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Prostate-specific antigen-activated thapsigargin prodrug as targeted therapy for prostate cancer

Denmeade, SR; Jakobsen, CM; Janssen, S; Khan, SR; Garrett, ES; Lilja, Hans LU ; Christensen, SB and Isaacs, JT (2003) In Journal of the National Cancer Institute 95(13). p.990-1000
Abstract
Background: Standard anti-proliferative chemotherapy is relatively ineffective against slowly proliferating androgen-independent prostate cancer cells within metastatic sites. In contrast, the lipophilic cytotoxin thapsigargin, which causes apoptosis by disrupting intracellular free Ca2+ levels, is effective against both proliferative and quiescent (i.e., G(0)-arrested) cells. However, thapsigargin's mechanism of action indicates that it is unlikely to be selective for cancer cells or prostate cells. Methods: We coupled a chemically modified form of thapsigargin, L12ADT, to a peptide carrier that is a substrate for the prostate-specific antigen (PSA) protease to produce a soluble, cell-impermeant latent prodrug that is specifically... (More)
Background: Standard anti-proliferative chemotherapy is relatively ineffective against slowly proliferating androgen-independent prostate cancer cells within metastatic sites. In contrast, the lipophilic cytotoxin thapsigargin, which causes apoptosis by disrupting intracellular free Ca2+ levels, is effective against both proliferative and quiescent (i.e., G(0)-arrested) cells. However, thapsigargin's mechanism of action indicates that it is unlikely to be selective for cancer cells or prostate cells. Methods: We coupled a chemically modified form of thapsigargin, L12ADT, to a peptide carrier that is a substrate for the prostate-specific antigen (PSA) protease to produce a soluble, cell-impermeant latent prodrug that is specifically activated extracellularly within metastatic prostate cancer sites by PSA. We analyzed the kinetics of PSA hydrolysis of the prodrug, the in vitro cytoxicity of the prodrug against PSA-producing LNCaP human prostate cancer and PSA non-producing HCT-116 human colon cancer cells, and the in vivo pharmacokinetics of the prodrug in mice. We also analyzed antitumor efficacy of the prodrug in nude mice xenograft models of prostate cancer (using LNCaP cells) and renal carcinoma (using human SN12C cells). Results: The L12ADT peptide prodrug was hydrolyzed efficiently by PSA, was selectively toxic to PSA-producing prostate cancer cells in vitro, and was stable in human plasma. A single dose of 7 mg/kg resulted in a peak serum prodrug concentration of 15.4 +/- 1.1 muM and a half-life of approximately 2.8 hours. Over 24 hours, less than 0.5% of free L12ADT was observed in plasma. Levels of prodrug and liberated L12ADT in prostate cancer xenograft tumors were approximately eightfold and sixfold, respectively, higher than the in vitro LD(50)s. Prostate cancer xenograft tumors in mice treated with prodrug by intravenous administration were growth-inhibited without substantial host toxicity. Continuous subcutaneous prodrug administration in mice produced complete growth inhibition of established PSA-producing prostate cancer xenograft tumors but had no effect on PSA non-producing renal carcinoma xenograft tumors. Conclusion: Further development of PSA-activated thapsigargin prodrugs as therapy for metastatic prostate cancer is warranted. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of the National Cancer Institute
volume
95
issue
13
pages
990 - 1000
publisher
Oxford University Press
external identifiers
  • wos:000183912900014
  • pmid:12837835
  • scopus:0042308774
ISSN
1460-2105
DOI
10.1093/jnci/95.13.990
language
English
LU publication?
yes
id
5fa43515-ccb7-416d-8a30-99deffec401a (old id 307114)
date added to LUP
2007-08-29 11:34:35
date last changed
2018-01-14 04:02:09
@article{5fa43515-ccb7-416d-8a30-99deffec401a,
  abstract     = {Background: Standard anti-proliferative chemotherapy is relatively ineffective against slowly proliferating androgen-independent prostate cancer cells within metastatic sites. In contrast, the lipophilic cytotoxin thapsigargin, which causes apoptosis by disrupting intracellular free Ca2+ levels, is effective against both proliferative and quiescent (i.e., G(0)-arrested) cells. However, thapsigargin's mechanism of action indicates that it is unlikely to be selective for cancer cells or prostate cells. Methods: We coupled a chemically modified form of thapsigargin, L12ADT, to a peptide carrier that is a substrate for the prostate-specific antigen (PSA) protease to produce a soluble, cell-impermeant latent prodrug that is specifically activated extracellularly within metastatic prostate cancer sites by PSA. We analyzed the kinetics of PSA hydrolysis of the prodrug, the in vitro cytoxicity of the prodrug against PSA-producing LNCaP human prostate cancer and PSA non-producing HCT-116 human colon cancer cells, and the in vivo pharmacokinetics of the prodrug in mice. We also analyzed antitumor efficacy of the prodrug in nude mice xenograft models of prostate cancer (using LNCaP cells) and renal carcinoma (using human SN12C cells). Results: The L12ADT peptide prodrug was hydrolyzed efficiently by PSA, was selectively toxic to PSA-producing prostate cancer cells in vitro, and was stable in human plasma. A single dose of 7 mg/kg resulted in a peak serum prodrug concentration of 15.4 +/- 1.1 muM and a half-life of approximately 2.8 hours. Over 24 hours, less than 0.5% of free L12ADT was observed in plasma. Levels of prodrug and liberated L12ADT in prostate cancer xenograft tumors were approximately eightfold and sixfold, respectively, higher than the in vitro LD(50)s. Prostate cancer xenograft tumors in mice treated with prodrug by intravenous administration were growth-inhibited without substantial host toxicity. Continuous subcutaneous prodrug administration in mice produced complete growth inhibition of established PSA-producing prostate cancer xenograft tumors but had no effect on PSA non-producing renal carcinoma xenograft tumors. Conclusion: Further development of PSA-activated thapsigargin prodrugs as therapy for metastatic prostate cancer is warranted.},
  author       = {Denmeade, SR and Jakobsen, CM and Janssen, S and Khan, SR and Garrett, ES and Lilja, Hans and Christensen, SB and Isaacs, JT},
  issn         = {1460-2105},
  language     = {eng},
  number       = {13},
  pages        = {990--1000},
  publisher    = {Oxford University Press},
  series       = {Journal of the National Cancer Institute},
  title        = {Prostate-specific antigen-activated thapsigargin prodrug as targeted therapy for prostate cancer},
  url          = {http://dx.doi.org/10.1093/jnci/95.13.990},
  volume       = {95},
  year         = {2003},
}