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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 important factor in the regulation of both viral and cellular protein synthesis. We have produced a monoclonal antibody (TJ4C4) which specifically detects p68, and which can be used to detect this antigen in formalin-fixed, paraffin-embedded tissues. Because p68 plays an important role in cellular protein synthesis, we hypothesized that it may correlate with normal and neoplastic cellular differentiation. One hundred and seventy-seven head and neck squamous cell carcinoma specimens, representing 82 patients, were studied. The relative amount, frequency, and distribution of p68 expression were determined by microscopic evaluation of ABC immunoperoxidase-stained specimens. A spectrum of immunoreactivity was detected in 156 of 177 tumors, as well as within the normal squamous epithelium. Normal, actively proliferating cells, such as the basal layer of squamous epithelium, expressed comparatively little p68. Increased p68 expression was noted to parallel the morphologic features of cellular differentiation. In neoplastic tissue, p68 expression also increased with the degree of cellular differentiation. These data demonstrate that the expression of p68 parallels the degree of cellular differentiation in squamous cell carcinoma of the head and neck region, as well as within normal squamous mucosa. Therefore, p68 may provide an objective biologic measure of cellular differentiation which does not depend on morphologic features.

Expression of the protein kinase p-68 recognized by the monoclonal antibody TJ4C4 in human lung neoplasms

P68 is a protein kinase expressed by eukaryotic cells, which is inducible by alpha interferon, and is believed to be an important factor in the regulation of viral and cellular protein synthesis. We have previously reported on a monoclonal antibody, TJ4C4, which is able to specifically detect p68 in formalin-fixed, paraffin-embedded tissue. Because of its important role in regulating cellular protein synthesis, we hypothesized that p68 expression would vary among lung neoplasms with level of differentiation and degree of biosynthetic activity. A total of 246 untreated primary pulmonary and pleural neoplasms were studied. The frequency and relative intensity of p68 expression was determined by light microscopic evaluation of ABC immunoperoxidase stained specimens. All categories of tumors studied demonstrated a spectrum of p68 expression. Expression of p68 correlated well with degree of differentiation in squamous cell carcinomas (SQCC) and acinar adenocarcinomas (AAC). Papillary adenocarcinoma (PAC) and bronchioalveolar carcinoma (BAC) expressed low levels of p68, despite their well differentiated appearance. Expression of the antigen in large cell carcinoma (LCC) was higher than that seen in either poorly differentiated AAC or SQCC. Neuroendocrine tumors generally showed low levels of p68 expression with the intermediate variant of small cell carcinoma expressing higher levels of p68 than the classic "oat cell" form (SCC). Carcinoid tumors expressed higher levels of p68 than did atypical carcinoid tumors. Mesotheliomas showed weak expression of p68, limited primarily to areas of glandular differentiation in the epithelioid form.(ABSTRACT TRUNCATED AT 250 WORDS)