The immunohistochemical expression of calcitonin receptor-like receptor (CRLR) in human gliomas.
BACKGROUND
Gliomas are the most common primary tumours of the central nervous system and exhibit rapid growth that is associated with neovascularisation. Adrenomedullin is an important tumour survival factor in human carcinogenesis. It has growth promoting effects on gliomas, and blockade of its actions has been experimentally shown to reduce the growth of glioma tissues and cell lines. There is some evidence that the calcitonin receptor-like receptor (CRLR) mediates the tumorigenic actions of adrenomedullin.


OBJECTIVE
To determine whether CRLR is expressed in human gliomas and the probable cellular targets of adrenomedullin.


METHODS
Biopsies from 95 human gliomas of varying grade were processed for immunohistochemical analysis using a previously developed and characterised antibody to CRLR.


RESULTS
All tumour specimens were positive for CRLR. As previously found in normal peripheral tissues, CRLR immunostaining was particularly intense in the endothelial cells. This was evident in all the various vascular conformations that were observed, and which are typical of gliomas. In addition, clear immunostaining of tumour cells with astrocyte morphology was observed. These were preferentially localised around vessels.


CONCLUSIONS
This study has shown for the first time that the CRLR protein is present in human glioma tissue. The expression of the receptor in endothelial cells and in astrocytic tumour cells is consistent with the evidence that its endogenous ligand, adrenomedullin, may influence glioma growth by means of both direct mitogenic and indirect angiogenic effects. CRLR may be a valuable target for effective therapeutic intervention in these malignant tumours.
Benes
L
L
Department of Neurosurgery, Philipps-University Marburg, D-35043 Marburg, Germany. benes@med.uni-marburg.de
Kappus
C
C
McGregor
G P
GP
Bertalanffy
H
H
Mennel
H D
HD
Hagner
S
S
D058286:Calcitonin Receptor-Like Protein; D004730:Endothelium, Vascular / Q000378:metabolism; D005910:Glioma / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007124:Immunoenzyme Techniques; D009363:Neoplasm Proteins / Q000378:metabolism; D009389:Neovascularization, Pathologic / Q000378:metabolism; D018003:Receptors, Calcitonin / Q000378:metabolism*
C545578:CALCRL protein, human; D058286:Calcitonin Receptor-Like Protein; D009363:Neoplasm Proteins; D018003:Receptors, Calcitonin