PMID- 10766189
OWN - NLM
STAT- MEDLINE
DCOM- 20000504
LR  - 20220317
IS  - 0008-5472 (Print)
IS  - 0008-5472 (Linking)
VI  - 60
IP  - 7
DP  - 2000 Apr 1
TI  - Molecular determinants of apoptosis induced by the cytotoxic ribonuclease 
      onconase: evidence for cytotoxic mechanisms different from inhibition of protein 
      synthesis.
PG  - 1983-94
AB  - Cytotoxic endoribonucleases (RNases) possess a potential for use in cancer 
      therapy. However, the molecular determinants of RNase-induced cell death are not 
      well understood. In this work, we identify such determinants of the cytotoxicity 
      induced by onconase, an amphibian cytotoxic RNase. Onconase displayed a 
      remarkable specificity for tRNA in vivo, leaving rRNA and mRNA apparently 
      undamaged. Onconase-treated cells displayed apoptosis-associated cell blebbing, 
      nuclear pyknosis and fragmentation (karyorrhexis), DNA fragmentation, and 
      activation of caspase-3-like activity. The cytotoxic action of onconase 
      correlated with inhibition of protein synthesis; however, we present evidence for 
      the existence of a mechanism of onconase-induced apoptosis that is independent of 
      inhibition of protein synthesis. The caspase inhibitor 
      benzyloxycarbonyl-Val-Ala-Asp(OMe) fluoromethyl ketone (zVADfmk), at 
      concentrations that completely prevent apoptosis and caspase activation induced 
      by ligation of the death receptor Fas, had only a partial protective effect on 
      onconase-induced cell death. The proapoptotic activity of the p53 tumor 
      suppressor protein and the Fas ligand/Fas/Fas-associating protein with death 
      domain (FADD)/caspase-8 proapoptotic cascade were not required for 
      onconase-induced apoptosis. Procaspases-9, -3, and -7 were processed in 
      onconase-treated cells, suggesting the involvement of the mitochondrial apoptotic 
      machinery in onconase-induced apoptosis. However, the onconase-induced activation 
      of the caspase-9/caspase-3 cascade correlated with atypically little release of 
      cytochrome c from mitochondria. In turn, the low levels of cytochrome c released 
      from mitochondria correlated with a lack of detectable translocation of 
      proapoptotic Bax from the cytosol onto mitochondria in response to onconase. This 
      suggests the possibility of involvement of a different, potentially Bax- and 
      cytochrome c-independent mechanism of caspase-9 activation in onconase-treated 
      cells. As one possible mechanism, we demonstrate that procaspase-9 is released 
      from mitochondria in onconase-treated cells. A detailed understanding of the 
      molecular determinants of the cytotoxic action of onconase could provide means of 
      positive or negative therapeutic modulation of the activity of this potent 
      anticancer agent.
FAU - Iordanov, M S
AU  - Iordanov MS
AD  - Department of Cell and Developmental Biology, Oregon Health Sciences University, 
      Portland 97201, USA.
FAU - Ryabinina, O P
AU  - Ryabinina OP
FAU - Wong, J
AU  - Wong J
FAU - Dinh, T H
AU  - Dinh TH
FAU - Newton, D L
AU  - Newton DL
FAU - Rybak, S M
AU  - Rybak SM
FAU - Magun, B E
AU  - Magun BE
LA  - eng
GR  - CA-39360/CA/NCI NIH HHS/United States
GR  - ES-08456/ES/NIEHS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Cancer Res
JT  - Cancer research
JID - 2984705R
RN  - 0 (Antineoplastic Agents)
RN  - 0 (BAX protein, human)
RN  - 0 (Cytochrome c Group)
RN  - 0 (Egg Proteins)
RN  - 0 (Protein Synthesis Inhibitors)
RN  - 0 (Proto-Oncogene Proteins)
RN  - 0 (Proto-Oncogene Proteins c-bcl-2)
RN  - 0 (RNA, Messenger)
RN  - 0 (bcl-2-Associated X Protein)
RN  - 9014-25-9 (RNA, Transfer)
RN  - 98600C0908 (Cycloheximide)
RN  - EC 3.1.- (Ribonucleases)
RN  - GMW67QNF9C (Leucine)
RN  - X8D5EPO80M (Emetine)
RN  - ZE15FIT23E (ranpirnase)
SB  - IM
MH  - Antineoplastic Agents/*toxicity
MH  - Apoptosis/*drug effects/physiology
MH  - Cell Death/drug effects
MH  - Cell Survival/drug effects
MH  - Cycloheximide/toxicity
MH  - Cytochrome c Group/metabolism
MH  - Egg Proteins/*metabolism/*toxicity
MH  - Emetine/toxicity
MH  - HeLa Cells
MH  - Humans
MH  - Leucine/metabolism
MH  - Mitochondria/drug effects/metabolism
MH  - Protein Biosynthesis/*drug effects
MH  - Protein Synthesis Inhibitors/*toxicity
MH  - Proto-Oncogene Proteins/metabolism
MH  - *Proto-Oncogene Proteins c-bcl-2
MH  - RNA, Messenger/metabolism
MH  - RNA, Transfer/*metabolism
MH  - Ribonucleases/*metabolism/*toxicity
MH  - Substrate Specificity
MH  - bcl-2-Associated X Protein
EDAT- 2000/04/15 00:00
MHDA- 2000/04/15 00:01
CRDT- 2000/04/15 00:00
PHST- 2000/04/15 00:00 [pubmed]
PHST- 2000/04/15 00:01 [medline]
PHST- 2000/04/15 00:00 [entrez]
PST - ppublish
SO  - Cancer Res. 2000 Apr 1;60(7):1983-94.