Expression of vascular endothelial growth factor and its receptors in human anterior pituitary adenomas
IP Adams1, R Henderson1, VL Green1, PM Foy2, I Macfarlane2 & SL Atkin1
Vascular Endothelial Growth Factor (VEGF) is an important growth factor, simulating the process of angiogenesis which is required for tumour progression. It mainly acts through 2 receptors VEGF-R1 and VEGF-R2. Whilst the presence of VEGF has been shown in pituitary adenomas, no study has undertaken the quantification of the expression of VEGF121, VEGF165, VEGF-R1 and VEGF-R2, and whether their expression may correlate.
METHODS. We have used the technique of quantitative RT-PCR to investigate the expression of two isoforms of VEGF (165,121) and the two receptors in 20 pituitary adenomas. The adenomas consisted of 5 corticophinomas, 5 macroprolactinomas, 5 non-functioning ademomas and 5 somatotrophinomas. Human umbilical vein endothelial cell cDNA was used as a control for expression of VEGF and its receptors. PCR for Beta glucuronidase was used as a control of cDNA integrity.
RESULTS. VEGF121 and VEGF165 were expressed in 65 % and 75% respectively of the adenomas and the level of this expression varied greatly. There was no correlation between expression of the two receptors or between VEGF expression and adenoma type. Only two adenomas didn't express any VEGF. VEGF-R1 and VEGF-R2 were expressed in 35 % and 25 % respectively of the adenomas and the level of this expression again varied greatly. There was no correlation between receptor expression and VEGF expression, or receptor expression and adenoma type. 55 % of the adenomas didn't express any receptor. Only one adenoma was found not to express any VEGF or receptor.
CONCLUSION. The presence of VEGF in 95% of the adenomas and VEGF receptor in 55 % of the adenomas is in accord with immunostaining data that suggests that VEGF may have a role in the tumorigenesis of pituitary adenomas.