Doxorubicin-induced death in neuroblastoma does not involve death receptors in S-type cells and is caspase-independent in N-type cells

Abstract

Death induced by doxorubicin (dox) in neuroblastoma (NB) cells was originally thought to occur via the Fas pathway, however since studies suggest that caspase-8 expression is silenced in most high stage NB tumors, it is more probable that dox-induced death occurs via a different mechanism. Caspase-8 silenced N-type invasive NB cell lines LAN-1 and IMR-32 were investigated for their sensitivity to dox, and compared to S-type noninvasive SH-EP NB cells expressing caspase-8. All cell lines had similar sensitivities to dox, independently of caspase-8 expression. Dox induced caspase-3, -7, -8 and -9 and Bid cleavage in S-type cells and death was blocked by caspase inhibitors but not by oxygen radical scavenger BHA. In contrast, dox-induced death in Ntype cells was caspase-independent and was inhibited by BHA. Dox induced a drop in mitochondrial membrane permeability in all cell lines. Dox-induced death in Stype cells gave rise to apoptotic nuclei, whereas in Ntype cells nuclei were non-apoptotic in morphology. Transfection of SH-EP cells with a dominant negative FADD mutant inhibited TRAIL-induced death, but had no effect on dox-induced apoptosis. These results suggest that S-type cells undergo apoptosis after dox treatment independently of death receptors, whereas N-type cells are killed by a caspase-independent mechanism.

Stress via p53 pathway causes apoptosis by mitochondrial Noxa upregulation in doxorubicin-treated neuroblastoma cells

“…The wild-type p53-expressing SH-SY5Y line was purchased from ATCC (Manassas, VA, USA). The wild-type p53 status was demonstrated in previous reports (IMR32: Hopkins-Donaldson et al, 2002;SK-N-SH: Wolff et al, 2001) and p53 sequencing, which was performed according to the previous report (Tweddle et al, 2001), confirmed the wild-type p53 status in these cell lines. In terms of the copy number of MYCN by Southern blot analysis, SH-SY5Y, SK-N-SH and NB-69 are single-copy NB cells; NB-9, IMR32, NB-1 and NB-19 cells have 50, >150, >150 and 25 copies, respectively (data not shown).…”

Doxorubicin-induced cell death requires cathepsin B in HeLa cells

“…Blocking Caspase activation did not prevent cell killing in leukemic blast cells and neuroblastoma cells induced by chemotherapeutics including doxorubicin [16;17]. Additionally, doxorubicin induced death in neuroblastoma cells is also Caspase-independent [18] and Caspase inhibition switches doxorubicin induced apoptosis to senescence [17]. These data strongly suggest that additional factors play a pivotal role in cell death.…”

“…Activation of caspases seems not to be mandatory for cell death upon doxorubicin [16][17][18] suggesting the presence of additional factors. In the last decade numerous reports highlight the potential role of cathepsin B in controlling apoptosis but its role in drug induced apoptosis has not been addressed in a systematic manner.…”

Key role for p27Kip1, retinoblastoma protein Rb, and MYCN in polyamine inhibitor-induced G1 cell cycle arrest in MYCN-amplified human neuroblastoma cells

“…Our findings are particularly relevant because DFMO and SAM486A cause rapid and prolonged growth inhibition of two MYCN-amplified NB cell lines, which (1) are representative of MYCN-amplified tumors with aggressive behavior, and (2) are deficient in p53. Mutated p53 is often associated with relapsed and more progressive tumors, which circumvent p53-mediated apoptosis and exhibit chemoresistance (Hopkins-Donaldson et al, 2002). Since DFMO and SAM486A have been recently evaluated in Phase III and Phase II human trials, respectively (Levin et al, 2003;Pless et al, 2004), there is considerable information available regarding their concurrent side effects, pharmacokinetics, and maximum tolerated doses.…”