Interleukin-1β-Induced Promatrilysin Expression is Mediated by NFκB-Regulated Synthesis of Interleukin-6 in the Prostate Carcinoma Cell Line, LNCaP

Previously, our laboratory showed that interleukin-1β (IL-1β) secreted by lipopolysaccharide-activated monocytes induces promatrilysin expression in the prostate carcinoma cell line, LNCaP. We now demonstrate that IL-1β-induced promatrilysin expression is mediated by an indirect mechanism that requires nuclear factor Kappa B (NFκB)-dependent synthesis of IL-6. Inhibition of protein synthesis with cyclohexamide blocked IL-1β-mediated induction of matrilysin mRNA suggesting that synthesis of one or more additional factors is required for IL-1β-induced promatrilysin protein expression. Blockage of NFκB transactivation activity abrogated IL-1β-induced promatrilysin expression to baseline levels suggesting that NFκB transactivation activity is necessary. Inhibition of IL-6 activity attenuated IL-1β-induced promatrilysin, but not NFκB transactivation activity indicating that IL-6 acts downstream of NFκB in potentiation of IL-1β-mediated promatrilysin expression. Inhibition of protein synthesis with cyclohexamide did not alter IL-6-induced induction of matrilysin mRNA indicating that, contrary to the mechanism by which IL-1β regulates promatrilysin expression, IL-6-mediated matrilysin mRNA expression does not require new protein synthesis. Transient transfection with dominant negative STAT3 inhibited IL-1β- and IL-6-induced promatrilysin. These data provide evidence that NFκB-mediated IL-6 synthesis is required for IL-1β-induced promatrilysin expression, and IL-6 signaling through STAT3 plays a role in IL-1β-induced promatrilysin expression

Aberrant activation of stress-response pathways leads to TNF-alpha oversecretion in Fanconi anemia.

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