Chronic stress promotes oral squamous cell carcinoma progression via GLUD1-mediated metabolic reprogramming.

Stress is a risk factor for the development of various types of cancer. However, its impact and related underlying mechanisms in oral squamous cell carcinoma (OSCC) progression remain unclear. Therefore, the present study aimed to investigate how chronic stress affects OSCC progression. We assessed mitochondrial metabolism by investigating tumor growth and performing behavioral analysis and molecular assessment, including non-targeted metabolomics and U-13C5-glutamine isotope metabolic flow analysis. We knocked down glutamate dehydrogenase 1 (GLUD1) using lentiviral vectors and investigated it both in vitro (HSC3 and HN6 cells) and in vivo (xenograft models). Our results indicated that chronic stress enhanced glutamate oxidative deamination and tricarboxylic acid cycle metabolism in OSCC cells. It also increased α-ketoglutarate (α-KG) levels, adenosine triphosphate synthesis, and oxygen consumption. Notably, GLUD1-knockdown suppressed these metabolic pathways and significantly inhibited tumor growth both in vitro and in vivo. Furthermore, under chronic stress, GLUD1 regulated OSCC progression through histone H3 trimethylation at lysine 4. However, α-KG supplementation partially reversed GLUD1-knockdown-induced OSCC progression inhibition. Collectively, our results indicate that the glutamate-dependent metabolic phenotype regulated by the GLUD1-α-KG metabolic axis is involved in the progression of OSCC under chronic stress.