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Updated: Jan 29, 2026
Generation and Isolation of Cell Cycle-arrested Cells with Complex Karyotypes
Published on: April 13, 2018
53BP1 regulates cell cycle arrest in esophageal cancer model
1Department of Radiotherapy, Department of Medical Oncology, Department of Chest Surgery; The Fourth Hospital of Hebei Medical University, Shijiazhuang, China. lw964729825@outlook.com.
Objective:
This study aims to investigate effects of checkpoint kinase, mediator of DNA damage checkpoint 1 (MDC1) and p53-binding protein 1 (53BP1) silencing on p53, checkpoint kinase 1 and 2 (CHK1 and CHK2), and CHK2-T68 expression.
Materials And Methods:
Eca109 cells were divided into untransfected Eca109, Blank-vector, MDC1-RNAi transfection, and 53BP1-RNAi transfection group. Streptavidin-peroxidase (SP) immunohistochemical assay was used to examine CHK2-T68 expression. About 4 groups were used to establish esophageal carcinoma nude-mouse models, and assigned as Eca-109 control (or Eca-109 plus 15 Gy γ-rays irradiation, Eca-109+IR), Blank-vector (or Blank-vecor+IR), 53BP1-RNAi (or 53BP1-RNAi+IR), and MDC1-RNAi group (or MDC1-RNAi+IR group) by injecting. The expression of p53, CHK1, CHK2 were evaluated using SP immunohistochemical assay.
Results:
53BP1 and MDC1 down-regulation significantly inhibited expression of CHK2-T68 in Eca-109 cells compared to untreated group (p<0.05). There were significant differences for CHK2-T68 expressions in different time and groups (p<0.05). 53BP1 down-regulation significantly reduced p53 and enhanced CHK1 and CHK2 expression compared to that of Eca-109 control group (p<0.05) in Eca-109 cells. 53BP1 down-regulation significantly regulated CHK1, CHK2, and p53 in xenograft nude mice models exposed to γ-ray irradiation compared to that of untreated group (p<0.05). p53 was negatively correlated with CHK1 and CHK2 in xenograft nude mice models.
Conclusions:
53BP1 regulated the cell cycle arrest by modulating p53, CHK1, and CHK2 expression in both Eca-109 cells and xenograft nude mice models.
Insights
Silencing 53BP1 and MDC1 inhibits CHK2-T68 expression in esophageal cancer cells. 53BP1 down-regulation impacts p53, CHK1, and CHK2, affecting cell cycle arrest.
Area of Science:
- Molecular Biology
- Cancer Research
- Cell Cycle Regulation
Background:
- Mediator of DNA damage checkpoint 1 (MDC1) and p53-binding protein 1 (53BP1) are crucial in DNA damage response.
- Understanding their role in regulating key cell cycle proteins is vital for cancer therapy.
Purpose of the Study:
- To investigate the impact of MDC1 and 53BP1 silencing on p53, checkpoint kinase 1 (CHK1), and checkpoint kinase 2 (CHK2) expression.
- To analyze the effect on CHK2-T68 phosphorylation, a marker of CHK2 activation.
Main Methods:
- Utilized RNA interference (RNAi) to silence MDC1 and 53BP1 in Eca109 esophageal cancer cells.
- Established esophageal carcinoma nude-mouse models with silenced MDC1 or 53BP1, some exposed to gamma-ray irradiation.
- Assessed expression of p53, CHK1, CHK2, and CHK2-T68 using streptavidin-peroxidase (SP) immunohistochemical assay.
Main Results:
- Down-regulation of 53BP1 and MDC1 significantly inhibited CHK2-T68 expression in Eca109 cells.
- 53BP1 silencing reduced p53 expression while enhancing CHK1 and CHK2 levels in cells and mouse models.
- p53 expression was negatively correlated with CHK1 and CHK2 in xenograft models.
Conclusions:
- 53BP1 plays a regulatory role in cell cycle arrest by modulating p53, CHK1, and CHK2 expression.
- These findings were consistent in both esophageal cancer cell lines and in vivo mouse models.
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