Small molecule inhibitors of Apaf-1-related caspase- 3/-9 activation that control mitochondrial-dependent apoptosis

The apoptosome: emerging insights and new potential targets for drug design

Apoptosis plays a crucial role in tissue homeostasis, development and many diseases. The relevance of Apaf1, the molecular core of apoptosome, has been underlined in mitochondria-dependent apoptosis, which according to a growing body of evidence, is involved in various pathologies where the equilibrium of life-and-death is dysregulated, such as heart attack, stroke, liver failure, cancer and autoimmune diseases. Consequently, great interest has emerged in devising therapeutic strategies for regulating the key molecules involved in the life-and-death decision. Here we review recent progress in apoptosis-based pharmacological therapies and, in particular, we point out a possible role of the apoptosome as an emerging and promising pharmacological target.

Modulation of cellular apoptosis with apoptotic protease-activating factor 1 (Apaf-1) inhibitors

The programmed cell death or apoptosis plays both physiological and pathological roles in biology. Anomalous activation of apoptosis has been associated with malignancies. The intrinsic mitochondrial pathway of apoptosis activation occurs through a multiprotein complex named the apoptosome. We have discovered molecules that bind to a central protein component of the apoptosome, Apaf-1, and inhibits its activity. These new first-in-class apoptosome inhibitors have been further improved by modifications directed to enhance their cellular penetration to yield compounds that decrease cell death, both in cellular models of apoptosis and in neonatal rat cardiomyocytes under hypoxic conditions.

Polymer-drug conjugates as modulators of cellular apoptosis

The successful clinical application of polymer-protein conjugates (PEGylated enzymes and cytokines) and the promising results arising from clinical trials with polymer-bound chemotherapy (eg, doxorubicin or paclitaxel) have established their potential to reduce toxicity and improve activity in chemotherapy-refractory patients. Furthermore, and more important, they have also provided a firm foundation for more sophisticated second-generation constructs that deliver the newly emerging target-directed bioactive agents (eg, modulators of apoptosis, cell cycle, anti-angiogenic drugs) in addition to polymer-based drug combinations (eg, endocrine therapy and chemotherapy). This review will focus on polymer-drug conjugate modulators of cellular apoptosis to be used as single pro-apoptotic (eg, cancer) or anti-apoptotic (eg, ischemia) agents or as a combination therapy.

Conjugation of a novel Apaf-1 inhibitor to peptide-based cell-membrane transporters: effective methods to improve inhibition of mitochondria-mediated apoptosis

We have identified a family of peptoids that inhibits in vitro the activity of the apoptosome, a macromolecular complex that activates mitochondrial-dependent apoptosis pathways. The analysis of peptide-based cell compatible delivery systems of the most active peptoid is presented. The active peptoid was then fused to cell penetrating peptides (CPP) as penetratin (PEN-peptoid) and HIV-1 TAT (TAT-peptoid). PEN-peptoid showed greater cell viability and as a consequence better efficiency as an apoptosis inhibitor than the TAT-peptoid. The intracellular trafficking of both inhibitors was studied by flow cytometry and confocal fluorescence microscopy. Finally, the influence of the cargo (peptoid) molecules on the conformational behavior of the CPP in buffers and in membrane mimetic environments was analyzed using circular dichroism (CD) spectroscopy.