IMMUNOHISTOCHEMICAL EVALUATION OF PARATHYROID HORMONE-RELATED PROTEIN (PTHRP) IN THE UTERINE CERVIX

We investigated the immunohistochemical localization of parathyroid hormone-related protein (PTHrP), a major factor responsible for the humoral hypercalcemia of malignancy, in uterine cervical lesions. Formalin-fixed paraffin-embedded specimens from 16 cases of normal and reactive conditions, 45 cases of cervical intra-epithelial neoplasm (CIN) and 63 cases of invasive cancer were studied immunohistochemically by the avidine-biotin-peroxidase method, using an anti-PTHrP monoclonal antibody (MAb), 4B3. In normal and reactive conditions, PTHrP was positive in parabasal cells, squamous metaplasia, and hyperplastic reserve cells. In neoplastic conditions, 96% (43/45) of invasive squamous-cell carcinomas were positive for PTHrP, regardless of the patients' serum calcium levels. Two cases with hypercalcemia were strongly positive for PTHrP and showed prominent stromal interaction of the scirrhous type. In CIN, including koilocytic atypia, 76% (32/42) of cases were positive for PTHrP. In contrast, 91% (10/11) of adenocarcinomas were negative for PTHrP. In conclusion, we found, first, that in non-neoplastic conditions, the presence of PTHrP was correlated with the transformation of progenitor cells into squamous epithelia and with the maturation of keratinocytes and, second, that in squamous-cell carcinoma, the degree of keratinization and stromal interaction was higher in direct proportion to the apparent incidence of detectable PTHrP.