The surprising dual roles of glycolytic genes in cancer progression
For nearly a century, scientists have known that cancer cells possess what can be described as a "sweet tooth"—an unusual preference for consuming glucose at an astonishing rate, even when oxygen is plentiful. This phenomenon, known as the Warburg effect (after its discoverer Otto Warburg), has long puzzled researchers. Why would cancer cells choose to produce energy through glycolysis (a relatively inefficient process that generates only 2 ATP molecules per glucose) when they could harness the much more efficient mitochondrial oxidative phosphorylation (which yields up to 36 ATP molecules per glucose)? 1
The answer, we now understand, is far more fascinating than simply energy production. Recent research has revealed that the glycolytic genes responsible for this metabolic reprogramming are not merely metabolic regulators—they are multifunctional molecules that influence nearly every aspect of cancer progression, from tumor growth and metastasis to treatment resistance and immune evasion. These double-agent proteins perform moonlighting functions that make them crucial players in cancer's deadly agenda 2 3 .
The Warburg effect was first described by Otto Warburg in the 1920s, yet its full implications for cancer biology are still being discovered nearly a century later.
Hexokinase, the enzyme that catalyzes the first step of glycolysis, does more than just prime glucose for breakdown. When HK2 (the isoform prevalent in cancer cells) localizes to mitochondria, it binds to voltage-dependent anion channels (VDAC). This interaction not only gives HK2 preferential access to mitochondrial ATP but also helps cancer cells resist apoptosis by preventing the release of pro-apoptotic factors and blocking the opening of mitochondrial permeability transition pores 3 .
This second glycolytic enzyme, which converts glucose-6-phosphate to fructose-6-phosphate, leads a double life as autocrine motility factor (AMF). When secreted outside cells, G6PI/AMF binds to its receptor (gp78) and stimulates cell motility, angiogenesis, and metastasis. It also possesses anti-apoptotic properties that enhance tumor cell survival. Notably, cancer patients show significantly increased levels of this enzyme in their blood, making it a potential early detection marker 3 .
The M2 isoform of pyruvate kinase is particularly abundant in embryonic tissues and cancers. Unlike other isoforms, PKM2 has relatively low kinase activity—an apparent paradox that actually benefits cancer cells. By slowing the final step of glycolysis, PKM2 allows glycolytic intermediates to accumulate and be diverted into biosynthetic pathways that produce nucleotides, amino acids, and lipids needed for rapid cell division 2 4 . PKM2 can also travel to the nucleus, where it influences gene expression by interacting with transcription factors like HIF-1α and Oct4, thereby promoting metabolic reprogramming and maintaining cancer stem cell properties 3 .
Why would glycolytic enzymes develop these additional functions? The answer may lie in evolution. Glycolysis is one of the most ancient metabolic pathways, emerging when Earth's atmosphere was largely anaerobic. As more complex metabolic systems evolved, these ancient enzymes may have been co-opted for additional regulatory functions, especially in contexts requiring rapid proliferation—such as embryonic development, wound healing, and unfortunately, cancer 3 .
| Enzyme | Glycolytic Step | Moonlighting Functions | Role in Cancer |
|---|---|---|---|
| Hexokinase 2 (HK2) | Glucose → Glucose-6-P | Inhibits apoptosis, regulates mitochondrial stability | Promotes survival, therapy resistance |
| Glucose-6-P isomerase (G6PI) | Glucose-6-P ↔ Fructose-6-P | Autocrine motility factor (AMF), neuroleukin | Stimulates migration, angiogenesis, metastasis |
| Phosphofructokinase-1 (PFK-1) | Fructose-6-P → Fructose-1,6-BP | Regulates transcription factors, forms molecular condensates | Supports tumor progression, cell signaling |
| Pyruvate kinase M2 (PKM2) | Phosphoenolpyruvate → Pyruvate | Transcriptional coactivator, regulates cell cycle | Controls metabolic switching, promotes stemness |
A groundbreaking 2025 study published in Nature dramatically expanded our understanding of how tumor microenvironment signals influence cancer metabolism through glycolytic genes 5 . The research team investigated how the bone marrow microenvironment supports the progression of aggressive myeloid leukemias, including blast-crisis chronic myeloid leukemia (bcCML) and acute myeloid leukemia (AML).
The researchers employed an impressive array of cutting-edge techniques:
The study revealed a startling finding: taurine, a common amino acid derivative, emerged as a critical regulator of leukemia progression through its interaction with the taurine transporter (TAUT, encoded by SLC6A6) 5 .
The researchers discovered that:
| Experimental Manipulation | Effect on Leukemia Cells | Impact on Survival |
|---|---|---|
| CDO1 knockdown in osteolineage cells | Reduced growth and colony formation | Improved survival |
| TAUT inhibition in leukemia cells | Impaired in vivo progression | Extended lifespan |
| Combined TAUT inhibition + venetoclax | Synergistic growth inhibition | Potential novel combination therapy |
This research is groundbreaking for several reasons:
The study exemplifies how glycolytic genes and transporters do more than just process glucose—they serve as critical integration points between environmental signals and cellular metabolic programs 5 .
Investigating the multifaceted roles of glycolytic genes requires specialized experimental approaches. Here are key methods and reagents essential to this field of research:
Scientists use several techniques to measure glycolytic flux in cancer cells:
Commercial kits and bioanalyzers can quantify glucose consumption and lactate production in cell culture media, providing a straightforward assessment of glycolytic activity 6 7 .
This instrument simultaneously measures the extracellular acidification rate (ECAR, primarily from lactate excretion) and oxygen consumption rate (OCR), allowing researchers to assess both glycolytic and mitochondrial respiratory activities in real-time 6 .
To study the functional importance of specific glycolytic genes, researchers employ:
CRISPR/Cas9 gene editing, RNA interference (siRNA/shRNA), and overexpression constructs to manipulate expression of specific glycolytic enzymes 5 9 .
Small molecule compounds that target specific glycolytic enzymes, such as 2-deoxyglucose (hexokinase inhibitor), lonidamine (HK2 inhibitor), and shikonin (PKM2 inhibitor) .
Enzymatic assays that measure the conversion of NAD⁺ to NADH or NADP⁺ to NADPH (which absorb light at 340 nm) to quantify the activity of rate-limiting glycolytic enzymes 7 .
| Reagent/Method | Application | Key Insight Provided |
|---|---|---|
| 2-NBDG | Fluorescent glucose analog | Visualizes glucose uptake at single-cell level |
| Seahorse XF Analyzer | Simultaneous ECAR and OCR measurement | Assesses real-time glycolytic and respiratory rates |
| ¹³C-glucose tracing | Mass spectrometry-based metabolite tracking | Maps carbon flux through metabolic networks |
| CRISPR screening | Genome-wide functional genetics | Identifies essential glycolytic genes and regulators |
| HK2 inhibitors (e.g., lonidamine) | Pharmacological enzyme inhibition | Tests therapeutic targeting of specific glycolytic enzymes |
The multifaceted roles of glycolytic genes have important implications for cancer diagnosis and treatment.
The Warburg effect has already been exploited clinically through ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging, which detects tumors based on their heightened glucose uptake 6 8 . Additionally, blood levels of certain glycolytic enzymes, such as G6PI/AMF, show promise as diagnostic biomarkers for early cancer detection 3 .
Glycolytic gene expression patterns have significant prognostic implications. Research has shown that glycolysis-related gene signatures can predict outcomes in various cancers, including hepatocellular carcinoma, where an 8-gene signature (AURKA, CDK1, CENPA, DEPDC1, HMMR, KIF20A, PFKFB4, STMN1) was significantly correlated with both overall survival and recurrence-free survival .
Targeting glycolytic genes offers promising therapeutic strategies:
Targeting glycolytic enzymes offers multiple therapeutic approaches:
The story of glycolytic genes in cancer continues to evolve from simple metabolic regulators to multifunctional orchestrators of tumor progression. These proteins wear multiple hats—as enzymes, signaling molecules, transcriptional regulators, and structural components—that collectively drive cancer development, metastasis, and therapy resistance.
Understanding these moonlighting functions provides not only deeper insights into cancer biology but also exciting opportunities for innovative diagnostic and therapeutic approaches. As we continue to unravel the complex relationships between metabolism, signaling, and gene expression, targeting the multifaceted roles of glycolytic genes may offer new hope for cancer patients.