Receptor activator of NF-kappaB ligand (RANKL) is expressed in chondroblastoma: possible involvement in osteoclastic giant cell recruitment.
OBJECTIVE
Chondroblastoma is a rare, locally aggressive bone tumour that causes osteolytic destruction at the epiphyseal end of the affected bone. It is possible that tumour cells may stimulate osteoclastogenesis and osteolytic destruction through the production of receptor activator of NF-kappaB ligand (RANKL), which is a key molecule essential for regulating osteoclast formation and activity. Therefore, the expression of RANKL at both the mRNA and the protein level was investigated in chondroblastoma tumour tissue obtained from patients.


METHODS
The expression of RANKL gene transcripts was analysed by the reverse transcription-polymerase chain reaction (RT-PCR), and the cellular localisation of RANKL mRNA and protein was demonstrated by means of in situ hybridisation and immunohistochemistry.


RESULTS
RT-PCR analysis indicated that RANKL mRNA was present in all chondroblastoma specimens and normal cancellous bone samples, but not in normal articular cartilage and chondrosarcoma tissues. In contrast, gene transcripts of osteoprotegerin (OPG), the decoy receptor of RANKL, were detected in all types of tissues. The chondroid origin of neoplastic mononuclear cells in chondroblastoma was confirmed by positive S-100 immunohistochemical staining. Both RANKL mRNA and protein were exclusively expressed in these neoplastic mononuclear cells.


CONCLUSIONS
These findings suggest that RANKL may be involved in the tumour cell induced recruitment of osteoclast-like cells and consequent osteolytic bone destruction in chondroblastoma.
Huang
L
L
Department of Orthopaedics and Traumotology, Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR.
Cheng
Y Y
YY
Chow
L T C
LT
Zheng
M H
MH
Kumta
S M
SM
D000293:Adolescent; D000328:Adult; D001859:Bone Neoplasms / Q000378:metabolism* / Q000473:pathology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D002648:Child; D002804:Chondroblastoma / Q000378:metabolism* / Q000473:pathology; D005260:Female; D015870:Gene Expression; D006801:Humans; D007124:Immunoenzyme Techniques; D008024:Ligands; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D016328:NF-kappa B / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D010010:Osteoclasts / Q000502:physiology; D053245:RANK Ligand; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D053246:Receptor Activator of Nuclear Factor-kappa B; D020133:Reverse Transcriptase Polymerase Chain Reaction
D002352:Carrier Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D009363:Neoplasm Proteins; D053245:RANK Ligand; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D053246:Receptor Activator of Nuclear Factor-kappa B; C505686:TNFRSF11A protein, human; C505688:TNFSF11 protein, human