TY - JOUR
T1 - Low dose IR-induced IGF-1-sCLU expression
T2 - A p53-repressed expression cascade that interferes with TGFβ1 signaling to confer a pro-survival bystander effect
AU - Klokov, D.
AU - Leskov, K.
AU - Araki, S.
AU - Zou, Y.
AU - Goetz, E. M.
AU - Luo, X.
AU - Willson, D.
AU - Boothman, D. A.
N1 - Funding Information:
This work was supported by DOE Grant #DE-FG02-06ER64186 to DAB, a pilot grant from NASA to develop BLI imaging of hCLUp-Luc to DW and DAB, a DOD BCRP predoctoral fellowship (W81XWH-06-0748) to E.M.G and a DOD PCRP post-doctoral fellowship (X8IXWH-09-1-0168) to XL. We thank Ms Lakshmi Sampath and Mr Andrew Bruening for their help with this work. We are also grateful to Dr Mary Helen Barcellos-Hoff for her advice with the animal experiments. We are also grateful to the Robert B. and Virginia Payne Endowment to DAB. This is CSCN 065 and used the Flow Cytometry and Biostatistics Cores, Simmons Cancer Center.
PY - 2013/1/24
Y1 - 2013/1/24
N2 - Inadvertent mammalian tissue exposures to low doses of ionizing radiation (IR) after radiation accidents, remediation of radioactive-contaminated areas, space travel or a dirty bomb represent an interesting trauma to an organism. Possible low-dose IR-induced bystander effects could impact our evaluation of human health effects, as cells within tissue are not equally damaged after doses of IR ≤10 cGy. To understand tissue responses after low IR doses, we generated a reporter system using the human clusterin promoter fused to firefly luciferase (hCLUp-Luc). Secretory clusterin (sCLU), an extracellular molecular chaperone, induced by low doses of cytotoxic agents, clears cell debris. Low-dose IR (≥2 cGy) exposure induced hCLUp-Luc activity with peak levels at 96 h, consistent with endogenous sCLU levels. As doses increased (≥1 Gy), sCLU induction amplitudes increased and time-to-peak response decreased. sCLU expression was stimulated by insulin-like growth factor-1, but suppressed by p53. Responses in transgenic hCLUp-Luc reporter mice after low IR doses showed that specific tissues (that is, colon, spleen, mammary, thymus and bone marrow) of female mice induced hCLUp-Luc activity more than male mice after whole body (≥10 cGy) irradiation. Tissue-specific, non-linear dose- and time-responses of hCLUp-Luc and endogenous sCLU levels were noted. Colon maintained homeostatic balance after 10 cGy. Bone marrow responded with delayed, but prolonged and elevated expression. Intraperitoneal administration of α-transforming growth factor (TGF)β1 (1D11), but not control (13C4) antibodies, immediately following IR exposure abrogated CLU induction responses. Induction in vivo also correlated with Smad signaling by activated TGFβ1 after IR. Mechanistically, media with elevated sCLU levels suppressed signaling, blocked apoptosis and increased survival of TGFβ1-exposed tumor or normal cells. Thus, sCLU is a pro-survival bystander factor that abrogates TGFβ1 signaling and most likely promotes wound healing.
AB - Inadvertent mammalian tissue exposures to low doses of ionizing radiation (IR) after radiation accidents, remediation of radioactive-contaminated areas, space travel or a dirty bomb represent an interesting trauma to an organism. Possible low-dose IR-induced bystander effects could impact our evaluation of human health effects, as cells within tissue are not equally damaged after doses of IR ≤10 cGy. To understand tissue responses after low IR doses, we generated a reporter system using the human clusterin promoter fused to firefly luciferase (hCLUp-Luc). Secretory clusterin (sCLU), an extracellular molecular chaperone, induced by low doses of cytotoxic agents, clears cell debris. Low-dose IR (≥2 cGy) exposure induced hCLUp-Luc activity with peak levels at 96 h, consistent with endogenous sCLU levels. As doses increased (≥1 Gy), sCLU induction amplitudes increased and time-to-peak response decreased. sCLU expression was stimulated by insulin-like growth factor-1, but suppressed by p53. Responses in transgenic hCLUp-Luc reporter mice after low IR doses showed that specific tissues (that is, colon, spleen, mammary, thymus and bone marrow) of female mice induced hCLUp-Luc activity more than male mice after whole body (≥10 cGy) irradiation. Tissue-specific, non-linear dose- and time-responses of hCLUp-Luc and endogenous sCLU levels were noted. Colon maintained homeostatic balance after 10 cGy. Bone marrow responded with delayed, but prolonged and elevated expression. Intraperitoneal administration of α-transforming growth factor (TGF)β1 (1D11), but not control (13C4) antibodies, immediately following IR exposure abrogated CLU induction responses. Induction in vivo also correlated with Smad signaling by activated TGFβ1 after IR. Mechanistically, media with elevated sCLU levels suppressed signaling, blocked apoptosis and increased survival of TGFβ1-exposed tumor or normal cells. Thus, sCLU is a pro-survival bystander factor that abrogates TGFβ1 signaling and most likely promotes wound healing.
KW - TGFβ1
KW - bystander effects
KW - insulin-like growth factor-1
KW - low-dose ionizing radiation
KW - p53 suppression
KW - secretory clusterin
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UR - http://www.scopus.com/inward/citedby.url?scp=84873055366&partnerID=8YFLogxK
U2 - 10.1038/onc.2012.64
DO - 10.1038/onc.2012.64
M3 - Article
C2 - 22391565
AN - SCOPUS:84873055366
SN - 0950-9232
VL - 32
SP - 479
EP - 490
JO - Oncogene
JF - Oncogene
IS - 4
ER -