Prostate-specific antigen-activated thapsigargin prodrug as targeted therapy for prostate cancer.
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...
| Main Authors: | , , , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
2003
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| _version_ | 1797086602264051712 |
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| author | Denmeade, SR Jakobsen, C Janssen, S Khan, SR Garrett, E Lilja, H Christensen, S Isaacs, J |
| author_facet | Denmeade, SR Jakobsen, C Janssen, S Khan, SR Garrett, E Lilja, H Christensen, S Isaacs, J |
| author_sort | Denmeade, SR |
| collection | OXFORD |
| description | 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., G0-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 cytotoxicity 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 microM 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 LD50s. 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. |
| first_indexed | 2024-03-07T02:24:13Z |
| format | Journal article |
| id | oxford-uuid:a507d3c5-e1cc-4738-a1da-5a2df22f59ca |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T02:24:13Z |
| publishDate | 2003 |
| record_format | dspace |
| spelling | oxford-uuid:a507d3c5-e1cc-4738-a1da-5a2df22f59ca2022-03-27T02:37:40ZProstate-specific antigen-activated thapsigargin prodrug as targeted therapy for prostate cancer.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:a507d3c5-e1cc-4738-a1da-5a2df22f59caEnglishSymplectic Elements at Oxford2003Denmeade, SRJakobsen, CJanssen, SKhan, SRGarrett, ELilja, HChristensen, SIsaacs, J 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., G0-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 cytotoxicity 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 microM 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 LD50s. 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. |
| spellingShingle | Denmeade, SR Jakobsen, C Janssen, S Khan, SR Garrett, E Lilja, H Christensen, S Isaacs, J Prostate-specific antigen-activated thapsigargin prodrug as targeted therapy for prostate cancer. |
| title | Prostate-specific antigen-activated thapsigargin prodrug as targeted therapy for prostate cancer. |
| title_full | Prostate-specific antigen-activated thapsigargin prodrug as targeted therapy for prostate cancer. |
| title_fullStr | Prostate-specific antigen-activated thapsigargin prodrug as targeted therapy for prostate cancer. |
| title_full_unstemmed | Prostate-specific antigen-activated thapsigargin prodrug as targeted therapy for prostate cancer. |
| title_short | Prostate-specific antigen-activated thapsigargin prodrug as targeted therapy for prostate cancer. |
| title_sort | prostate specific antigen activated thapsigargin prodrug as targeted therapy for prostate cancer |
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