Co-expression of parathyroid hormone-related protein (PTHrP) and PTH/PTHrP receptor in cartilaginous tumours: a marker for malignancy?
OBJECTIVE
Parathyroid hormone-related protein (PTHrP) is one of the critical factors for the differentiation and growth of chondrocytes. We examined the correlation between the co-expression of PTHrP and PTH/PTHrP receptor and the grade of malignancy in cartilaginous tumours.


METHODS
We analysed PTHrP and PTH/PTHrP receptor expression in chondrosarcoma by immunohistochemistry and compared specific staining with the expression in benign cartilaginous tumours. There were 38 cartilaginous bone tumours consisting of 26 chondrosarcoma, six enchondroma and six osteochondroma. Chondrosarcoma were composed of 20 conventional chondrosarcoma (10 grade 1, seven grade 2, and three grade 3), two dedifferentiated chondrosarcoma, two clear cell chondrosarcoma, and two myxoid chondrosarcoma. We performed the standard peroxidase-labelled streptavidin-biotin detection method for immunohistochemistry using an antibody raised against PTHrP (1-14) and PTH/PTHrP receptor. The magnitude of receptor positivity of PTHrP and PTH/ PTHrP in each tumour was assessed as a percentage of PTHrP and PTH/PTHrP-positive cells per thousand tumour cells in the most histologically aggressive area of the tumour.


RESULTS
All chondrosarcoma, five of six enchondroma, and four of six osteochondroma showed PTHrP-positive cells, and all chondrosarcoma, five of six enchondroma and five of six osteochondroma showed PTHrP receptor-positive cells. The grade of malignancy correlated with the percentage of both PTHrP and PTH/PTHrP receptor-positive tumour cells (P < 0.0001, either). Each grade of chondrosarcoma showed statistically higher expression of both PTHrP and PTH/PTHrP receptor than benign cartilaginous tumour.


CONCLUSIONS
This is the first report of the co-expression of PTHrP and PTH/PTHrP receptor in chondrosarcoma. PTHrP and PTH/PTHrP receptor positivity may be valuable for differentiating between benign and malignant cartilaginous tumours.
Kunisada
Toshiyuki
T
Department of Orthopaedics, St Vincent's Hospital, Fitzroy, Victoria, Australia.
Moseley
Jane M
JM
Slavin
John L
JL
Martin
T John
TJ
Choong
Peter F M
PF
D000293:Adolescent; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D001859:Bone Neoplasms / Q000378:metabolism* / Q000473:pathology; D002452:Cell Count; D002813:Chondrosarcoma / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000378:metabolism*; D044162:Parathyroid Hormone-Related Protein; D036361:Peptide Hormones / Q000378:metabolism*; D044168:Receptor, Parathyroid Hormone, Type 1; D018016:Receptors, Parathyroid Hormone / Q000378:metabolism*
D014408:Biomarkers, Tumor; C470121:PTHLH protein, human; D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D036361:Peptide Hormones; D044168:Receptor, Parathyroid Hormone, Type 1; D018016:Receptors, Parathyroid Hormone