Implications of the Cuproptosis Protein SLC31A1 for the Immune Microenvironment and Temozolomide Sensitivity in Glioblastoma

Background/Aim: Glioblastoma is the most common and aggressive primary malignant tumor in the adult central nervous system, with a high incidence rate. It accounts for approximately half of all gliomas, and its prognosis is extremely poor. Due to the difficulty in achieving complete surgical resection and the development of chemotherapy resistance, the median survival time of patients is only about 15 months. Recently, cuproptosis has been proposed as a new form of cell death, playing a crucial role in tumor-targeted therapy. This study aimed to investigate the distribution of the cuproptosis-related key protein SLC31A1 in the immune microenvironment of glioblastoma (GBM) and to evaluate the effect of cuproptosis agonists on temozolomide (TMZ) sensitivity.

Materials and Methods: We first analyzed GBM transcriptomic and single-cell sequencing data to explore the correlation between SLC31A1 and immune cell infiltration. Expression of SLC31A1 in tumor tissues was subsequently verified using immunohistochemistry, western blot, and quantitative fluorescence PCR. We then performed cell proliferation, scratch wound healing, and western blot assays to assess the inhibitory effect of TMZ combined with the cuproptosis agonist elesclomol (ES) on GBM cells and its influence on SLC31A1 protein expression. Finally, a xenograft tumor model was established to further validate the enhanced anti-tumor efficacy of the combination therapy.

Results: Bioinformatic analysis revealed that SLC31A1 expression was notably elevated in macrophages and microglia within GBM and showed a negative correlation with M1-type macrophages and T cells. Both in vitro and in vivo experiments demonstrated that the combination of TMZ and ES exerted a significantly stronger inhibitory effect on GBM proliferation and migration compared to TMZ alone. Moreover, combined treatment upregulated the protein expression of SLC31A1.

Conclusion: The cuproptosis pathway and its key protein SLC31A1 play a potential role in regulating GBM proliferation, migration, and TMZ sensitivity, and is closely associated with the tumor immune microenvironment, particularly macrophages. These findings may contribute to the selection of more effective clinical treatment strategies.