18F-FDG对于乳腺癌模型小鼠治疗作用的研究

Therapeutic effect of positron emission tomography agent 18F-FDG on MCF-7 in nude mice

关键词:  18氟-氟代脱氧葡萄糖（ 18F-FDG）  乳腺癌  凋亡  动物模型  BCL-2  CASPASE-3

Key words:  18F-FDG  breast cancer  apoptosis  animal model  BCL-2  CASPASE-3

摘要:

[目的] 探讨18氟-氟代脱氧葡萄糖（ 18F-FDG）诱导乳腺癌细胞的凋亡作用及分子机制。[方法] 使用0～7.4×10 6  Bq/mL 18F-FDG作用于体外培养乳腺癌细胞MCF-7，应用γ高能计数仪测定细胞摄取射线量；接种MCF-7细胞至24只雌性裸鼠腋下构建小鼠乳腺癌模型，成瘤后分别由尾静脉注射生理盐水、3.7 MBq、11.1 MBq和37 MBq 18F-FDG，观察肿瘤生长情况，Micro-animal PET进行瘤体显像；Western Blot方法检测肿瘤瘤体凋亡相关蛋白BCL-2及cleaved CASPASE-3表达情况。[结果] 体外MCF-7细胞摄取实验表明，在一定剂量范围内，随着射线剂量的增加，对数生长期的MCF-7细胞摄取射线剂量基本呈线性增长；治疗后，各治疗组小鼠肿瘤体积增长速度明显放缓，而高剂量组（11.1 MBq与37 MBq）较低剂量组（3.7 MBq）显示出更低的增长速度。Micro-animal PET显示荷瘤裸鼠的肿瘤部位可见 18F-FDG浓聚，治疗组浓聚程度低于对照组，且随着治疗剂量增加，浓聚程度亦随之降低。Western Blot结果显示注射 18F-FDG后，荷瘤裸鼠瘤体cleaved CASPASE-3相对表达量各治疗组（37 MBq、11.1 MBq、3.7 MBq 18F-FDG）分别为4.935±1.521、5.560±1.459及2.138±0.844，均高于对照组的0.019±0.049（P<0.05或P<0.01），尽管在11.1 MBq剂量组与37 MBq剂量组间表达差异无显著性意义（P>0.05），但两组均高于3.7 MBq剂量组（P<0.05）；BCL-2蛋白相对表达量分别为1.489±0.691、1.929±0.949、3.421±1.554，均低于对照组的5.143±1.813（P<0.05或P<0.01），尽管11.1 MBq剂量组与37 MBq剂量组间差异无显著性意义（P>0.05），但两组均低于3.7 MBq剂量组（P<0.05）。[结论] 18F-FDG在适量情况下，能下调肿瘤BCL-2蛋白的表达和激活CASPASE-3表达诱导乳腺癌细胞凋亡。

Abstract:

[Objective] To study the therapeutic potential of PET agent [18F]labeled 2-deoxy-2-fluoro-D-glucose(18F-FDG) to MCF-7 in nude mice and its molecular mechanism. [Methods] The breast cancer cell line MCF-7 was cultured with 18F-FDG in different doses (0-7.4×106 Bq/mL). The γ-ray high energy counting machine was used to detect uptake of γ-ray by MCF-7 cells. The MCF-7 cells were inoculated in nude mice. The tumor-bearing mice were treated with normal saline, 3.7 MBq, 11.1 MBq and 37 MBq 18F-FDG, respectively. Dynamic changes of xenogafts volume were calculated. Then these mice were imaged by microPET with 18F-FDG. Tumors were analyzed for expression of cleaved CASPASE-3 and BCL-2 by western blot. [Results] In vitro uptake of 18F-FDG by MCF-7 cells was linear dose dependence. All treatment groups showed significant reduction of tumor growth rate compared with the control group (P<0.05)．The rate of tumor growth was lower in groups of higher treatment dose (11.1 MBq and 37 MBq) than in group of lower treatment dose (3.7 MBq). Images of microPET showed that the concentration of 18F-FDG was lower in tumor site of treatment groups than that in control group, and it was decreasing with the increasing of treatment dose. The expression levels of cleaved CASPASE-3 in treatment groups (3.7 MBq, 11.1 MBq and 37 MBq) were significantly higher than that in the control group (4.935±1.521, 5.560±1.459, 2.138±0.844 vs 0.019±0.049) (P<0.05 or P<0.01), while the expression levels of BCL-2 were significantly lower in treatment groups than that in the control group (1.489±0.691,1.929±0.949,3.421±1.554 vs 5.143±1.813) (P<0.05 or P<0.01). There were no significant difference in the expression levels of BCL-2 and cleaved CASPASE-3 between 11.1 MBq and 37 MBq group(P>0.05), but the expression levels of BCL-2 in the two groups were both lower than that in 3.7 MBq group(P<0.05), and the expression levels of cleaved CASPASE-3 were higher than that in 3.7 MBq group (P<0.05). [Conclusions] The study suggested that 18F-FDG had a therapeutic effect in breast cancer by decreasing of BCL-2 expression and increasing of cleaved CASPASE-3 expression.