Design, Synthesis, and Pharmacological Evaluation of Thapsigargin Analogues for Targeting Apoptosis to Prostatic Cancer Cells

Jakobsen, Carsten M.; Denmeade, Samuel R.; Isaacs, John T.; Gady, Alyssa M.; Olsen, Carl Erik; Christensen, Søren Brøgger

doi:10.1021/jm010985a

Cited by 128 publications

(109 citation statements)

References 16 publications

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“…Surprisingly, the inhibition of Ca 2ϩ -ATPase by Boc-12ADT, the structure for interaction with Ca 2ϩ -ATPase that we previously published (15), is much less efficient (48 Ϯ 4 nM) than that of Tg and the other analogs. The much smaller effect of Boc-12ADT was somewhat unexpected, because the analog with Leu-12ADT linker previously was reported to be as efficient as Tg in producing apoptosis in prostate cancer cell lines (29). The sluggishness of Boc-12ADT may have to be considered in connection with the slow kinetic features of the compound in the interaction with SERCA as indicated by the data presented below.…”

Section: Inhibitory Effects and Binding Of Thapsigargin And Analogs Tmentioning

confidence: 89%

“…These desubstituted derivatives were prepared by previously described methods (17,28,29), but we note that the unavailability of desoctanoyl Tg forced us to use as a model compound the previously described dihydronortrilobolide, which differs from desoctanoyl Tg by having a saturated bond between C-4 and C-5 (30). From the activity/inhibitor concentration curves, we find for all desubstituted compounds substantial reductions in the affinity, from a subnanomolar value (0.2 nM) for unmodified Tg to 3.5-113 nM after loss of the side chains.…”

Section: Thapsigargin-ca 2ϩ -Atpase Structure and Interaction-inmentioning

confidence: 99%

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Critical Roles of Hydrophobicity and Orientation of Side Chains for Inactivation of Sarcoplasmic Reticulum Ca2+-ATPase with Thapsigargin and Thapsigargin Analogs

Winther

Liu

Sonntag

et al. 2010

Journal of Biological Chemistry

100

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Thapsigargin (Tg), a specific inhibitor of sarco/endoplasmic Ca 2؉ -ATPases (SERCA), binds with high affinity to the E2 conformation of these ATPases. SERCA inhibition leads to elevated calcium levels in the cytoplasm, which in turn induces apoptosis. We present x-ray crystallographic and intrinsic fluorescence data to show how Tg and chemical analogs of the compound with modified or removed side chains bind to isolated SERCA 1a membranes. This occurs by uptake via the membrane lipid followed by insertion into a resident intramembranous binding site with few adaptative changes. Our binding data indicate that a balanced hydrophobicity and accurate positioning of the side chains, provided by the central guaianolide ring structure, defines a pharmacophore of Tg that governs both high affinity and access to the protein-binding site. Tg analogs substituted with long linkers at O-8 extend from the binding site between transmembrane segments to the putative N-terminal Ca 2؉ entry pathway. The long chain analogs provide a rational basis for the localization of the linker, the presence of which is necessary for enabling prostate-specific antigen to cleave peptide-conjugated prodrugs targeting SERCA of cancer cells (Denmeade, S. R., Jakobsen, C. M., Janssen, S., Khan, S. R., Garrett, E. S., Lilja, H., Christensen, S. B., and Isaacs, J. T. (2003) J. Natl. Cancer Inst. 95, 990 -1000). Our study demonstrates the usefulness of a simple in vitro system to test and direct development toward the formulation of new Tg derivatives with improved properties for SERCA targeting. Finally, we propose that the Tg binding pocket may be a regulatory site that, for example, is sensitive to cholesterol.Understanding protein-membrane interaction and the activity of lipophilic drugs and specific lipids like sterols attracts increasing attention and represents a challenge to our current models of protein-solvent interactions and protein dynamics. Sarco/endoplasmic Ca 2ϩ -ATPase (SERCA) 6 offers an attractive model for the analysis of such interactions due to favorable biochemical properties with sensitive assays of function, a large resource of inhibitors, and a wealth of crystal structures related to the functional cycle. In conjunction with plasma membrane Ca 2ϩ -ATPases and Ca 2ϩ channel proteins, SERCA orchestrates spatiotemporal changes in the concentration of Ca 2ϩ inside the cell, providing the background essential for the function of Ca 2ϩ as a second messenger in the regulation of numerous cellular processes (1-3). At the same time, high cytosolic (Ͼ1 M) concentrations of Ca 2ϩ , induced by depletion of the endoplasmic Ca 2ϩ stores and uptake of extracellular Ca 2ϩ by the endoplasmic store-regulated mechanism (4), are involved as essential factors in the induction of apoptotic processes, leading to mitochondrial disruption with release of cytochrome c, activation of intracellular caspases, and cell death (5). As a consequence, interference of cellular function by inhibition of SERCA may lead to apoptotic cell death irrespective of the...

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Section: Inhibitory Effects and Binding Of Thapsigargin And Analogs Tmentioning

confidence: 89%

Section: Thapsigargin-ca 2ϩ -Atpase Structure and Interaction-inmentioning

confidence: 99%

Critical Roles of Hydrophobicity and Orientation of Side Chains for Inactivation of Sarcoplasmic Reticulum Ca2+-ATPase with Thapsigargin and Thapsigargin Analogs

Winther

Liu

Sonntag

et al. 2010

Journal of Biological Chemistry

100

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“…A new approach is therefore to develop agents that induce apoptosis in androgen-independent prostate cancer cells, in a proliferation-independent manner. Several of these agents are under preclinical development, and include PSA-activated prodrugs 80,81 and targeted anti-angiogenic agents 82 . Several are also in early clinical trials.…”

Section: Future Directionsmentioning

confidence: 99%

A history of prostate cancer treatment

2002

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The increased incidence of prostate cancer has led to remarkable changes in diagnosis and treatment over the past century. What were the first ways in which prostate cancer was treated, and how did these evolve into the variety of therapeutic strategies from which patients have to choose today?In 1853, J. Adams, a surgeon at The London Hospital, described the first case of prostate cancer, which he discovered by histological examination 1 . Adams noted in his report that this condition was "a very rare disease". Remarkably, 150 years later, prostate cancer has become a significant health problem. In the United States, it is the most commonly diagnosed cancer in men, with 180,000 new cases and about 31,000 deaths occurring annually 2 . This dramatic increase in the number of prostate cancer cases can be attributed to several causes. First, prostate cancer was not differentiated from other types of urinary obstruction until the early 1900s. Second, the incidence of prostate cancer increases more rapidly with age than any other cancer type 2 . The number of cases has risen as the average life expectancy has increased over the past century. Third, the increased incidence seems to be, in some way, related to the 'Western' lifestyle: the incidence of clinical prostate cancer is significantly lower in Asian populations, compared with Western populations 3 , and it

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“…The C-terminal carboxyl of this peptide was then coupled to a primary amine, containing analogue of thapsigargin to produce a novel prodrug that is selectively activated by PSA within PSA-producing tumors. The prodrug HSSKLQ-L12ADT, on hydrolysis by PSA, releases the potent cytotoxic thapsigargin analogue (L12ADT) into the tumor microenvironment (9,10). Because PSA is a secreted protein, this approach has the added benefit that nearby cells that do not produce PSA can also be targeted, resulting in a local bystander effect that could kill prostate cancer cells, as well as supporting endothelial cells and stromal cells within the tumor microenvironment.…”

Section: Introductionmentioning

confidence: 99%

A prostate-specific antigen–activated N-(2-hydroxypropyl) methacrylamide copolymer prodrug as dual-targeted therapy for prostate cancer

Chandran

Nan

Rosen

et al. 2007

Molecular Cancer Therapeutics

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Prostate cancer targeted peptide prodrugs that are activated by the serine protease activity of prostatespecific antigen (PSA) are under development in our laboratory. To enhance delivery and solubility of these prodrugs, macromolecular carriers consisting of N-(2-hydroxypropyl) methacrylamide (HPMA) -based copolymers were covalently coupled to a PSA-activated peptide prodrug. HPMA copolymers are water-soluble, nonimmunogenic synthetic carriers that exhibit promise for drug delivery applications. These macromolecular copolymers enter the interstitium of solid tumors by the enhanced permeability and retention effect. The PSA-activated peptide substrate imparts selectivity because it is specifically hydrolyzed to release a cytotoxin at the site of prostate tumor. Enzymatically active PSA is present in high amounts in the extracellular fluid of a tumor, but PSA is inactivated in blood by binding to serum protease inhibitors. As an initial proof of concept, the HPMA copolymer was synthesized with a peptide substrate (HSSKLQ) bound to a fluorophore, 7-amino-4-

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Design, Synthesis, and Pharmacological Evaluation of Thapsigargin Analogues for Targeting Apoptosis to Prostatic Cancer Cells

Cited by 128 publications

References 16 publications

Critical Roles of Hydrophobicity and Orientation of Side Chains for Inactivation of Sarcoplasmic Reticulum Ca2+-ATPase with Thapsigargin and Thapsigargin Analogs

Critical Roles of Hydrophobicity and Orientation of Side Chains for Inactivation of Sarcoplasmic Reticulum Ca2+-ATPase with Thapsigargin and Thapsigargin Analogs

A history of prostate cancer treatment

A prostate-specific antigen–activated N-(2-hydroxypropyl) methacrylamide copolymer prodrug as dual-targeted therapy for prostate cancer

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