COMMON EXPRESSION OF PARATHYROID HORMONE-RELATED PROTEIN AND NO CORRELATION OF CALCIUM LEVEL IN RENAL-CELL CARCINOMAS

Background. Parathyroid hormone-related protein (PTHrP) is the predomi nant cause of humoral hypercalcemia of malignancy (HHM). Methods. Usin g a PTHrP-specific monoclonal antibody (MoAb), 4B3, the authors invest igated the immunohistochemical localization of PTHrP in formalin-fixed and paraffin-embedded sections of normal human kidney tissues and tis sues from 42 human renal cell carcinomas obtained at operation or auto psy. Results. In normal renal tissues, the distal tubules and collecti ng ducts showed positive immunostaining. PTHrP was detected in 40 of 4 2 renal cell carcinoma tissues (95%). Histopathologically, the granula r cell subtypes of renal cell carcinomas tended to be more strongly po sitive than the clear cell subtypes. There was no significant correlat ion between the level of immunostaining and each patient's serum calci um level. Conclusion. PTHrP was commonly observed in renal cell carcin omas, and no significant correlation was seen between the intensity of PTHrP staining and the serum calcium level.