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Updated: Feb 14, 2026

A Sensitive Method to Quantify Senescent Cancer Cells
Published on: August 2, 2013
BRD4 regulates cellular senescence in gastric cancer cells via E2F/miR-106b/p21 axis
Xingchen Dong1, Xiangming Hu1, Jinjing Chen1
1Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
Abstract:
Small molecules targeting bromodomains of BET proteins possess strong anti-tumor activities and have emerged as potential therapeutics for cancer. However, the underlying mechanisms for the anti-proliferative activity of these inhibitors are still not fully characterized. In this study, we demonstrated that BET inhibitor JQ1 suppressed the proliferation and invasiveness of gastric cancer cells by inducing cellular senescence. Depletion of BRD4, which was overexpressed in gastric cancer tissues, but not other BET proteins recapitulated JQ1-induced cellular senescence with increased cellular SA-β-Gal activity and elevated p21 levels. In addition, we showed that the levels of p21 were regulated at the post-transcriptional level by BRD4-dependent expression of miR-106b-5p, which targets the 3'-UTR of p21 mRNA. Overexpression of miR-106b-5p prevented JQ1-induced p21 expression and BRD4 inhibition-associated cellular senescence, whereas miR-106b-5p inhibitor up-regulated p21 and induced cellular senescence. Finally, we demonstrated that inhibition of E2F suppressed the binding of BRD4 to the promoter of miR-106b-5p and inhibited its transcription, leading to the increased p21 levels and cellular senescence in gastric cancer cells. Our results reveal a novel mechanism by which BRD4 regulates cancer cell proliferation by modulating the cellular senescence through E2F/miR-106b-5p/p21 axis and provide new insights into using BET inhibitors as potential anticancer drugs.
Insights
BET inhibitor JQ1 halts gastric cancer growth by triggering cellular senescence. This occurs via the E2F/miR-106b-5p/p21 pathway, revealing a novel therapeutic mechanism for cancer treatment.
Area of Science:
- Oncology
- Molecular Biology
- Cellular Biology
Background:
- Bromodomain and Extra-Terminal (BET) proteins are epigenetic regulators implicated in cancer.
- BET inhibitors show anti-tumor potential, but their precise anti-proliferative mechanisms require further elucidation.
- Gastric cancer remains a significant health concern with a need for novel therapeutic strategies.
Purpose of the Study:
- To investigate the mechanism by which BET inhibitor JQ1 suppresses gastric cancer cell proliferation.
- To identify the specific BET protein and molecular pathways involved in JQ1-induced anti-cancer effects.
- To explore the role of cellular senescence in the anti-proliferative activity of BET inhibitors in gastric cancer.
Main Methods:
- Gastric cancer cell lines were treated with BET inhibitor JQ1.
- BRD4 expression was modulated using genetic depletion techniques.
- Cellular senescence was assessed via SA-β-Gal staining and p21 expression analysis.
- MicroRNA (miR-106b-5p) levels and their interaction with p21 mRNA were investigated.
- Chromatin immunoprecipitation and E2F inhibition were employed to study transcriptional regulation.
Main Results:
- JQ1 treatment induced cellular senescence and suppressed proliferation and invasiveness in gastric cancer cells.
- Depletion of BRD4, but not other BET proteins, mimicked JQ1's senescence-inducing effects.
- BRD4 regulated p21 levels post-transcriptionally through miR-106b-5p, which targets p21 mRNA.
- E2F inhibition disrupted BRD4 binding to the miR-106b-5p promoter, decreasing its transcription and increasing p21 levels and senescence.
Conclusions:
- BRD4 plays a critical role in regulating gastric cancer cell proliferation through the induction of cellular senescence.
- A novel regulatory axis involving E2F, BRD4, miR-106b-5p, and p21 mediates JQ1's anti-cancer effects.
- These findings offer new insights into BET inhibitor mechanisms and potential therapeutic applications in gastric cancer.
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