内皮抑素基因转移联合电离辐射对肺腺癌移植瘤生长的影响

Combined effects of endostatin gene transfer and ionizing radiation on lung adenocarcinoma model of A549 cells

目的探讨内皮抑素(endostatin)基因转移联合电离辐射对肺腺癌移植瘤生长的抑制作用。方法以逆转录病毒为载体,转导内皮抑素基因至肺腺癌A549细胞,获得含内皮抑素基因的A549/Endo细胞。20只裸鼠平均分为4组(A549、A549/Endo、A549+辐照、A549/Endo+辐照组),A549、A549+辐照组裸鼠皮下种植A549细胞,A549/Endo、A549/Endo+辐照组裸鼠皮下种植A549/Endo细胞,建立移植瘤模型。A549、A549/Endo组裸鼠用于观察成瘤时间,并计算抑瘤率;另2组裸鼠于种植瘤细胞后第28天,用直线加速器电离辐照移植瘤体,剂量为20Gy,3d后重复照射20Gy;照射后继续饲养荷瘤鼠,定期观察移植瘤体积变化。于瘤细胞移植后第42天(照射后第14天)处死荷瘤鼠,用免疫组化法测定4组裸鼠瘤体的微血管密度(MVD)。结果聚合酶链测定(PCR)法证实,A549/Endo细胞基因组中整合有内皮抑素基因。裸鼠成瘤时间A549组(78±16)d、A549/Endo组(122±17)d,两组比较差异有显著性(P<005);瘤细胞移植后42d,移植瘤体积A549组(9278±2692)mm3、A549/Endo组(2175±815)mm3,两组比较差异有显著性(P<001),抑瘤率为765%。电离辐照后第14天,移植瘤体积A549+辐照组为(1577±490)mm3,A549/Endo+辐照组为(46±29)mm3,两组比较差异有显著性(P<001)。裸鼠移植瘤组织MVDA549组3578?

Objective The combined inhibition effects of endostatin gene transfer and ionizing radiation on lung adenocarcinoma model of A549 cell were investigated Methods Human endostatin gene was transferred into lung adenocarcinoma A549 cell by retrovirus mediation to obtain an A549/Endo cell A549 and A549/Endo cells were xenoimplanted in nude mice respectively (each group included 10 mice) Then, the changes of the tumor size of each group ( n =5) and its growth inhibition rate were estimated The implanted tumors of each group ( n =5) were exposed to radiation with 20 Gy at 28 day after implantation They were irradiated again with 20 Gy 3 day later The ionizing radiation was strictly confined to the tumor by shielding the rest of the body with lead The size of tumor was measured periodically The microvessel density (MVD) of 4 groups of implanted tumors(A549 、 A549/Endo、 A549+IR and A549/Endo+IR) were compared on day 42 postgrafting by the immunohistochemical method Results PCR confirmed that endostatin gene was inserted into the genomic DNA of human lung adenocarcinoma A549 cell The tumor formation time showed significant difference( P <0 05)between group A549(7 8±1 6)d and group A549/Endo (12 2±1 7)d At the time of day 42 postgrafting , the tumor sizes of group A549 and group A549/Endo were(927 8±269 2)mm 3 and (217 5±81 5)mm 3 respectively ( P <0 01),and the tumor growth inhibition rate was 76 5% At the time of day 14 after irradiation, the tumor sizes of group A549 and group A549/Endo were (157 7±49 0)mm 3 and (4 6±2 9)mm 3 respectively( P <0 01) The results of immunohistochemical detection showed that the MVD of A549/Endo implanted tumor was significantly decreased [21 62±3 55 compared with A549 implanted tumor 35 78±5 67( P <0 01)] Moreover , it also showed that ionizing radiation could further reduce the MVD of A549/Endo implanted tumor from 21 62±3 55 to 11 32±2 78 ( P <0 01) Conclusions Retroviruses can highly mediate the transfer of endostatin gene into the adenocarcinoma cells Endostatin gene transfer can inhibit the xenoimplanted tumor growth by its direct inhibition on neovascularization The combination of endostatin gene transfer with ionizing radiation treatment can synergistically inhibit the neovascularization and the growth of lung adenocarcinoma