Expression of menin gene mRNA in pituitary tumours

Objective: Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal domi nant inherited disorder characterised by the combined occurrence of parathy roid, endocrine pancreas and anterior pituitary tumours. The gene responsib le for MEN 1, the menin gene, a putative tumour-suppressor gene located on human chromosome 11q13, has been cloned. To investigate the role of the men in gene in sporadic anterior pituitary tumorigenesis, its mRNA was assessed in a group of pituitary tumours. Methods: Menin gene expression, along with glyceraldehyde phosphate dehydro genase (GAPDH) gene expression, has been studied in a group of normal pitui taries and in 23 pituitary tumours not associated with the MEN 1 syndrome. The pituitary tumours included 4 prolactinomas, 11 growth-hormone-secreting tumours and 8 non-functional tumours. Total RNA was extracted from the nor mal pituitaries and tumours, and cDNA was synthesised with standard reverse transcriptase methods. Duplex polymerase chain reaction (PCR) was standard ised in order to quantify the expression of the menin gene using intron-spa nning primers across exons 9 and 10 in relation to thc 'house-keeping' gene GAPDH. The PCR products were separated on agarose gel and densitometric an alysis of the bands allowed semi-quantification. Results: There was no evidence for a change in menin gene expression in any of the pituitary tumours when compared with normal pituitaries. Conclusions: These studies complement previous work on mutational analysis, and do not suggest a major role for the menin suppressor gene in sporadic pituitary tumorigenesis.