Three-dimensional organoid culture technologies have revolutionized cancer research by allowing for more realistic and scalable reproductions of both tumour and microenvironmental structures^1,2,3. This has enabled better modelling of low-complexity cancer cell behaviours that occur over relatively short periods of time⁴. However, available organoid systems do not capture the intricate evolutionary process of cancer development in terms of tissue architecture, cell diversity, homeostasis and lifespan. As a consequence, oncogenesis and tumour formation studies are not possible in vitro and instead require the extensive use of animal models, which provide limited spatiotemporal resolution of cellular dynamics and come at a considerable cost in terms of resources and animal lives. Here we developed topobiologically complex mini-colons that are able to undergo tumorigenesis ex vivo by integrating microfabrication, optogenetic and tissue engineering approaches. With this system, tumorigenic transformation can be spatiotemporally controlled by directing oncogenic activation through blue-light exposure, and emergent colon tumours can be tracked in real-time at the single-cell resolution for several weeks without breaking the culture. These induced mini-colons display rich intratumoural and intertumoural diversity and recapitulate key pathophysiological hallmarks displayed by colorectal tumours in vivo. By fine-tuning cell-intrinsic and cell-extrinsic parameters, mini-colons can be used to identify tumorigenic determinants and pharmacological opportunities. As a whole, our study paves the way for cancer initiation research outside living organisms.

三维类器官培养技术通过允许更真实和可扩展的肿瘤和微环境结构复制^1,2,3彻底改变了癌症研究。这使得能够更好地对在相对较短的时间内发生的低复杂性癌细胞行为进行建模⁴。然而，现有的类器官系统无法捕捉癌症发展在组织结构、细胞多样性、稳态和寿命方面的复杂进化过程。因此，肿瘤发生和肿瘤形成研究不可能在体外进行，而是需要广泛使用动物模型，而动物模型提供的细胞动力学时空分辨率有限，并且在资源和动物生命方面付出了相当大的代价。在这里，我们开发了拓扑生物学复杂的迷你结肠，通过整合微加工、光遗传学和组织工程方法，它们能够在体外发生肿瘤。借助该系统，可以通过蓝光照射引导致癌激活来在时空上控制致瘤转化，并且可以在不破坏培养物的情况下以单细胞分辨率实时跟踪新出现的结肠肿瘤数周。这些诱导的迷你结肠显示出丰富的肿瘤内和肿瘤间多样性，并概括了体内结直肠肿瘤所显示的关键病理生理学特征。通过微调细胞内在和细胞外在参数，迷你冒号可用于识别致瘤决定因素和药理学机会。总的来说，我们的研究为活体生物体之外的癌症发生研究铺平了道路。