剂量分割模式照射人肺腺癌移植瘤后基因表达谱差异的初步研究

Initial microarray analysis on different fractionated radiation regimens in xenografts with human lung adenocarcinoma

目的 研究总相同照射剂量、不同剂量分割方案对BALB/c-nu裸鼠移植瘤（人肺腺癌细胞系Anip973）基因表达的差异.方法 将移植瘤种鼠的肿瘤组织制备成肿瘤组织块,选择裸鼠右后肢外侧小腿腓肠肌处接种,建立移植瘤裸鼠模型.待肿瘤直径达1.0 cm时将48只裸鼠分成4个组：未照射空白对照组、2 Gy30次常规照射组（2 Gy组）、6 Gy10次大分割组（6 Gy组）、10 Gy6次大分割组（10 Gy组）.大分割组均在2周内完成,所有照射完成后继续观察裸鼠1个半月.采用基因谱芯片技术检测4个组移植瘤细胞的基因表达差异,并进行实时PCR验证.结果 6、10 Gy组较2 Gy组上调了抑制细胞增殖和诱导凋亡的基因如Bax和BCL2L10,下调了促进细胞增殖基因如c-myc和EGF、抗凋亡基因以及XRCCA、RAD21、RAD23B等DNA损伤修复基因.PCR证实6 Gy10次组c-myc基因表达丰度明显低于2 Gy30次组和10 Cy6次组,分别为2.9%、5.6%、4.8%（P=0.000;P=0.002）;10 Gy6次组c-myc基因水平相对于2 Gy30次组也有下降（P=0.069）.结论 两个大分割方案较常规分割方案对BALB/c-nu裸鼠移植瘤（人肺腺癌细胞系Xnip973）在基因水平上生长抑制显著,6 Gy10次分割方案较10 Gy6次分割方案有更强的生长抑制作用.

Objective To indentify the gene expression on different fractionated radiation regimens with the same total radiation dose in xenografts with human lung adenocarcinoma. Methods Forty-eight BALB/c-nu mice, implanted with human lung adenocarcinoma （ Anip973 ）, were randomized into 4 groups ： normal control group,60 Gy in 30 fractions conventional radiation group （ 2 Gy group） ,60 Gy in 10 fractions hypofractionated radiation group （6 Gy group） ,60 Gy in 6 fractions hypofractionaed radiation group （ 10 Gy group）. Gene alterations were investigated with the microchip analytical procedures covering the entire genome. Genes with significantly different expression were further validated by the quantitative real-time polymerase chain reaction （RT-PCR）. Results Compared to the 2 Gy group, the expression of the genes related with the cell growth inhibition and apoptosis was increased, while the genes related with the cell proliferation, anti-apoptosis and DNA damage repair were decreased in the 6 Gy and 10 Gy groups. Confirmed by RT-PCR, c-myc gene was distinctly suppressed in the 6 Gy group （2. 9% ） comparing with 2 Gy （5. 6% ） group and 10 Gy （4. 8% ） group （P =0. 000,P =0. 002）, and was slightly suppressed in the 10 Gy group comparing with 2 Gy group （P = 0. 069 ）. Conclusions In the BALB/c-nu mice implanted with human lung adenocarcinoma, the hypofractionated radiation regimens clearly inhibit the tumor growth more than conventional fractionation group, though with the same total dose. The 6 Gy group seem to be more effective than 10 Gy group in the inhibition of tumor growth.