{"id":207864,"date":"2026-06-08T11:38:12","date_gmt":"2026-06-08T09:38:12","guid":{"rendered":"https:\/\/univet.hu\/?p=207864"},"modified":"2026-06-08T11:38:12","modified_gmt":"2026-06-08T09:38:12","slug":"researchers-uncover-an-alternative-cellular-survival-pathway-that-challenges-established-biochemical-paradigms","status":"publish","type":"post","link":"https:\/\/univet.hu\/en\/2026\/06\/researchers-uncover-an-alternative-cellular-survival-pathway-that-challenges-established-biochemical-paradigms\/","title":{"rendered":"Researchers uncover an alternative cellular survival pathway that challenges established biochemical paradigms"},"content":{"rendered":"

A previously unrecognised metabolic escape route may help explain how cancer cells and cells carrying defects in key enzymatic systems maintain viability under adverse conditions, according to a study published in Nature Chemical Biology. Researchers from the Redox Biology Research Group at the University of Veterinary Medicine Budapest, working in collaboration with the National Institute of Oncology and several international partner institutions, have identified an alternative mechanism by which cells can secure a supply of the essential amino acid cysteine when canonical reduction pathways are impaired.<\/p>

Cysteine, a sulfur-containing amino acid, is indispensable for cellular homeostasis and tumour growth. It contributes to numerous redox-regulated processes, and its depletion ultimately leads to cell death. Until now, it was widely accepted that cells obtain cysteine from extracellular sources primarily through disulfide reduction, a process that cleaves sulfur\u2013sulfur (S\u2013S) bonds.<\/p>

The new findings reveal that cells possess a remarkably robust backup strategy. When conventional disulfide-reducing enzyme systems are disrupted or absent, cells can switch to an alternative biochemical route that bypasses the established pathway altogether.<\/p>

A molecular escape mechanism<\/h5>

To investigate cellular adaptation to impaired sulfur metabolism, the researchers generated cellular models lacking key disulfide reductase enzymes. Based on current biochemical understanding, these cells should have been unable to produce sufficient cysteine to sustain survival. Unexpectedly, however, they remained viable.<\/p>

To elucidate the underlying mechanism, the team examined intracellular sulfur metabolism using isotope-tracing approaches. Stable isotope-labelled sulfur atoms enabled the researchers to follow the fate of sulfur-containing molecules within living cells with high precision.<\/p>

Their analyses revealed that, rather than cleaving the conventional sulfur\u2013sulfur bond of cystine, cells initiate the breakdown of a carbon\u2013sulfur (C\u2013S) bond. The pathway begins with an enzymatic cleavage step and is subsequently completed through a cascade of spontaneous, non-enzymatic reactions, ultimately generating cysteine and supporting cellular survival.<\/p>

The findings suggest that cellular metabolism is considerably more adaptable than previously appreciated. When a primary biochemical route becomes inaccessible, cells can engage an alternative chemical solution to maintain essential metabolic functions.<\/p>

Implications for cancer research<\/h5>

The discovery has important implications for understanding metabolic plasticity in cancer. Tumour cells are known to exploit alternative metabolic programmes to sustain proliferation and withstand therapeutic interventions. Within the nutrient-limited tumour microenvironment, the ability to generate essential amino acids through non-canonical pathways may provide a significant survival advantage.<\/p>

Characterising this newly identified pathway could therefore open new opportunities for therapeutic intervention. Targeted inhibition of the mechanism may help deprive tumour cells of a critical source of cysteine, potentially enhancing the effectiveness of future anticancer strategies.<\/p>

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Tracking sulfur through cellular metabolism<\/h5>

The study employed stable isotope tracing to map sulfur fluxes within cells. Sulfur atoms labelled with the stable isotope ^34S enabled the researchers to monitor the conversion of extracellular methionine through the methionine cycle and transsulfuration pathway, revealing how cells sustain the production of proteins and glutathione (GSH), a central component of cellular antioxidant defence and tumour survival mechanisms.<\/p>

The work was published in Nature Chemical Biology, one of the leading international journals in the field, and includes researchers from the Redox Biology Research Group of the University of Veterinary Medicine Budapest among its authors.<\/p>

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