SphK1及其抑制剂对人胃癌裸鼠移植瘤的作用

Role of SphK1 in the growth of human gastric cancer xenograft in nude mice

目的研究鞘氨醇激酶-1（sphingosinekinase-1，SphKl）及其抑制剂在人胃癌裸鼠移植瘤生长中的作用，并探讨其作用机制。方法对数生长期SGC7901细胞注射于裸鼠皮下建立人胃癌裸鼠移植瘤模型，建模成功后将裸鼠随机分为4组（每组8只），分别用生理盐水、SKI-Ⅱ、顺铂（DDP）、SKI-Ⅱ联合DDP进行治疗，每周注射1次，共3次。定期测量肿瘤体积，绘制肿瘤时间-体积生长曲线。在治疗结束后的第7天脱颈处死裸鼠，取瘤体组织，免疫组化法检测瘤体内SphKl、Bax、Bcl-2蛋白的表达，TUNEL法检测肿瘤组织细胞凋亡。结果成功构建了人胃癌裸鼠移植瘤模型。SKI-Ⅱ联合DDP较SKI-Ⅱ、DDP更显著地减少肿瘤组织SphK1、Bcl-2蛋白的表达（P〈0．05），并增加Bax蛋白的表达（P〈0．05），且更明显地增加了肿瘤细胞的凋亡率并抑制了肿瘤的生长（P〈0．05）。结论SphK1通过引起胃癌细胞内Bax／Bcl-2比值的降低，在胃癌的生长过程中发挥了抑制胃癌细胞凋亡、促进肿瘤生长的作用，SphK1抑制剂SKI—Ⅱ与DDP有协同抗肿瘤作用。

Objective To investigate the role of SphK1 in the growth of human gastric cancer xenografi in nude mice and to explore its mechanism. Methods Human gastric cancer cells SGC -7901 were cultured in RPMI 1640 medium to exponential phase of growth and then transplanted under the skin of BALB/c nude mice to develop the tumor model of hu-man gastric cancer. After the model was successfully developed, 38 mice were randomly divided into four groups： normal saline （NS） control group, cisplantin （DDP） group, SKI - Ⅱ group, and SKI - Ⅱ combined with DDP group. All rats were given intraperitoneal injection of drugs on seven days for 3 times. The tumor mass volume was observed every 3 days and inhibition rate of tumor growth was also calculated. All nude mice in each group were killed at the 7th day after the injection of drugs and tumor were dislodged. Immunohistochemistry staining was used to detect the protein expression of SphK1, Bax and Bcl - 2. The apoptosis of tumor was measured by terminal dUTP nick - end labeling （TUNEL）. Results The tumor model of human gastric cancer was successfully developed. SphK1 and Bcl - 2 protein expression in SKI-Ⅱ combined with DDP group significantly decreased （P 〈 0.05 ）. Compared with DDP group and SKI-Ⅱ group, Bax protein expression in SKI - Ⅱ combined with DDP group significantly increased （ P 〈 0.05 ）. As a result, SKI - Ⅱ combined with DDP could raise the rate of apoptosis and inhibit the growth of tumor model of human gastric cancer. Con-clusion Sphkl can promote tumor cell proliferation through down - regulating the ratio of Bax/Bcl - 2. SKI - Ⅱ has synergistic anti - tumor effect of eisplatin.