TY - JOUR
T1 - Inhibition of Transforming Growth Factor-β Signaling in Normal Lung Epithelial Cells Confers Resistance to Ionizing Radiation
AU - Reeves, Anna
AU - Zagurovskaya, Marianna
AU - Gupta, Seema
AU - Shareef, Mohammed M.
AU - Mohiuddin, Mohammed
AU - Ahmed, Mansoor M.
N1 - Funding Information:
This work was supported by grants from the National Cancer Institute (NCI) (R01CA86937) and from the Kentucky Lung Cancer Program to M.M.A.
PY - 2007/5/1
Y1 - 2007/5/1
N2 - Purpose: To address the functional role of radiation-induced transforming growth factor-β (TGF-β) signaling in a normal epithelial background, we selected a spontaneously immortalized lung epithelial cell line derived from the normal lung tissue of a dominant-negative mutant of the TGF-β RII (ΔRII) transgenic mouse that conditionally expressed ΔRII under the control of the metallothionein promoter (MT-1), and assessed this cell line's response to radiation. Methods and Materials: A spontaneously immortalized lung epithelial cell culture (SILECC) was established and all analyses were performed within 50 passages. Colony-forming and terminal transferase dUPT nick end labeling (TUNEL) assays were used to assess clonogenic inhibition and apoptosis, respectively. Western-blot analysis was performed to assess the kinetics of p21, bax, and RII proteins. Transforming growth factor-β-responsive promoter activity was measured using dual-luciferase reporter assay. Results: Exposure to ZnSO4 inhibited TGF-β signaling induced either by recombinant TGF-β1 or ionizing radiation. The SILECC, treated with either ZnSO4 or neutralizing antibody against TGF-β, showed a significant increase in radio-resistance compared to untreated cells. Furthermore, the expression of ΔRII inhibited the radiation-induced up-regulation of the TGF-β effector gene p21waf1/cip1. Conclusions: Our findings imply that inhibition of radiation-induced TGF-β signaling via abrogation of the RII function enhances the radio-resistance of normal lung epithelial cells, and this can be directly attributed to the loss of TGF-β signaling function.
AB - Purpose: To address the functional role of radiation-induced transforming growth factor-β (TGF-β) signaling in a normal epithelial background, we selected a spontaneously immortalized lung epithelial cell line derived from the normal lung tissue of a dominant-negative mutant of the TGF-β RII (ΔRII) transgenic mouse that conditionally expressed ΔRII under the control of the metallothionein promoter (MT-1), and assessed this cell line's response to radiation. Methods and Materials: A spontaneously immortalized lung epithelial cell culture (SILECC) was established and all analyses were performed within 50 passages. Colony-forming and terminal transferase dUPT nick end labeling (TUNEL) assays were used to assess clonogenic inhibition and apoptosis, respectively. Western-blot analysis was performed to assess the kinetics of p21, bax, and RII proteins. Transforming growth factor-β-responsive promoter activity was measured using dual-luciferase reporter assay. Results: Exposure to ZnSO4 inhibited TGF-β signaling induced either by recombinant TGF-β1 or ionizing radiation. The SILECC, treated with either ZnSO4 or neutralizing antibody against TGF-β, showed a significant increase in radio-resistance compared to untreated cells. Furthermore, the expression of ΔRII inhibited the radiation-induced up-regulation of the TGF-β effector gene p21waf1/cip1. Conclusions: Our findings imply that inhibition of radiation-induced TGF-β signaling via abrogation of the RII function enhances the radio-resistance of normal lung epithelial cells, and this can be directly attributed to the loss of TGF-β signaling function.
KW - Ionizing radiation
KW - Normal lung cells
KW - Radiation resistance
KW - TGF-β1 signaling
KW - p21
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U2 - 10.1016/j.ijrobp.2006.12.057
DO - 10.1016/j.ijrobp.2006.12.057
M3 - Article
C2 - 17448872
AN - SCOPUS:34247236654
SN - 0360-3016
VL - 68
SP - 187
EP - 195
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 1
ER -