Pituitary Growth Hormone Secretion In Tumor Excitatory G Protein ¦Á Subunit Gene Mutations And Clinical Characteristics Of The Study

Growth hormone-secreting pituitary adenomas is one of the most common pituitary hormone-secreting tumors. It was reported that a subset of human GH-secreting pituitary tumors contains a mutant form of the a-subunit of stimulating GTP-binding protein (Gsa) which mediates the signal transmission between GHRH receptor and adenylate cyclase (AC).In these tumors, the Gsa mutation at codon 201 and 227, so-called gsp mutation, inhibits the activity of its GTPase, thus GTP can't be hydrolyzed to GDP, the combination of activated Gsa with GTP maintains. The continuously activated Gsa stimulates AC and plays a direct causal role in hormone secretion and tumor growth.We have investigated the incidence and the clinical characteristics of the Chinese acromegalic patients with Gsa gene mutation. 26 acromegalic patients which were diagnosed by GH-glucose suppressing test and CT or magnetic resonance images ( MRI) of sella region were studied. All of the 26 pituitary adenomas were removed by the transsphenoidal hypophysectomy. The clinical presentation of the patients was got preoperatively by history taking and physical examination. The sizes of pituitary tumors were determined by CT, MRI or by intraoperative measurements. Serum hormone levels of pituitary and target glands were also measured. GH-TRH stimulating test was done before the operation. Deoxynbonucleic acid (DNA) was extracted from the frozen fresh tumor tissue, and the DNA fragment encompassing codons 201 and 227 of the Gsa gene was amplified by polymerase chain reaction (PCR). Mutations at...