Objective: To investigate the effect of silencing DJ-1 on xenografted human laryngeal squamous cell carcinoma (LSCC) Hep-2 cells in nude mice. Methods: Xenograft model of human LSCC was established by subcutaneous transplantation of Hep-2 cells in 24 nude mice. The LSCC-bearing nude mice were randomly divided into 3 groups (n=8 in each):DJ-1 siRNA low dose group and DJ-1 siRNA high dose group were injected in tumors with 20 μg of DJ-1 siRNA or 40 μg of DJ-1 siRNA in 50 μL, respectively; control group was injected with 5% glucose solution in 50 μL, twice a week for 3 weeks. The weight and size of tumors were measured before injection. The animals were sacrificed 48 h after the final treatment, and the tumors were harvested and weighed. The apoptosis and proliferation of tumor cells were determined; the expressions of Caspase-3 and Ki-67 in tumor specimens were detected with immunohistochemistry. The expression of DJ-1, PTEN, survivin mRNA and protein in tumor tissues were detected by RT-PCR and Western blotting, respectively. Results: Tumor weight in low dose group[(0.66±0.15)g] and high dose group[(0.48±0.11)g] were significantly lower than that in control group[(0.83±0.16)g, all P<0.05]. The inhibition rates of low dose group and high dose group were (20.48±0.18)% and (42.16±0.13)%, respectively. Immunohistochemistry showed that the expression of Caspase-3 was increased and Ki-67 was reduced in tumor specimens, compared with the control group (all P<0.05). RT-PCR and Western blot results showed that in low dose group and high dose group the mRNA and protein expression of DJ-1 and survivin significantly decreased (all P<0.05), while PTEN mRNA and protein content increased (all P<0.05). Conclusion: High dose DJ-1 siRNA can inhibit the tumor growth in human LSCC xenograft nude mouse model, which indicates that down-regulating DJ-1 and survivin, and up-regulating PTEN expression may lead to blockage of PI3K-PKB/Akt signaling pathway and promoting tumor cell apoptosis.
目的: 观察沉默DJ-1基因对人喉癌Hep-2细胞株裸鼠移植瘤的作用及其机制。
方法: 建立人喉癌Hep-2裸鼠移植瘤模型，24只裸鼠随机分为三组（每组8只）：对照组（5%葡萄糖溶液）、小剂量组（20μg的DJ-1基因特异性小干扰RNA）、大剂量组（40μg的DJ-1基因特异性小干扰RNA）。各组瘤体内分别注射相应液体50μL，2次/周，共6次，每次测量瘤体质量及大小。停药后48 h脱颈椎法处死裸鼠，剥离瘤体，测瘤体质量，计算抑瘤率。采用免疫组织化学法分别检测剥离瘤体组织Caspase-3、Ki-67的表达情况；实时定量RT-PCR和蛋白质印迹法分别检测各组移植瘤DJ-1、PTEN、survivin基因和蛋白的表达。
结果: 小剂量组[（0.66±0.15）g]和大剂量组[（0.48±0.11）g]的瘤体质量均小于对照组[（0.83±0.16）g，均 P < 0.05]，且抑瘤率分别为（20.48±0.18）%和（42.16±0.13）%。小剂量组和大剂量组Caspase-3表达增高，Ki-67表达减少，与对照组差异均有统计学意义（均 P < 0.05）；与对照组比较，小剂量组和大剂量组DJ-1、survivin的mRNA和蛋白表达均减少（均 P < 0.05），而PTEN的mRNA和蛋白表达均增加（均 P < 0.05）。
结论: 大剂量的DJ-1小干扰RNA可能通过下调DJ-1和促进PTEN的表达，从而阻断PI3K-PKB/Akt信号通路并调节survivin表达来促进肿瘤细胞凋亡，抑制人喉癌Hep-2裸鼠移植瘤的生长。