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Updated: May 26, 2026
Induction and Testing of Hypoxia in Cell Culture
Published on: August 12, 2011
Effect of small interfering RNA targeting hypoxia-inducible factor-1α on radiosensitivity of PC3 cell line
Yuhua Huang1, Jiang Yu, Chunyin Yan
1Department of Urology, First Affiliated Hospital of Soozhow University, Suzhou, Jiangsu, China.
Objective:
To evaluate the effect of silencing hypoxia-inducible factor-1α (HIF-1α) expression by small interfering RNA (siRNA) on the radiosensitivity of the PC3 cell line.
Methods:
The expression of HIF-1α in PC3, a p53-null and androgen-independent prostate cancer cell line, was knocked down by siRNA. Irradiation was performed at 48 hours after transfection. The cells were divided into 3 groups: the PC3 group, control group (transfected with scramble siRNA), and HIF-1α silence group. HIF-1α expression was determined using real-time polymerase chain reaction and Western immunoblotting. A clonogenic assay and the cell counting kit-8 assay were performed to determine the radiosensitivity. Flow cytometry was used to assess apoptosis and cell cycle distribution.
Results:
HIF-1α siRNA downregulated HIF-1α expression in PC3 cells on the mRNA level and protein level, and its silencing effect on mRNA level was evident at 24-72 hours. The HIF-1α silence group had a low final slope of exponential part of a radiation survival curve, survival fraction of 2 Gy, quasi-threshold dose, and extrapolation number, and the sensitizing enhancement ratio was 1.24. The cell counting kit-8 assay showed decreased cellular viability (24 hours, F = 139.74, P < .01; 48 hours, F = 495.49, P < .01; 72 hours, F = 426.89, P < .01; 96 hours, F = 471.11, P < .01) in the HIF-1α silence group. Silencing HIF-1α also induced more apoptosis (PC3, 17.9% ± 1.65%; control group, 18.6% ± 1.37%; HIF-1α silence group, 29.1% ± 2.16%; F = 169.9, P < .01) and cell cycle arrest at the S, G(2)/M phase.
Conclusion:
The suppression of HIF-1α in PC3 cells sensitizes the PC3 cells to irradiation. We have shown that HIF-1α inhibition attenuates repair of postradiation injury, with an increase in both interphase death and reproductive death after irradiation, apoptotic potential, and cell cycle arrest at the proliferative phase.
Insights
Silencing hypoxia-inducible factor-1α (HIF-1α) with siRNA enhances prostate cancer cell radiosensitivity. This inhibition reduces cell viability and increases apoptosis and cell cycle arrest after irradiation.
Area of Science:
- Oncology
- Molecular Biology
- Radiotherapy
Background:
- Hypoxia-inducible factor-1α (HIF-1α) is a key regulator of cellular response to hypoxia and is often overexpressed in various cancers, including prostate cancer.
- HIF-1α plays a significant role in tumor radioresistance by promoting survival, angiogenesis, and metabolic adaptation.
- The PC3 cell line is a p53-null, androgen-independent prostate cancer model frequently used in radiobiology research.
Purpose of the Study:
- To investigate the impact of inhibiting HIF-1α expression on the radiosensitivity of the PC3 prostate cancer cell line.
- To determine if small interfering RNA (siRNA)-mediated silencing of HIF-1α can sensitize PC3 cells to ionizing radiation.
Main Methods:
- PC3 cells were transfected with siRNA targeting HIF-1α or a control scramble siRNA.
- HIF-1α expression levels were quantified using real-time PCR and Western immunoblotting.
- Radiosensitivity was assessed via clonogenic assays and cell counting kit-8 assays.
- Apoptosis and cell cycle distribution were analyzed using flow cytometry.
Main Results:
- siRNA successfully downregulated HIF-1α mRNA and protein expression in PC3 cells.
- HIF-1α silencing significantly decreased cell viability and increased sensitivity to radiation, indicated by a sensitizing enhancement ratio of 1.24.
- Silencing HIF-1α led to increased apoptosis and cell cycle arrest in the S and G2/M phases post-irradiation.
Conclusions:
- Suppression of HIF-1α expression in PC3 cells enhances their sensitivity to radiation therapy.
- HIF-1α inhibition impairs the repair of radiation-induced damage, leading to increased cell death (both interphase and reproductive death).
- Targeting HIF-1α may represent a promising strategy to improve the efficacy of radiotherapy for prostate cancer.
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