New rationales for using TGFbeta inhibitors in radiotherapy.
OBJECTIVE
The first reports that ionizing radiation (IR) induces rapid and persistent activation of transforming growth factor beta1 (TGFbeta) were nearly two decades ago. Subsequent studies have shown that TGFbeta is a major mediator of cellular and tissue responses to IR and have revealed novel facets of its complex biology.


RESULTS
We and others have recently shown that inhibition of production or signaling of TGFbeta in epithelial cells modulates radiosensitivity and impedes activation of the DNA damage response program. The primary transducer of cellular response to DNA damage caused by ionizing radiation is the nuclear protein kinase ataxia telangiectasia mutated, whose activity is severely compromised when TGFbeta is inhibited. Thus, in conjunction, with its well-recognized contribution to normal tissue fibrosis, the role of TGFbeta in the genotoxic stress program provides a previously unsuspected avenue to modulate radiotherapy.


CONCLUSIONS
We hypothesize that identification of the circumstances and tumors in which TGFbeta manipulation enhances tumor cell radiosensitivity, while protecting normal tissues, could significantly increase therapeutic index.
Andarawewa
Kumari L
KL
Life Sciences Division, Berkeley, California 94720, USA.
Paupert
Jenny
J
Pal
Anupama
A
Barcellos-Hoff
Mary Helen
MH
D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D008954:Models, Biological; D009369:Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000532:radiotherapy*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011836:Radiation Tolerance / Q000187:drug effects / Q000502:physiology; D011853:Radiobiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors* / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D016212:Transforming Growth Factor beta; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases