Li Xiaohong, Xiao Ying, Fan Shaoqing, Xiao Mingbing, Wang Xiaotong, Chen Xudong, Li Chunsun, Zong Guijuan, Zhou Guoxiong, Wan Chunhua
Department of General Surgey, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, China.
Department of Gastroenterology, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, China; Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Nantong University, Nantong 226001, Jiangsu, China.
Exp Mol Pathol. 2016 Oct;101(2):176-186. doi: 10.1016/j.yexmp.2016.08.001. Epub 2016 Aug 3.
The receptor for activated protein kinase C (RACK1) is a scaffold protein involved in multiple intracellular signal pathways. Previous studies have shown that RACK1 is associated with the progression of multiple cancer types, including hepatocellular carcinoma and gastric cancer. However, the role of RACK1 in human pancreatic ductal adenocarcinoma (PDAC) remains unclear.
In this study, the expression of RACK1 was evaluated by Western blot analysis in 8 paired fresh PDAC tissues and immunohistochemistry on 179 paraffin-embedded slices. Then, we used Fisher exact test to analyze the correlation between RACK1 expression and clinicopathological characteristics. Starvation and re-feeding assay was used to assess cell cycle. Western blot, CCK8, flow cytometry assays, and colony formation analyses demonstrated that RACK1 played an essential role in PDAC development. Annexin-V/PI apoptotic assay and western blot showed that RACK1 was involved in regulating the apoptosis of PDAC cells.
RACK1 was highly expressed in PDAC tissues and cell lines and was significantly associated with multiple clinicopathological factors. Univariate and multivariate analyses showed that high RACK1 expression was identified to be an independent prognostic factor for PDAC patients' survival. In vitro, serum starvation-refeeding experiment suggested that RACK1 was upregulated in proliferating PDAC cells, together with the percentage of cells at the S phase, and was correlated with the expression of Cyclin D1. Moreover, Overexpression of RACK1 facilitated the proliferation and cell cycle progression of PDAC cells, while downregulation of RACK1 induced growth impairment, G1/S cell cycle arrest and apoptosis in PDAC cells. Silencing RACK1 decreased bcl-2 expression, increased cleaved caspase3 expression level and induced the apoptosis of PDAC cells.
Our results suggest that RACK1 could play an important role in the tumorigenesis of PDAC and serve as a potential therapeutical target in PDAC treatment.
活化蛋白激酶C受体（RACK1）是一种参与多种细胞内信号通路的支架蛋白。先前的研究表明，RACK1与多种癌症类型的进展相关，包括肝细胞癌和胃癌。然而，RACK1在人类胰腺导管腺癌（PDAC）中的作用仍不清楚。
在本研究中，通过蛋白质免疫印迹分析评估了8对新鲜PDAC组织中RACK1的表达，并对179张石蜡包埋切片进行了免疫组织化学分析。然后，我们使用Fisher精确检验分析RACK1表达与临床病理特征之间的相关性。采用饥饿和再喂养试验评估细胞周期。蛋白质免疫印迹、CCK8、流式细胞术分析和集落形成分析表明，RACK1在PDAC发展中起重要作用。膜联蛋白V/PI凋亡试验和蛋白质免疫印迹表明，RACK1参与调节PDAC细胞的凋亡。
RACK1在PDAC组织和细胞系中高表达，且与多种临床病理因素显著相关。单因素和多因素分析表明，RACK1高表达是PDAC患者生存的独立预后因素。在体外，血清饥饿-再喂养实验表明，RACK1在增殖的PDAC细胞中上调，同时S期细胞百分比增加，且与细胞周期蛋白D1的表达相关。此外，RACK1的过表达促进了PDAC细胞的增殖和细胞周期进程，而RACK1的下调则导致PDAC细胞生长受损、G1/S期细胞周期阻滞和凋亡。沉默RACK1可降低bcl-2表达，增加裂解的caspase3表达水平，并诱导PDAC细胞凋亡。
我们的结果表明，RACK1可能在PDAC的肿瘤发生中起重要作用，并可作为PDAC治疗的潜在靶点。
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