pe
pep-05291 v1 CC-BY-SA-4.0

Beta-defensin 2 anticancer peptide

A lab-made peptide being studied for its potential to attack cancer cells; experimental, not an approved drug.

statuscomputed targetANTICANCER length51 aa refs1
anticancer
EARLY ENTRY This candidate is newly indexed — supporting evidence is still being added. Have a paper or data point? Contribute below.
status 2 / 5 · 2 contributors
prediction metrics boltz-2 2.2.1
ipTM0.000
pTM0.454
avg pLDDT56.1
ranking score0.540
STRUCTURE · PEP-05291 × ANTICANCER
ranking0.540
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RECEPTOR UNKNOWN
peptide conformation only · no target structure
target interface 4.5Å peptide drag rotate · ctrl+scroll zoom · right-click pan
sequence51 aa
1510152025303540455051
AVGSLKSIGYEAELDHC HTNGGYCVRAICPPSAR RPGSCFPEKNPCCKYMK
in the news 27 articles
Hypotheses5 directions▾ collapse

Research directions for this peptide, selected from the current sources — hypotheses you can explore and model. None of it is proven yet; tap any one to see the full thinking.

openupdated 2026-06-05

Does this peptide need its full complex structure to attack cancer, or could a simpler version work just as well?

If the full 3D structure turns out not to be needed, this peptide could be made faster, cheaper, and more consistently in a lab, which could lower the cost and speed up early research for anyone developing it as a cancer therapy.

The hypothesis
The anticancer activity of pep-05291 does not require the three canonical beta-defensin disulfide bonds; the linear or partially oxidized form of the peptide retains membrane-disruptive cytotoxicity against cancer cells through the cationic amphipathic N-terminal segment AVGSLKSIGY.
Why it’s plausible
Two independent literature sources (10.1074/jbc.M709238200 and 10.1186/s12866-018-1190-z) establish that beta-defensin antimicrobial and chemoattractant activities persist when cysteines are alkylated or replaced with alanine, and that disulfide bridges primarily confer protease resistance rather than activity. The N-terminal stretch of pep-05291 (AVGSLKSIGY) is hydrophobic-amphipathic and cationic (K6), a feature sufficient for membrane perturbation. Cancer cell membranes are enriched in anionic phosphatidylserine on their outer leaflet compared to normal cells, making them selectively vulnerable to cationic membrane-active peptides.
Why it matters
If disulfides are dispensable for anticancer activity, the peptide could be synthesized in a reduced linear form, eliminating oxidative folding bottlenecks, cutting manufacturing cost, and improving batch-to-batch consistency for preclinical development.
Plausibility.70
Novelty.25
Impact.62
Basis · grounding2 papers · 1 computed/note
[1]
paper
Full-length beta-defensins with alkylated or alanine-substituted cysteines remain strongly antimicrobial; N-terminal fragments retain potent activity.
doi: 10.1074/jbc.m709238200
[2]
paper
Linear peptides lacking disulfide-stabilized tertiary structure are more susceptible to proteolysis but not necessarily less active.
doi: 10.1186/s12866-018-1190-z
[3]
sequenceN-terminal AVGSLKSIGY contains K6 conferring positive charge and Y10 for aromatic membrane insertion, consistent with amphipathic helix models of membrane-active peptides.
openupdated 2026-06-05

Could just the front half of this peptide attack cancer cells, and might it work even better inside the acidic environment of a tumor?

If a shorter fragment works as well as the full molecule, it would be far easier and cheaper to produce. The bonus: tumors are more acidic than normal tissue, and one amino acid in this fragment could become more active in that environment, potentially giving it a built-in way to seek out tumors while leaving healthy tissue alone.

The hypothesis
The N-terminal alpha-helical propensity segment (approximately residues 1-16, AVGSLKSIGYEAELDH) and the C-terminal beta-sheet core formed by the six cysteines operate as structurally and functionally independent modules in pep-05291, and truncation to the N-terminal 16-20 residues retains anticancer membrane activity while eliminating the CC anomaly and reducing the synthesis length below the SPPS efficiency threshold.
Why it’s plausible
For defensin Defb14, N-terminal fragments show potent antimicrobial activity independently of the disulfide-stabilized C-terminal core (10.1074/jbc.M709238200). The first 16 residues of pep-05291 (AVGSLKSIGYEAELDH) include K6 for charge, Y10 for hydrophobic insertion, and H16 as a pH-sensitive ionizable residue, all features of membrane-active segments. Tumor microenvironment acidity could protonate H16, increasing net positive charge and enhancing selective affinity for the anionic cancer cell surface specifically at the tumor site. The manufacturing axis hit notes that SPPS is limited to approximately 50 residues and is costly; a 16-20 aa fragment would be far cheaper and faster to produce.
Why it matters
A validated N-terminal fragment would provide a shorter, cheaper, and better-characterized lead compound, resolving the CC anomaly and the undefined target simultaneously, while the pH-dependent histidine adds a tumor-selective activation mechanism.
Plausibility.48
Novelty.47
Impact.65
Basis · grounding2 papers · 1 computed/note
[1]
paper
N-terminal Defb14 fragments display potent antimicrobial activity; chemoattractant and antimicrobial functions can be separated.
doi: 10.1074/jbc.m709238200
[2]
sequenceResidues 1-16 (AVGSLKSIGYEAELDH) contain K6, Y10, and H16, giving amphipathic character and a titratable histidine for pH-sensitive membrane selectivity.
[3]
paper
SPPS is limited to approximately 50 residues and is costly; shorter fragments would substantially improve manufacturability.
doi: 10.1038/s41467-023-37003-z
openupdated 2026-06-05

Could one peptide both punch holes in cancer cells and send a distress signal that brings the immune system running?

If this dual action holds up, the peptide could be injected directly into a tumor, killing cells while also turning that site into a kind of on-the-spot vaccine. This approach sidesteps the hard problem of getting a peptide drug to survive in the bloodstream, and it could complement existing immunotherapy strategies.

The hypothesis
Pep-05291 has dual-mode activity in the tumor microenvironment: direct cytotoxicity against tumor cells via membrane disruption, plus recruitment of dendritic cells and T cells through CCR6-mediated chemoattraction, making it more effective as an intratumoral immunostimulant than as a systemic cytotoxic agent.
Why it’s plausible
Beta-defensin 2 is a known chemoattractant for immature dendritic cells and memory T cells via CCR6 (10.1074/jbc.M709238200). Intratumoral injection of defensin-like peptides could simultaneously kill tumor cells at high local concentrations and attract professional antigen-presenting cells to the resulting debris, generating an in situ vaccination effect. This dual mechanism is distinct from either pure cytotoxic peptides or pure checkpoint inhibitors and would not require systemic exposure, side-stepping the oral bioavailability and serum half-life limitations flagged in the axis hits.
Why it matters
If confirmed, the peptide would be developed as a local immunostimulant rather than a systemic drug, a formulation strategy that circumvents the core PK liabilities of peptide therapeutics identified in the oral-bioavailability and half-life axis hits and aligns with the growing intratumoral immunotherapy field.
Plausibility.43
Novelty.47
Impact.67
Basis · grounding3 papers
[1]
paper
Beta-defensins act through CCR6 to chemoattract immune cells; this activity is independent of antimicrobial function and persists in structural variants.
doi: 10.1074/jbc.m709238200
[2]
paper
Systemic peptide drug delivery faces degradation and poor bioavailability; local administration strategies are a preferred alternative.
doi: 10.1038/s41392-024-02107-5
[3]
paper
Defensin-engineered peptides described as attractive candidates for therapeutic development.
doi: 10.1371/journal.pone.0077031
openupdated 2026-06-05

Instead of just punching holes in cells at random, does this peptide actually dock with a specific target that cancer cells have in unusually high numbers?

If a defined receptor turns out to be the key, researchers could move from trial-and-error to rational drug design: tweaking the peptide to fit that receptor better, identifying which cancer types are most likely to respond, and building a clearer case for clinical testing.

The hypothesis
Pep-05291 engages CCR6 on cancer cells as its primary anticancer target, and the anticancer activity annotated for this peptide is mechanistically identical to the chemoattractant signaling that human beta-defensin 2 exerts through CCR6.
Why it’s plausible
The sole annotated target is null, yet the sequence is explicitly modeled on beta-defensin 2. The literature in the selectivity axis (10.1074/jbc.M709238200) documents that beta-defensins including HBD-2 and murine Defb14 signal through CCR6, a GPCR that is overexpressed in colorectal, breast, and pancreatic cancers and drives tumor cell migration. The N-terminal region AVGSLKSIGY carries the amphipathic character shared with defensins shown to retain CCR6 agonism even without disulfide bonds. If pep-05291 binds CCR6 on tumor cells, it could either recruit immune effectors to the tumor microenvironment or, at high occupancy, desensitize CCR6-dependent pro-metastatic signaling.
Why it matters
Identifying CCR6 as the anticancer target would reframe the peptide from a nonspecific membrane-disruptor into a receptor-targeted agent, opening a rational SAR path and clarifying which tumor types are most likely to respond.
Plausibility.42
Novelty.38
Impact.70
Basis · grounding2 papers · 1 computed/note
[1]
paper
HBD-2, HBD-3, and Defb14 all signal through CCR6; chemoattractant activity persists in linearized analogs and depends on residues across the full peptide length.
doi: 10.1074/jbc.m709238200
[2]
sequenceSequence is 51 aa with six cysteines spaced in a pattern consistent with the beta-defensin fold, anchoring structural homology to CCR6-binding defensins.
[3]
paper
Parent protein is mouse Defb2, a canonical beta-defensin upregulated by LPS, placing pep-05291 in the CCR6-ligand family.
doi: 10.1016/s0014-5793(98)01630-5
openupdated 2026-06-05

Could a single peptide tackle a cancer site while also clearing up the bacterial infections that frequently develop there?

Patients with ulcerating tumors or post-surgical wounds often face polymicrobial infections that standard antibiotics cannot clear. If this peptide proves active against both cancer cells and bacteria like Staph and Pseudomonas, it could become a practical topical treatment for an underserved and difficult clinical problem, where simpler formulations are acceptable and full drug stability is less critical.

The hypothesis
Pep-05291 has antibiofilm activity against Pseudomonas aeruginosa and Staphylococcus aureus in the context of tumor-associated wound infections, because its beta-defensin 2 ancestry predicts LPS-responsive upregulation mimicry and the NF-kB-linked antimicrobial axis that the parent Defb2 serves in airway epithelia.
Why it’s plausible
The reference paper (10.1016/s0014-5793(98)01630-5) describes mouse Defb2 being upregulated in airways by LPS, an innate response to gram-negative bacteria. The mechanism axis hit (10.1016/j.bbrc.2010.07.028) links beta-defensins to NF-kB-regulated antimicrobial expression. Tumor patients with ulcerating or surgically accessed tumors frequently suffer polymicrobial wound infections where standard antibiotics fail due to biofilm. A peptide that is both anticancer and antibacterial at the same site would have unique clinical utility as a topical wound treatment in oncology, a use case that does not require overcoming the PK barriers of systemic administration.
Why it matters
Establishing dual anticancer and antibacterial activity would expand the indication space from pure oncology to wound-oncology, an underserved niche, and would make the peptide viable for topical formulation where peptide stability constraints are less severe.
Plausibility.40
Novelty.47
Impact.47
Basis · grounding3 papers
[1]
paper
Parent protein mouse Defb2 is upregulated in airways by LPS, establishing innate antibacterial function as the ancestral activity of this peptide class.
doi: 10.1016/s0014-5793(98)01630-5
[2]
paper
NF-kB-mediated transcriptional regulation of human beta-defensin-2 gene links this defensin family to gram-negative bacterial response.
doi: 10.1016/j.bbrc.2010.07.028
[3]
paper
SAR studies on beta-defensins show activities on both bacterial and host cells, and synthetic analogs retain both antimicrobial and immunomodulatory properties.
doi: 10.1042/bj20082242
details expand to inspect
full evidence table1 metrics
metricvaluetool
ranking score 0.5400311350822449 boltz-2
3-letter notation
Ala-Val-Gly-Ser-Leu-Lys-Ser-Ile-Gly-Tyr-Glu-Ala-Glu-Leu-Asp-His-Cys-His-Thr-Asn-Gly-Gly-Tyr-Cys-Val-Arg-Ala-Ile-Cys-Pro-Pro-Ser-Ala-Arg-Arg-Pro-Gly-Ser-Cys-Phe-Pro-Glu-Lys-Asn-Pro-Cys-Cys-Lys-Tyr-Met-Lys
recipeboltz-2 2.2.1
parametervalue
modelboltz-2 2.2.1
weights
hardwarevast_v100_32gb
mlx version
python
random seed1
msa strategynone_monomer
runtime
predicted by
predicted at2026-05-23
citationbibtex
peptidemodel (2026). Beta-defensin 2 anticancer peptide (pep-05291, v1). PeptideModel. https://peptidemodel.com/card/pep-05291
@peptide{pep05291,
  sequence = {AVGSLKSIGYEAELDHCHTNGGYCVRAICPPSARRPGSCFPEKNPCCKYMK},
  target   = {anticancer},
  author   = {peptidemodel},
  year     = {2026},
  status   = {computed}
}
references 1 papers
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