Cell-cycle fate-monitoring distinguishes individual chemosensitive and chemoresistant cancer cells in drug-treated heterogeneous populations demonstrated by real-time FUCCI imaging

Essentially every population of cancer cells within a tumor is heterogeneous, especially with regard to chemosensitivity and resistance. In the present study, we utilized the fluorescence ubiquitination-based cell cycle indicator (FUCCI) imaging system to investigate the correlation between cell-cycle behavior and apoptosis after treatment of cancer cells with chemotherapeutic drugs. HeLa cells expressing FUCCI were treated with doxorubicin (DOX) (5 μM) or cisplatinum (CDDP) (5 μM) for 3 h. Cell-cycle progression and apoptosis were monitored by time-lapse FUCCI imaging for 72 h. Time-lapse FUCCI imaging demonstrated that both DOX and CDDP could induce cell cycle arrest in S/G2/M in almost all the cells, but a subpopulation of the cells could escape the block and undergo mitosis. The subpopulation which went through mitosis subsequently underwent apoptosis, while the cells arrested in S/G2/M survived. The present results demonstrate that chemoresistant cells can be readily identified in a heterogeneous population of cancer cells by S/G2/M arrest, which can serve in future studies as a visible target for novel agents that kill cell-cycle-arrested cells.

实质上，肿瘤内的每一个癌细胞群体均具有异质性，尤其在化疗敏感性与耐药性层面差异显著。本研究借助荧光泛素化细胞周期指示器（fluorescence ubiquitination-based cell cycle indicator, FUCCI）成像系统，探究癌细胞经化疗药物处理后，细胞周期行为与细胞凋亡之间的关联。实验中，表达FUCCI的HeLa细胞经5μM多柔比星（doxorubicin, DOX）或5μM顺铂（cisplatinum, CDDP）处理3小时，随后通过延时FUCCI成像对细胞周期进程与细胞凋亡进行了72小时的连续监测。延时FUCCI成像结果显示，DOX与CDDP均可诱导几乎全部细胞出现S/G2/M期细胞周期阻滞，但存在一小部分细胞能够逃脱阻滞并进入有丝分裂；经历有丝分裂的该细胞亚群随后发生凋亡，而处于S/G2/M期阻滞的细胞则得以存活。本研究结果表明，通过S/G2/M期阻滞这一特征，可在异质性癌细胞群体中便捷地识别出化疗耐药细胞，该特征可在未来研究中作为靶向杀伤周期阻滞细胞的新型药物的可视化靶点。