The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region, China.
Int J Colorectal Dis. 2012 Dec;27(12):1569-78. doi: 10.1007/s00384-012-1510-y. Epub 2012 Jun 9.
Sphingosine kinase (SphK) 1 is an oncogenic enzyme promoting transformation, proliferation, and survival of a number of human tumor cells. However, its effect on colon cancer cell behavior has not been fully clarified.
SphK1 plasmid or SphK1 shRNA transfection and N,N-dimethylsphingosine (DMS) was used to regulate the expression and activity of SphK1 in colon cancer line LOVO. Cell proliferation, apoptosis, invasion, and protein expression were detected by MTT, flow cytometry, transwell chambers model, and western blot. The levels of metalloproteinases-2/9 (MMP-2/9) and urokinase plasminogen activator (uPA) were detected by ELISA.
Overexpression of SphK1 after plasmid transfection markedly enhanced LOVO cell viability and invasiveness and reduced cell apoptosis. In contrast, inhibition of SphK1 by DMS and shRNA significantly suppressed cell viability and invasiveness but promoted cell apoptosis. SphK1 increased the constitutive expression of extracellular signal-regulated kinase1/2 (ERK1/2) but reduced the constitutive expression of p38 mitogen-activated protein kinase (MAPK). Blocking ERK1/2 pathway inhibited the biological effects induced by overexpression of SphK1. Blocking p38 MAPK pathway reversed the effects of DMS and SphK1 shRNA. Moreover, SphK1 was required for the production of MMP-2/9 and uPA in tumor cells, which was suppressed by ERK1/2 inhibitor U0126, but enhanced by the p38 MAPK inhibitor SB203580.
SphK1 enhances colon cancer cell proliferation and invasiveness, meanwhile suppressing cell apoptosis. SphK1 promoting the secretion of MMP-2/9 and uPA via activation of ERK1/2 and suppression of p38 MAPK pathways maybe the molecular mechanisms for its regulation of the malignant behavior of colon cancer cell.
鞘氨醇激酶（SphK）1 是一种致癌酶，可促进多种人类肿瘤细胞的转化、增殖和存活。然而，其对结肠癌细胞行为的影响尚未完全阐明。
采用 SphK1 质粒或 SphK1 shRNA 转染及 N,N-二甲基鞘氨醇（DMS）调节 LOVO 结肠癌细胞系 SphK1 的表达和活性。MTT、流式细胞术、Transwell 室模型和 Western blot 检测细胞增殖、凋亡、侵袭和蛋白表达。ELISA 检测金属蛋白酶-2/9（MMP-2/9）和尿激酶纤溶酶原激活物（uPA）的水平。
质粒转染后 SphK1 的过表达显著增强了 LOVO 细胞的活力和侵袭能力，同时降低了细胞凋亡率。相反，DMS 和 shRNA 抑制 SphK1 显著抑制了细胞活力和侵袭能力，但促进了细胞凋亡。SphK1 增加了细胞外信号调节激酶 1/2（ERK1/2）的组成性表达，同时降低了丝裂原激活蛋白激酶 p38（p38 MAPK）的组成性表达。阻断 ERK1/2 通路抑制了 SphK1 过表达诱导的生物学效应。阻断 p38 MAPK 通路逆转了 DMS 和 SphK1 shRNA 的作用。此外，SphK1 是肿瘤细胞中 MMP-2/9 和 uPA 产生所必需的，ERK1/2 抑制剂 U0126 抑制了其产生，而 p38 MAPK 抑制剂 SB203580 增强了其产生。
SphK1 增强结肠癌细胞的增殖和侵袭能力，同时抑制细胞凋亡。SphK1 通过激活 ERK1/2 和抑制 p38 MAPK 通路促进 MMP-2/9 和 uPA 的分泌，可能是其调节结肠癌细胞恶性行为的分子机制。
