Research progress on therapeutic targeting of quiescent cancer cells.

Cellular quiescence (G0) is a sleep-like cellular state that allows cells to maintain the ability to re-enter and exit the proliferative cycle. Quiescent cancer cells are considered a therapeutic challenge since they are often resistant to conventional chemoradiotherapy resulting in disease progression and relapse. To date, the majority of published studies have focused on identifying molecules that target proliferating tumor cells while limited information is available on methods to target quiescent cancer cells. This review provides a summary of the relevant molecular mechanisms underlying quiescence maintenance and pharmacological interventions aimed at either eliminating this cancer cell subpopulation or indefinitely maintaining the quiescence state. Furthermore, the irradiation responses of quiescent cancer cells, in particular, the influence of manipulating intratumor hypoxia and radiation properties on radiosensitivity, are discussed. The main aim of this article is to provide a theoretical basis for the effective targeted killing of dormant tumor cells.