PARATHYROID HORMONE-RELATED PROTEIN IN GASTRIC CANCERS WITH HETEROTOPIC OSSIFICATION

Background. Parathyroid hormone-related protein (PTHrP) has been regar ded as one of the substances causing humoral hypercalcemia of malignan cy. Methods. The immunohistochemical localization of PTHrP was investi gated in 33 cases of gastric cancer (4 with heterotopic ossification a nd 29 without heterotopic ossification) to clarify the role of PTHrP i n heterotopic ossification by using the anti-PTHrP monoclonal antibody , 4B3. Results. The four cases with heterotopic ossification showed po sitive staining at primary or metastatic sites, and in one case fibrob lasts in the stroma surrounding the heterotopic ossifying foci also sh owed positive. On the other hand, of the 29 cases without heterotopic ossification, only 5 showed positive staining. Conclusions. The presen ce of PTHrP in ossifying gastric carcinomas at a relatively high rate indicates that PTHrP also might be related to heterotopic ossification associated with malignancies. It is speculated that PTHrP would contr ibute to heterotopic ossification by facilitating the process of miner alization.