Glucocorticoid receptor regulates accurate chromosome segregation and is associated with malignancy

Abstract

The glucocorticoid receptor (GR) is a member of the nuclear receptor superfamily, which controls programs regulating cell proliferation, differentiation, and apoptosis. We have identified an unexpected role for GR in mitosis. We discovered that specifically modified GR species accumulate at the mitotic spindle during mitosis in a distribution that overlaps with Aurora kinases. We found that Aurora A was required to mediate mitosis-driven GR phosphorylation, but not recruitment of GR to the spindle. GR was necessary for mitotic progression, with increased time to complete mitosis, frequency of mitotic aberrations, and death in mitosis observed following GR knockdown. Complementation studies revealed an essential role for the GR ligand-binding domain, but no clear requirement for ligand binding in regulating chromosome segregation. The GR N-terminal domain, and specifically phosphosites S203 and S211, were not required. Reduced GR expression results in a cell cycle phenotype, with isolated cells from mouse and human subjects showing changes in chromosome content over prolonged passage. Furthermore, GR haploinsufficient mice have an increased incidence of tumor formation, and, strikingly, these tumors are further depleted for GR, implying additional GR loss as a consequence of cell transformation. We identified reduced GR expression in a panel of human liver, lung, prostate, colon, and breast cancers. We therefore reveal an unexpected role for the GR in promoting accurate chromosome segregation during mitosis, which is causally linked to tumorigenesis, making GR an authentic tumor suppressor gene.glucocorticoid receptor | mitosis | aneuploidy | DNA damage | cancer G lucocorticoids (Gcs) act through the glucocorticoid receptor (GR), a member of the nuclear hormone receptor superfamily, and a ligand-activated transcription factor (1-4). The GR is ubiquitously expressed and regulates energy metabolism, immunity, and cell fate decisions. The quiescent GR resides in the cytoplasm in a complex with heat shock proteins and immunophilins, attached to the microtubule architecture of the cell in a heat shock protein 90-dependent manner (5). Ligand binding drives GR transformation, involving N-terminal phosphorylation on S203 and S211 and rapid translocation to the nucleus requiring attachment to dynein by heat shock protein 90, immunophilins, and dynamitin (6). Once in the nucleus, GR binds directly to DNA to regulate transcription, or tethers to other DNA-bound transcription factors, such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and activator protein 1 (AP1), to regulate their function (7-10).In mitosis, GR is phosphorylated on both S203 and S211, but in a ligand-independent manner (11), and more comprehensive phosphoproteomic analyses identify the presence of multiple N-terminal GR phosphoforms in purified mitotic spindle fractions (12). Although altered GR function in mitosis has been shown (11, 13, 14), the kinases responsible and cellular consequences have not been defined. The role of G...

Haploinsufficiency for NR3C1, the gene encoding the glucocorticoid receptor, in blastic plasmacytoid dendritic cell neoplasms

“…61,62 We propose that hormone-dependent, epigenetic reprogramming is the ultimate consequence of NR3C1 haploinsufficiency in BPDCN ( Figure 6). This hypothesis is supported by our clinical and functional analysis in vitro and in vivo and by reports in other cancers showing that low NR3C1/GCR expression is linked to poor prognosis 57,63,64 and tumor progression. 65 This postulate is also consistent with analyses showing increased tumor incidence in Nr3c1 haploinsufficient mice.…”

Glucocorticoid receptors in lung cancer: new perspectives

“…Our work showed that SCLC cell lines contained reduced GR transcripts when compared to NSCLC cell lines. A recent report has extended these observations to show that the GR appears downregulated in many cancers including liver, prostate, colon and breast (Matthews et al 2015). In SCLC, GR downregulation occurs due to methylation of the GR promoter (Kay et al 2011, Singh et al 2014.…”

“…A recent study has definitively shown that the GR is an authentic TSG (Matthews et al 2015). Aged GR haploinsufficient mice display increased numbers of microtumours and DNA damage compared to their wildtype counterparts and, in cultured B lymphocytes from patients with GR haploinsufficiency, the chromosome complement was significantly lower than from unaffected family members.…”

“…These data point to an important role for the GR regulating mitotic progression. GR loss results in errors in chromosome segregation leading to aneuploidy and eventually carcinogenesis (Matthews et al 2015).…”

Chromosome 7 Multiplication in EGFR-positive Lung Carcinomas Based on Tissue Microarray Analysis

“…mitotic progression and its reduced expression is detected in a panel of human liver, lung, prostate, colon, and breast cancers, improves our molecular knowledge in understanding mechanisms that induce chromosomal instability (8).…”