SSTR2 is a prognostic factor and a promising therapeutic target in glioma

Gliomas are the most prevalent primary malignant central nervous system tumors among all tumors occurring in the brain and spinal cord. The poor outcome of glioma requires the discovery of novel biomarkers with potential therapeutic value. Somatostatin receptor subtype 2 (SSTR2) represents a diagnostic biomarker and potential therapeutic target in many cancers, such as meningioma and neuroendocrine tumors (NETs). However, the relationship of SSTR2 and glioma was unclear. Therefore, this study aimed to investigate the expression of SSTR2 and assess its prognostic and potential therapeutic value in a large cohort of patients with WHO grade I to IV glioma from a single Chinese center. Immunohistochemical analysis revealed that SSTR2 was highly expressed in 23.84% (72 of 302) of glioma (I-IV grade) samples. Among all glioma subtypes, high SSTR2 expression was detected mainly in oligodendroglioma, anaplastic oligodendroglioma, and astrocytoma, whereas SSTR2 was expressed at a low level, or not at all, in glioblastoma. Western blotting also confirmed the low expression of SSTR2 in glioblastoma cell lines. Statistical analysis showed that SSTR2 protein expression correlated significantly with WHO grade, the location of the tumor, epilepsy syndrome, mitosis (PHH3), proliferation index (Ki-67), IDH and 1p/19q-codeleted status. Kaplan-Meier analysis indicated that SSTR2 high expression was a good prognostic factor in glioma. In summary, this study demonstrated that SSTR2 might be a valuable prognostic factor and therapeutic target in certain glioma subtypes.