The glucocorticoid receptor (GR) regulates gene expression, governing aspects of homeostasis,
but is also involved in cancer. Pharmacological GR activation is frequently used to
alleviate therapy-related side-effects. While prior studies have shown GR activation
might also have anti-proliferative action on tumours, the underpinnings of glucocorticoid
action and its direct effectors in non-lymphoid solid cancers remain elusive. Here,
we study the mechanisms of glucocorticoid response, focusing on lung cancer. We show
that GR activation induces reversible cancer cell dormancy characterised by anticancer
drug tolerance, and activation of growth factor survival signalling accompanied by
vulnerability to inhibitors. GR-induced dormancy is dependent on a single GR-target
gene, CDKN1C, regulated through chromatin looping of a GR-occupied upstream distal
enhancer in a SWI/SNF-dependent fashion. These insights illustrate the importance
of GR signalling in non-lymphoid solid cancer biology, particularly in lung cancer,
and warrant caution for use of glucocorticoids in treatment of anticancer therapy
related side-effects. Glucocorticoids (GC) are reported to block cancer cell proliferation,
but the mode of action is unclear. Here the authors show that glucocorticoid receptor
activation induces cancer cell dormancy in lung cancer by regulating CDKN1C expression
through a distal enhancer, and these dormant cells are addicted to IGF-1R signalling
pathway.
