Differences in C/EBPs in normal tissue and papillomas of the larynx

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Abstract
Transcription factors belonging to the family of CAAT enhancer binding proteins (C/EBPs) programme differentiation in a wide variety of cells. We asked about the expression of C/EBPs in squamous epithelium. Using immunohistochem‐istry, C/EBPα and C/EBPβ were easily detected in tissue sections from normal larynx or laryngeal papillomas, benign tumours with a papillomavirus aetiology and characterized by abnormal differentiation. A temporal expression of these C/EBPs occured as keratinocytes differentiated. In both tissues, C/EBPβ appeared to be exclusively nuclear. In normal tissue, the greatest amount of C/EBPβ was present in the spinous layer, and much less occurred in the granular layer. The basal layer of the laryngeal papillomas contained the most C/EBPβ. Less was present in the spinous layer. Little C/EBPβ was in the granular layer. Much C/EBPα was in the cytoplasm in both tissues. In normal tissue, nuclear C/EBPα staining was virtually absent in the basal layer, and became present in the spinous layer. Nuclear C/EBPα was randomly distributed in all layers in papillomas. Using immunoblots and Southwestern blots, we detected abundant truncated isoforms of C/EBPα in the papillomas. Since differentiation of many tissues is determined by the relative amounts of different C/EBPs, our data supports a role for C/EBPs in the differentiation of squamous epithelium.