RELATIVE AMOUNTS OF KERATIN-17 ARE HIGHER THAN THOSE OF KERATIN-16 INHAIR-FOLLICLE-DERIVED TUMORS IN COMPARISON WITH NONFOLLICULAR EPITHELIAL SKIN TUMORS

Specimens of trichilemmal cyst, malignant trichilemmoma, keratoacantho ma, and epidermal cyst were examined to characterize keratin peptides in hair-follicle-derived tumors. Keratins were extracted from the spec imens and analyzed by two-dimensional gel electrophoresis and densitom etry; the results were then compared with those for normal epidermis, the outer root sheath of hair follicles, psoriatic epidermis, and vari ous nonfollicular cutaneous epithelial tumors. The specific nonfollicu lar tumors examined were squamous cell carcinoma, Bowen disease, actin ic keratosis, eccrine porocarcinoma, and sebaceous carcinoma, Immunohi stochemistry also was performed with a few anti-keratin monoclonal ant ibodies. As a general rule, K6 and K16 were expressed in hyperprolifer ative conditions, such as epidermal tumors, and K17 was coexpressed in the same lesions, The ratio of K16 to K17 in many epithelial skin tum ors has been unclear until now, K17 content exceeded K16 content in mo st follicular tumors, whereas in almost all the nonfollicular tumors a nd the psoriatic epidermis, K17 levels were less than or about equal t o K16 levels, There was a significant difference in the ratio of K16 t o K17 between follicular and nonfollicular skin tumors, These results indicate that alterations in the content of these keratins may be asso ciated with follicular differentiation.