| Different Expressions of HIF-1alpha, Bcl-2 and Baxin DU145 Prostate Cancer Cells Transplanted in Nude Mouse between X-Ray and Neutron Irradiation |
| Moonkyoo Kong, Jin Oh Kang, Sang Ki Kim, Dong Oh Shin, Seo Hyun Park, Chang Ju Kim, Hyun Kyung Chang |
1Department of Radiation Oncology, Kyung Hee University School of Medicine, Seoul, Korea. kangjino@paran.com
2Department of Physiology, Kyung Hee University School of Medicine, Seoul, Korea. |
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| ABSTRACT |
PURPOSE:
To investigate the radiobiologic effects of neutron and X-ray irradiation on DU-145 prostate carcinoma cells by identifying the differences of HIF-1alpha expression and apoptosis.
MATERIALS AND METHODS:
Nude mice were injected with the human prostate cancer cell line, DU-145, and then irradiated with 2 Gy and 10 Gy X-rays, or 0.6 Gy and 3.3 Gy neutrons, respectively. The mice were sacrificed at 24 hours and 120 hours after irradiation. The expression levels of HIF-1alpha, Bcl-2 and Bax were compared with immunohistochemical staining and western blotting. The apoptotic indexes were compared with the Terminal deoxynucleotidyl biotin-dUTP nick and labeling (TUNEL) assay.
RESULTS:
At day 1, HIF-1alpha and Bcl-2 expression decreased, while Bax expression and the number of TUNEL positive cells increased in neutron irradiated groups for the control and X-ray irradiated groups. The Bcl-2/Bax ratio was significantly lower in the neutron irradiated groups regardless of dose (p=0.001). The same pattern of the differences in the expressions of the HIF-1alpha, Bcl-2, Bax, Bcl-2/Bax ratio, and apoptotic indexes were indentified at day 5. HIF-1alpha expression was related with Bcl-2 (p=0.031), Bax (p=0.037) expressions and the apoptotic indexes (p=0.016) at day 5.
CONCLUSION:
Neutron irradiation showed a decrease in HIF-1alpha, Bcl-2 expression, and Bcl-2/Bax ratio, but increased Bax expression regardless of dose. This study suggests that the differences radiobiological responses between photon and neutron irradiation may be related to different HIF-1alpha expression and subsequent apoptotic protein expressions. |
| Key Words:
HIF-1alpha, Bcl-2, Bax, Neutron, Prostate cancer |
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