School of Chemistry, Monash University, Clayton, 3800, Australia.
Biomedical Research Institute, Hasselt University, 3590, Diepenbeek, Belgium.
BMC Biol. 2021 Dec 11;19(1):260. doi: 10.1186/s12915-021-01164-4.
The integrity of microtubule filament networks is essential for the roles in diverse cellular functions, and disruption of its structure or dynamics has been explored as a therapeutic approach to tackle diseases such as cancer. Microtubule-interacting drugs, sometimes referred to as antimitotics, are used in cancer therapy to target and disrupt microtubules. However, due to associated side effects on healthy cells, there is a need to develop safer drug regimens that still retain clinical efficacy. Currently, many questions remain open regarding the extent of effects on cellular physiology of microtubule-interacting drugs at clinically relevant and low doses. Here, we use super-resolution microscopies (single-molecule localization and optical fluctuation based) to reveal the initial microtubule dysfunctions caused by nanomolar concentrations of colcemid.
We identify previously undetected microtubule (MT) damage caused by clinically relevant doses of colcemid. Short exposure to 30-80 nM colcemid results in aberrant microtubule curvature, with a trend of increased curvature associated to increased doses, and curvatures greater than 2 rad/μm, a value associated with MT breakage. Microtubule fragmentation was detected upon treatment with ≥ 100 nM colcemid. Remarkably, lower doses (< 20 nM after 5 h) led to subtle but significant microtubule architecture remodelling characterized by increased curvature and suppression of microtubule dynamics.
Our results support the emerging hypothesis that microtubule-interacting drugs induce non-mitotic effects in cells, and establish a multi-modal imaging assay for detecting and measuring nanoscale microtubule dysfunction. The sub-diffraction visualization of these less severe precursor perturbations compared to the established antimitotic effects of microtubule-interacting drugs offers potential for improved understanding and design of anticancer agents.
微管丝网络的完整性对于其在多种细胞功能中的作用至关重要，并且其结构或动力学的破坏已被探索作为治疗癌症等疾病的一种方法。微管相互作用药物，有时被称为抗有丝分裂药物，用于癌症治疗以靶向和破坏微管。然而，由于对健康细胞的相关副作用，需要开发仍然保留临床疗效的更安全的药物方案。目前，对于微管相互作用药物在临床相关和低剂量下对细胞生理学的影响程度，仍有许多问题尚未解决。在这里，我们使用超分辨率显微镜（单分子定位和基于光学波动）来揭示临床相关浓度的秋水仙素引起的初始微管功能障碍。
我们确定了以前未检测到的秋水仙素（临床相关剂量）引起的微管（MT）损伤。短时间暴露于 30-80 nM 秋水仙素会导致微管异常弯曲，随着剂量的增加，弯曲趋势增加，曲率大于 2 rad/μm，这与 MT 断裂有关。在用≥100 nM 秋水仙素处理时检测到微管断裂。值得注意的是，较低的剂量（<20 nM 后 5 h）导致微管结构重塑，特征是曲率增加和微管动力学抑制。
我们的结果支持了微管相互作用药物在细胞中诱导非有丝分裂效应的新兴假说，并建立了一种用于检测和测量纳米级微管功能障碍的多模态成像测定法。与微管相互作用药物的已建立的抗有丝分裂效应相比，这些不太严重的前体扰动的亚衍射可视化为更好地理解和设计抗癌剂提供了潜力。
