CORRELATION OF THE EXPRESSION OF DOUBLE-STRANDED RNA-DEPENDENT PROTEIN-KINASE (P68) WITH DIFFERENTIATION IN HEAD AND NECK SQUAMOUS-CELL CARCINOMA

p68 is an inducible protein kinase which is believed to be an importan t factor in the regulation of both viral and cellular protein synthesi s. We have produced a monoclonal antibody (TJ4C4) which specifically d etects p68, and which can be used to detect this antigen in formalin-f ixed, paraffin-embedded tissues. Because p68 plays an important role i n cellular protein synthesis, we hypothesized that it may correlate wi th normal and neoplastic cellular differentiation. One hundred and sev enty-seven head and neck squamous cell carcinoma specimens, representi ng 82 patients, were studied. The relative amount, frequency, and dist ribution of p68 expression were determined by microscopic evaluation o f ABC immunoperoxidase-stained specimens. A spectrum of immunoreactivi ty was detected in 156 of 177 tumors, as well as within the normal squ amous epithelium. Normal, actively proliferating cells, such as the ba sal layer of squamous epithelium, expressed comparatively little p68. Increased p68 expression was noted to parallel the morphologic feature s of cellular differentiation. In neoplastic tissue, p68 expression al so increased with the degree of cellular differentiation. These data d emonstrate that the expression of p68 parallels the degree of cellular differentiation in squamous cell carcinoma of the head and neck regio n, as well as within normal squamous mucosa. Therefore, p68 may provid e an objective biologic measure of cellular differentiation which does not depend on morphologic features.