PACE4-based molecular targeting of prostate cancer using an engineered ⁶⁴Cu-radiolabeled peptide inhibitor.

The potential of PACE4 as a pharmacological target in prostate cancer has been demonstrated as this proprotein convertase is strongly overexpressed in human prostate cancer tissues and its inhibition, using molecular or pharmacological approaches, results in reduced cell proliferation and tumor progression in mouse tumor xenograft models. We developed a PACE4 high-affinity peptide inhibitor, namely, the multi-leucine (ML), and sought to determine whether this peptide could be exploited for the targeting of prostate cancer for diagnostic or molecular imaging purposes. We conjugated a bifunctional chelator 1,4,7-triazacyclononane-1,4,7- triacetic acid (NOTA) to the ML peptide for copper-64 ((64)Cu) labeling and positron emission tomography (PET)- based prostate cancer detection.

Optimization of furin inhibitors to protect against the activation of influenza hemagglutinin H5 and Shiga toxin.

Proprotein convertases (PCs) are crucial in the processing and entry of viral or bacterial protein precursors and confer increased infectivity of pathogens bearing a PC activation site, which results in increased symptom severity and lethality. Previously, we developed a nanomolar peptide inhibitor of PCs to prevent PC activation of infectious agents. Herein, we describe a peptidomimetic approach that increases the stability of this inhibitor for use in vivo to prevent systemic infections and cellular damage, such as that caused by influenza H5N1 and Shiga toxin.

Knockdown strategies for the study of proprotein convertases and proliferation in prostate cancer cells.

Gene silencing strategies targeting mRNA are suitable methods to validate the functions of specific genes. In this chapter, we sought to compare two knockdown strategies for the study of proprotein convertases and proliferation in prostate cancer cells. We used both SOFA-HDV ribozyme and lentiviral-mediated shRNA delivery system to reduce PACE4 mRNA levels and validate its implication in the proliferation of DU145 prostate cancer cells.

Role of proprotein convertases in prostate cancer progression.

Better understanding of the distinct and redundant functions of the proprotein convertase (PC) enzyme family within pathophysiological states has a great importance for potential therapeutic strategies. In this study, we investigated the functional redundancy of PCs in prostate cancer in the commonly used androgen-sensitive LNCaP and the androgen-independent DU145 human cell lines. Using a lentiviral-based shRNA delivery system, we examined in vitro and in vivo cell proliferation characteristics of knockdown cell lines for the endogenous PCs furin, PACE4, and PC7 in both cell lines.

The Multi-Leu peptide inhibitor discriminates between PACE4 and furin and exhibits antiproliferative effects on prostate cancer cells.

The proprotein convertases (PCs) play an important role in protein precursor activation through processing at paired basic residues. However, significant substrate cleavage redundancy has been reported between PCs. The question remains whether specific PC inhibitors can be designed.

Ovarian cancer molecular pathology.

Ovarian cancer (OVC) is the fourth leading cause of cancer mortality among women in Europe and the United States. Its early detection is difficult due to the lack of specificity of clinical symptoms. Unfortunately, late diagnosis is a major contributor to the poor survival rates for OVC, which can be attributed to the lack of specific sets of markers.

Disruption of proprotein convertase 1/3 (PC1/3) expression in mice causes innate immune defects and uncontrolled cytokine secretion.

The proprotein convertase 1/3 is expressed in the regulated secretory pathway of neural and endocrine cells. Its major function is in the post-translational processing and activation of precursor proteins. The PC1/3 knock-out (KO) mouse model has allowed us to elucidate its physiological functions in studies focused primarily on neuroendocrine tissues.

On the cutting edge of proprotein convertase pharmacology: from molecular concepts to clinical applications.

There is increasing interest in the therapeutic targeting of proteases for the treatment of important diseases. Additionally new protein-based therapeutic strategies have the potential to widen the available treatments against these pathologies. In the last decade, accumulated evidence has confirmed that the family of proteases known as proprotein convertases (PCs) are potential targets for viral infections, osteoarthritis, cancer and cardiovascular disease, among others.

Molecular Validation of PACE4 as a Target in Prostate Cancer.

Prostate cancer remains the single most prevalent cancer in men. Standard therapies are still limited and include androgen ablation that initially causes tumor regression. However, tumor cells eventually relapse and develop into a hormone-refractory prostate cancer.

Silencing of SPC2 expression using an engineered delta ribozyme in the mouse betaTC-3 endocrine cell line.

Endoproteolytic processing is carried out by subtilase-like pro-protein convertases in mammalian cells. In order to understand the distinct roles of a member of this family (SPC2), gene silencing in cultured cells is an ideal approach. Previous studies showed limited success in either the degree of inhibition obtained or the stability of the cell lines.