Division of Gastroenterology and Hepatology, Renji Hospital,Shanghai Jiao-Tong University School of Medicine, Shanghai Institute of Digestive Disease, Key Laboratory of Gastroenterology and Hepatology, Ministry of Health, State Key Laboratory of Oncogene and Related Genes, Shanghai, China.
Mol Carcinog. 2014 Feb;53 Suppl 1:E72-84. doi: 10.1002/mc.22031. Epub 2013 Apr 26.
The extracellular signal-regulated kinase (ERK), mitogen-activated protein kinase (MAPK) pathway is an important cell proliferation pathway. We previously reported that the transport protein particle complex 4 (TRAPPC4), ERK2 interaction may activate ERK1/2, modulate pERK2 nuclear localization and regulate proliferation and apoptosis in colorectal cancer (CRC) cells. The present study further investigated the function of the TRAPPC4-ERK2 interaction in CRC in vitro and in vivo. Silencing of TRAPPC4 induced G0/G1 phase cell cycle arrest, upregulated p21 and downregulated cyclin B1 in CRC cells. Overexpression of TRAPPC4 after ERK2 silencing decreased the percentage of G0/G1 phase cells, increased the percentage of G2/M and S phase cells, downregulated p21, upregulated cyclin B1, and enhanced CRC cell viability. Immunohistochemical staining revealed that knockdown of TRAPPC4 downregulated pERK2, whereas overexpression of TRAPPC4 upregulated pERK2. Epidermal growth factor (EGF) stimulated upregulation of TRAPPC4 and pERK2 in SW1116 cells; EGF stimulation or overexpression of TRAPPC4 induced pERK2 nuclear translocation. Silencing of TRAPPC4 reduced SW1116 xenograft tumor growth in vivo, whereas overexpression of TRAPPC4 increased tumor growth, compared to control tumors. Moreover, modulation of TRAPPC4 expression in vivo affected the levels of pERK2 in the cytoplasm and nucleus and expression of p21. These results conclusively demonstrate that TRAPPC4 regulates ERK2 activation and also affects the distribution of activated pERK2 in CRC cells. The ability of ERK2 to play a role in colorectal carcinogenesis depends, at least in part, on TRAPPC4.
细胞外信号调节激酶（ERK）、丝裂原激活蛋白激酶（MAPK）途径是重要的细胞增殖途径。我们之前报道过，运输蛋白颗粒复合物 4（TRAPPC4）与 ERK2 的相互作用可能会激活 ERK1/2，调节 pERK2 的核定位，并调节结直肠癌细胞（CRC）的增殖和凋亡。本研究进一步探讨了 TRAPPC4-ERK2 相互作用在 CRC 中的体外和体内功能。沉默 TRAPPC4 诱导 CRC 细胞 G0/G1 期细胞周期停滞，上调 p21 并下调细胞周期蛋白 B1。ERK2 沉默后过表达 TRAPPC4 降低了 G0/G1 期细胞的百分比，增加了 G2/M 和 S 期细胞的百分比，下调了 p21，上调了细胞周期蛋白 B1，并增强了 CRC 细胞活力。免疫组织化学染色显示，敲低 TRAPPC4 下调了 pERK2，而过表达 TRAPPC4 则上调了 pERK2。表皮生长因子（EGF）刺激 SW1116 细胞中 TRAPPC4 和 pERK2 的上调；EGF 刺激或过表达 TRAPPC4 诱导 pERK2 核转位。与对照肿瘤相比，沉默 TRAPPC4 减少了 SW1116 异种移植肿瘤在体内的生长，而过表达 TRAPPC4 则增加了肿瘤的生长。此外，体内 TRAPPC4 表达的调节影响了细胞质和细胞核中 pERK2 的水平以及 p21 的表达。这些结果明确表明，TRAPPC4 调节 ERK2 的激活，并且还影响 CRC 细胞中激活的 pERK2 的分布。ERK2 在结直肠发生中的作用能力至少部分取决于 TRAPPC4。
