ASK1-P38 pathway is important for anoikis induced by microtubule-targeting aryl chloroethylureas.
OBJECTIVE
We investigated the involvement of MAPK signaling in the cell death mechanisms of classical microtubule interfering agents (MIA) and aryl-3-(2-chloroethyl)ureas (CEU) acting as antimitotics, along with CEU that don't affect directly microtubules (non-MIA CEU).


METHODS
To ascertain the activated signaling pathway profile of MIA and non-MIA CEU, Western blot, immunoprecipitation and transfection experiments were performed.


RESULTS
Non-MIA CEU do not activate p38, as opposed to MIA, and the extent of ERK and JNK activation is lower than in response to MIA. The effect of MIA and non-MIA CEU on focal adhesion associated protein was also studied; MIA were shown to induce focal adhesion dismantlement associated with a sustained increase in paxillin phosphorylation and FAK cleavage, as opposed to non-MIA CEU. In addition, bcl-2 phosphorylation and AKT cleavage, induced by all MIA tested, was not observed in response to non-MIA CEU further emphasizing the differential cell death mechanisms induced by MIA and non-MIA CEU. Pharmacologic and genetic approaches emphasize that the ASK1-p38 pathway activation contributes to the cytotoxic mechanism of MIA, in contrast to non-MIA CEU. ASK1-p38 is important for increased paxillin phosphorylation and FAK cleavage, suggesting that ASK-1-p38 is an upstream event of FA structure dismantlement induced by MIA. Moreover, the endogen inhibitor of ASK-1, thioredoxin, is released from ASK-1 in response to MIA as opposed to non-MIA CEU.


CONCLUSIONS
Our study supports that ASK1-p38 activation is an important signaling event, induced by MIA, which impairs focal adhesion structure and induces anchorage-dependent apoptosis or anoikis.
Fortin
Jessica
J
1Centre de recherche, Unité de Biotechnologie et de Bioingénierie, C.H.U.Q., Hôpital Saint-François d'Assise, Québec, Canada.
Patenaude
Alexandre
A
Deschesnes
Réna G
RG
Côté
Marie-France
MF
Petitclerc
Eric
E
C-Gaudreault
René
R
D000818:Animals; D023102:Anoikis / Q000187:drug effects; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D022001:Focal Adhesions / Q000378:metabolism; D006801:Humans; D048848:MAP Kinase Kinase Kinase 5 / Q000378:metabolism*; D051379:Mice; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism; D009369:Neoplasms / Q000188:drug therapy / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D050257:Tubulin Modulators / Q000494:pharmacology*; D014508:Urea / Q000031:analogs & derivatives / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D000970:Antineoplastic Agents; D050257:Tubulin Modulators; D014508:Urea; D048051:p38 Mitogen-Activated Protein Kinases; D048848:MAP Kinase Kinase Kinase 5; C482858:MAP3K5 protein, human; C482859:Map3k5 protein, mouse