Effects and molecular mechanisms of Epac1 on pituitary adenoma cell proliferation and cell cycle / 局解手术学杂志

ABSTRACT

Objective To explore the molecular mechanism of pituitary growth hormone adenoma cell proliferation.Methods Functional growth hormone-secreting pituitary adenoma(fGH-PA)tissue samples were collected from 12 patients with acromegaly.The exchange protein 1 directly activated by cAMP(Epac1)mRNA expression levels in fGH-PA tissues and rat RGC-5,MMQ and GH3 cells were determined by qPCR.The expression levels of Epac1 in fGH-PA tissues were determined by immunohistochemistry.Western blot was used to determine the expression levels of Epac1 in MMQ and GH3 cells.Overexpression or knockdown of Epac1,or knockdown of cAMP response element-binding protein(CREB)in GH3 cells,cell cycle changes were determined by flow cytometry,cell proliferation ability was determined by CCK-8 assay,and the expression levels of p-CREB,CREB,Cyclin D1,CDK2 and p21 in cells were determined by Western blot.Results qPCR and immunohistochemistry results showed that the expression levels of Epac1 mRNA and protein in fGH-PA tissues were significantly higher than those in adjacent normal tissues(P<0.05).qPCR and Western blot results showed that compared with RGC-5 cells,the expression levels of Epac1 mRNA and protein in MMQ and GH3 cells were significantly increased(P<0.05).After overexpres-sion of Epac1 in GH3 cells,compared with the Control group,the proportion of cells in G0/G1 phase and S phase in the Epac1-OE group were significantly reduced(P<0.05),and the proportion of cells in G2/M phase were significantly increased(P<0.05);the cell prolifera-tion ability were significantly enhanced(P<0.05);the expression levels of p-CREB and Cyclin D1 in cells were significantly increased(P<0.05),the expression levels of CDK2 and p21 were significantly decreased(P<0.05),while there was no significant change in the expression level of CREB between the two groups(P>0.05).After knockdown of Epac1 or knockdown of CREB in GH3 cells,all of the above results were reversed(P<0.05).Conclusion The overexpression of Epac1 in pituitary growth hormone adenoma cells can up-regulate the levels of p-CREB in cells,and promote adenoma cells to pass through G1/S phase checkpoint,resulting in cell cycle checkpoint disorder and massive proliferation,but it does not affect the expression levels of CREB.