Increased radioresistance, g(2)/m checkpoint inhibition, and impaired migration of bone marrow stromal cell lines derived from Smad3(-/-) mice.
Smad3 protein is a prominent member of the Tgfb receptor signaling pathway. Smad3(-/-) mice display decreased radiation-induced skin fibrosis, suggesting a defect in both Tgfb-mediated fibroblast proliferation and migration. We established bone marrow stromal cell lines from Smad3(-/-) mice and homozygous littermate(+/+) mice. Smad3(-/-) cells displayed a significant increase in radiation resistance with a D(0)=2.25+/- 0.14 Gy compared to Smad3(+/+) cells with a D(0)=1.75+/- 0.03 (P=0.023). Radioresistance was abrogated by reinsertion of the human SMAD3 transgene, resulting in a D(0)=1.49 0.10 (P=0.028) for Smad3(-/-)(3) cells. More Smad3(-/-) cells than Smad3(+/+) cells were in the G(2)/M phase; Smad3(-/-)(3) cells were similar to Smad3(+/+) cells. Smad3(+/+) cells exhibited increased apoptosis 24 h after 5 Gy (15%) or 8 Gy (43%) compared to less than 1% in Smad3(-/-) cells exposed to either dose. The movement of Smad3(-/-) cells, measured in an automated cell tracking system, was slower than that of Smad3(+/+) cells. Smad3(-/-)(3) cells resembled Smad3(+/+) cells. These studies establish concordance of a defective Tgfb signal transduction pathway, an increased proportion of G(2)/M cells, and radioresistance. The decreased migratory capacity of Smad3(-/-) cells in vitro correlates with decreased radiation fibrosis in vivo in mice deficient in Tgfb signaling.
Epperly
Michael W
MW
Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania 15213, USA.
Goff
Julie P
JP
Zhang
Xichen
X
Niu
Yunyun
Y
Shields
Donna S
DS
Wang
Hong
H
Shen
Hongmei
H
Franicola
Darcy
D
Bahnson
Alfred B
AB
Nie
Suhua
S
Greenberger
Emily E
EE
Greenberger
Joel S
JS
D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D001854:Bone Marrow Cells / Q000166:cytology* / Q000502:physiology* / Q000528:radiation effects; D002460:Cell Line; D002465:Cell Movement / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D018816:Genes, cdc / Q000502:physiology / Q000528:radiation effects; D051379:Mice; D011836:Radiation Tolerance / Q000502:physiology; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism*; D051900:Smad3 Protein / Q000378:metabolism*; D017154:Stromal Cells / Q000166:cytology / Q000502:physiology / Q000528:radiation effects
D018125:Receptors, Transforming Growth Factor beta; D051900:Smad3 Protein; C497791:Smad3 protein, mouse