The Experimental And Clinical Research Of RET In Growth Hormone Type Pituitary Adenoma

Pituitary adenoma(pituitary adenoma,PA)is is the third most common intracranial tumors after glioblastoma and meningioma.Growth hormone-pituitary adenoma(GH-PA)is a common functional pituitary adenoma(about 20%).Patients often have acromegaly,or giant diseasee before the onset of piphyseal closure.At present,the safest and most effective treatment for GH-PA is the endonasal pituitary tumor resection.Low GH(<2.5 ng / ml)and age,gender-appropriate insulin-like growth factor(IGF-1)one week after surgery indicates clinical remission.But in fact,some patients have delayed remission symptoms,which did not meet the immediate remission criteria but the hormone level dropped to normal,the existing laboratory indicators such as GH,IGF-1 are not enough to accurately predict long-term prognosis and delayed remission,so the efficacy of postoperative prediction of GH-PA should be studied further.RET(rearranged during transfection)is a transmembrane tyrosine kinase receptor that has been shown to be closely associated with the outcome and prognosis of various endocrine tumors.So far,the expression of RET in normal pituitary has not been reported,and its expression in pituitary adenomas requires further study.In this study,we aimed to clarify the role of RET in of pituitary adenoma in both clinical and experimental ways.On the one hand,clinical data collection and RET immunostaining were done to investigate the correclation beween RET expression and disease development and prognosin;On the other hand,we have set up animal models(PA and Epilepsy)to observe the changed outcome during RET/GDNF singnaling regulation.Experiment one:Analysis of the correlation of RET expression with growth hormone level of patients with growth hormone-secreting pituitary adenoma Objective: To investigate the correlation of RET expression with postoperative remission and growth hormone levels of patient with growth hormone-secreting pituitary adenoma(GH-PA).Methods: 20 patients(no remission 10,immediate remission 6,delayed remission 4)underwent transsphenoidal endoscopic surgery for GH-PA from 2010 to 2013 in Xijing hospital were collected and followed up to measure the changes of GH levels at different time points(before surgery,1 week,3month and 1 year after surgery),and the specimen were collected for RET immunohistochemical staining.Results: The level of RET expression in the delayed remission ones tend to be lower than no remission and immediate remission groups(P<0.05).There is no significant relationship between RET expression and GH levels before,3months and 1year after surgery(P>0.05),however the GH elevation(1year-1week)tend to have a positive relationship with RET expression.Conclusion: RET expression to some degree helps predict delayed remission,and tend to have a positive relationship with GH elevation after surgery in GH-PA patientsExperiment two:The Effect of RET-dependent GDNF Signaling-regulation in rat models Objective: To investigate the effect of bilateral stereotactic administration of anti-GDNF antibody rat models of pilocarpine-induced epilepsy and estradiol benzoate-induced pituitary adenoma(PA).Methods: 120 adult SD(male and female 60 each)rats were randomly divided into 6 groups: epilepsy: the sham1 group(n=20),model1 group(n=20)and anti-GDNF1 group(n=20);PA: the sham2 group(n=20),model2 group(n=20)and anti-GDNF2 group(n=20);Lithium chloride and pilocarpine were intraperitoneally injected to induce seizures.The sham group was given lithium chloride only and anti-GDNF group was given a stereotactic injection of anti-GDNF antibody into bilateral hippocampal CA1 region(model1)or into the pituitary(model2)2h before model establishment.Then video monitoring of seizure incidence of the epileptic rats was done at 1,3,7d and EEG monitoring was performed at 7d;Tumor size of the pituitary was monitored at 7d(model2).Immunohistochemical staining was used to analyze the amount of neurons(NeuN expression)in the hippocapal CA1 region(model1)or pituitary(model2)at 7d,and western blot was carried out to explore the expression of protein levels of GDNF,RET and P53 at 1d.Results: Model1 group tend to have more spike-slow waves than Sham1 group,and anti-GDNF1 group tend to have less than Model1 group in the parameters above(P<0.05),at the same time anti-GDNF2 group tend to have smaller tumor size than model2(P<0.05);the amount of apoptotic neurons in the hippocampal CA1 region of Model group were large,but apoptotic cells of the anti-GDNF group were comparatively less than Model group(P<0.05);In both model groups,GDNF and RET levels were increased in different degrees,and the P53 levels tend to decrease.The protein levels of GDNF and RET were obviously down-regulated and P53 up-regulated in the anti-GDNF1 group compared to Model1 group(P<0.05),and the same result was observed in anti-GDNF2 group compared to Model2 group(P<0.05).Conclusions: Bilateral stereotactic administration of anti-GDNF antibody in the hippocampal CA1 region could prevent the progression of diseases and have protective effects on neurons,which was probably related to suppression of GDNF/RET/P53 signaling.