Geldanamycin / ROS 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):

N-terminal HSP90 ATPase inhibition, producing prolonged disruption of the HSP90 chaperone cycle.
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.
Simultaneous suppression of multiple oncogenic survival and proliferation networks, particularly PI3K/AKT, RAF/MEK/ERK, receptor tyrosine kinase, and hormone-receptor signalling.
Induction of cell-cycle arrest and mitochondrial or caspase-dependent apoptosis after client-protein depletion.
Inhibition of hypoxia and angiogenic signalling through destabilization of HIF-1α and associated reduction of VEGF signalling in responsive models.
Radiosensitization and context-dependent chemosensitization through depletion of EGFR, HER2, AKT, DNA-damage-response, and anti-apoptotic proteins.
Secondary activation of HSF1 and induction of HSP70 and other heat-shock proteins, creating a compensatory cytoprotective response that can restrict antitumour efficacy.
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

ROS, Reactive Oxygen Species: Click to Expand ⟱

Source: HalifaxProj (inhibit)

Type:

Reactive oxygen species (ROS) are highly reactive molecules that contain oxygen and can lead to oxidative stress in cells. They play a dual role in cancer biology, acting as both promoters and suppressors of cancer.
ROS can cause oxidative damage to DNA, leading to mutations that may contribute to cancer initiation and progression. So normally you want to inhibit ROS to prevent cell mutations.
However excessive ROS can induce apoptosis (programmed cell death) in cancer cells, potentially limiting tumor growth. Chemotherapy typically raises ROS.
-mitochondria is the main source of reactive oxygen species (ROS) (and the ETC is heavily related)
ROS Homeostasis in Cancer Cells and Its Potential as a Therapeutic Target

"Reactive oxygen species (ROS) are two electron reduction products of oxygen, including superoxide anion, hydrogen peroxide, hydroxyl radical, lipid peroxides, protein peroxides and peroxides formed in nucleic acids 1. They are maintained in a dynamic balance by a series of reduction-oxidation (redox) reactions in biological systems and act as signaling molecules to drive cellular regulatory pathways."
"During different stages of cancer formation, abnormal ROS levels play paradoxical roles in cell growth and death 8. A physiological concentration of ROS that maintained in equilibrium is necessary for normal cell survival. Ectopic ROS accumulation promotes cell proliferation and consequently induces malignant transformation of normal cells by initiating pathological conversion of physiological signaling networks. Excessive ROS levels lead to cell death by damaging cellular components, including proteins, lipid bilayers, and chromosomes. Therefore, both scavenging abnormally elevated ROS to prevent early neoplasia and facilitating ROS production to specifically kill cancer cells are promising anticancer therapeutic strategies, in spite of their contradictoriness and complexity."
"ROS are the collection of derivatives of molecular oxygen that occur in biology, which can be categorized into two types, free radicals and non-radical species. The non-radical species are hydrogen peroxide (H 2O 2 ), organic hydroperoxides (ROOH), singlet molecular oxygen ( 1 O 2 ), electronically excited carbonyl, ozone (O3 ), hypochlorous acid (HOCl, and hypobromous acid HOBr). Free radical species are super-oxide anion radical (O 2•−), hydroxyl radical (•OH), peroxyl radical (ROO•) and alkoxyl radical (RO•) [130]. Any imbalance of ROS can lead to adverse effects. H2 O 2 and O 2 •− are the main redox signalling agents. The cellular concentration of H2 O 2 is about 10−8 M, which is almost a thousand times more than that of O2 •−".
"Radicals are molecules with an odd number of electrons in the outer shell [393,394]. A pair of radicals can be formed by breaking a chemical bond or electron transfer between two molecules."

Recent investigations have documented that polyphenols with good antioxidant activity may exhibit pro-oxidant activity in the presence of copper ions, which can induce apoptosis in various cancer cell lines but not in normal cells. "We have shown that such cell growth inhibition by polyphenols in cancer cells is reversed by copper-specific sequestering agent neocuproine to a significant extent whereas iron and zinc chelators are relatively ineffective, thus confirming the role of endogenous copper in the cytotoxic action of polyphenols against cancer cells. Therefore, this mechanism of mobilization of endogenous copper." > Ions could be one of the important mechanisms for the cytotoxic action of plant polyphenols against cancer cells and is possibly a common mechanism for all plant polyphenols. In fact, similar results obtained with four different polyphenolic compounds in this study, namely apigenin, luteolin, EGCG, and resveratrol, strengthen this idea.
Interestingly, the normal breast epithelial MCF10A cells have earlier been shown to possess no detectable copper as opposed to breast cancer cells [24], which may explain their resistance to polyphenols apigenin- and luteolin-induced growth inhibition as observed here (Fig. 1). We have earlier proposed [25] that this preferential cytotoxicity of plant polyphenols toward cancer cells is explained by the observation made several years earlier, which showed that copper levels in cancer cells are significantly elevated in various malignancies. Thus, because of higher intracellular copper levels in cancer cells, it may be predicted that the cytotoxic concentrations of polyphenols required would be lower in these cells as compared to normal cells."

Majority of ROS are produced as a by-product of oxidative phosphorylation, high levels of ROS are detected in almost all cancers.
-It is well established that during ER stress, cytosolic calcium released from the ER is taken up by the mitochondrion to stimulate ROS overgeneration and the release of cytochrome c, both of which lead to apoptosis.

Note: Products that may raise ROS can be found using this database, by:
Filtering on the target of ROS, and selecting the Effect Direction of ↑

Targets to raise ROS (to kill cancer cells):
• NADPH oxidases (NOX): NOX enzymes are involved in the production of ROS.
    -Targeting NOX enzymes can increase ROS levels and induce cancer cell death.
    -eNOX2 inhibition leads to a high NADH/NAD⁺ ratio which can lead to increased ROS
• Mitochondrial complex I: Inhibiting can increase ROS production
• P53: Activating p53 can increase ROS levels(by inducing the expression of pro-oxidant genes)
• Nrf2 inhibition: regulates the expression of antioxidant genes. Inhibiting Nrf2 can increase ROS levels
• Glutathione (GSH): an antioxidant. Depleting GSH can increase ROS levels
• Catalase: Catalase converts H2O2 into H2O+O. Inhibiting catalase can increase ROS levels
• SOD1: converts superoxide into hydrogen peroxide. Inhibiting SOD1 can increase ROS levels
• PI3K/AKT pathway: regulates cell survival and metabolism. Inhibiting can increase ROS levels
• HIF-1α inhibition: regulates genes involved in metabolism and angiogenesis. Inhibiting HIF-1α can increase ROS
• Glycolysis: Inhibiting glycolysis can increase ROS levels • Fatty acid oxidation: Cancer cells often rely on fatty acid oxidation for energy production.
-Inhibiting fatty acid oxidation can increase ROS levels
• ER stress: Endoplasmic reticulum (ER) stress can increase ROS levels
• Autophagy: process by which cells recycle damaged organelles and proteins.
-Inhibiting autophagy can increase ROS levels and induce cancer cell death.
• KEAP1/Nrf2 pathway: regulates the expression of antioxidant genes.
    -Inhibiting KEAP1 or activating Nrf2 can increase ROS levels and induce cancer cell death.
• DJ-1: regulates the expression of antioxidant genes. Inhibiting DJ-1 can increase ROS levels
• PARK2: regulates the expression of antioxidant genes. Inhibiting PARK2 can increase ROS levels
• SIRT1 inhibition:regulates the expression of antioxidant genes. Inhibiting SIRT1 can increase ROS levels
• AMPK activation: regulates energy metabolism and can increase ROS levels when activated.
• mTOR inhibition: regulates cell growth and metabolism. Inhibiting mTOR can increase ROS levels
• HSP90 inhibition: regulates protein folding and can increase ROS levels when inhibited.
• Proteasome: degrades damaged proteins. Inhibiting the proteasome can increase ROS levels
• Lipid peroxidation: a process by which lipids are oxidized, leading to the production of ROS.
    -Increasing lipid peroxidation can increase ROS levels
• Ferroptosis: form of cell death that is regulated by iron and lipid peroxidation.
    -Increasing ferroptosis can increase ROS levels
• Mitochondrial permeability transition pore (mPTP): regulates mitochondrial permeability.
    -Opening the mPTP can increase ROS levels
• BCL-2 family proteins: regulate apoptosis and can increase ROS levels when inhibited.
• Caspase-independent cell death: a form of cell death that is regulated by ROS.
    -Increasing caspase-independent cell death can increase ROS levels
• DNA damage response: regulates the repair of DNA damage. Increasing DNA damage can increase ROS
• Epigenetic regulation: process by which gene expression is regulated.
    -Increasing epigenetic regulation can increase ROS levels

-PKM2, but not PKM1, can be inhibited by direct oxidation of cysteine 358 as an adaptive response to increased intracellular reactive oxygen species (ROS)

ProOxidant Strategy:(inhibit the Mevalonate Pathway (likely will also inhibit GPx)
-HydroxyCitrate (HCA) found as supplement online and typically used in a dose of about 1.5g/day or more
-Atorvastatin typically 40-80mg/day, -Dipyridamole typically 200mg 2x/day Combined effect research
-Lycopene typically 100mg/day range (note debatable as it mainly lowers NRF2)

Dual Role of Reactive Oxygen Species and their Application in Cancer Therapy

ROS-Inducing Interventions in Cancer — Canonical + Mechanistic Reference
-generated from AI and Cancer database
ROS rating:  +++ strong | ++ moderate | + weak | ± mixed | 0 none
NRF2:        ↓ suppressed | ↑ activated | ± mixed | 0 none
Conditions:  [D] dose  [Fe] metal  [M] metabolic  [O₂] oxygen
             [L] light [F] formulation [T] tumor-type [C] combination


Item  ROS↑  NRF2  Condition  Mechanism Class  Remarks  

ROS">Piperlongumine
+++  ↓  [D][T]  ROS-dominant
Selective <span class="wphighlight">ROS</span> stressor, Prevents compensatory upregulation of NRF2, ie GSH↓



ROS">Shikonin
+++ ↓/± [D][T] ROS-dominant
<span class="wphighlight">ROS</span> + glycolysis + GPX4 inhibition



ROS">Vitamin K3 (menadione)
+++ ↓ [D] ROS-dominant
Quinone redox cycler; toxicity limits use



ROS">Copper (ionic / nano)
+++ ↓ [Fe][F] ROS-dominant
Fenton-type redox chemistry



ROS">Sodium Selenite
+++ ↓ [D] ROS-dominant
Pro-oxidant, depletes GSH



ROS">Juglone
+++ ↓ [D] ROS-dominant
Strong quinone <span class="wphighlight">ROS</span> chemistry



ROS">Auranofin
+++ ↓ [D] ROS-dominant
TrxR inhibition → redox collapse



ROS">Photodynamic Therapy (PDT)
+++ 0 [L][O₂] ROS-dominant
Singlet oxygen is core cytotoxic mechanism



ROS">Radiotherapy / Radiation
+++ 0 [O₂] ROS-dominant
DNA damage largely via <span class="wphighlight">ROS</span>



ROS">Doxorubicin
+++ ↓ [D] ROS-dominant
Chemo; redox cycling + mitochondrial <span class="wphighlight">ROS</span>



ROS">Cisplatin
++ ↓ [D][T] ROS-dominant
<span class="wphighlight">ROS</span> contributes to DNA/protein damage



ROS">Salinomycin
++ ↓ [D][T] ROS-dominant
<span class="wphighlight">ROS</span>-mediated CSC toxicity



ROS">Artemisinin / DHA
++ ↓ [Fe][T] ROS-dominant
Iron-activated radical generation



ROS">Sulfasalazine
++ ↓ [C][T] ROS-dominant
Ferroptosis; xCT inhibition → lipid <span class="wphighlight">ROS</span>



ROS">FMD / fasting
++ ↓ [M][C][O₂] ROS-dominant
Metabolic stress → mitochondrial <span class="wphighlight">ROS</span>



ROS">Vitamin C (pharmacologic)
++ ↓ [Fe][D] ROS-dominant
Extracellular H₂O₂ at high dose



ROS">Silver nanoparticles
++ ± [F][D] ROS-dominant
<span class="wphighlight">ROS</span> common; selectivity unreliable



ROS">Gambogic acid
++ ↓ [D][T] ROS-dominant
<span class="wphighlight">ROS</span>-mediated apoptosis



ROS">Parthenolide
++ ↓ [D][T] ROS-dominant
<span class="wphighlight">ROS</span> + NF-κB suppression



ROS">Plumbagin
++ ↓ [D] ROS-dominant
Quinone <span class="wphighlight">ROS</span> driver



ROS">Allicin
++ ↓ [D] ROS-dominant
Thiol-reactive oxidative stress



ROS">Ashwagandha (Withaferin A)
++ ↓ [D][T] ROS-dominant
<span class="wphighlight">ROS</span>-mediated apoptosis



ROS">Berberine
++ ↓ [D][M] ROS-dominant
Mitochondrial <span class="wphighlight">ROS</span> induction



ROS">PEITC
++ ↓ [D][C] ROS-dominant
GSH depletion + <span class="wphighlight">ROS</span>



ROS">Methionine restriction
+ ↓ [M][C][T] ROS-secondary
Redox vulnerability increased; <span class="wphighlight">ROS</span> indirect



ROS">DCA
+ ± [M][T] ROS-secondary
<span class="wphighlight">ROS</span> via forced OXPHOS



ROS">Capsaicin
+ ± [D][T] ROS-secondary
Ca²⁺ stress → <span class="wphighlight">ROS</span>



ROS">Galloflavin
+ 0 [D] ROS-secondary
<span class="wphighlight">ROS</span> not primary driver



ROS">Piperine
+ ± [D][F] ROS-secondary
Weak <span class="wphighlight">ROS</span> induction



ROS">Propyl gallate
+ ↓ [D] ROS-secondary
Pro-oxidant at high dose



ROS">Scoulerine
+ ? [D][T] ROS-secondary
Sparse <span class="wphighlight">ROS</span> data



ROS">Thymoquinone
± ± [D][T] Dual redox
Antioxidant ↔ pro-oxidant switch



ROS">Emodin
± ± [D][T] Dual redox
Not cancer-exclusive



ROS">Alpha-lipoic acid (ALA)
± ↑ [D][M] NRF2-dominant
Antioxidant at low dose



ROS">Curcumin
± ↑/↓ [D][F] NRF2-dominant
Hormetic redox behavior



ROS">EGCG
± ↑/↓ [D][O₂] NRF2-dominant
Auto-oxidation artifacts common



ROS">Quercetin
± ↑/↓ [D][Fe] NRF2-dominant
GSH-dependent cycling



ROS">Resveratrol
± ↑ [D][M] NRF2-dominant
<span class="wphighlight">ROS</span> only at high dose



ROS">Sulforaphane
± ↑↑ [D] NRF2-dominant
Strong NRF2 activator



ROS">Lycopene
0 ↑ — Antioxidant
Consistently antioxidant



ROS">Rosmarinic acid
0 ↑ — Antioxidant
Primarily antioxidant



ROS">Citrate
0 0 — Neutral
Metabolic; not a <span class="wphighlight">ROS</span> agent

Scientific Papers found: Click to Expand⟱

8254-

LCA,

Geld,

Licochalcone A enhances geldanamycin-induced apoptosis through reactive oxygen species-mediated caspase activation

in-vitro,

Ovarian,

MMP↓, Cyt‑c↑, Casp↑, cl‑PARP1↑, ROS↑, GSH↓, eff↓,

Showing Research Papers: 1 to 1 of 1

* indicates research on normal cells as opposed to diseased cells
Total Research Paper Matches: 1

Pathway results for Effect on Cancer / Diseased Cells:

Drug Metabolism & Resistance(tgid=21) ⓘ

eff↓, 1,
Total Targets: 7

Pathway results for Effect on Normal Cells:

Total Targets: 0

Scientific Paper Hit Count for: ROS, Reactive Oxygen Species

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#:275  State#:%  Dir#:2
  wNotes=0  sortOrder:rid,rpid

Geldanamycin / ROS Cancer Research Results

Mechanistic Effects of Geldanamycin

Pathway results for Effect on Cancer / Diseased Cells:

Redox & Oxidative Stress(tgid=1) ⓘ

Mitochondria & Bioenergetics(tgid=3) ⓘ

Cell Death(tgid=5) ⓘ

DNA Damage & Repair(tgid=10) ⓘ

Drug Metabolism & Resistance(tgid=21) ⓘ

Pathway results for Effect on Normal Cells:

Home Page