^(131)I-VIP-ASON在荷结肠腺癌裸鼠体内的抑瘤作用

Antitumor effects of radioiodinatedantisense oligonuclide mediated VIP receptor

目的 探讨1 31 I标记血管活性肠肽 (VIP)受体介导的C mycmRNA反义寡核苷酸复合物(1 31 I VIP ASON)对荷瘤裸鼠结肠腺癌的抑制效果。方法 以TlCl3为氧化剂 ,将1 31 I标记于互补于C mycmRNA的ASON。VIP与1 31 I ASON通过多聚赖氨酸偶联形成放射性反义复合物 (1 31 I VIP ASON) ;通过荷瘤裸鼠体内分布实验观察其在肿瘤中的浓集情况 ;以1 31 I ASON和1 31 I标记的正义寡核苷酸 (SON)、无义寡核苷酸 (MON)为对照 ,观察1 31 I VIP ASON对活体肿瘤的治疗效果。组织切片观察肿瘤组织形态学变化 ,Envision免疫组织染色法观察反义治疗对C myc癌蛋白表达的影响。结果 注射后 2h ,1 31 I VIP ASON在肿瘤部位浓聚显著高于1 31 I ASON (t=7 79,P <0 0 1) ,肿瘤 肌肉放射性比值于 4h达到最高。 7 4MBq1 31 I VIP ASON组能有效抑制肿瘤生长 ,肿瘤生长终点抑制时间为 2 5 4d ,效果明显优于 3 7MBq组 (q=4 2 6 1,P <0 0 1) ,未见明显副作用。组织形态学和免疫组织化学染色观察示 ,注射1 31 I VIP ASON后 ,肿瘤出现大片坏死区和脂肪变性。1 31 I VIP ASON组C myc蛋白表达得分值明显低于其他组 (q =5 5 1,P <0 0 1)。结论 1 31 I VIP ASON可明显抑制荷瘤裸鼠结肠腺癌肿瘤生长及癌蛋白表达 ,可望为肿瘤的诊断和治?

Objective To observe the antitumor effect of 131I-vasoactive intestinal peptide (VIP)-antisense oligonucleotide (ASON) in HT29 human colon adenocarcinoma xenografts. Methods A 15-mer phosphorothioate ASON, which was complementary to the translation start region of the C-myc oncogene mRNA, was labeled with 131I and linked to the VIP bound covalently to a polylysine chain so as to deliver oligonucleotide into tumor cells. Distribution experiments for evaluating the radiolabeled antisense complex uptake in tumor tissue were performed in BALB/c nude mice bearing HT29 tumor xenografts. Nude mice bearing HT29 tumor xenografts were adminstered 131I-VIP-ASON (3.7,7.4 MBq) or 131I-ASON (3.7 MBq), 131I labeled control sense and nosense DNA (SON, MON, 3.7 MBq), or saline. Antitumor effects were assessed using endpoints of tumor growth delay. C-myc-encoded protein expression of tumor was measured by immunocytohistochemical staining. Results The distribution experiments performed with nude mice bearing human colon tumor xenografts revealed the maximal accumulation of conjugated ASON in the tumor tissue 2 h after administration and the mean %ID/g was significantly higher than that in nude mice injected unconjugated ASON [(5.89±1.03)%ID/g vs (1.56±0.31)%ID/g, t=7.79, P<0.01]. The radioratio of tumor to muscle was peaked 4 h after administration. 131I-VIP-ASON exhibited strong antitumor effects against HT29 xenografts, decreasing their growth rate 7-fold compared with that in saline-treated mice. The antitumor effects of unconjugated 131I-ASON were much less profound than that of 131I-VIP-ASON (7.4 MBq) [tumor growth delay, (3.2±1.3) vs (25.4±0.89) d, q=51.41, P<0.01]. SON or MON with VIP carrier caused no therapeutic effect. There was no progressive weight loss or petechiae observed in the mice. Immunocytohistochemical staining showed that tumor treated with 131I-VIP-ASON expressed much less C-myc-encoded protein than tumor treated with 131I-ASON, SON or MON (q=5.51, P<0.01) did. Conclusions The use of a VIP carrier greatly increased tumor uptake and treatment with 131I-VIP-ASON complexes resulted in tumor growth delay in human colon cancer xenograft. This study might afford a new idea or method for the therapy of tumors.