一种用于乳腺癌联合筛查和局部成像的基因策略。
A genetic strategy for combined screening and localized imaging of breast cancer.
机构信息
Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
School of Dentistry, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
出版信息
Mol Imaging Biol. 2011 Jun;13(3):452-461. doi: 10.1007/s11307-010-0377-y.
PURPOSE
Improvements are needed for the early detection of breast cancer, as current imaging methods lack sensitivity to detect small tumors and assess their disease phenotype.
PROCEDURES
To address this issue, the dual reporter adenoviral vector (Ad5/3-Id1-SEAP-Id1-mCherry) was produced with a cancer-specific Id1 promoter driving expression of a blood-based screening reporter (secreted embryonic alkaline phosphatase, SEAP) and a fluorescent imaging reporter (mCherry). This diagnostic system was assessed for its screening potential on breast cancer cell lines of various aggressive phenotypes. Reporter expression was measured and correlated with promoter level expression using Western blot. Adenovirus receptor expression was normalized against reporter expression with luciferase infectivity assays. Ad5/3-Id1-SEAP-Id1-mCherry infected MDA-MB-231 cells combined with uninfected cells were implanted into the mammary fat pad of athymic nude mice to recapitulate low-dose tumor delivery. Id1 driven SEAP expression and mCherry imaging were monitored to validate diagnostic sensitivity and efficacy.
RESULTS
Infected breast cancer cell lines displayed SEAP levels in the media that were 10-fold above background by 2 days after infection. Ad5/3-Id1-SEAP-Id1-mCherry infected cells (multiplicity of infection = 10) implanted in athymic nude mice demonstrated a 14-fold increase in serum SEAP levels over baseline when as little as 2.5% of the tumor contained infected cells. This robust response was also found for the mCherry reporter, which was clearly visible in tumor xenografts on day 2 post implantation.
CONCLUSIONS
This diagnostic system that combines screening with imaging for early detection and monitoring of breast cancer can be easily extended to other reporters/modalities and cancer-targeting methods. Combining screening with imaging in a genetic, cancer-specific mechanism allows sensitive multi-modal detection and localization of breast cancer.
目的
需要改进乳腺癌的早期检测方法，因为目前的成像方法对检测小肿瘤和评估其疾病表型的灵敏度不足。
方法
为了解决这个问题，我们制备了双报告基因腺病毒载体（Ad5/3-Id1-SEAP-Id1-mCherry），该载体由一个肿瘤特异性 Id1 启动子驱动表达一种血液筛查报告基因（分泌型碱性磷酸酶，SEAP）和一种荧光成像报告基因（mCherry）。我们评估了该诊断系统在不同侵袭性表型的乳腺癌细胞系中的筛查潜力。使用 Western blot 检测报告基因的表达，并与启动子水平的表达进行相关性分析。用荧光素酶感染实验将腺病毒受体表达归一化为报告基因的表达。将感染 Ad5/3-Id1-SEAP-Id1-mCherry 的 MDA-MB-231 细胞与未感染的细胞一起植入裸鼠的乳腺脂肪垫中，以重现低剂量肿瘤接种。通过监测 Id1 驱动的 SEAP 表达和 mCherry 成像来验证诊断的敏感性和疗效。
结果
感染的乳腺癌细胞系在感染后 2 天，培养基中的 SEAP 水平比背景高 10 倍。在裸鼠中植入感染 Ad5/3-Id1-SEAP-Id1-mCherry 的细胞（感染复数为 10）时，当肿瘤中只有 2.5%的细胞被感染时，血清 SEAP 水平就比基线升高了 14 倍。mCherry 报告基因也有类似的结果，在植入后第 2 天，肿瘤异种移植中可以清楚地看到。
结论
这种结合筛查和成像的诊断系统可用于早期检测和监测乳腺癌，且易于扩展到其他报告基因/模式和针对癌症的靶向方法。通过基因、肿瘤特异性机制将筛查与成像相结合，可以实现对乳腺癌的敏感多模态检测和定位。
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