68Ga-PSMA-I&T与前列腺癌细胞特异性结合的研究

Study on the specific binding of 68Ga-PSMA-I&T to prostate cancer cells

目的:合成前列腺特异性膜抗原(PSMA)靶向诊断药物68Ga-PSMA-I&T并探讨其与前列腺癌LNCaP细胞特异性结合。方法:合成68Ga-PSMA-I&T,检测其标记率、放化纯及稳定性。用2-PMPA和68Ga-PSMA-I&T与LNCaP细胞竞争性结合,计算不同时间点细胞的放射性摄取值。用不同浓度PSMA-I&T和68Ga-PSMA-I&T与LNCaP细胞竞争性结合,计算细胞的放射性摄取值。进行68Ga-PSMA-I&T在ICR小鼠体内生物分布实验,计算每克组织放射性摄取值。对ICR小鼠和LNCaP荷瘤鼠行68Ga-PSMA-I&T micro-PET/CT动态显像,绘制时间放射性摄取值曲线。切除荷瘤鼠的肿瘤组织进行免疫化学染色,观察PSMA的表达情况。结果:68Ga-PSMA-I&T标记率为(95.4±2.5)%,放化纯大于99%,体内外稳定性好。结合组、阻断组反应30 min、90 min时细胞放射性摄取值分别为(3.3±0.5)%、(10.2±0.4)%、(0.99±0.03)%和(1.54±0.05)%(P<0.001),PSMA-I&T的半抑制浓度(IC50)为38.64nmol/L。荷瘤鼠68Ga-PSMA-I&T micro-PET/CT动态显像示15 min肿瘤组织已有明显放射性摄取,并且肿瘤组织的放射性摄取随时间延长逐渐增加。免疫化学染色结果显示LNCaP荷瘤鼠离体肿瘤组织表达丰富的PSMA蛋白。结论:68Ga-PSMA-I&T合成过程简便易行,标记率和放化纯高,稳定性好;68Ga-PSMA-I&T能与LNCaP细胞特异性结合,体内分布良好,是理想的前列腺癌靶向诊断示踪剂。

AIM:To synthesize 68Ga-PSMAI&T for targeted diagnosis of prostate specific membrane antigen(PSMA)and explore its specific binding to LNCaP cells of prostate cancer.METHODS:68Ga-PSMA-I&T was synthesized and its labeling rate,radiochemical purity and stability were measured.LNCaP cells were competitively bound with 2-PMPA and 68Ga-PSMA-I&T,and the radioactive uptake values of cells at different time points were calculated.LNCaP cells were then competitively combined with 68Ga-PSM-I&T and PSM-I&T at different concentrations,and the values of cell radioactive uptake values were calculated.The biological distribution experiment of 68Ga-PSM-I&T in ICR mice was conducted,and the radioactive uptake values per gram of tissue were calculated.Dynamic imaging with 68Ga-PSM-I&T micro-PET/CT was performed on ICR mice and LNCaP tumor-bearing mice,and the time radioactive uptake value curve was plotted.Immunochemical staining was performed to observe the expression of PSMA in the tumor tissues of mice.RESULTS:The radioactive labeling rate of 68GaPSMA-I&T was(95.4±2.5)%,with the purity more than 99%and the stability in vitro and in vivo was good.The radioactive uptake values of cells at 30 min and 90 min in the binding group and the blocking group were(3.3±0.5)%,(10.2±0.4)%,(0.99±0.03)%,and(1.54±0.05)%,respectively(P<0.001).The semi-inhibitory concentration(IC50)of PSMA-I&T was 38.64 nmol/L.The dynamic imaging of 68Ga-PSMA-I&T micro-PET/CT of tumor-bearing mice showed significant radioactive uptake in tumor tissues at 15 min,with the radioactive uptake of tumor tissues gradually increased with time.Immunochemical staining results showed that the expression of PSMA protein was abundant in the isolated tumor tissues of LNCaP tumor-bearing mice.CONCLUSION:The synthesis of 68Ga-PSMA-I&T was simple and easy,and its radioactive labeling rate and radiochemical purity were high and its stability was good.68Ga-PSMA-I&T can specifically bind to LNCaP cells,and its distribution in vivo is good.It shows that it is an ideal tracer for targeted diagnosis of prostate cancer.