007 | Dysregulation of the trans-sulfuration-sphingosine-1-phosphate signaling axis in glioblastoma: preclinical evidence

Elsa Calcaterra¹, Michela Campolo¹, Melania Correale², Rossella Basilotta¹, Maria Caffo³, Roberta D’Emmanuele Di Villa Bianca², Emma Mitidieri², Giovanna Casili¹, Emanuela Esposito¹ | ¹Department of Chemical, Biological, Pharmaceutical, Environmental Sciences, University of Messina, Italy; ²Department of Pharmacy, School of Medicine and Surgery, University of Study of Naples - Federico II, Naples, Italy; ³Unit of Neurosurgery, Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Italy.

Sphingosine-1-phosphate (S1P) is a bioactive lipid that promotes the progression of several cancers, including glioblastoma multiforme (GBM), the most aggressive primary brain tumor. Emerging evidence suggests that S1P biosynthesis is linked to L-serine availability, which can derive from the transsulfuration pathway during cystathionine β-synthase (CBS)–mediated conversion of L-cysteine to hydrogen sulfide (H₂S). H₂S is a gaseous neurotransmitter with complex and still controversial roles in GBM biology. This study aimed to define the contribution of transsulfuration-derived H₂S and its interplay with S1P signaling in GBM using an in vivo model. A GBM xenograft model was employed to investigate modulation of the L-cysteine/H₂S/L-serine/S1P axis. Expression of key enzymes involved in this pathway—CBS, 3-mercaptopyruvate sulfurtransferase (3-MST), serine palmitoyltransferase (SPT), and neuronal and inducible nitric oxide synthases (nNOS and iNOS)—was assessed by immunohistochemistry and RT-PCR. Intratumoral levels of H₂S, S1P, and nitric oxide (NO) were quantified and compared with control tissues. GBM xenografts exhibited marked upregulation of CBS and 3-MST, indicating enhanced trans-sulfuration pathway activity, while cystathionine γ-lyase (CSE) expression remained unchanged, suggesting a GBM-specific enzymatic profile. SPT expression was significantly elevated, consistent with increased S1P biosynthetic capacity. In parallel, both nNOS and iNOS were robustly upregulated. Biochemical analyses confirmed significantly increased intratumoral concentrations of H₂S, S1P, and NO, supporting coordinated activation of this metabolic and signaling axis. In conclusion these findings reveal a hyperactivated L-cysteine/H₂S/L-serine/S1P pathway in GBM and identify a mechanistic link between H₂S signaling and S1P production in vivo. This axis may contribute to tumor growth, invasiveness, and microenvironmental remodeling, and represents a potential therapeutic target for modulating GBM progression and blood–brain barrier dynamics.