School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore 637457, Singapore.
Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 636921, Singapore.
J Am Chem Soc. 2024 Aug 14;146(32):22689-22698. doi: 10.1021/jacs.4c07286. Epub 2024 Aug 5.
Bioorthogonal pretargeting optical imaging shows the potential for enhanced diagnosis and prognosis. However, the bioorthogonal handles, known for being "always reactive", may engage in reactions at unintended sites with their counterparts, resulting in nonspecific fluorescence activation and diminishing detection specificity. Meanwhile, despite the importance of detecting senescent cancer cells in cancer therapy, current methods mainly rely on common single senescence-associated biomarkers, which lack specificity for differentiating between various types of senescent cells. Herein, we report a dual-locked enzyme-activatable bioorthogonal fluorescence (DEBOF) turn-on imaging approach for the specific detection of senescent cancer cells. A dual-locked bioorthogonal targeting agent (DBTA) and a bioorthogonally activatable fluorescent imaging probe (BAP) are synthesized as the biorthogonal pair. DBTA is a tetrazine derivative dually caged by two enzyme-cleavable moieties, respectively, associated with senescence and cancer, which ensures that its bioorthogonal reactivity ("clickability") is only triggered in the presence of senescent cancer cells. BAP is a fluorophore caged by trans-cyclooctane (TCO), whose fluorescence is only activated upon bioorthogonal reaction between its TCO and the decaged tetrazine of DBTA. As such, the DEBOF imaging approach differentiates senescent cancer cells from nonsenescent cancer cells or other senescent cells, allowing noninvasive tracking of the population fluctuation of senescent cancer cells in the tumor of living mice to guide cancer therapies. This study thus provides a general molecular strategy for biomarker-activatable in vivo bioorthogonal pretargeting imaging with the potential to be applied to other imaging modalities beyond optics.
生物正交预靶向光学成像是一种很有前途的诊断和预后方法。然而，生物正交试剂以“永远反应”而闻名，它们可能会与相应的试剂在非预期的部位发生反应，导致非特异性荧光激活，降低检测的特异性。同时，尽管在癌症治疗中检测衰老癌细胞很重要，但目前的方法主要依赖于常见的单一衰老相关生物标志物，这些生物标志物缺乏区分不同类型衰老细胞的特异性。在这里，我们报告了一种用于特异性检测衰老癌细胞的双锁酶激活型生物正交荧光（DEBOF）开启型成像方法。合成了一种双锁生物正交靶向试剂（DBTA）和一种生物正交可激活的荧光成像探针（BAP）作为生物正交对。DBTA 是一个四嗪衍生物，分别被两个酶可切割的部分双重笼状化，分别与衰老和癌症相关，这确保了其生物正交反应性（“点击性”）只有在存在衰老癌细胞时才会被触发。BAP 是一个被反式环辛烷（TCO）笼状化的荧光团，只有当它的 TCO 与 DBTA 的去笼化四嗪发生生物正交反应时，其荧光才会被激活。因此，DEBOF 成像方法可以将衰老癌细胞与非衰老癌细胞或其他衰老细胞区分开来，允许在活小鼠的肿瘤中对衰老癌细胞群体的波动进行非侵入性跟踪，从而指导癌症治疗。这项研究为基于生物标志物激活的体内生物正交预靶向成像提供了一种通用的分子策略，有望应用于光学以外的其他成像模式。
