PMID- 10344216
OWN - NLM
STAT- MEDLINE
DCOM- 19990604
LR  - 20190915
IS  - 0270-4137 (Print)
IS  - 0270-4137 (Linking)
VI  - 39
IP  - 4
DP  - 1999 Jun 1
TI  - Inhibition of caspase activity does not prevent the signaling phase of apoptosis 
      in prostate cancer cells.
PG  - 269-79
AB  - BACKGROUND: Caspases are a family of cysteine proteases capable of 
      characteristically cleaving after an aspartic acid residue. Various members of 
      the caspase family (e.g., caspases 8 and 9) have been implicated as critical 
      initiators in the signaling phase, while others (e.g., caspases 3, 6, and 7) have 
      been implicated in the effector or execution phase of apoptosis. Thapsigargin 
      (TG) is capable of inducing cell proliferation-independent apoptosis of prostate 
      cancer cells. This study was undertaken to determine if caspase inhibition can 
      prevent TG- or 5-fluorodeoxyuridine (5-FrdU)-induced apoptosis in prostate cancer 
      cells. METHODS: Caspase activity was evaluated by Western blot analysis of the 
      cleavage of retinoblastoma (Rb) protein, a caspase substrate during TG-induced 
      death of prostate cancer cells. In addition, hydrolysis of caspase-specific 
      fluorescent peptide substrates was assayed in lysates from TG-treated cells. 
      Clonogenic survival assays were performed following treatment of rat AT3 and 
      human TSU-Pr1 prostate cancer cell lines with TG and 5-FrdU in the presence and 
      absence of peptide caspase inhibitors. AT3.1 cells transfected with the crmA 
      gene, encoding a viral protein with caspase-inhibitory activity, were also tested 
      for clonogenic survival following TG and 5-FrdU exposure. RESULTS: During 
      treatment with TG, Rb is first dephosphorylated and then proteolytically cleaved 
      into 100-kDa and 40-kDa forms, indicative of caspase activity. A 6-8-fold 
      increase in class II (i.e., caspases 3, 7, and 10) hydrolysis of the caspase 
      substrate Z-DEVD-AFC was observed after 24 hr of TG or 5-FrdU. AT3 cells 
      expressing crmA (i.e., an inhibitor of caspases 1, 4, and 8) were not protected 
      from apoptosis induced by TG or 5-FrdU. The caspase inhibitors Z-DEVD-fmk (i.e., 
      an inhibitor of caspases 3, 7, and 10) and Z-VAD-fmk (i.e., a general caspase 
      inhibitor) were also unable to protect TSU and AT3 cells from apoptosis induced 
      by TG or 5-FrdU. CONCLUSIONS: Caspase activation may play a role in the 
      downstream effector phase of the apoptotic cascade; however, in this study, 
      caspase inhibition did not prevent the signaling phase of apoptosis induced by 
      two agents with distinct mechanisms of cytotoxicity, TG or 5-FrdU. These results 
      suggest that caspase inhibition by recently described endogenous caspase 
      inhibitors should not lead to development of resistance to TG. A strategy for 
      targeting TG's unique cytotoxicity to metastatic prostate cancer cells is 
      currently under development.
FAU - Denmeade, S R
AU  - Denmeade SR
AD  - Johns Hopkins Oncology Center, Johns Hopkins University School of Medicine, 
      Baltimore, Maryland 21287, USA.
FAU - Lin, X S
AU  - Lin XS
FAU - Tombal, B
AU  - Tombal B
FAU - Isaacs, J T
AU  - Isaacs JT
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Prostate
JT  - The Prostate
JID - 8101368
RN  - 0 (Amino Acid Chloromethyl Ketones)
RN  - 0 (Antimetabolites, Antineoplastic)
RN  - 0 (Caspase Inhibitors)
RN  - 0 (Cysteine Proteinase Inhibitors)
RN  - 0 (Enzyme Inhibitors)
RN  - 0 (Oligopeptides)
RN  - 0 (Retinoblastoma Protein)
RN  - 0 (benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone)
RN  - 0 (benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone)
RN  - 039LU44I5M (Floxuridine)
RN  - 67526-95-8 (Thapsigargin)
SB  - IM
MH  - Amino Acid Chloromethyl Ketones/*pharmacology
MH  - Animals
MH  - Antimetabolites, Antineoplastic/pharmacology
MH  - *Apoptosis/drug effects
MH  - Blotting, Western
MH  - *Caspase Inhibitors
MH  - Cell Survival
MH  - Clone Cells
MH  - Cysteine Proteinase Inhibitors/*pharmacology
MH  - Enzyme Inhibitors/pharmacology
MH  - Floxuridine/pharmacology
MH  - Humans
MH  - Male
MH  - Oligopeptides/*pharmacology
MH  - Prostatic Neoplasms/enzymology/*metabolism
MH  - Rats
MH  - Retinoblastoma Protein/*metabolism
MH  - *Signal Transduction/drug effects
MH  - Thapsigargin/pharmacology
MH  - Tumor Cells, Cultured
EDAT- 1999/05/27 06:00
MHDA- 2000/06/20 09:00
CRDT- 1999/05/27 06:00
PHST- 1999/05/27 06:00 [pubmed]
PHST- 2000/06/20 09:00 [medline]
PHST- 1999/05/27 06:00 [entrez]
AID - 10.1002/(SICI)1097-0045(19990601)39:4<269::AID-PROS7>3.0.CO;2-F [pii]
AID - 10.1002/(sici)1097-0045(19990601)39:4<269::aid-pros7>3.0.co;2-f [doi]
PST - ppublish
SO  - Prostate. 1999 Jun 1;39(4):269-79. doi: 
      10.1002/(sici)1097-0045(19990601)39:4<269::aid-pros7>3.0.co;2-f.