Association of Klotho Gene Polymorphism and Serum Level of α Klotho Protein with Different Tumor Grades, Overall Survival and Cytokine Profile in Glioma Patients

Gliomas are the most common and lethal forms of malignant brain tumors. We attempted to identify the role of the aging-suppressor Klotho gene and Klotho protein in the immunopathogenesis of gliomas. We examined Klotho genetic variants by PCR-RFLP and measured serum Klotho levels using the ELISA method. We found a statistically significantly increased frequency of rs1207568A allele and rs1207568 GA genotypes in co-dominant, dominant and over-dominant models in grade IV as compared to grade II and III glioma patients. The levels of soluble α Klotho (sαKL) were significantly lower in grade III and IV glioma patients than in healthy controls (p = 0.034; 0.0083). Patients with sαKL levels above 2500 pg/mL survived significantly longer than patients with sαKL below 2500 pg/mL (p = 0.038). We also found a positive correlation of the serum levels of sαKL with seven biomarkers, like angiogenic vascular endothelial growth factor (p = 0.0008), chemokine fractalkine (p = 0.0009), interferon γ (p = 0.003), glial derived neurotrophic factor (p = 0.0268), pro-inflammatory and pro-Th1 cytokine IL-6 (p = 0.0347), anti-inflammatory, pro-Th2 cytokines IL-4 (p = 0.0037) and IL-13 (p = 0.0004). Our results suggest the impact of Klotho genetic variants and Klotho levels on advanced-grade glioma.