MATERIAL and METHODS: This study included 15 brain tumor tissues [pituitary adenoma (1), pilocytic astrocytoma (1), mixed meningioma (2), mesothelial meningioma (2), atypical meningioma (1), immature teratoma (1), glioblastoma (4), meningioma (2), and bladder cancer metastasis (1)]. The expression levels of genes in brain tumor tissues were analyzed using real-time PCR. Sanger sequencing was performed to identify the IDH1 gene R132H codon.

RESULTS: All cases were wild-type in terms of IDH1 R132H: nucleotide 395 G>A; codon CGT>CAT. The mRNA level of PDK1 was lower in grade I tumor tissues (0.675-fold) and increased in grades II-III-IV (7.135, 16.912, and 7.081-fold, respectively) (p<0.001). The mRNA level of SLC2A1 decreased in all grades I-II-III-IV [(0.424-, 0.093-, 0.234 (p<0.001), and 0.141-fold (p<0.005), respectively)]. The mRNA level of EGFR increased in all grades I-II-III-IV [1.388, 5.452 (p<0.017), 4.624-, and 4.137-fold, respectively]. The mRNA level of PTEN increased in grades I-II-III [1.802-, 1.702-, and 1.5-fold, respectively] and decreased in grade IV (0.176-fold). The mRNA level of CD276 increased in all grades I-II-III-IV [1.8-, 5.756-(p<0.001), 10.303 (p<0.001), and 2.5-fold, respectively].

CONCLUSION: We obtained similar findings for previously reported PDK1, EGFR, PTEN, and CD276 gene expression levels. In contrast, SLC2A1 expression was markedly downregulated, as reported in other tumor studies. These findings may be due to the unique nature of brain tumor tissues. Additionally, a decrease in PTEN gene expression has been observed in grade IV brain tumors, including glioblastoma and meningioma. Although the size of the analyzed study group was limited, the gene expression results showed similarities in the behavior of genes during cancer staging. Keywords : IDH1, PDK1, SLC2A1, EGFR, PTEN, CD276, brain tumors