Biochemical Origin of the Warburg Effect in Light of 15 Years of Research Experience: A Novel Evidence-Based View (An Expert Opinion Article)

Figures & data

Figure 1 The Warburg effect is the hallmark of malignancy and differentiates energetics in hyperglycolytic cancer cells from normal cells.

Box 1 Which Comes First: Mitochondrial Damage, the Warburg Effect or Carcinogenesis?

For the author: Mitochondrial damage precedes the occurrence of both the Warburg effect and carcinogenesis. A relatively significant degree of mitochondrial damage forces the energy metabolism of the transforming cells to rely on glycolysis resulting in overproduction of the end product pyruvate that is converted immediately into lactate via LDH. In transformed cells and hyperglycolytic cancer cells, the Warburg effect occurs secondary to a vicious cycle and a closed circuit between GAPDH (producing NADH.H) and LDH (consuming NADH.H and producing lactate). Excess NADH.H produced by GAPDH forces LDH to persistently form lactate (not pyruvate). This deprives cancer cells from pyruvate antioxidant effects and favours increased endogenous oxidative stress and subsequent carcinogenesis.

Table 1 Comparison Between Pyruvate and Lactate

	Pyruvate (Pyruvic Acid)	Lactate (Lactic Acid)
Structure
Biochemical formula	2 hydrogen atoms less than lactate	2 hydrogen atoms more than pyruvate
Formation	From (lactate + NAD^+) (using LDH) Many other sources	From (pyruvate + NADH.H) (using LDH)
Antioxidant function	Strong (so pyruvate participates in preventing an endogenous oxidative stress inside the normal cells). Adding pyruvate to H2O2 scavenged it^Citation13	Absent. Lactate is pro-oxidant (so participates in increasing the endogenous oxidative stress in cancer cells). Adding lactate to exogenous H2O2 did not scavenge it^Citation13
Normally formed as an end product of glucose oxidation	If oxygen is present (aerobic condition) to start the Krebs cycle	If oxygen is absent (anaerobic condition)
Formation (as an end product of glucose oxidation) in cancer cells form glucose	Transiently formed (as an end product) due to rapid conversion into lactate in hyperglycolytic cancer cells exhibiting the Warburg effect	Continuously formed inside cancer cells then becomes extruded to its microenvironment
Cytotoxicity to normal cells	Not cytotoxic. On the contrary, pyruvate is tissue-protective against oxidative stress	Excess lactate favours oxidant-induced cytotoxicity and acidic microenvironment

Table 2 Lactate is More Vital Than Pyruvate for Cancer Cells

	Pyruvate (Pyruvic Acid)	Lactate (Lactic Acid)
Contribution to cancer cells’ extracellular acidity	No	Strong contribution
Conversion to acetyl CoA (active acetate) to start the cycle, ketogenesis, or lipogenesis	Directly via the enzyme pyruvate dehydrogenase. This occurs less in hyperglycolytic cancer cells due to consumption of pyruvate to form lactate and mitochondrial damage	None. Lactate must be converted first into pyruvate via LDH enzyme activity. Usually this does not occur in hyperglycolytic cancer cells due to consumption of pyruvate in forming lactate and the mitochondrial defects that impair the Krebs cycle
Fate in hyperglycolytic cancer cells exhibiting the Warburg effect	Formed from glucose then is rapidly converted to lactate (using LDH to produce the Warburg effect)	Formed from pyruvate, then becomes extruded outside cancer cells producing acidic microenvironment and does not become pyruvate again
Formation and transport	Mainly in normal cells' cytoplasm (from glucose oxidation), then enters the mitochondria using pyruvate translocase enzyme to give acetyl CoA to start the Krebs cycle that needs intact mitochondria and oxygen	In the cytoplasm (from pyruvate resulting from glucose oxidation). Then, lactate goes outside the cells. If lactate enters the mitochondria, it cannot be metabolized further due to mitochondrial lesions. Lactate formation is enhanced by mitochondrial lesions, and absent oxygen (in normal cells), tumour hypoxia or even in the presence of oxygen in cancer cells
Functions in hyperglycolytic cancer cells	Is converted to lactate If there is significant mitochondrial damage, pyruvate cannot start the Krebs cycle or mitochondrial pathways for energy formation (as ketolysis) Helps cancer cells’ migration and metastasis^Citation13	Helps cancer cells' metastasis and invasion If there is significant mitochondrial damage, lactate cannot start the Krebs cycle or mitochondrial pathways for energy formation (as ketolysis) Helps cancer cells migration and metastasis^Citation13
Causing immunological evasion (escape) of tumours	Never	Very powerful. Lactate inhibits T lymphocytes and suppresses anticancer immunity

Figure 2 Origin of the Warburg effect. The Warburg effect originates from a vicious cycle and a closed circle existing between the two reversible glycolytic enzymes: glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and lactate dehydrogenase (LDH) where the former continuously produces NADH.H and the latter continuously utilizes it to form lactate from glucose even in the presence of oxygen (Warburg effect). Both enzymes act in harmony to supply the needed coenzymes (GAPDH utilizes NAD⁺ and LDH utilizes NADH.H) to each other.

Figure 3 Mitochondrial damage precedes the development of the Warburg effect. The closed vicious cycle (GAPDH–LDH) maintains the Warburg effect and prevents pyruvate formation and deprive transforming cells and cancer cells from pyruvate-induced antioxidant effects.

Figure 4 Cytoplasmic enzymes using NAD/NADH.H as a coenzyme. Those include malate dehydrogenase and acetaldehyde dehydrogenase but not isocitrate dehydrogenase (utilizes NADP/NADPH.H). Malate dehydrogenase and acetaldehyde dehydrogenase form NADH.H when they catalyse forming glucose and Ketone bodies, respectively and this adds to excess cytoplasmic NADH.H reserves ie stimulating formation of more lactate and more Warburg effect.

Figure 5 Otto Warburg was truthful. The best of the author’s knowledge and understanding agrees with Otto Warburg’s findings and reports: mitochondrial damage precedes the Warburg effect that precedes carcinogenesis.

Box 2 Natural Antioxidants of Prophetic Medicine are Promising for Preventing and Treating the Warburg Effect

*This occurs due to the so many natural antioxidant ingredients that may antagonize the Warburg effect (lactate-induced increased oxidative stress). *Natural and nutritional antioxidant ingredients may cause antioxidant–oxidant antagonism. *Natural and nutritional antioxidant ingredients may cause antioxidant–lactate (pro-oxidant) antagonism. *******Such promising natural antioxidants include: Ajwa date fruit (Phoenix dactylifera) rich in polyphenols, flavonoids, and antioxidant minerals. Al-hijamah via direct percutaneous excretion of oxidants (as malondialdehyde) and lactate. Natural honey rich in polyphenols and flavonoids. Nigella sativa rich in thymoquinone, nigellone, carvacrol, carvone, α-pinene, and others. Costus (Saussurea lappa) rich in costunolide and dehydrocostus lactone and santamarin. Senna (Cassia angustifolia) rich in sennosides, emodin, cassine, alaternin, and norrubrofusarin. Fennel (Foeniculum vulgare Mill) rich in anethol, limonene, fenchone, and flavonoids. Olive oil rich in oleic acid, hydroxytyrosol, oleuropein, homovanillic acid, and alcohol. Barley rich in glutathione S-transferases antioxidant enzymes, phenolics,and β-glucan fibres. Zamzam water (alkaline pH) rich in antioxidant minerals: selenium, strontium, Zn, Mg, and Mn. Apple cider vinegar rich in gallic acid, chlorogenic acid, tyrosol, caftaric acid, and resveratrol. Desert truffles rich in phenolic antioxidants (caffeic acid), amino acids, and minerals eg Mg. Camel milk rich in aliphatic alcohols and aldehydes and sulphur-containing compounds. Camel urine rich in canavanine, d-glucuronic acid, and antioxidant minerals. Henna (Lawsonia inermis) rich in Lawson, coumarin, quinones, and flavonoids.

El Sayed S, Abou El-Magd R, Shishido Y, et al. 3-Bromopyruvate antagonizes effects of lactate and pyruvate, synergizes with citrate and exerts novel anti-glioma effects. J Bioenerg Biomembr. 2012;44:61–79. doi:10.1007/s10863-012-9409-4

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