ASK1-P38 Pathway is Important for Anoikis Induced by Microtubule-Targeting Aryl Chloroethylureas

Abstract

PURPOSE. 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. CONCLUSION. 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.

Antitumor Indolequinones Induced Apoptosis in Human Pancreatic Cancer Cells via Inhibition of Thioredoxin Reductase and Activation of Redox Signaling

“…Phosphorylation and dephosphorylation of Ser83 have both been correlated with ASK1 activation (Kim et al, 2001;Gu et al, 2009;Fortin et al, 2010;Yang et al, 2010). However, recent work have emphasized the role of Ser83 phosphorylation of ASK1 in induction of apoptosis (Fortin et al, 2010;Yang et al, 2010), and this is in agreement with our observations of IQ-induced ASK1 phosphorylation at Ser83 and subsequent apoptosis. Because p38/JNK could also be activated by other upstream kinases in addition to ASK1, further experiments are needed to determine whether ASK1 plays a critical role in apoptotic signaling.…”

A small molecule, MTBT, prevents cancer cell growth by activating p38 MAPK

“…[22. 23-26] Since we showed that MTBT-induced G 2 /M arrest depends on functional p38, it is possible that mitotic arrest induced by other drugs is also p38 dependent. Thus, we tested if p38 is required for the cell cycle arrest induced by microtubule disruption under our experimental conditions.…”

ASK1/p38‑mediated NLRP3 inflammasome signaling pathway contributes to aberrant retinal angiogenesis in diabetic retinopathy

“…The MAPK member, p38, is a serine/threonine protein kinase, which responds to several cellular processes and external stress signaling, such as cell differentiation, cell proliferation, inflammation regulation and cell death (14,15). ASK1 is the most well-studied family member and is an upstream kinase of the JNK and p38 pathways (16,17). It has been demonstrated that ASK1 is activated in response to a variety of stress-related stimuli via distinct mechanisms and activates MKK4 and MKK3, which in turn activate JNK and p38 (18).…”