Specific Targeting of Caspase-9/PP2A Interaction as Potential New Anti-Cancer Therapy

Abstract

PurposePP2A is a serine/threonine phosphatase critical to physiological processes, including apoptosis. Cell penetrating peptides are molecules that can translocate into cells without causing membrane damage. Our goal was to develop cell-penetrating fusion peptides specifically designed to disrupt the caspase-9/PP2A interaction and evaluate their therapeutic potential in vitro and in vivo.Experimental DesignWe generated a peptide containing a penetrating sequence associated to the interaction motif between human caspase-9 and PP2A (DPT-C9h), in order to target their association. Using tumour cell lines, primary human cells and primary human breast cancer (BC) xenografts, we investigated the capacity of DPT-C9h to provoke apoptosis in vitro and inhibition of tumour growth (TGI) in vivo. DPT-C9h was intraperitonealy administered at doses from 1 to 25 mg/kg/day for 5 weeks. Relative Tumour Volume (RTV) was calculated.ResultsWe demonstrated that DPT-C9h specifically target caspase-9/PP2A interaction in vitro and in vivo and induced caspase-9-dependent apoptosis in cancer cell lines. DPT-C9h also induced significant TGI in BC xenografts models. The mouse-specific peptide DPT-C9 also induced TGI in lung (K-Ras model) and breast cancer (PyMT) models. DPT-C9h has a specific effect on transformed B cells isolated from chronic lymphocytic leukemia patients without any effect on primary healthy cells. Finally, neither toxicity nor immunogenic responses were observed.ConclusionUsing the cell-penetrating peptides blocking caspase-9/PP2A interactions, we have demonstrated that DPT-C9h had a strong therapeutic effect in vitro and in vivo in mouse models of tumour progression.

High antitumor activity of pladienolide B and its derivative in gastric cancer

“…When the tumor volume reached 100–300 mm 3 , the pladienolide B derivative (10 mg/kg) or vehicle was administered intraperitoneally to each mouse on days 0, 2, 4 and 6. Chronological changes in tumor volume were expressed as the relative tumor volume (RTV) in comparison to the tumor volume at the start of drug administration . All animal experiments were performed according to the Guideline for Animal Experiments at Tokushima University.…”

Strategies to Stabilize Cell Penetrating Peptides forIn VivoApplications

“…Similarly, a metabolic study performed with Tat peptide manifested that the main initial fragmentation occurred at the C-terminal Arg residues, an area that was identified as a putative furin cleavage site [46,47]. In a recent study of serum stability of a CPP derived from casein kinase 2α [48,49], the primary cleavage site was located at position R8-E9. Substitution of this Arg residue by either Lys, Asn or Ala improved peptide stability and pharmacokinetic properties, without altering the penetration capability [50].…”

“…Some of these sequences have been mapped and further demonstrated their ability to cross cell membranes when used as isolated peptides. This was the origin of the so-called 'cell penetrating peptides' (CPPs) that were defined in the mid-1990s after the discovery of Tat peptide, derived from the TransActivator of Transcription protein of human immunodeficiency virus [1] and pAnt (43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58), further known as penetratin, derived from the third helix of the Antennapedia homeodomain protein [2]. Since then, CPPs have demonstrated to be efficient shuttles for introducing different kind of cargoes within a great variety of cells, both in vitro and in vivo [3][4][5][6][7].…”

ϵ‐Polylysine‐Capped Mesoporous Silica Nanoparticles as Carrier of the C9h Peptide to Induce Apoptosis in Cancer Cells

“…Some of us previously generated a new bifunctional peptide that specifically binds PP2Acα (drug phosphatase technology‐human caspase‐9‐derived peptide (DPT‐C9 h ) or drug phosphatase technology‐mouse caspase‐9‐derived peptide (DPT‐C9)), composed by the cell‐penetrating peptide (CPP) DPT‐sh1 followed by a caspase‐9‐derived sequence ( C 9 h ) . The resulting sychnologic peptide targets caspase‐9/PP2Acα interaction, leading to caspase‐9 activation, mitochondrial membrane permeabilization, cytochrome c release and apoptosis in a variety of human and mouse cancer cell lines.…”

“…The resulting sychnologic peptide targets caspase‐9/PP2Acα interaction, leading to caspase‐9 activation, mitochondrial membrane permeabilization, cytochrome c release and apoptosis in a variety of human and mouse cancer cell lines. The mouse‐specific peptide DPT‐C9 also induced tumor growth inhibition in lung (K‐RasLA‐1) and breast cancer (PolyomaMiddleT, PyMT) mouse models showing neither toxicity nor immunogenic response . DPT‐ C 9 h had a specific effect on transformed B cells isolated from chronic lymphocytic leukemia patients without any effect on T‐cells, NK‐cells and monocytes, but did not show any effect on primary B cells from healthy donors …”