Skin calcium-binding protein in squamous metaplasia of human uterine cervix

The distribution of skin calcium-binding protein in squamous cell metaplasia of human endocervix, in normal human skin, and in ovarian cancer was determined by the immunofluorescence technique. A rabbit antiserum specific to rat SCaBP was characterized by Ouchterlony immunodiffusion and by immunoprecipitation of 125I-labeled SCaBP. The specificity of antibody labeling was demonstrated by using preimmune rabbit serum and SCaBP antiserum competitively absorbed with purified SCaBP. In normal human skin SCaBP was found exclusively in the basal layer cell cytoplasm. This protein was not detected in normal columnar epithelium of endocervix. Epithelial tissues in the zone of transition between the cylindrical epithelium of the endocervical mucosa and the stratified squamous epithelium of the exocervix were obtained from 14 patients with a wide variety of squamous cell metaplasia. In the early stage of metaplasia SCaBP was detected exclusively in the cytoplasm of reserve undifferentiated cells. In the terminal stage of metaplasia the SCaBP was present only in the basal cell layer. SCaBP was found in several layers of dysplastic tissue, and this distribution appeared to be related to the loss of normal maturation of the epithelium. SCaBP was also present in squamous cell carcinoma of endocervix especially in the least differentiated regions of the tumor. No SCaBP was detected in any ovarian cancer cells. These findings are potentially useful as a means of early detection of squamous metaplasia and of distinguishing premalignant anaplastic lesions from those that are benign and nonproliferative. In addition, the presence of SCaBP in tumors derived from metaplastic epithelia and its absence in the ovarian cancer indicate that immunohistochemical search for this protein might be of value in tumors in which an epidermoid origin is a possibility.