Caffeic acid / PKM2 Cancer Research Results

CA, Caffeic acid: Click to Expand ⟱
Features:
Caffeic acid is a polyphenol antioxidant found in coffee, fruits, vegetables, and herbs. It may have anti-inflammatory, anticancer, anti-aging, and other health benefits.
Caffeic acid (CA) is a dietary hydroxycinnamic acid found widely in plant foods and in coffee largely as chlorogenic acids (caffeoylquinic acids). CA is generally antioxidant / anti-inflammatory and is frequently reported to modulate Nrf2 and NF-κB signaling, with downstream effects on survival pathways (PI3K/AKT), MAPKs, cell cycle, and apoptosis in preclinical cancer models. A notable mechanistic nuance is a context-dependent pro-oxidant effect described in the presence of copper (Cu), where CA can drive oxidative DNA damage in vitro (often discussed as potentially relevant to tumors with higher copper levels).

-Caffeic acid phenethyl ester, the main representative component of propolis
-Black chokeberry 141.14 mg/100 g F
-Sunflower seed, meal 8.17 mg/100 g FW
-Common sage, dried 26.40 mg/100 g FW
-Ceylan cinnamon 24.20 mg/100 g FW
-Nutmeg 16.30 mg/100 g FW

-Dual capacity of CA to act as an antioxidant during carcinogenesis and as a pro-oxidant against cancer cells, promoting their apoptosis or sensitizing them to chemotherapeutic drugs.

Pathways:
-Caffeic acid is a potent antioxidant
-Caffeic acid may also exhibit pro-oxidant behavior. At higher concentrations( 50–100 µM ?) or/and in the presence of transition metal ions (such as copper or iron), caffeic acid can participate in Fenton-like reactions, potentially leading to increased ROS generation.
-Shown to inhibit NF-κB activation
-Inhibitory effects on MAPK/ERK Pathway
-PI3K/Akt Signaling Pathway
-Activation of the Nrf2/ARE pathway
-Cell cycle arrest at various checkpoints
-Angiogenesis Inhibition

Caffeic acid typically shows low oral bioavailability (sometimes only a few percent of the ingested dose is systemically available) and a short plasma half-life (around 1–2 hours in animal models).

Caffeic acid — Caffeic acid is a dietary hydroxycinnamic acid polyphenol present in coffee, fruits, vegetables, and many herbs, and is also generated from hydrolysis of chlorogenic acids. It is formally classified as a small-molecule plant phenolic acid with redox-active, anti-inflammatory, and signal-modulating properties. Standard abbreviations include CA for caffeic acid; it should be distinguished from CAPE (caffeic acid phenethyl ester), which is a different propolis-derived ester with overlapping but not identical pharmacology. In cancer research, CA is best viewed as a pleiotropic preclinical modulator of inflammatory signaling, stress adaptation, metabolism, apoptosis, invasion, and angiogenesis, with translation limited by rapid conjugation and generally low free-aglycone systemic exposure.

Primary mechanisms (ranked):

  1. Suppression of inflammatory/pro-survival transcription, especially IL-6/JAK/STAT3 and NF-κB signaling.
  2. Redox modulation, usually antioxidant/cytoprotective in normal cells but capable of context-dependent pro-oxidant activity in cancer models, particularly with transition metals or higher in-vitro exposure.
  3. Down-modulation of ERK and PI3K/AKT survival signaling with downstream effects on proliferation and apoptosis.
  4. Induction of mitochondrial apoptosis and cell-cycle arrest in susceptible tumor models.
  5. Anti-invasive and anti-angiogenic effects, including reduced MMP/EMT outputs and suppression of STAT3-HIF-1α-VEGF signaling.
  6. Metabolic reprogramming in some models, including AMPK-linked disruption of tumor energy homeostasis and glycolytic dependence.
  7. Clinical translation constraint: extensive phase-II metabolism means circulating exposure is dominated by conjugated metabolites rather than sustained free caffeic acid.

Bioavailability / PK relevance: CA is absorbable in humans, but after oral intake much of the circulating material appears rapidly as sulfate, glucuronide, and methylated metabolites rather than persistent free aglycone. Peak plasma timing is typically early, and delivery is constrained less by gut uptake than by fast metabolic conversion and short-lived free exposure.

In-vitro vs systemic exposure relevance: Many anticancer studies use tens of micromolar CA, and some mechanistic claims depend on 50–100 µM or higher conditions that are not reliably reproduced as sustained free systemic exposure after ordinary oral intake. Accordingly, anti-inflammatory/adjuvant interpretations translate better than claims requiring strong direct tumor-cidal free-drug concentrations; metal-assisted pro-oxidant effects are especially context-dependent.

Clinical evidence status: Primarily preclinical. The cancer evidence base consists mainly of cell and animal studies, with some adjunct/chemosensitization signals. Human oncology evidence remains very limited; at least one registered esophageal squamous cell carcinoma trial has been reported, but caffeic acid is not an established anticancer drug or standard adjunct.

Mechanistic matrix

Rank Pathway / Axis Cancer Cells Normal Cells TSF Primary Effect Notes / Interpretation
1 IL-6 / JAK / STAT3 signaling ↓ ↔ / ↓ inflammatory tone R, G Anti-survival transcription One of the cleaner current cancer axes for CA itself; suppression links to reduced proliferation, migration, and anti-apoptotic signaling.
2 NF-κB inflammatory transcription ↓ ↓ inflammatory stress R, G Anti-inflammatory / anti-survival Consistent across reviews and multiple models, but CA is generally a weaker and less canonical NF-κB inhibitor than CAPE.
3 ROS redox modulation ↔ / ↑ (context-dependent) ↓ oxidative injury P, R Redox reprogramming CA is usually antioxidant in normal tissues, yet can become pro-oxidant in tumor or copper-rich settings; direction is strongly model- and dose-dependent.
4 ERK and PI3K / AKT survival signaling ↓ ↔ R, G Growth and resistance suppression Frequently appears upstream of reduced clonogenicity, apoptosis sensitization, and lower chemoresistance in acidic or stressed tumor states.
5 Mitochondrial apoptosis Bax ↑, caspase-3 ↑, Bcl-2 ↓ ↔ / relative sparing G Cell death execution Usually a downstream endpoint rather than the first event; strongest in susceptible cell lines and higher in-vitro exposure.
6 Cell-cycle machinery cyclin D ↓, arrest ↑ ↔ G Cytostasis Phase of arrest varies by model; best treated as a secondary phenotype following signaling and redox changes.
7 MMP / EMT / invasion programs MMP2/9 ↓, EMT ↓, migration ↓ ↔ G Anti-invasive effect Supported in several tumor models, though part of the older invasion literature is stronger for caffeic-acid derivatives than for CA itself.
8 STAT3-HIF-1α-VEGF angiogenesis axis HIF-1α ↓, VEGF ↓ ↔ G Anti-angiogenic support Includes in-vivo support in renal carcinoma xenograft work; useful mechanistically, but still preclinical.
9 AMPK and tumor energy metabolism AMPK ↑, glycolytic dependence ↓ ↔ / context-dependent R, G Metabolic stress Relevant in selected cancers rather than universally. Better framed as model-dependent metabolic rewiring than as a universal glycolysis inhibitor.
10 NRF2 antioxidant response ↔ / ↑ (context-dependent) ↑ R, G Stress adaptation Important for normal-cell protection and toxicity mitigation. In tumors, NRF2 activation may be beneficial, neutral, or counterproductive depending on context, so it is not a uniformly favorable anticancer axis.
11 Clinical Translation Constraint Free CA exposure limited Conjugated metabolites predominate — PK limitation Human absorption occurs, but circulating chemistry is dominated by rapid conjugation. Many direct in-vitro tumoricidal concentrations likely exceed sustained free systemic levels achievable by routine oral dosing.

Time-Scale Flag (TSF): P / R / G

  • P: 0–30 min (rapid redox/metal interactions; early signaling shifts)
  • R: 30 min–3 hr (acute stress-response + transcription signaling changes)
  • G: >3 hr (gene-regulatory adaptation and phenotype outcomes)
PKM2, Pyruvate Kinase, Muscle 2: Click to Expand ⟱
Source:
Type: enzyme
PKM2 (Pyruvate Kinase, Muscle 2) is an enzyme that plays a crucial role in glycolysis, the process by which cells convert glucose into energy. PKM2 is a key regulatory enzyme in the glycolytic pathway, and it is primarily expressed in various tissues, including muscle, brain, and cancer cells.
-C-myc is a common oncogene that enhances aerobic glycolysis in the cancer cells by transcriptionally activating GLUT1, HK2, PKM2 and LDH-A
-PKM2 has been shown to be overexpressed in many types of tumors, including breast, lung, and colon cancer. This overexpression may contribute to the development and progression of cancer by promoting glycolysis and energy production in cancer cells.
-inhibition of PKM2 may cause ATP depletion and inhibiting glycolysis.
-PK exists in four isoforms: PKM1, PKM2, PKR, and PKL
-PKM2 plays a role in the regulation of glucose metabolism in diabetes.
-PKM2 is involved in the regulation of cell proliferation, apoptosis, and autophagy.
– Pyruvate kinase catalyzes the final, rate-limiting step of glycolysis, converting phosphoenolpyruvate (PEP) to pyruvate with the production of ATP.
– The PKM2 isoform is uniquely regulated and can exist in both highly active tetrameric and less active dimeric forms.
– Cancer cells often favor the dimeric form of PKM2 to slow pyruvate production, thereby accumulating upstream glycolytic intermediates that can be diverted into anabolic pathways to support cell growth and proliferation.
– Under low oxygen conditions, cancer cells rely on altered metabolic pathways in which PKM2 is a key player. – The shift to aerobic glycolysis (Warburg effect) orchestrated in part by PKM2 helps tumor cells survive and grow in hypoxic conditions.

– Elevated expression of PKM2 is frequently observed in many cancer types, including lung, breast, colorectal, and pancreatic cancers.
– High levels of PKM2 are often correlated with enhanced tumor aggressiveness, poor differentiation, and advanced clinical stage.

PKM2 in carcinogenesis and oncotherapy

Inhibitors of PKM2:
-Shikonin, Resveratrol, Baicalein, EGCG, Apigenin, Curcumin, Ursolic Acid, Citrate (best known as an allosteric inhibitor of phosphofructokinase-1 (PFK-1), a key rate-limiting enzyme in glycolysis) potential to directly inhibit or modulate PKM2 is less well established

Full List of PKM2 inhibitors from Database
-key connected observations: Glycolysis↓, lactateProd↓, ROS↑ in cancer cell, while some result for opposite effect on normal cells.
Tumor pyruvate kinase M2 modulators

Flavonoids effect on PKM2
Compounds name IC50/AC50uM Effect
Flavonols
1. Fisetin 0.90uM Inhibition
2. Rutin 7.80uM Inhibition
3. Galangin 8.27uM Inhibition
4. Quercetin 9.24uM Inhibition
5. Kaempferol 9.88uM Inhibition
6. Morin hydrate 37.20uM Inhibition
7. Myricetin 0.51uM Activation
8. Quercetin 3-b- D-glucoside 1.34uM Activation
9. Quercetin 3-D -galactoside 27-107uM Ineffective
Flavanons
10. Neoeriocitrin 0.65uM Inhibition
11. Neohesperidin 14.20uM Inhibition
12. Naringin 16.60uM Inhibition
13. Hesperidin 17.30uM Inhibition
14. Hesperitin 29.10uM Inhibition
15. Naringenin 70.80uM Activation
Flavanonols
16. (-)-Catechin gallateuM 0.85 Inhibition
17. (±)-Taxifolin 1.16uM Inhibition
18. (-)-Epicatechin 1.33uM Inhibition
19. (+)-Gallocatechin 4-16uM Ineffective
Phenolic acids
20. Ferulic 11.4uM Inhibition
21. Syringic and 13.8uM Inhibition
22. Caffeic acid 36.3uM Inhibition
23. 3,4-Dihydroxybenzoic acid 78.7uM Inhibition
24. Gallic acid 332.6uM Inhibition
25. Shikimic acid 990uM Inhibition
26. p-Coumaric acid 22.2uM Activation
27. Sinapinic acids 26.2uM Activation
28. Vanillic 607.9uM Activation


Scientific Papers found: Click to Expand⟱
1640- CA,  MET,    Caffeic Acid Targets AMPK Signaling and Regulates Tricarboxylic Acid Cycle Anaplerosis while Metformin Downregulates HIF-1α-Induced Glycolytic Enzymes in Human Cervical Squamous Cell Carcinoma Lines
- in-vitro, Cerv, SiHa
GLS↓, NADPH↓, ROS↑, TumCD↑, AMPK↑, Hif1a↓, GLUT1↓, GLUT3↓, HK2↓, PFK↓, PKM2↓, LDH↓, cMyc↓, BAX↓, cycD1/CCND1↓, PDH↓, ROS↑, Apoptosis↑, eff↑, ACLY↓, FASN↓, Bcl-2↓, Glycolysis↓,

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:


Redox & Oxidative Stress ⓘ

ROS↑, 2,  

Core Metabolism/Glycolysis ⓘ

ACLY↓, 1,   AMPK↑, 1,   cMyc↓, 1,   FASN↓, 1,   GLS↓, 1,   Glycolysis↓, 1,   HK2↓, 1,   LDH↓, 1,   NADPH↓, 1,   PDH↓, 1,   PFK↓, 1,   PKM2↓, 1,  

Cell Death ⓘ

Apoptosis↑, 1,   BAX↓, 1,   Bcl-2↓, 1,   TumCD↑, 1,  

Cell Cycle & Senescence ⓘ

cycD1/CCND1↓, 1,  

Angiogenesis & Vasculature ⓘ

Hif1a↓, 1,  

Barriers & Transport ⓘ

GLUT1↓, 1,   GLUT3↓, 1,  

Drug Metabolism & Resistance ⓘ

eff↑, 1,  

Clinical Biomarkers ⓘ

LDH↓, 1,  
Total Targets: 23

Pathway results for Effect on Normal Cells:


Total Targets: 0

Scientific Paper Hit Count for: PKM2, Pyruvate Kinase, Muscle 2
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#:51  Target#:772  State#:%  Dir#:1
  wNotes=0  sortOrder:rid,rpid

 

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