基于CDCP1纳米液滴造影剂靶向超声成像在前列腺癌侵袭性及疗效评估的研究

The assessment of the aggressiveness and therapeutic response of prostate cancer plays a crucial role in treatment decision and prognosis prediction. However, a non-invasive diagnostic tool which could accurately assess the aggressiveness and therapeutic response of prostate cancer is still not available in clinical. Our preliminary study demonstrated that targeted contrast enhanced ultrasound could improve prostate cancer detection by imaging tumor-specific biomarkers. Based on the preliminary findings,this study employs solvent emulsion/evaporation method to fabricate nanodroplet contrast agents targeting CDCP1 antigen expressed on prostate cancer cell membrane. Prostate cancer xenograft models with different aggressiveness are established using PC-3, DU145 and LNCaP cell lines. The in vivo targeting ability of nanodroplet contrast agents are studied by laser scanning confocal microscopy, immunohistochemistry and Western-blotting. Quantitative analysis software is employed for the evaluation of nanodroplet contrast agents in imaging prostate cancer aggressiveness. After cryoablation and radiofrequency ablation of PC-3 prostate cancer xenograft model, the therapeutic response is imaged using nanodroplet contrast agents. The treatment evaluation method is further established with quantitative analysis in comparison with pathologic findings. Our study will lay the groundwork for ultrasonic imaging of the biologic behavior and therapeutic response of prostate cancer.

前列腺癌的侵袭性和疗效评估对提高前列腺癌治愈率具有十分重要作用，目前临床尚缺乏一种能早期、准确、可重复评估前列腺癌侵袭性和疗效的无创方法。我们的前期研究证实靶向超声造影成像可反映前列腺癌组织的蛋白表达状况。本项目在此基础上，以前列腺上皮细胞为靶点，采用乳化溶剂挥发法制备针对CDCP1抗原的纳米液滴靶向造影剂，通过建立PC-3、DU145和LNCaP人前列腺癌裸鼠皮下移植模型，应用Western blot、激光共聚焦显微镜、免疫组化分析CDCP1的表达情况和造影剂体内靶向结合情况，利用超声定量分析软件分析靶向造影剂对评估前列腺癌侵袭性的作用。在完成PC-3前列腺癌裸鼠移植瘤的冷冻和射频治疗后，应用靶向造影剂超声造影成像及其分析软件进行疗效评估，与病理为对照研究创建靶向超声造影的前列腺癌疗效评估方法。为临床通过无创的超声影像方法获得前列腺癌肿瘤的生物特性及治疗后变化机制奠定基础。

前列腺癌细胞表面表达的CDCP1能反映肿瘤的侵袭性，本课题以CDCP1作为靶点，采用双乳化法及冷冻干燥技术成功制备了CDCP1靶向纳米液滴。该纳米液滴在电镜下呈球形，分布均匀，平均粒径为172 ± 5.76 nm，聚合物分散指数为0.19，Zeta电位为-0.04mV。体外超声成像实验显示CDCP1靶向纳米液滴的回声强度与其浓度呈正相关。激光共聚焦显微镜及流式细胞技术显示CDCP1纳米液滴能与前列腺癌细胞尤其是高侵袭性的PC3细胞株靶向结合。MTT实验证实CDCP1靶向纳米液滴无明显细胞毒性。在体内成像实验中，PC3皮下移植瘤的超声增强强度及造影剂消退减半时间最高，DU145皮下移植瘤次之，LNCaP皮下移植瘤最低。在对前列腺癌皮下移植瘤进行局部治疗后，治疗区域均未见明显造影剂灌注。本研究所合成的造影剂能对前列腺癌的侵袭性及局部治疗疗效进行评估，从而为前列腺癌的临床诊治提供了新的方法和思路。