ABSTRACT. Hypomethylation of the O6-methylguanine-DNAmethyltransferase (MGMT) promoter in glioma cells has been associated with temozolomide resistance. S-adenosylmethionine (SAM), which is produced during folate metabolism, is the main source of methyl groups during DNA methylation. As a key enzyme during folate metabolism, polymorphisms of 5,10-methylenetetrahydrofolate reductase (MTHFR) may regulate folate end-products. We investigated the effect of typical polymorphisms of MTHFR (C677T and A1298C) on MGMT methylation based on different serum folate levels in patients with glioma from Northeast China. A total of 275 patients with glioma and 329 without malignant MTHFR polymorphisms and MGMT methylation tumors were tested. Serum folate concentration was assayed by using the electrochemiluminescence immunoassay. MTHFR polymorphisms were detected by Taqman-Fluorescence quantitative polymerase chain reaction (PCR). Methylation-specific PCR was used to assess MGMT methylation. The constituent ratio of glioma patients below the serum folate biological reference value was significantly higher than that of the control population (P < 0.001). In patients with oligodendroglioma and glioblastoma, heterozygotes for the A1298C mutation were found in higher frequency than homozygotes or wild types (oligodendroglioma, P < 0.001; glioblastoma, P < 0.01). When grouped by the median or biological reference value of serum folate, only homozygotes for C677T with low levels of folate were significantly associated with decreased methylation of MGMT (median, P < 0.001; biological reference value, P = 0.036). These data suggest that, in combination with a negative folate balance in glioma patients, T/T genotypes in MTHFR C677T may be associated with MGMT demethylation.

Purpose/Objective(s): Poor prognosis of high grade glioma (HGG) is attributed to an intrinsic tumor radio-and chemo-resistance. Ataxia-telangiectasia mutated (ATM) gene encodes a serine/threonine protein kinase activated by autophosphorylated upon DNA double strand breaks arising from ionizing radiation. To identify the association of somatic mATM with improved radiotherapy (RT) sensitivity, we retrospectively reviewed the next-generation sequencing data from HGG patients. Materials/Methods: This analysis includes 45 individuals diagnosed with HGG (diffuse astrocytoma IDH-wild type nZ2, anaplastic astrocytoma nZ16, and glioblastoma nZ27) between June 2017 and September 2018. Patients who underwent subtotal (nZ28, 62.2%), partial (nZ16, 35.6%) removal or biopsy (nZ1, 2.2%) were included in this analysis for interpreting radio-sensitivity of residual tumor. After diagnosis, most representative FFPE specimens were analyzed by next generation sequencing with a TruSight Tumor 170 (TST-170) cancer panel. Most patients underwent follow-up MRI 1 month after the planned RT as well as every 3 months for the first 2 years, and every 6 to 12 months thereafter. New enhancing lesions on Gd-enhanced T1-weighted MRI or increased extent on T2-weighted MRI within the radiation field without evidence of progression from MR spectroscopy or perfusion MRI were defined as radiation-related change (RC). Disease progression was defined by RANO criteria as well as neurologic and clinical findings. Results: Among 45 samples, mATM was detected in 15.6% of cases (nZ7). There was no significant difference in patient or tumor characteristics between mATM and wild-type patients. Among mATM patients, there were 4 patients with glioblastoma and 3 patients with anaplastic astrocytoma IDH-wildtype. Most mutation was missense mutation (nZ6, 85.7%). Median variant allele frequency was 46.3% (Interquartile range, IQR, 6.5-79.9%). Median follow-up duration after RT was 8.1 (IQR, 6.0-12.2) months. RC was observed in 29 patients (64.4%). Tumors with mATM were related to higher frequency of RC than tumors without mATM; 6-month cumulative incidence was 85.7% and 54.1%, respectively (p Z 0.031). Median interval to development in radiation-related change was shorter than in ATM mutation group (median 0.8 (IQR, 0.3-1.2) versus. 1.3 (IQR, 0.9-3.8) months, p Z 0.075). Among 29 cases with RC, there was no progression until last follow-up in tumors with mATM while almost half of cases without mATM progressed. Although there was no statistical difference in survival outcome, cases with mATM exhibited excellent outcomes; 1-year overall survival 100% vs. 74.2% (p Z 0.210) and 1-year progression free survival 100% vs. 44.6% (p Z 0.061). Conclusion: Our results demonstrated that mATM is involved in radiosensitivity with immediate RC after RT followed by favorable RC and clinical outcome beyond the aggressive nature of HGG. Further studies are necessary to uncover the potential role of ATM as candidate therapeutic targets in HGG.