Xie Tao, Tang Yifan, Luo Rongkui, Zhang Xiaobiao, Wu Silin, Gu Ye, Liu Tengfei, Hu Fan
Department of Neurosurgery, Zhongshan Hospital, Fudan University, Shanghai, China.
Department of Pathology, Zhongshan Hospital, Fudan University, Shanghai, China.
Endocrine. 2020 Jun;68(3):629-639. doi: 10.1007/s12020-020-02263-y. Epub 2020 Mar 16.
There is an increasing agreement that acromegaly caused by growth hormone (GH) cell adenoma has two distinct subtypes: densely granulated (DG) and sparsely granulated (SG). We hypothesized that differential molecular signatures may explain their behavior.
Total transcriptome sequencing was performed on ten DG and seven SG adenomas. The differentially expressed RNAs were identified by bioinformatic analyses, and a candidate RNA was verified by quantitative real-time PCR. Immunohistochemical staining was also performed to detect the protein expression of the candidate. Clinical parameters were correlated with protein expression. Subsequently, cell proliferation, colony formation, and cell cycle progression were analyzed after knockdown of the candidate in pituitary GH3 cells. Activation of the cAMP pathway was assessed by ELISA and Western blot.
We confirmed that there were obvious differentially expressed genes between the subtypes. Through gene profiling, we discovered that an orphan adhesion G protein-coupled receptor, GPR64, was overexpressed in more aggressive SG adenomas. Noticeably, GPR64 knockdown significantly inhibited the proliferation of GH3 tumor cells and decreased colony formation. The knockdown also induced cell cycle arrest in GH3 tumor cells. Further studies revealed that GPR64 knockdown decreased cAMP levels and the ratios of p-CREB/CREB, indicating that it suppressed the cAMP/CREB pathway.
Our results indicated that GPR64 may promote aggressiveness in SG-type GH cell adenomas and that it is a key factor regulating the cAMP pathway to promote aggressiveness of GH cell adenomas.
越来越多的人认为，生长激素（GH）细胞腺瘤引起的肢端肥大症有两种不同的亚型：密集颗粒型（DG）和稀疏颗粒型（SG）。我们推测，不同的分子特征可能解释它们的行为。
对10个DG腺瘤和7个SG腺瘤进行全转录组测序。通过生物信息学分析鉴定差异表达的RNA，并通过定量实时PCR验证候选RNA。还进行了免疫组织化学染色以检测候选蛋白的表达。临床参数与蛋白表达相关。随后，在垂体GH3细胞中敲低候选基因后，分析细胞增殖、集落形成和细胞周期进程。通过ELISA和蛋白质印迹评估cAMP途径的激活。
我们证实各亚型之间存在明显的差异表达基因。通过基因谱分析，我们发现一种孤儿粘附G蛋白偶联受体GPR64在侵袭性更强的SG腺瘤中过度表达。值得注意的是，敲低GPR64可显著抑制GH3肿瘤细胞的增殖并减少集落形成。敲低还诱导GH3肿瘤细胞的细胞周期停滞。进一步研究表明，敲低GPR64可降低cAMP水平以及p-CREB/CREB的比率，表明它抑制了cAMP/CREB途径。
我们的结果表明，GPR64可能促进SG型GH细胞腺瘤的侵袭性，并且它是调节cAMP途径以促进GH细胞腺瘤侵袭性的关键因素。
