Cell-Penetrating CEBPB and CEBPD Leucine Zipper Decoys as Broadly Acting Anti-Cancer Agents

Abstract

Transcription factors are key players underlying cancer formation, growth, survival, metastasis and treatment resistance, yet few drugs exist to directly target them. Here, we characterized the in vitro and in vivo anti-cancer efficacy of novel synthetic cell-penetrating peptides (Bpep and Dpep) designed to interfere with the formation of active leucine-zipper-based dimers by CEBPB and CEBPD, transcription factors implicated in multiple malignancies. Both peptides similarly promoted apoptosis of multiple tumor lines of varying origins, without such effects on non-transformed cells. Combined with other treatments (radiation, Taxol, chloroquine, doxorubicin), the peptides acted additively to synergistically and were fully active on Taxol-resistant cells. The peptides suppressed expression of known direct CEBPB/CEBPD targets IL6, IL8 and asparagine synthetase (ASNS), supporting their inhibition of transcriptional activation. Mechanisms by which the peptides trigger apoptosis included depletion of pro-survival survivin and a required elevation of pro-apoptotic BMF. Bpep and Dpep significantly slowed tumor growth in mouse models without evident side effects. Dpep significantly prolonged survival in xenograft models. These findings indicate the efficacy and potential of Bpep and Dpep as novel agents to treat a variety of cancers as mono- or combination therapies.

Cell-penetrating peptides enhance peptide vaccine accumulation and persistence in lymph nodes to drive immunogenicity

“…We included several CPPs that have been previously reported to augment peptide vaccines: penetratin (pAntp) ( 36 , 39 ), HIV transactivator of transcription (Tat) ( 38 , 44 ), Arg 8 ( 45 ), and MPG ( 46 ). Additionally, this series included CPPs that, to our knowledge, have never been tested for vaccine antigen delivery: Bpep ( 29 ), Diatos peptide vector 6 (DPV6) ( 47 ), vascular endothelial cadherin-derived peptide (pVEC) ( 48 ), and Transportan 10 (TP10) ( 49 ). Each CPP was conjugated via copper(I)-catalyzed click chemistry to the C terminus of an 18-mer-long peptide (gp100 20–38 , hereafter gp100) encompassing the H-2D b –restricted epitope EGPRNQDWL (gp100 25–33 ) of the melanoma tumor-associated antigen ( Fig.…”

“…CPPs are linear peptides ∼5- to 40-amino acid residues in length that are generally comprised of cationic or amphipathic membrane-interactive sequences. CPPs can be natural sequences derived from proteins (e.g., penetratin from the Antennapedia homeodomain of Drosophila ) ( 28 ), designed de novo sequences (e.g., Arg 8 ) ( 26 , 27 ), or hybrid natural/synthetic sequences (e.g., Bpep) ( 29 ). They can promote endocytosis and, in some cases, direct cytosolic delivery of linked cargos ranging from small molecules to oligonucleotides, and proteins via interactions with various components of the cell surface, including glycans, endocytic receptors, and the plasma membrane itself ( 30 – 32 ).…”

CEBPB knockdown sensitizes nasopharyngeal carcinoma cells to cisplatin by promoting the expression of serine protease inhibitor Kazal-type 5

“…In the present work, their binding (at the −1076 to −932 region of the SPINK5 promoter) and negative relation has been verified using ChIP, dual-luciferase report assay, correlation analysis as well as western blot assays. CEBPB has been revealed to promote survival, growth, metastasis and treatment resistance of a broad spectrum of cancer cell types [22]. Similarly, CEBPG has been established to activate the PI3K/ protein kinase B signaling in esophageal squamous cell carcinoma cells by directly binding to promoters of genes in this pathway, including CCND1, MYC and CDK2 [23].…”

Advancements in Activating Transcription Factor 5 Function in Regulating Cell Stress and Survival

“…A recent study reported that CP-DN-ATF5 can also interfere with endogenous CCAAT enhancer-binding protein beta (CEBPB) and delta (CEBPD) activities, whose inhibition promotes tumor cell death [85]. Consequently, Bpep and Dpep were designed to interfere with ATF5, CEBPB, and CEBPD and promote cell death by down-regulating the anti-apoptotic protein survivin and up-regulating proapoptotic BCL2modifying factor (BMF) [86]. CP-DN-ATF5 has also been shown to induce apoptosis by down-regulating survivin [87].…”