Enzyme GDH1 Keeps Breast Cancer Persister Cells Alive During Chemotherapy

Chemotherapy is designed to kill cancer cells without mercy, yet in triple-negative breast cancer it almost always leaves behind a small, stubborn remnant. These survivors, known as drug-tolerant persister cells, are not genetically resistant mutants in the classical sense. Instead, they slip into a temporary, slow-growing state that allows them to endure the chemical assault, and once the pressure of treatment is lifted, they can repopulate the tumor and drive a relapse that is often more aggressive than the original disease. A new study published in Cellular and Molecular Life Sciences has now identified a central metabolic player that keeps these persister cells alive, and the finding points to a potentially powerful way to make chemotherapy work harder in one of the most difficult breast cancer subtypes.

The research, led by Biswajit Dey and Santosh Kumar Guru at the National Institute of Pharmaceutical Education and Research in Hyderabad, India, together with colleagues at Sambalpur University and other Indian institutions, focused on an enzyme called glutamate dehydrogenase 1, or GDH1. This enzyme sits at a critical junction of cellular metabolism, where it converts glutamate, the breakdown product of the amino acid glutamine, into alpha-ketoglutarate, a molecule that feeds directly into the Krebs cycle inside mitochondria. In doing so, GDH1 performs what biologists call an anaplerotic function: it replenishes the intermediates that the Krebs cycle constantly consumes, keeping the mitochondrial engine running. The new work shows that persister cells in triple-negative breast cancer lean heavily on this engine, and that without it, they simply cannot survive.

Triple-negative breast cancer is defined by the absence of the three molecular targets that modern therapy exploits most effectively: the estrogen receptor, the progesterone receptor, and the HER2 protein. Because none of these handles exist for drugs to grab, patients with this subtype rely almost entirely on chemotherapy, which makes the emergence of drug-tolerant persister cells a particularly dangerous problem. The Indian team began by mining publicly available clinical datasets and found that breast cancer patients with elevated GDH1 expression had significantly worse prognoses. That epidemiological clue set the stage for a detailed mechanistic investigation into what GDH1 actually does inside cells that have just survived a chemotherapeutic hit.

Using laboratory models of triple-negative breast cancer, the researchers generated persister cells by exposing them to chemotherapy and isolating the survivors. Multiple independent techniques then converged on the same conclusion. Western blotting and quantitative reverse-transcription polymerase chain reaction showed that GDH1 protein and messenger RNA were both upregulated in the persister population. Immunofluorescence microscopy visualized the increased enzyme directly inside the surviving cells, and mass spectrometry provided an unbiased proteomic confirmation. Extracellular flux assays, which measure the real-time oxygen consumption and acidification of living cells, revealed that this GDH1 surge came with a shift in mitochondrial metabolism, indicating that the persisters were not merely idle survivors but metabolically reprogrammed cells actively burning glutamine-derived fuel.

The functional consequences of this reprogramming were striking. When the team measured cell viability and migratory capacity, GDH1-high persister cells proved both hardier and more mobile than their non-persister counterparts. Wound healing assays, a standard test of cell migration, showed that the persister cells closed scratches faster, a behavior consistent with the acquisition of invasive traits. Conversely, when the researchers suppressed GDH1, either pharmacologically or through genetic silencing, cell viability dropped and migration slowed. The enzyme was not a passive marker of the persister state; it was actively maintaining it.

One of the most intriguing aspects of the study concerns the physical architecture of mitochondria. Mitochondria are dynamic organelles that constantly fuse and split, and the balance between these two processes shapes their function. The researchers found that GDH1 supports a program of fusion-associated remodeling in persister cells, involving the mitofusin proteins MFN1 and MFN2, which tether neighboring mitochondria together, and the phosphorylation state of dynamin-related protein 1, or DRP1, the master regulator of mitochondrial fission. Specifically, the persister cells showed evidence of increased phosphorylation of DRP1 at serine 637, a modification that inhibits fission and favors elongated, fused mitochondrial networks. This fused state is thought to protect mitochondria during stress, preserving their integrity and their capacity to generate energy when the cell is under attack from chemotherapy. In other words, GDH1 appears to coordinate two survival strategies at once: it supplies the metabolic substrate that keeps the Krebs cycle turning, and it shapes the mitochondrial network into a configuration that is more resilient to damage.

The study also connected GDH1 to epithelial-to-mesenchymal transition, or EMT, the developmental program through which epithelial cancer cells abandon their anchored, orderly identity and adopt the mobile, invasive character of mesenchymal cells. EMT is closely associated with drug tolerance, because the transition suppresses proliferation and activates survival pathways, exactly the phenotype that persister cells display. When the researchers stably knocked down GDH1, they found that EMT markers diminished and the cells lost their ability to form the persister state in the first place. This suggests that GDH1 is not merely a consequence of EMT but an enabler of it, linking glutamine metabolism to the transcriptional and structural changes that allow cancer cells to hunker down under therapy.

Perhaps the most clinically significant experiments came from the animal studies. The team implanted triple-negative breast cancer cells into mice as xenografts and compared tumors with normal GDH1 levels to tumors in which GDH1 had been knocked down. When chemotherapy was administered, the GDH1-deficient tumors responded far more dramatically, demonstrating that removing the enzyme restored chemosensitivity in vivo. Analysis of the tumor tissue showed reduced levels of Ki-67 and PCNA, two well-established markers of cell proliferation, confirming that GDH1 loss impaired the growth machinery of the tumor. Together, these results elevate GDH1 from an interesting biochemical observation to a validated therapeutic target whose inhibition could sensitize tumors to existing drugs.

An important nuance emerged when the researchers followed persister cells over time. After thirty days without drug exposure, GDH1 expression declined back toward baseline, indicating that the enzyme plays a transient, state-dependent role rather than causing a permanent genetic change. This reversibility is characteristic of the non-genetic mechanisms that underpin drug tolerance, and it explains why persister cells can eventually exit their dormant state and resume rapid proliferation, seeding recurrence. It also suggests a therapeutic window: if clinicians could target GDH1 during the period when it is elevated, they might eliminate persisters before they revert to a proliferative, treatment-resistant state.

The implications for patients are considerable. Combination strategies that pair conventional chemotherapy with GDH1 inhibition could, in principle, prevent the establishment of the persister reservoir that so often leads to relapse in triple-negative breast cancer. Because GDH1 acts on both metabolism and mitochondrial dynamics, inhibitors of the enzyme might be particularly effective in tumors that have already adopted a glutamine-dependent survival mode. The work also adds to a growing appreciation that cancer therapy must target not only the dividing cells that dominate a tumor’s bulk but also the quiet, metabolically rewired survivors that hide among them. As the authors conclude, GDH1 stands out as a crucial regulator of persister survival, and drugs aimed at this mitochondrial gatekeeper may represent a promising path toward overcoming chemoresistance in one of breast cancer’s most feared forms.

Subject of Research: Role of glutamate dehydrogenase 1 in the survival of drug-tolerant persister cells in triple-negative breast cancer

Article Title: Glutamate dehydrogenase 1 (GDH1) sustains triple-negative breast cancer persister cell survival by coordinating mitochondrial fusion and anaplerotic flux

Article References: Dey, B., Chatterjee, E., Pandey, N., Singh, H., Basak, S., Kumar, R., Sharma, A., Bhalerao, H. A., Dharavath, A., S., S. L., Singh, P. K., Sonti, R., Naik, P. K., Doijad, N., & Guru, S. K. (2026). Glutamate dehydrogenase 1 (GDH1) sustains triple-negative breast cancer persister cell survival by coordinating mitochondrial fusion and anaplerotic flux. Cellular and Molecular Life Sciences. https://doi.org/10.1007/s00018-026-06316-9

Image Credits: AI Generated

DOI: 10.1007/s00018-026-06316-9

Keywords: triple-negative breast cancer, GDH1, drug-tolerant persister cells, mitochondrial fusion, anaplerotic flux, glutaminolysis, EMT, chemoresistance, cancer metabolism, MFN2, DRP1, tumor recurrence