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目的:探讨大豆异黄酮诱导人胃癌原代细胞裸鼠移植瘤凋亡的机制。方法:建立人胃癌原代细胞裸鼠移植瘤模型并测定移植瘤的生长曲线;25只BALB/C裸鼠接种胃癌原代细胞悬液生成移植瘤后,不同剂量的大豆异黄酮进行瘤旁注射,透射电镜和TUNEL法检测肿瘤组织细胞凋亡情况,免疫组化法和RT-PCR法检测肿瘤组织的凋亡相关基因bcl-2和bax的表达情况。结果:大豆异黄酮对胃癌原代细胞移植瘤有明显的抑制作用,在剂量为0.5 mg/kg、1 mg/kg、1.5 mg/kg时,其抑制率分别为10.6%、29.7%和39.1%;透射电镜发现大豆异黄酮导致移植瘤内大量细胞发生调亡;TUNEL染色法发现大豆异黄酮注射组瘤细胞的凋亡指数是随剂量递增(28.7%±1.1%、33.4%±1.4%和37.1%±1.0%)。免疫组织化学法发现大豆异黄酮注射组的Bcl -2蛋白阳性细胞率随剂量递减(11.8%±0.9%、5.7%±0.8%和4.0%±0.8%),而Bax蛋白阳性细胞率随剂量递增(20.0%±±1.2%、24.7%±0.9%和29.3%±1.6%);RT-PCR法发现,大豆异黄酮注射组的bcl -2mRNA条带强度随剂量的增大而递减,并明显低于对照组(P<0.05);而baxmRNA条带强度递增,并明显低于对照组(P<0.05),而2对照组bcl -2,bax之间差异无统计学意义(P>0.05)。结论:大豆异黄酮对胃癌原代细胞移植瘤有明显的抑制作用,通过下调bcl -2的表达和上调bax的表达而诱导胃癌裸鼠移植瘤细胞发生凋亡,是其抗胃癌作用的机制之一。
Objective: To investigate the mechanism of soybean isoflavones inducing apoptosis of primary human gastric cancer cell xenografts in nude mice. METHODS: The primary human gastric cancer xenograft model was established and the growth curve of the xenografts was determined. Twenty-five BALB / C nude mice were inoculated with the primary cell suspension of gastric cancer to generate the xenografts. Tumor injection was performed with different doses of soy isoflavones , Transmission electron microscopy and TUNEL method were used to detect the apoptosis of tumor cells. The expression of bcl-2 and bax in tumor tissues was detected by immunohistochemistry and RT-PCR. Results: Soy isoflavones had significant inhibitory effect on the primary tumor of gastric cancer. The inhibitory rates were 10.6%, 29.7% and 39.1% at doses of 0.5 mg / kg, 1 mg / kg and 1.5 mg / kg, respectively Transmission electron microscopy revealed that isoflavones led to the apoptosis of a large number of transplanted tumor cells. TUNEL staining showed that the apoptotic index of tumor cells in the isoflavone injection group increased with dose (28.7% ± 1.1%, 33.4% ± 1.4% and 37.1% % ± 1.0%). Immunohistochemistry showed that the rate of Bcl-2 protein positive cells decreased with dose (11.8% ± 0.9%, 5.7% ± 0.8% and 4.0% ± 0.8%), but Bax protein positive cells increased with dose (20.0% ± ± 1.2%, 24.7% ± 0.9% and 29.3% ± 1.6% respectively). The band intensity of bcl-2 mRNA in soybean isoflavone injection group decreased with the increase of dose (P <0.05). However, the intensity of bax mRNA bands increased significantly and was significantly lower than that of the control group (P <0.05), while there was no significant difference between the two control groups (P> 0.05). CONCLUSION: Soy isoflavones have significant inhibitory effects on the primary tumor of gastric cancer cells, and induce the apoptosis of the transplanted tumor cells in nude mice by down-regulating the expression of bcl-2 and up-regulating the expression of bax, which is the mechanism of its anti-gastric cancer effect one.