Phosphorylation of sst2 receptors in neuroendocrine tumors after octreotide treatment of patients.
Phosphorylation of sst2 receptors in neuroendocrine tumors after octreotide treatment of patients.
复制标题
奥曲肽治疗患者后神经内分泌肿瘤中 sst2 受体的磷酸化。
DOI：
10.1016/j.ajpath.2012.01.041
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Reubi,JeanClaude
中科院分区：
文献类型：
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作者：
Waser,Beatrice;Cescato,Renzo;Liu,Qisheng;Kao,YachuJ;Körner,Meike;Christ,Emanuel;Schonbrunn,Agnes;Reubi,JeanClaude
用于治疗神经内分泌肿瘤的生长抑素类似物，针对在这些癌症中高水平表达的生长抑素受体亚型2(SSTR1；别名Sst2)。然而，一些肿瘤对生长抑素类似物具有耐药性，目前尚不清楚缺陷是存在于Sst2激活还是下游信号事件。由于Sst2在受体激活后迅速发生磷酸化，我们研究了神经内分泌肿瘤中是否存在Sst2的磷酸化。用新的针对Sst2受体的Ra-1124抗体对受体阳性的神经内分泌肿瘤的Sst2受体磷酸化进行免疫组织化学和Western印迹分析。用免疫荧光和共聚焦显微镜检测Sst2受体磷酸化的特异性、时程和亚细胞定位。所有7个奥曲肽原始肿瘤均显示细胞表面非磷酸化Sst2的表达。相比之下，奥曲肽治疗的10个肿瘤中有9个含有主要内化的磷酸化Sst2。Western印迹分析证实了IHC的数据。奥曲肽对体外培养的人胚胎激酶-Sst2细胞的作用表明，经10秒刺激后，磷酸化的Sst2定位于细胞膜，随后内化为内吞囊泡。这些数据首次表明，据我们所知，大多数接受奥曲肽治疗的胃肠道神经内分泌肿瘤中都存在磷酸化的Sst2，但这些肿瘤中磷酸化受体的亚细胞分布存在显著的差异。
Somatostatin analogues, which are used to treat neuroendocrine tumors, target the high levels of somatostatin receptor subtype 2 (SSTR1; alias sst2) expressed in these cancers. However, some tumors are resistant to somatostatin analogues, and it is unknown whether the defect lies in sst2 activation or downstream signaling events. Because sst2 phosphorylation occurs rapidly after receptor activation, we examined whether sst2 is phosphorylated in neuroendocrine tumors. The sst2 receptor phosphorylation was evaluated by IHC and Western blot analysis with the new Ra-1124 antibody specific for the sst2 receptor phosphorylated at Ser341/343 in receptor-positive neuroendocrine tumors obtained from 10 octreotide-treated and 7 octreotide-naïve patients. The specificity, time course, and subcellular localization of sst2 receptor phosphorylation were examined in human embryo kinase–sst2 cell cultures by immunofluorescence and confocal microscopy. All seven octreotide-naïve tumors displayed exclusively nonphosphorylated cell surface sst2 expression. In contrast, 9 of the 10 octreotide-treated tumors contained phosphorylated sst2 that was predominantly internalized. Western blot analysis confirmed the IHC data. Octreotide treatment of human embryo kinase–sst2 cells in culture demonstrated that phosphorylated sst2 was localized at the plasma membrane after 10 seconds of stimulation and was subsequently internalized into endocytic vesicles. These data show, for the first time to our knowledge, that phosphorylated sst2 is present in most gastrointestinal neuroendocrine tumors from patients treated with octreotide but that a striking variability exists in the subcellular distribution of phosphorylated receptors among such tumors.