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Medline ® Abstract for Reference 59

of 'Clinical manifestations and diagnosis of Fanconi anemia'

Aberrant activation of stress-response pathways leads to TNF-alpha oversecretion in Fanconi anemia.
Briot D, Macé-AiméG, Subra F, Rosselli F
Blood. 2008;111(4):1913.
Fanconi anemia (FA), an inherited syndrome that associates bone marrow failure, cancer predisposition, and genetic instability, is characterized by an overproduction of the myelosuppressive cytokine TNF-alpha through unknown mechanisms. We demonstrate here that FANC pathway loss-of-function results in the aberrant activation of 2 major stress-signaling pathways: NF-kappaB and MAPKs. These responses are independent on TNF-alpha expression. On the contrary, inhibition of the MAPK pathways normalizes TNF-alpha oversecretion in FA. Moreover, our data show that the overexpression of the matrix metalloproteinase MMP-7 is the key event directly responsible for the high rate of TNF-alpha shedding and release from the cytoplasmic membrane in FA. TNF-alpha overproduction is, indeed, normalized by MMP-7 inhibition. Finally, MAPK inhibition impacts on MMP-7 overexpression. Evidence is provided of the existence of a linear pathway in which FANC mutations activate MAPK signaling that induces MMP-7 overexpression leading, in fine, to TNF-alpha oversecretion. TNF-alpha may, in turn, sustain or amplify both MAPKs and NF-kappaB activation. Aberrant expression or activity of NF-kappaB and/or MAPKs has been already involved in bone marrow failure and leukemia, and their inhibition offered clinical benefit for patients. In conclusion, our data provide a strong rationale for new clinical trials on FA patients.
Centre National de la Recherche Scientifique (CNRS) FRE2939, UniversitéParis-Sud, Institut Gustave Roussy, Villejuif, France.