摘要目的 研究肿瘤生长抑制因子4 (ING4)和白细胞介素-24 (IL-24) 双基因共表达腺病毒载体对肺腺癌细胞SPC-A-1的体内外放疗增敏作用及其潜在的作用机制.方法 用Western blot法检测ING4和IL-24在SPC-A-1细胞中的表达;四甲基偶氮唑盐比色(MTT)法和流式细胞仪分别检测Ad-ING4-IL-24联合放疗对SPC-A-1肺腺癌细胞的生长抑制作用和促凋亡作用.应用抽签法将25只裸鼠随机均分为5组:PBS组、腺病毒(Ad)组、双基因组、放疗组及联合组,除放疗组外其余各组均采用瘤体内注射干预用药,隔日1次,共注射6次.第1次治疗前及开始治疗后隔日测量各组瘤体的长径(L)和短径(W),计算瘤体体积(V=L×W2/2),绘制瘤体体积-时间变化曲线.采用 SPC-A-1细胞株建立肺腺癌裸鼠模型,观察Ad-ING4-IL-24联合放疗对移植瘤的抑制作用.免疫组织化学法检测天冬氨酸特异性半胱氨酸蛋白酶-3(Caspase-3)、B细胞淋巴瘤/白血病-2 (Bcl-2)、Bcl-2相关X蛋白(Bax)及血管内皮细胞生长因子(VEGF)基因的表达.采用金正均法计算q值并判断其放疗增敏作用.结果 Western blot法检测结果显示,目的 基因在SPC-A-1细胞中成功表达;MTT和流式细胞仪检测结果显示,Ad-ING4-IL-24联合放疗组对SPC-A-1细胞的生长抑制和促细胞凋亡作用[(86.2±0.8)%、(60.9±1.0)%]明显高于Ad-ING4-IL-24双基因组[(49.8±0.3)%、(26.3±1.3)%]和放疗组[(44.4±2.2)%、(33.3±0.8)%](生长抑制率比较,F=550.88,P＜0.01;凋亡率比较,F=614.08,P＜0.01),Ad-ING4-IL-24联合放疗具有放疗增敏协同作用(q=1.20);裸鼠体内瘤重抑瘤率Ad-ING4-IL-24组、放疗组及Ad-ING4-IL-24联合放疗组分别为49.5%(样本5只)、35.4%(样本5只)和79.8%(样本5只),Ad-ING4-IL-24联合放疗能明显抑制移植瘤生长,具有放疗增敏协同作用(q=1.18);免疫组织化学法检测结果显示,Ad-ING4-IL-24联合放疗可明显上调Bax和Caspase-3基因表达,下调Bcl-2及VEGF基因表达.结论 Ad-ING4-IL-24具有放疗增敏作用,是理想的放疗增敏剂,其作用机制可能与诱导肿瘤细胞凋亡和抑制血管形成有关.

abstractsObjective To study the radiosensitivity of the recombinant adenoviral vector (called Ad-ING4-IL-24) carrying and co-expressing inhibitor of growth 4 (ING4) and interleukin-24 (IL-24) to human lung adenocarcinoma and the underlying mechanisms. Methods The expression levels of ING4 and IL-24 were detected by Western blot. The growth-suppressing and apoptosis-inducing effect of Ad-ING4-IL-24 combined with radiotherapy on SPC-A-1 lung carcinoma cells were assessed by MTT assay and FCM respectively. The 25 nude mice were randomly divided into 5 groups of 5 mice ecah: PBS group,Ad group,Ad-ING4-IL-24 group,radiotherapy group and joint group (Ad-ING4-IL-24 combined radiotherapy). Mice in all groups except radiotherapy group were intratumorally injected every other day for 6 cycles. The short and long axes of the tumor were measured dynamically, tumor volume was calculated as: V=L×W2/2, changes in tumor volume were graphed. The human lung carcinoma model was established with SPC-A-1 cells in nude mice. The ratios of tumor-suppression and q were calculated. The expression of Caspase-3, Bcl-2, Bax, VEGF in tumor samples were detected by immunohistochemistry. Results The expressions of ING4 and IL-24 were successfully expressed in SPC-A-1 cells. MTT assay and FCM showed that the levels of cell-growth inhibition and apoptosis induction in Ad-ING4-IL-24 combined with radiotherapy group [(86.2±0.8)%,(60.9±1.0)%] were higher than in Ad-ING4-IL-24 group [(49.8±0.3)%,(26.3±1.3)%] and in radiotherapy group [(44.4±2.2)%,(33.3±0.8)%] (ratio of cell-growth inhibition, F=550.88,P＜0.01; ratio of induced apoptosis F=614.08,P＜0.01). Ad-ING4-IL-24 combined with radiotherapy showed an enhanced radiosensitivity effect on human lung adenocarcinoma(q=1.20). In Ad-ING4-IL-24 group, radiotherapy group and Ad-ING4-IL-24 combined with radiotherapy group, the weight inhibition ratio was 49.5% (5 nude mice), 35.4%(5 nude mice), 79.8%(5 nude mice) respectively. Ad-ING4-IL-24 combined with radiotherapy had a synergetic and enhanced radiosensitivity effect on inhibiting the growth of transplanted tumor(q=1.18). According to immunohistochemistry, Ad-ING4-IL-24 was shown to up-regulate the expression of Bax and Caspase-3 but down-regulate the expression of Bcl-2 and VEGF. Conclusion Ad-ING4-IL-24 had an enhanced radiosensitivity effect on human lung adenocarcinoma, and therefore acted as a radiotherapy sensitizer, which may be related to its effect on apoptosis-induction and antiangiogenesis.