Cancer cells enter an adaptive persistence to survive radiotherapy and repopulate tumor 1

Tumor cell repopulation represents a critical factor in the failure of radiotherapy. Analogous to the concept of “drug-tolerant persistence (DTP)” in stress of chemo- or targeted therapy, here, we show that cancer cells enter a “radiation-tolerant persistence (RTP)” to survive radiotherapy and repopulate tumor. These RTP cells exhibit a distinct phenotype characterized by enlargement of cell sizes and nucleus, complex karyotype, cell cycle arrest and engagement of quiescence. A fraction of RTPs unexpectedly give birth to mitotic-competent progeny cells via a viral budding-mimicking cell division. To gain insight into the molecular mechanisms how RTPs generating progenies and repopulating tumors, we applied single cell SMART RNA-sequencing and 10x RNA-sequencing to different status of human colorectal cancer cells HCT116 before and exposed to irradiation. For the first time, we profiled two transitional transcriptional waves throughout budding process and characterized two gene panels associated with budding of RTPs, illustrating the therapeutic potential for blocking tumor repopulation after radiation. We performed single cell SMART RNA-seq of isolated unirradiated cells, RTPs, budding RTPs, budded progenies and repopulated cells. Furthermore, we performed 10× single cell RNA-seq (mixture of unirradiated cells, irradiated cells and progenies)