Assessing drug response within live native tissue provides increased fidelity with regards to optimizing efficacy while minimizing off-target effects. Here, using longitudinal intravital imaging of a Rac1-Förster resonance energy transfer (FRET) biosensor mouse coupled with in vivo photoswitching to track intratumoral movement, we help guide treatment scheduling in a live breast cancer setting to impair metastatic progression. We uncover altered Rac1 activity at the center versus invasive border of tumors and demonstrate enhanced Rac1 activity of cells in close proximity to live tumor vasculature using optical window imaging. We further reveal that Rac1 inhibition can enhance tumor cell vulnerability to fluid-flow-induced shear stress and therefore improves overall anti-metastatic response to therapy during transit to secondary sites such as the lung. Collectively, this study demonstrates the utility of single-cell intravital imaging in vivo to demonstrate that Rac1 inhibition can reduce tumor progression and metastases in an autochthonous setting to improve overall survival.

评估活的天然组织内的药物反应提供了关于优化功效同时最小化脱靶效应的更高保真度。在这里，使用与体内耦合的 Rac1-Förster 共振能量转移 (FRET) 生物传感器小鼠的纵向活体成像通过光开关跟踪瘤内运动，我们帮助指导活体乳腺癌环境中的治疗计划，以削弱转移性进展。我们发现中心的 Rac1 活性与肿瘤的侵入性边界发生了变化，并使用光学窗口成像证明了靠近活肿瘤脉管系统的细胞的 Rac1 活性增强。我们进一步揭示，Rac1 抑制可以增强肿瘤细胞对流体流动诱导的剪切应力的脆弱性，因此在转移到肺等次要部位期间改善对治疗的整体抗转移反应。总的来说，这项研究证明了体内单细胞活体成像的效用，以证明 Rac1 抑制可以在原地环境中减少肿瘤进展和转移，从而提高总体存活率。