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HGF c-Met signaling

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HGF / c-Met signaling

What it is

Hepatocyte growth factor (HGF) is a pleiotropic cytokine that activates the c-Met receptor tyrosine kinase — governing cell survival, proliferation, scattering, angiogenesis, and synaptogenesis. The pathway is named after its two founding members and is a recognized target in oncology (c-Met inhibitors are anti-cancer drugs) and, more controversially, in neuroplasticity (via compounds like Dihexa).

Pathway overview

  1. HGF pro-protein is secreted as single-chain inactive precursor
  2. HGF activation: proteolytic cleavage → two-chain active HGF (α-chain + β-chain)
  3. HGF dimerization brings two c-Met receptors together (autophosphorylation)
  4. c-Met activation → phosphorylation of cytoplasmic tyrosines
  5. Downstream cascades:
    • PI3K/Akt → cell survival, synaptogenesis
    • MAPK/ERK → proliferation, plasticity
    • STAT → gene transcription
    • RAC1/CDC42 → cytoskeletal remodeling (cell scatter)

Why it matters for Vitals

The HGF/c-Met axis is directly relevant to structural neuroplasticity — synaptogenesis, dendritic spine formation, and neural repair. In coaching and wearables logic:

  • Synaptogenesis is the structural substrate for memory consolidation
  • HGF/c-Met activation may support recovery from neurotoxic insults (alcohol, stimulants)
  • The pathway is also angiogenic — relevant to vascular health and tissue repair more broadly
  • The oncogenic risk is the primary counterargument: chronic systemic c-Met activation is contraindicated in anyone with cancer risk

Dihexa specifically

Dihexa is not a direct c-Met agonist — this is a critical distinction:

  • At 10 pM or 1 nM alone: zero c-Met activation
  • Mechanism: allosteric facilitator of HGF dimerization — requires endogenous HGF present
  • Kd for HGF: 65 picomolar (extremely high affinity)

This means Dihexa’s effect is conditional on existing HGF levels — not a guaranteed pharmacological effect.

Proof of mechanism (independent):

  • Hinge (HGF dimerization antagonist): completely abolishes Dihexa effects
  • shRNA c-Met knockdown: Dihexa loses all efficacy
  • Wortmannin (PI3K inhibitor): nullified all benefits in APP/PS1 mice

Fosgonimeton (ATH-1017) — human context

  • Phosphate prodrug of Dihexa; water-soluble; subcutaneous
  • Designed to solve Dihexa’s 13-day half-life problem
  • LIFT-AD Phase 2/3 (2024): biomarkers responded (p-tau217 ↓, P<0.01) but behavioral endpoints missed
  • Proof of mechanism in humans, but behavioral efficacy not established

ATH-1105 — next generation

  • Oral small molecule HGF modulator (not a peptide)
  • Pivoted to ALS (after AD/PD failures)
  • Phase 1 in healthy volunteers (May 2025): favorable safety signal
  • Worth watching as a cleaner future HGF/c-Met option

Cancer risk — the core concern

This is the primary safety issue for any c-Met-activating strategy:

  • c-Met is a recognized proto-oncogene — aberrant activation drives hepatocellular carcinoma, breast cancer, NSCLC progression and metastasis
  • Oncology has spent decades developing c-Met inhibitors as anti-cancer drugs
  • Dihexa activates the same pathway in the opposite direction
  • Chronic systemic activation could theoretically accelerate pre-existing micrometastases

The 13-day half-life of Dihexa makes this worse: if tumor promotion is detected, the drug cannot be rapidly cleared.

BPC-157 + Dihexa stacking is particularly concerning:

  • BPC-157: pro-angiogenic via VEGF + ECM remodeling → provides vascular supply to tumors
  • Dihexa: c-Met “scatter factor” signaling → provides motility for tumor metastasis
  • This combination simultaneously provides the two ingredients tumors need for rapid progression

Confidence level

  • Mechanism biology: high (well-characterized in oncology and developmental biology)
  • Dihexa as HGF facilitator: moderate (preclinical + independent replication; prodrug validated target engagement)
  • Human cognitive efficacy via this pathway: low (prodrug failed behavioral endpoints)
  • Safety for chronic use: very low (zero human toxicology)
  • Dihexa — primary anchor; allosteric HGF facilitator
  • BPC-157 — pro-angiogenic peptide; stacking risk with c-Met activators
  • TB-500 — same vascular/angiogenic concern in combination
  • Noopept Semax Selank — other synaptogenesis approaches with different risk profiles

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