Gene expression of adrenomedullin, leptin, their receptors and neuropeptide Y in hormone-secreting and non-functioning pituitary adenomas, meningiomas and malignant intracranial tumours in humans

The aim of this study was to assess human intracranial tumours for their ge ne expression pattern of the vasoactive peptide adrenomedullin (AM), its re ceptor (AM-R) and leptin, which exerts multiple biological effects includin g proliferation and angiogenesis via the leptin receptor (OB-Rb). Gene acti vity of neuropeptide Y (NPY) was monitored additionally. We investigated wh ether there was a characteristic gene expression pattern of AM and leptin i n different intracranial tumours, depending on their proliferation activity and biological behaviour. We investigated 35 non-functioning pituitary ade nomas (including eight null cell, four silent plurihormonal, 23 silent gona dotroph adenomas), seven somatotropinomas, seven prolactinomas, eight menin giomas, five astrocytomas, two glioblastoma multiformes and unaffected temp oral lobe (n = 8). Quantitative reverse transcriptase-polymerase chain reac tion (TaqMan((R)) RT-PCR) was performed. AM mRNA was detectable in all tumo ur specimens. AM/GAPDH (glyceraldehyde-3-phosphate dehydrogenase) ratio was significantly higher in somatotropinomas, as was AM/CD31 ratio in prolacti nomas, compared with inactive adenomas (P < 0.05). AM-R mRNA was found in a ll tumour subgroups in small quantities but, in general, higher in tumours than in temporal lobe tissue, respectively. AM-R/CD31 ratio was significant ly higher in prolactinomas than in inactive adenomas (P < 0.05). Leptin was detectable in very low quantities in each subgroup. OB-Rb gene expression was found in all tumour subgroups, OB-Rb/GAPDH ratio was highest for mening iomas (P < 0.0001, compared with temporal lobe). NPY mRNA was detectable in temporal lobe in higher quantities than in tumours (P < 0.0001), and almos t undetectable in prolactinomas and astrocytomas. Our data demonstrate that AM and AM-R, NPY, as well as leptin and OB-Rb, are expressed in various in tracranial tumours in humans but their particular function has to be elucid ated further. At present, there is no evidence for a cross-talk on transcri ptional level between the peptidergic vasodilative system AM and the putati ve angiogenic and proliferation affecting factor leptin.