Geldanamycin / RadioS Cancer Research Results

Geld, Geldanamycin: Click to Expand ⟱
Features: HSP90 inhibitor

Geldanamycin is a benzoquinone ansamycin antibiotic and natural-product HSP90 inhibitor originally isolated from Streptomyces hygroscopicus. It binds the N-terminal ATP-binding pocket of HSP90, suppressing its chaperone activity and promoting degradation of multiple HSP90 client proteins involved in cancer-cell survival, proliferation, and signalling. Reported downstream effects include inhibition of AKT, RAF/MEK/ERK, receptor tyrosine kinase, and steroid-receptor signalling, with induction of cell-cycle arrest and apoptosis in susceptible cancer cells. The parent compound is primarily a research tool because hepatotoxicity and other toxicities limited clinical development. Geldanamycin has derivatives, including 17-AAG/tanespimycin and 17-DMAG/alvespimycin. Reference.

Geldanamycin — a naturally occurring benzoquinone ansamycin antibiotic and first-generation heat-shock protein 90 inhibitor originally isolated from Streptomyces hygroscopicus. It is formally classified as an experimental natural-product HSP90 chaperone inhibitor and is commonly abbreviated GA or GDM. Geldanamycin competitively occupies the N-terminal ATP-binding pocket of HSP90, disrupting its ATPase-dependent chaperone cycle and destabilizing multiple oncogenic client proteins. The parent compound is used primarily as a research tool; poor aqueous solubility, reactive benzoquinone chemistry, and substantial hepatotoxicity prevented direct clinical development. Semisynthetic analogues include 17-AAG or tanespimycin and 17-DMAG or alvespimycin.

Primary mechanisms (ranked):

  1. N-terminal HSP90 ATPase inhibition, producing prolonged disruption of the HSP90 chaperone cycle.
  2. Ubiquitin-proteasome-dependent depletion of HSP90 client proteins, including context-dependent loss of HER2, EGFR, AKT, RAF, BCR-ABL, SRC, steroid receptors, mutant p53, and cell-cycle regulatory kinases.
  3. Simultaneous suppression of multiple oncogenic survival and proliferation networks, particularly PI3K/AKT, RAF/MEK/ERK, receptor tyrosine kinase, and hormone-receptor signalling.
  4. Induction of cell-cycle arrest and mitochondrial or caspase-dependent apoptosis after client-protein depletion.
  5. Inhibition of hypoxia and angiogenic signalling through destabilization of HIF-1α and associated reduction of VEGF signalling in responsive models.
  6. Radiosensitization and context-dependent chemosensitization through depletion of EGFR, HER2, AKT, DNA-damage-response, and anti-apoptotic proteins.
  7. Secondary activation of HSF1 and induction of HSP70 and other heat-shock proteins, creating a compensatory cytoprotective response that can restrict antitumour efficacy.
  8. Secondary quinone-dependent oxidative stress, which may contribute both to tumour-cell injury and to dose-limiting hepatotoxicity.

Bioavailability / PK relevance: Geldanamycin has poor aqueous solubility, formulation limitations, extensive tissue and hepatic exposure concerns, and a narrow preclinical therapeutic window. Its time-dependent, slow-dissociating interaction with HSP90 can produce prolonged target engagement despite extracellular drug removal. The parent compound has no validated clinical dose or established human pharmacokinetic regimen. More soluble derivatives were developed to improve administration and systemic exposure, but retained variable hepatic and gastrointestinal toxicity.

In-vitro vs systemic exposure relevance: Antiproliferative effects are commonly reported at low-nanomolar to submicromolar concentrations, while biochemical affinity estimates depend strongly on assay conditions, redox state, incubation time, and HSP90 conformation. Continuous or prolonged experimental exposure can exaggerate effects relative to feasible systemic administration. Parent-geldanamycin concentrations producing broad client-protein depletion cannot be assumed clinically achievable because the compound was not advanced into therapeutic human dosing.

Clinical evidence status: Preclinical research agent. Geldanamycin itself has no established therapeutic role, regulatory approval, or demonstrated clinical anticancer efficacy. Its derivatives 17-AAG and 17-DMAG entered phase I and phase II oncology studies and demonstrated pharmacodynamic HSP90 inhibition, but development was constrained by formulation, hepatic, gastrointestinal, ocular, and other toxicities and by limited durable efficacy. Geldanamycin should not be categorized as an approved chemotherapy or clinically validated adjunct.

Mechanistic Effects of Geldanamycin

Rank Pathway / Axis Cancer Cells Normal Cells TSF Primary Effect Notes / Interpretation
1 HSP90 chaperone cycle HSP90 ATPase activity ↓ HSP90 ATPase activity ↓ P/R Blocks ATP-dependent client-protein maturation Direct molecular mechanism; binds the N-terminal nucleotide-binding pocket with slow, tight, time-dependent inhibition.
2 HSP90 client-protein stability HER2, EGFR, AKT, RAF, SRC, BCR-ABL and other clients ↓ Physiological HSP90 clients ↓ (dose-dependent) R/G Destabilization and proteasomal degradation of signalling proteins The exact client-protein profile is tumour-type and mutation dependent; loss of several pathways can occur concurrently.
3 PI3K AKT survival signalling AKT and phosphorylated AKT ↓ AKT signalling ↓ (dose-dependent) R/G Reduced survival and treatment resistance Usually secondary to loss of HSP90-dependent AKT stability rather than direct kinase inhibition.
4 RAF MEK ERK signalling RAF stability ↓; ERK signalling ↓ MAPK signalling ↓ (context-dependent) R/G Reduced proliferation and mitogenic signalling Magnitude depends on tumour dependence on RAF and other HSP90 client kinases.
5 Cell-cycle regulation CDK and checkpoint signalling ↓; arrest ↑ Proliferation ↓ (dose-dependent) G G1 or G2/M arrest Phase of arrest varies by cell type and by the client proteins destabilized.
6 Mitochondrial apoptosis Mitochondrial dysfunction ↑; caspase-9 and caspase-3 cleavage ↑; PARP cleavage ↑ Apoptosis ↑ at toxic exposure G Programmed cell death Generally follows depletion of survival clients and is not uniformly induced in all tumour models.
7 HIF-1α and angiogenic signalling HIF-1α stability ↓; VEGF signalling ↓ Hypoxic adaptation ↓ (context-dependent) R/G Reduced hypoxia tolerance and angiogenic signalling HIF-1α is HSP90 dependent, but the magnitude of inhibition varies with oxygen status and tumour model.
8 Radiosensitization Radiation sensitivity ↑ Radiation sensitivity ↔ or ↑ (model-dependent) G Reduced clonogenic survival after irradiation Associated with depletion of EGFR, HER2, AKT, and other stress-response proteins; demonstrated preclinically rather than clinically.
9 Chemosensitization Drug sensitivity ↑ (context-dependent) Treatment toxicity ↑ (possible) G Reduced compensatory survival signalling Combination effects are drug- and tumour-specific and may be limited by overlapping systemic toxicity.
10 HSF1 heat-shock response HSF1 activity ↑; HSP70 and stress proteins ↑ HSF1 activity ↑; cytoprotection ↑ R/G Compensatory proteotoxic-stress response Potential resistance mechanism that partially opposes apoptosis and may protect both malignant and normal cells.
11 Quinone-dependent ROS ROS ↑ (dose-dependent) Hepatic ROS ↑; oxidative injury ↑ P/R Oxidative stress and cellular injury Secondary mechanism rather than the defining anticancer action; particularly important to hepatotoxicity of the benzoquinone scaffold.
12 Clinical Translation Constraint Broad pathway suppression but uncertain therapeutic window Hepatotoxicity and systemic proteostasis disruption ↑ G Prevents clinical use of the parent compound Poor solubility, formulation difficulty, reactive quinone metabolism, normal-tissue HSP90 inhibition, and absent human efficacy data limit translation.

P: 0–30 min    R: 30 min–3 hr    G: >3 hr
RadioS, RadioSensitizer: Click to Expand ⟱
Source:
Type:
A radiosensitizer is an agent that makes cancer cells more sensitive to the damaging effects of radiation therapy. By using a radiosensitizer, clinicians aim to enhance the effectiveness of radiation treatment by either increasing the damage incurred by tumor cells or by interfering with the cancer cells’ repair mechanisms. This can potentially allow for lower doses of radiation, reduced side effects, or improved treatment outcomes.
Pathways that help Radiosensitivity: downregulating HIF-1α, increase SIRT1, Txr

List of Natural Products with radiosensitizing properties:
-Curcumin:modulate NF-κB, STAT3 and has been shown in preclinical studies to enhance the effects of radiation by inhibiting cell survival pathways.
-Resveratrol:
-EGCG:
-Quercetin:
-Genistein:
-Parthenolide:

How radiosensitizers inhibit the thioredoxin (Trx) system in cellular contexts. Notable radiosensitizers, including:
-gold nanoparticles (GNPs),
-gold triethylphosphine cyanide ([Au(SCN) (PEt3)]),
-auranofin, ceria nanoparticles (CONPs),
-curcumin and its derivatives,
-piperlongamide,
-indolequinone derivatives,
-micheliolide,
-motexafin gadolinium, and
-ethane selenide selenidazole derivatives (SeDs)
Scientific Papers found: Click to Expand⟱
7099- Geld,    Geldanamycin, an inhibitor of Hsp90, sensitizes human tumour cells to radiation
- in-vitro, CRC, DLD1
RadioS↑, EF-1α↓, Akt↓, HSP90↓,
7100- Geld,  Rad,    Preferential sensitization of tumor cells to radiation by heat shock protein 90 inhibitor geldanamycin
- in-vitro, Var, NA
HSP90↓, Akt↓, RadioS↑, selectivity↑,

Showing Research Papers: 1 to 2 of 2

* indicates research on normal cells as opposed to diseased cells
Total Research Paper Matches: 2

Pathway results for Effect on Cancer / Diseased Cells:


Cell Death(tgid=5) ⓘ

Akt↓, 2,  

Kinase & Signal Transduction(tgid=6) ⓘ

EF-1α↓, 1,  

Protein Folding & ER Stress(tgid=8) ⓘ

HSP90↓, 2,  

Drug Metabolism & Resistance(tgid=21) ⓘ

RadioS↑, 2,   selectivity↑, 1,  
Total Targets: 5

Pathway results for Effect on Normal Cells:


Total Targets: 0

Scientific Paper Hit Count for: RadioS, RadioSensitizer
Query results interpretion may depend on "conditions" listed in the research papers.
Such Conditions may include : 
  -low or high Dose
  -format for product, such as nano of lipid formations
  -different cell line effects
  -synergies with other products 
  -if effect was for normal or cancerous cells

Filter Conditions: Pro/AntiFlg:%  IllCat:%  CanType:%  Cells:%  prod#:422  Target#:1107  State#:%  Dir#:%
  wNotes=0  sortOrder:rid,rpid

 

Home Page