Hypercalcaemia due to parathyroid hormone-related protein: long-term circulating levels may not reflect tumour activity

Parathyroid hormone-related protein as a potential tumor marker: A case report of ovarian clear cell carcinoma

Hypercalcemia is one of the important paraneoplastic syndromes, mostly occurring in patients with advanced cancer. Clear cell carcinoma is known to be one of the most common histological subtypes of ovarian tumor associated with hypercalcemia. We present a case of ovarian clear cell carcinoma with hypercalcemia caused by elevated serum parathyroid hormone-related protein (PTHrP). PTHrP mRNA and protein were detected by reverse transcription-polymerase chain reaction and immunohistochemical analysis in the primary and metastasis lesions. Serum calcium and PTHrP levels returned to normal after antihypercalcemic treatment and a radical operation, but they elevated along with the recurrence. Because tumor markers such as carcinoembryonic antigen, carbohydrate antigen (CA)125 and CA19-9 were unstable owing to the patient's liver cirrhosis and were not reliable data for management, serum calcium and PTHrP levels are shown to have been a potential indicator of the recurrence in this case.

PTHrP-Mediated Hypercalcemia in a Calcitonin-Producing Islet Cell Tumor

Calcitonin is a peptide hormone that may decrease serum calcium levels. This case report describes a patient with a calcitonin-producing islet cell tumor who was also hypercalcemic. Parathyroid hormone-related peptide (PTHrP) levels were elevated. No other cause for hypercalcemia was found. The hypercalcemia resolved when the tumor was treated with chemotherapy. PTHrP levels also decreased with the chemotherapeutic treatment. This is the first report of a patient with a calcitonin-producing islet cell tumor and hypercalcemia mediated by PTHrP.

Expression and secretion of parathyroid hormone-related protein by human bone-derived cells in vitro: effects of glucocorticoids

We investigated the production of parathyroid hormone-related protein (PTHrP) by cells derived from explants of human bone. Using an immunoradiometric assay (IRMA), PTHrP was detected in conditioned medium from cultures of bone-derived cells from 6 of 7 patients investigated in this study. PTHrP mRNA was identified in human bone cells using reverse transcriptase-linked polymerase chain reaction (RT-PCR) and by Northern analysis. Transcripts for PTHrP were detected in a purified population of alkaline phosphatase positive cells isolated from human bone marrow cultures by flow cytometry, confirming the expression of PTHrP mRNA by cells of the osteoblastic lineage. Production of PTHrP was inhibited by 10(-6) M of the glucocorticoids, prednisolone and desacetylated deflazacort, in a dose-dependent manner. In addition, RT-PCR followed by Southern blot analysis detected a decrease in steady-state PTHrP mRNA in cultures of human bone-derived cells treated with 10(-6) M prednisolone.