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Updated: Sep 21, 2026

Isolation of Proximal Fluids to Investigate the Tumor Microenvironment of Pancreatic Adenocarcinoma
Published on: November 5, 2020
Molecular forms of parathyroid hormone-related protein in tumours and biological fluids
S J Bowden1, S V Hughes, W A Ratcliffe
1Wolfson Research Laboratories, Department of Clinical Chemistry, Queen Elizabeth Medical Centre, Edgbaston, Birmingham, UK.
Objective:
We investigated the content and compared the molecular forms of parathyroid hormone-related protein in tumour tissue, plasma and pleural fluid.
Design:
Measurement of parathyroid hormone-related protein in tumour extracts and biological fluids and comparison of the elution profiles of parathyroid hormone-related protein (PTHRP) immunoreactivity following gel filtration chromatography on Bio-gel P100.
Patients:
Tumours and plasma from patients with humoral hypercalcaemia of malignancy were studied, together with tumours and pleural fluids from patients who were normocalcaemic.
Measurements:
Immunoreactivity in column fractions, plasma and tumour extracts was measured by a highly sensitive immunoradiometric assay for PTHRP 1-86 with specificity directed at the 17-61 region of PTHRP.
Results:
Similar levels of PTHRP immunoreactivity were measured in tumours from normocalcaemic and hyper-calcaemic patients. PTHRP 1-86 (28-4630 fmol/g) was detected in eight of the nine tumours studied. Immunoreactivity in tumour extracts eluted as major peaks in the range 22-33 kDa with an additional peak of 15 kDa in three out of six tumours studied. In contrast, immunoreactivity in plasma and pleural fluid eluted within the range 7-14 kDa.
Conclusions:
The major species of parathyroid hormone-related protein in plasma and pleural fluids was consistently smaller than that in tumour tissue (22-33 kDa) suggesting that tumour-derived parathyroid hormone-related protein is processed at the COOH-terminus to form a species of approximately 10 kDa which circulates in patients with humoral hypercalcaemia of malignancy.
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