature squamous metaplasia of bronchial mucosa, or uterine cervical mucosa, and squamous dysplasia of oral mucosa of endodermal origin, or uterine cervical mucosa in most cases expressed Ber-EP4.

Squamous epithelia of ectodermal origin never express Ber-EP4, whether normal, hyperplastic, dysplastic or neoplastic. In contrast, squamous epithelium of endodermal origin sometimes contains the target glycoproteins of Ber-EP4 when immature, metaplastic, dysplastic or neoplastic. The results indicate that the differences in expression of Ber-EP4 in squamous epithelium depend primarily on germ layer origin, and on the maturity of the epithelium.