The changing management of low-grade astrocytomas and oligodendrogliomas

Hsa-mir-127 impairs survival of patients with glioma and promotes proliferation, migration and invasion of cancerous cells by modulating replication initiator 1

This work aimed to investigate the inter-regulatory functions of hsa-mir-127 and replication initiator 1 (REPIN1) on the proliferation and metastasis of glioma cells. The in-silico data on the implication of hsa-mir-127 and REPIN1 in glioma were retrieved from The Cancer Genome Atlas (TCGA). The expression levels of hsa-mir-127 and REPIN1 mRNA were determined by qRT-PCR, whereas Western blot was used to detect REPIN1 protein expression in glioma cell lines. The proliferation of glioma cells was determined by means of the MTT assay, whereas the transwell assay was employed for assessing the extent of cell migration and invasion. The interaction among REPIN1 and hsa-mir-127 was checked using the luciferase reporter assay. The expression of hsa-mir-127 was markedly increased in clinical data obtained from TCGA and in glioma cells compared with normal tissues and control cells, respectively. Increased expression of hsa-mir-127 and decreased expression of REPIN1 were both associated with poor overall survival. Moreover, hsa-mir-127 overexpression noticeably promoted proliferation, inhibited apoptosis and increased the invasive and migratory capacities of glioma cells. Inverse effects were found with hsa-mir-127 antisense inhibitor. Interestingly, overexpression of hsa-mir-127 downregulated REPIN1 expression, and luciferase reporter assay showed that the tumorigenesis effect of hsa-mir-127 requires, in part, its direct targeting of REPIN1. In conclusion, the hsa-mir-127/REPIN1 pathway is involved in gliomas and could be a potential therapeutic target.

Usefulness of ¹¹C-methionine positron emission tomography for treatment-decision making in cases of non-enhancing glioma-like brain lesions

The present study evaluated usefulness of the positron emission tomography with (11)C-methionine for prediction of the clinical course and treatment decision-making in adult patients with newly diagnosed non-enhancing brain lesions mimicking low-grade gliomas. Retrospective analysis was done in 163 cases. In overall, 131 tumors underwent surgical resection, which in 34 cases was done after initial period of observation. Among the latter 5 patients were operated on after significant clinical deterioration. In overall, 3 resected neoplasms corresponded to WHO histopathological grade I, 87 to grade II, 39 to grade III, and 2 to grade IV. In all 163 cases the tumor/normal brain uptake ratio (T/N ratio) of (11)C-methionine ranged from 0.68 to 8.02 (mean 2.21 ± 1.16, median 1.81). Mean T/N ratios of non-operated lesions, low-grade and high-grade tumors were 1.60 ± 0.85, 2.27 ± 1.22, and 2.54 ± 1.09, respectively (P < 0.0001), but overlap between 3 groups was prominent. In patients who had clinical deterioration during the period of observation T/N ratios of the lesion varied from 1.49 to 3.38 (mean 2.23 ± 0.70, median 2.15). Comparison of the deterioration-free survival of patients with T/N ratios of the lesion above and below 1.90 revealed statistically significant difference (P < 0.0001). In conclusion, "wait-and-scan" strategy with delay of surgical treatment does not seem reasonable option if T/N ratio of (11)C-methionine in the non-enhancing glioma-like brain lesion constitutes ≥1.90, since it may be associated with significant risk of tumor progression and clinical deterioration during follow-up.

Radiation Therapy Oncology Group 9802: Controversy or Consensus in the Treatment of Newly Diagnosed Low-Grade Glioma?

Treatment of newly diagnosed or suspected low-grade glioma (LGG) is one of the most controversial areas in neuro-oncology. The heterogeneity of these tumors, concern regarding morbidity of treatment, and absence of proven overall survival benefit from any known treatment have resulted in a lack of consensus regarding the timing and extent of surgery, timing of radiotherapy (RT), and role of chemotherapy. The long-term results of Radiation Therapy Oncology Group (RTOG) 9802, a phase III randomized trial comparing RT alone with RT and 6 cycles of adjuvant procarbazine, CCNU, vincristine (PCV), demonstrated an unprecedented 5.5-year improvement in median overall survival with the addition of PCV chemotherapy in high-risk patients with LGG. These results are practice changing and define a new standard of care for these patients. However, in the intervening decade since the trial was completed, novel molecular markers as well as newer chemotherapy agents such as temozolomide have been developed, which make these results difficult to incorporate into clinical practice. This review summarizes the evidence for and against the role of upfront RT and PCV in newly diagnosed patients with LGG.

Supratentorial WHO grade II glioma invasion: a morphologic study using sequential conventional MRI

The natural morphological growth and invasion of World Health Organization (WHO) grade II glioma has not been well documented in previous literature. This study retrospectively analysed the morphological invasive characteristics of adult. Data from 20 patients (15 men, 5 women; mean age, 38 years; age range, 22-64 years), who had supratentorial WHO grade II gliomas and consecutively underwent serial preoperative conventional MR examinations were retrospectively analysed, for change in location, and evidence of haemorrhage, enhancement, necrosis, peri-tumoural oedema and mass effect. Seven tumours, initially located in the grey matter (3, insula; 4, frontal cortices), expanded without definite invasion along fibres. Thirteen tumours, originated from the junction of grey and white matter, invaded in different orientations (4, contralateral invasion; 1, ipsilateral remote dissemination; 8, ipsilateral invasion via the surrounding fibres). The increased proportion of haemorrhage, enhancement, necrosis, peri-tumoural oedema and mass effect in the first and last pre-operative examinations were 14% (1/7), 29% (2/7), 43% (3/7), 43% (3/7) and 29% (2/7), respectively, for the 7 tumours initially located in grey matter, and 15% (2/13), 38% (5/13), 31% (4/13), 15% (2/13) and 38% (5/13) respectively for the 13 tumours initially located at the junction of grey and white matter. The growth of supratentorial WHO grade II glioma is a complicated process. The growth directionality may be determined by initial tumour location.

Activation of PI3K/mTOR pathway occurs in most adult low-grade gliomas and predicts patient survival

Recent evidence suggests the Akt-mTOR pathway may play a role in development of low-grade gliomas (LGG). We sought to evaluate whether activation of this pathway correlates with survival in LGG by examining expression patterns of proteins within this pathway. Forty-five LGG tumor specimens from newly diagnosed patients were analyzed for methylation of the putative 5′-promoter region of PTEN using methylation-specific PCR as well as phosphorylation of S6 and PRAS40 and expression of PTEN protein using immunohistochemistry. Relationships between molecular markers and overall survival (OS) were assessed using Kaplan-Meier methods and exact log-rank test. Correlation between molecular markers was determined using the Mann-Whitney U and Spearman Rank Correlation tests. Eight of the 26 patients with methylated PTEN died, as compared to 1 of 19 without methylation. There was a trend towards statistical significance, with PTEN methylated patients having decreased survival (P = 0.128). Eight of 29 patients that expressed phospho-S6 died, whereas all 9 patients lacking p-S6 expression were alive at last follow-up. There was an inverse relationship between expression of phospho-S6 and survival (P = 0.029). There was a trend towards decreased survival in patients expressing phospho-PRAS40 (P = 0.077). Analyses of relationships between molecular markers demonstrated a statistically significant positive correlation between expression of p-S6(235) and p-PRAS40 (P = 0.04); expression of p-S6(240) correlated positively with PTEN methylation (P = 0.04) and negatively with PTEN expression (P = 0.03). Survival of LGG patients correlates with phosphorylation of S6 protein. This relationship supports the use of selective mTOR inhibitors in the treatment of low grade glioma.