Cancer metastasis is the major cause of death from cancer (Massague and Obenauf, 2016; Steeg, 2016). The extensive genetic heterogeneity and cellular plasticity of metastatic tumors set a prime barrier for the current cancer treatment protocols (Boumahdi and de Sauvage, 2020). In addition, acquired therapy resistance has become an insurmountable obstacle that abolishes the beneficial effects of numerous anti-cancer regimens (De Angelis et al., 2019; Boumahdi and de Sauvage, 2020). Here we report that deficiency of Ku leads to the exploitation of host cells in human cancer cell line models. We found that, upon conditional deletion of XRCC6 that codes for Ku70, HCT116 human colorectal cancer cells gain a parasitic lifestyle that is characterized by the continuous cycle of host cell exploitation. We also found that DAOY cells, a human medulloblastoma cell line, innately lack nuclear Ku70/Ku86 proteins and utilize the host-cell invasion/exit mechanism for maintenance of their survival, similarly to the Ku70 conditionally-null HCT116 cells. Our study demonstrates that a functional loss of Ku protein promotes an adaptive, opportunistic switch to a parasitic lifestyle in human cancer cells, providing evidence for a previously unknown mechanism of cell survival in response to severe genomic stress. We anticipate that our study will bring a new perspective for understanding the mechanisms of cancer cell evolution, leading to a shift in the current concepts of cancer therapy protocols directed to the prevention of cancer metastasis and therapy resistance.
Bibliographical noteFunding Information:
This work was supported, in part, by the start-up funds for OS by the University of Minnesota Medical School.
We thank Dr. Eric A. Hendrickson for providing the HCT116 Ku70 conditionally-null cells, and Drs. Brenda M. Ogle, Walter Low, and Thomas Strobel for the critical review and constructive comments on the manuscript, and Dr. Guillermo Marques and Mary Brown for the technical assistance with the confocal and live-cell imaging studies performed at the University of Minnesota University Imaging Center. Funding. This work was supported, in part, by the start-up funds for OS by the University of Minnesota Medical School.
© Copyright © 2021 Saydam and Saydam.
- ERM proteins
- Ku protein
- cancer metastasis
- cell invasion
- extracellular vesicles
- genome instability