Immunohistochemical expression of SKALP/elafin in squamous cell carcinoma of human lung and esophagus

To investigate the biological significance of skin-derived anti-leukoproteinase (SKALP)/elafin in squamous cell carcinoma (SqCC), the immunohistochemical expressions of SKALP/elafin in SqCC (lung 46 and esophagus 34) were studied. The results were compared with the immunohistochemical staining of a proliferating cell nuclear antigen (PCNA) and a TDT-mediated dUTP-digoxigenin nick end labeling (TUNEL) assay in serial sections. The expression of SKALP/elafin had a high incidence in SqCC (lung 82.6% and esophagus 73.5%). In contrast, no expression was observed in uninvolved bronchial epithelium and normal esophagus except for hyperplastic cells. SKALP/elafin expression was located in the cell layer just underneath the cornified envelope of each cell nest, and DNA fragmentation was observed in the same cell layer in which SKALP/elafin was expressed. PCNA expression was observed in the basal layer of each cornified envelope, and both expressions were clearly separated. In lung SqCC, immunoreactive score (IRS) of SKALP/elafin expression correlated significantly with the differentiation and it tended to increase in accordance with the degree of differentiation. In esophageal SqCC, there was also an obvious relationship between the expression of SKALP/elafin and its differentiation. There was no correlation between the expression and other clinicopathological factors. These results suggest that SKALP/elafin is possibly involved in the cell differentiation program, finally leading to keratinization in SqCC of human lung and esophagus. SKALP/elafin may be a beneficial molecular target for detection or even the development of a new therapeutic method against cancer. [Copyright &y& Elsevier]