PKCσ和B-Raf在垂体GH腺瘤胞内异常信号通路中的调控机制及其与gsp的关系

With the capacity of over secreting growth hormone, originated from the front lobe of pituitary gland, somatotropic adenoma, prefers to recurrence after surgical resection and medical therapy. It has been separated into two independent fields in fundamental and clinic researches, based on its two features. One of its two remarkable characters is endocrinal character, such as GHRH-controlled or self-conrolled hormone producing while the other is the general biological character of neoplasia, such as proliferation and invasion. To a certain extent, the separaction has restricted the comprehensive recognition and further research development of somatotrophic adenoma, and caused these two fields falling into an embarrassing position. For its special tumor initiating mechanism, interdiscipline of the two different characters, is nearly absent. Integrated researches and interdiscipline of the two fields are necessary for this special tumor. They are useful for us to find some methods to both inhibit tumor overgrowth and effectively decrease GH level right. As for this condition, the project would start with cell signaling pathway of GHRH and GHSR that regulates the GH secretion in somatotrophic adenoma, paying attention to the cooperative and feedback function and investigating their interaction between endocrinal regulation, proliferation and invasion. Based on above link, we will examine the relationships among PKCσ,B-Raf and the typical gsp mutation of the somatotrophic adenoma. It would be clarified the prominent position of PKCσ in regulating cell signaling pathway mediating GH secretion, proliferation and invasion. Also, the positive regulatory role for B-Raf in MEK-ERK and the impact of gsp mutation engaged in PKCσ and B-Raf will be investigated to explore their regulation in cell signaling mediating growth hormone secreting,cell proliferation and cell invasion of somatotropic adenoma in this project. Finally, with the superiority of our work on somatotropic adenoma, combined with clinical practice, we'd confirm that the key gene and enzymes(gsp,PKCσ and B-Raf) play a important role in judging prognosis and drug resistance of somatotropic adenoma.

垂体生长激素（GH）腺瘤发生于垂体前叶，位于激素分泌的中轴线上。在基础临床研究中分为内分泌和一般肿瘤生物学行为（增殖、侵袭）两个方向。交叉领域研究的欠缺限制了人们对这一特殊内分泌肿瘤发病机制的充分认识。如何兼顾抑制肿瘤生长和有效降低GH水平成为当前面临的首要难题。项目拟针对此状况，从腺瘤细胞调控GH分泌的GHRH和GHSR信号通路入手，研究通路间存在的协同和交叉反馈作用，探索其在内分泌调节、增殖、侵袭作用间的相互联系。重点研究PKCσ、B-Raf和其特有的gsp突变在上述环节中的相互关系；阐明PKCσ在介导GH分泌、增殖、侵袭信号通路间的联结作用和突出地位，B-Raf对ERK的调节作用及gsp突变对PKCσ、B-Raf作用的影响；深入探索它们在GH腺瘤中的作用机制。并凭借我们在该肿瘤研究中的优势，结合临床实际，证实上述关键基因、蛋白在判断GH腺瘤预后、生长抑素药物耐药中的作用。

垂体生长激素腺作为常见的垂体腺瘤之一，多呈侵袭性生长，同时由于生长激素升高严重影响患者的内分泌功能，尤为难治。本项目拟从腺瘤细胞调控 GH 分泌的GHRH和 GHSR 信号通路入手，研究通路间存在的协同和交叉反馈作用，探索其在内分泌调节、增殖、侵袭作用间的相互联系。B-raf和C-raf是我们在前期发现GH腺瘤PKC通路调控下游的重要分子，在本项目中我们发现B-Raf及C-Raf均参与了cAMP-ERK1/2交叉通讯对生长激素腺瘤的促增殖作用；通过外源性滴加Forskolin升高cAMP浓度增加了B-Raf及C-Raf激酶活性；在生长激素腺瘤中，B-Raf及C-Raf单独发挥作用，而非形成异源二聚体。同时，cAMP的直接下游效应分子Epac能够部分介导cAMP引起的GH3细胞的增殖，然而其在GH分泌中的无明显作用。在另一方面，本研究还观察gsp基因突变和腺瘤对于生长抑素作用敏感性相关，gsp阳性的腺瘤对生长抑素反应较好。我们也探索了免疫细胞在垂体瘤及卒中中的作用，发现TAMs可促进垂体瘤卒中。这些结果明确了GH腺瘤中cAMP下游关键分子的信号转导及交叉通讯对肿瘤侵袭和GH分泌的影响，可能为GH腺瘤的内分泌治疗及耐药提供新的理论依据。