A claudin 3 and claudin 4-targeted Clostridium perfringens protoxin is selectively cytotoxic to PSA-producing prostate cancer cells
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MR Molecular Imaging of Prostate Cancer with a Small Molecular CLT1 Peptide Targeted Contrast Agent
Published on: September 3, 2013
Victor Romanov1, Terry C Whyard1, Wayne C Waltzer1
1Department of Urology, Stony Brook University School of Medicine, Stony Brook, NY, United States.
Abstract:
Prostate cancer is the second leading cause of non-cutaneous cancer-related death in males, and effective strategies for treatment of metastatic disease are currently limited. The tight junction proteins, claudin 3 and claudin 4, serve as cell-surface receptors for the pore-forming Clostridium perfringens enterotoxin [CPE]. Most prostate cancer cells overexpress claudin 3 and claudin 4, and claudins are aberrantly distributed over the plasma membrane, making these cells particularly sensitive to cytolysis by CPE. Prostate cancer cells secrete PSA locally that is proteolytically active; however, circulating PSA is inactivated via binding to protease inhibitors. To overcome systemic toxicity of CPE, a modified protoxin was constructed with a tethered ligand attached to the C-terminus connected by a flexible linker containing a PSA-specific protease cleavage site. This engineered protoxin selectively and efficiently lyses PSA-producing prostate cancer cells whereas CLDN3 and CLDN4 positive cells that do not express PSA are resistant to cytolysis.
Insights
A novel engineered protoxin targets prostate cancer cells by utilizing claudin receptors and a PSA-specific cleavage site. This approach selectively lyses prostate cancer cells while sparing PSA-negative cells, offering a promising new treatment strategy.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Prostate cancer is a leading cause of cancer death in men, with limited treatment options for metastatic disease.
- Claudins 3 and 4 are cell-surface receptors for Clostridium perfringens enterotoxin (CPE), and are overexpressed in most prostate cancer cells.
- Prostate-specific antigen (PSA) is proteolytically active when secreted locally by prostate cancer cells.
Purpose of the Study:
- To develop a targeted therapy for prostate cancer that overcomes the limitations of existing treatments.
- To engineer a modified protoxin that selectively targets and lyses prostate cancer cells.
- To leverage the overexpression of claudins and the local activity of PSA for targeted cancer cell destruction.
Main Methods:
- Construction of a modified protoxin with a tethered ligand and a PSA-specific protease cleavage site.
- Testing the engineered protoxin's cytolytic activity against PSA-producing and PSA-negative prostate cancer cells.
- Evaluating the selectivity of the protoxin based on claudin expression and PSA secretion.
Main Results:
- The engineered protoxin selectively and efficiently lyses prostate cancer cells that produce PSA.
- Prostate cancer cells expressing claudins 3 and 4 but not PSA were resistant to cytolysis.
- The PSA-specific cleavage site in the protoxin linker enabled targeted activation and cell lysis.
Conclusions:
- The engineered PSA-targeted protoxin demonstrates high specificity for PSA-producing prostate cancer cells.
- This targeted approach offers a potential strategy to overcome systemic toxicity associated with CPE-based therapies.
- Further development of this protoxin could lead to novel therapeutic interventions for metastatic prostate cancer.
