基于整合素αvβ3受体的靶向磁共振/超声双模态造影技术评价人乳腺癌裸鼠移植瘤转移的研究

Breast cancer is the most common malignancy among women, and distant metastasis is the main reason of death for the cases with breast cancer. The metastatic process of breast cancer depends on degradation of the extracellular matrix before invasion and neovascularization of the tumor, which were closely related to high expression of integrainαvβ3. However, the detection of integrinαvβ3 is disadvantaged by invasiveness, poor repetition, difficult real-time monitoring, etc. Currently, the studies including our previous investigation also indicate that molecular imaging technique based on cRGD can specifically show integrainαvβ3 expression in breast cancer tissues. Thus, in this study, cRGD and Gd-DTPA coated by multi-functional blank PLGA microbubble were prepared as the targeted contrast agent which were proper for MRI/ultrasound dual-modality molecular radiography, and the successfully prepared nude mice models of breast cancer were employed, so as to monitor integrainαvβ3 expression in nude mice models of breast cancer by the targeted contrast agent (cRGD-Gd-DTPA-PLGA magnetic microbubble) mediated MRI/ultrasound dual-modality radiography dynamically and quantitatively. This study aimed to predict the risk of breast cancer metastasis, early detection and diagnosis of the metastatic tumor and dynamically assess outcomes of the molecular targeted therapy with integrainαvβ3 as the target, which is significant for science and potential clinical application.

乳腺癌远处转移是患者治疗失败的主因。乳腺癌转移依赖于浸润前沿细胞外基质的降解和肿瘤新生血管的生成，整合素αvβ3是乳癌发生转移的重要分子指标，其高表达与之密切相关。目前，针对整合素αvβ3表达的检测方法存在有创、可重复性差、难以实时动态监测等缺点。本团队在前期研究基础上，拟采用空白PLGA微泡包裹cRGD和Gd-DTPA制备成适用于磁共振/超声双模态分子成像的靶向造影剂（cRGD-Gd-DTPA-PLGA磁性微泡），借助于已成功建立的乳癌裸鼠模型，针对该靶向造影剂介导的磁共振/超声双模态成像技术是否能动态、量化的监测乳腺癌裸鼠模型整合素αvβ3表达情况开展系统性研究。本研究有望为预测乳腺癌转移风险、早期发现和诊断转移以及动态评估以整合素αvβ3为靶点的分子靶向治疗疗效等提供无创而有效的新技术手段，具有重要的科学意义和潜在的临床应用价值。

乳腺癌在全球女性癌症中的发病率为24.2%，位居女性恶性肿瘤的首位。随着分子成像技术的发展，可实现对乳腺癌的早期诊断、精准分期以及个体化治疗方案制定。通过精准表征肿瘤的特性及其生物学行为，分子成像技术在降低乳腺癌的发病率和死亡率方面具有重要意义。整合素αvβ3在乳腺癌肿瘤血管内皮细胞高度表达，并在肿瘤的侵袭与转移过程中发挥重要作用。本课题探索靶向整合素αvβ3的肿瘤微环境响应性多模态纳米颗粒的制备方法，并研究该纳米颗粒的乳腺癌分子靶向成像诊断应用前景，以期为乳腺癌的多模态成像研究提供参考依据。本研究基于双乳化法，制备以多功能空白聚乳酸-聚羟基乙酸共聚物（PLGA）为载体、具备肿瘤微环境响应性和多模态靶向成像能力的纳米颗粒造影剂。PLGA颗粒经精氨酸-甘氨酸-天冬氨酸多肽（RGD）修饰使其能靶向到整合素αvβ3蛋白；RGD修饰后的PLGA进一步包裹Na2CO3、Fe3O4和Cy5.5，从而合成分别用于实现超声、磁共振及荧光成像的靶向纳米分子探针Na2CO3/Fe3O4@PLGA/Cy5.5/RGD。借助透射电子显微镜、动态光散射、粒径分析仪、傅里叶变换红外光谱仪和振动样品磁力计等设备分别测定Na2CO3/Fe3O4@PLGA/Cy5.5/RGD的表征；将纳米颗粒探针与乳腺癌MDA-MB-231细胞进行体外孵育，验证其体外的靶向特异性及细胞毒性；通过尾静脉将靶向纳米颗粒注射入荷瘤裸鼠体内，验证其在超声、磁共振及荧光三种模态下的体内靶向显影效果。结果显示，通过PLGA包载的靶向分子探针Fe3O4/Fe3O4@PLGA/Cy5.5/RGD粒径分布均匀，具有良好分散性，并且在体内外表现出良好的靶向特异性及生物相容性，提示靶向分子探针Na2CO3/Fe3O4@PLGA/Cy5.5/RGD可为乳腺癌早期精准诊疗提供科学依据。基于本项目的资助研究，发表论文7篇（其中，SCI 3篇），培养研究生6名（其中博士研究生1名，硕士研究生5名），较好完成了研究内容和研究目标。综上所述，本研究为乳腺癌内皮血管整合素αvβ3的表达提供了一种有效、实时和无创的监测手段，为解决乳腺癌转移风险预测以及转移瘤早期诊断奠定了坚实的基础，同时有助于以整合素αvβ3为基础的靶向分子药物研发及疗效评估。