Related Experiment Videos
Glucocorticoid receptor overexpression exerts an antisurvival effect on human small cell lung cancer cells
P Sommer1, P Le Rouzic, H Gillingham
1Faculty of Medical and Human Sciences, Department of Medicine, Centre for Molecular Medicine and Endocrine Sciences Research Group, University of Manchester, Manchester, UK.
Abstract:
Small cell lung cancer (SCLC) is an aggressive tumour with an abysmal prognosis. These cancers are characteristically resistant to glucocorticoid (Gc) action, owing to impaired expression of the glucocorticoid receptor (GR). We identified reduced GR expression in human SCLC cell lines, compared to a non-SCLC cell line. The SCLC cells also showed no Gc inhibition of proliferation, in contrast to non-SCLC cells. Retroviral overexpression of GR resulted in significantly increased cell death, which was partially blocked by the GR antagonist, RU486. Indeed, in cells sorted for GR expression, there was rapid, near complete loss of live cells by 72 h, in contrast to control cells that proliferated as expected. Flow cytometry using Annexin V revealed that cell death was by apoptosis. In addition, confocal analysis of fixed cells showed that cells overexpressing GR displayed a significant increase in fragmenting apoptotic nuclei. Microarray studies showed that transgenic GR expression upregulated the proapoptotic genes, BAD and BAX. We have, therefore, identified a profound apoptotic effect of GR in SCLC cells, which may explain the low levels of endogenous GR in SCLC cells. Understanding how GR overexpression leads to apoptotic cell death in SCLC cells may uncover new therapeutic strategies.
Insights
Small cell lung cancer (SCLC) cells resist glucocorticoids due to low glucocorticoid receptor (GR) expression. Overexpressing GR in SCLC cells triggers apoptosis, offering potential new therapeutic strategies.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- Small cell lung cancer (SCLC) is an aggressive malignancy with a poor prognosis.
- SCLC exhibits characteristic resistance to glucocorticoid (Gc) treatment, linked to impaired glucocorticoid receptor (GR) expression.
- Reduced GR expression and lack of Gc-mediated proliferation inhibition are observed in SCLC cells compared to non-SCLC cells.
Purpose of the Study:
- To investigate the role of glucocorticoid receptor (GR) in small cell lung cancer (SCLC) cell death.
- To explore the potential of GR overexpression as a therapeutic strategy for SCLC.
Main Methods:
- Comparison of GR expression in SCLC and non-SCLC cell lines.
- Assessment of Gc effects on proliferation in SCLC cells.
- Retroviral overexpression of GR in SCLC cells.
- Analysis of cell death using Annexin V flow cytometry and confocal microscopy.
- Gene expression analysis using microarrays to identify upregulated proapoptotic genes.
Main Results:
- SCLC cells exhibit significantly reduced GR expression compared to non-SCLC cells.
- Overexpression of GR in SCLC cells led to substantial cell death, partially reversible with the GR antagonist RU486.
- GR overexpression induced apoptosis, evidenced by increased apoptotic nuclei and upregulation of proapoptotic genes BAD and BAX.
- Flow cytometry confirmed apoptosis as the mechanism of cell death.
Conclusions:
- Glucocorticoid receptor (GR) overexpression induces a profound apoptotic effect in small cell lung cancer (SCLC) cells.
- The observed apoptotic effect of GR may explain the typically low endogenous GR levels in SCLC.
- Targeting GR overexpression could represent a novel therapeutic approach for SCLC.
