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Updated: Jul 16, 2026
Investigation of the Transcriptional Role of a RUNX1 Intronic Silencer by CRISPR/Cas9 Ribonucleoprotein in Acute Myeloid Leukemia Cells
Published on: September 1, 2019
Frequent silencing of RUNX3 in esophageal squamous cell carcinomas is associated with radioresistance and poor
C Sakakura1, K Miyagawa, K-I Fukuda
1Dept of Surgery and Regenerative Medicine, Div of Surgery and Physiology of the Digestive System, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi, Kamigyo-ku, Kyoto 602-8566, Japan. sakakura@koto.kpu-m.ac.jp
Abstract:
Radiotherapy is an effective treatment for some esophageal cancers, but the molecular mechanisms of radiosensitivity remain unknown. RUNX3, a novel tumor suppressor of gastric cancer, functions in transforming growth factor (TGF)-beta-dependent apoptosis. We obtained paired samples from 62 patients with advanced esophageal cancers diagnosed initially as T3 or T4 with image diagnosis; one sample was obtained from a biopsy before presurgical radiotherapy, and the other was resected in surgical specimens after radiotherapy. RUNX3 was repressed in 67.7% cases of the pretreatment biopsy samples and 96.7% cases of the irradiated, resected samples. The nuclear expression of RUNX3 was associated with radiosensitivity and a better prognosis than cytoplasmic or no RUNX3 expression (P<0.003); cytoplasmic RUNX3 expression was strictly associated with radioresistance. RUNX3 was downregulated and its promoter was hypermethylated in all radioresistant esophageal cancer cell lines examined. Stable transfection of esophageal cancer cells with RUNX3 slightly inhibited cell proliferation in vitro, enhanced the antiproliferative and apoptotic effects of TGF-beta and increased radiosensitivity in conjunction with Bim induction. In contrast, transfection of RUNX3-expressing cells with a RUNX3 antisense construct or a Bim-specific small interfering RNA induced radioresistance. Treatment with 5-aza-2'-deoxycytidine restored RUNX3 expression, increased radiosensitivity and induced Bim in both control and radioresistant cells. These results suggest that RUNX3 silencing promotes radioresistance in esophageal cancers. Examination of RUNX3 expression in pretreatment specimens may predict radiosensitivity, and induction of RUNX3 expression may increase tumor radiosensitivity.
Insights
RUNX3, a tumor suppressor, is often repressed in esophageal cancers, leading to radioresistance. Restoring RUNX3 expression can enhance tumor radiosensitivity and improve patient prognosis.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Research
Background:
- Radiotherapy is a key treatment for esophageal cancer, but its effectiveness varies.
- The molecular basis of radiosensitivity in esophageal cancer is not fully understood.
- RUNX3, a known tumor suppressor in gastric cancer, regulates apoptosis via TGF-beta signaling.
Purpose of the Study:
- To investigate the role of RUNX3 in esophageal cancer radiosensitivity.
- To determine if RUNX3 expression levels correlate with treatment response and patient outcomes.
- To explore the potential of RUNX3 as a predictive biomarker and therapeutic target.
Main Methods:
- Analysis of paired tumor samples (pre-radiotherapy biopsy and post-radiotherapy resection) from 62 advanced esophageal cancer patients.
- Assessment of RUNX3 expression (nuclear vs. cytoplasmic) and promoter methylation in tumor tissues and cell lines.
- Functional studies involving stable transfection of esophageal cancer cells with RUNX3, RUNX3 antisense, Bim siRNA, and treatment with 5-aza-2'-deoxycytidine.
Main Results:
- RUNX3 was repressed in a majority of pre-treatment and post-radiotherapy esophageal cancer samples.
- Nuclear RUNX3 expression correlated with radiosensitivity and better prognosis, while cytoplasmic expression was linked to radioresistance.
- RUNX3 downregulation and promoter hypermethylation were observed in radioresistant cell lines; RUNX3 restoration increased radiosensitivity and Bim induction.
Conclusions:
- RUNX3 silencing is a mechanism promoting radioresistance in esophageal cancers.
- RUNX3 expression in pre-treatment biopsies may predict radiosensitivity.
- Inducing RUNX3 expression holds potential for enhancing tumor radiosensitivity in esophageal cancer treatment.
