Epigallocatechin Gallate Preferentially Inhibits O6-Methylguanine DNA-Methyltransferase Expression in Glioblastoma Cells Rather than in Nontumor Glial Cells.

OBJECTIVE: O6-methylguanine (O6-meG) DNA-methyltransferase (MGMT) is a main regulator of temozolomide (TMZ) resistance in glioblastomas. Some MGMT inhibitors have been studied in clinical trials but with very little success, because their inhibiting effects were not tumor-selective, and often cause severe toxicity in normal tissues in the presence of TMZ. The goal of this study is to explore whether Epigallocatechin gallate (EGCG), a natural small molecule, could preferentially modulate MGMT in glioblastoma cells. METHODS: Two MGMT-positive glioblastoma cell lines (GBM-XD and T98G) and one nontumor glial cell culture (GliaX) were included in this study. The MGMT promoter methylation status, mRNA abundance, and protein levels were determined before and after EGCG treatment. The mechanisms were characterized. RESULTS: EGCG substantially suppressed mRNA and protein expression of MGMT, and reversed TMZ resistance in MGMT-positive GBM-XD and T98G cells via the WNT/ß-catenin pathway. EGCG prevented ß-catenin translocation into the nucleus and might directly inhibit the transcription factors TCF1 and LEF1. Meanwhile, EGCG enhanced the MGMT expression in the nontumor glial cells, through inhibition of the DNMT1 and demethylation of MGMT promoter. CONCLUSIONS: EGCG preferentially inhibits MGMT and enhances TMZ cytotoxicity in glioblastoma cells rather than in nontumor glial cells.

Trephination mini-craniectomy for traumatic posterior fossa epidural hematomas in selected pediatric patients.

PURPOSE: Posterior fossa epidural hematomas (PFEDH) are uncommon in children but usually require timely surgical intervention due to the risk of life-threatening brainstem compression. We attempt to make the surgical procedure less invasive by treating selected pediatric patients with trephination mini-craniectomy. METHODS: We retrospectively reviewed the clinical courses, radiological findings, surgical procedures, and prognoses of the pediatric patients who were treated in our departments for traumatic PFEDH from January 2010 to January 2015. RESULTS: During this period, a total of 17 patients were surgically treated for PFEDH and 7 were managed with trephination mini-craniectomy for hematoma evacuation. The outcomes were good in all 7 patients as evaluated with Glasgow Outcome Score. There was no mortality in this series. The on average 30-month clinical follow-up showed that patients experienced satisfactory recoveries without complications. CONCLUSION: Our results suggest that trephination mini-craniectomy is a safe surgical technique for selected PFEDH patients with moderate hematoma volume and stabilized neurological functions. However, standard craniectomy is recommend when there are rapid deteriorations in patients' neurological functions or the hematomas are large and exerted severe mass effects.

Postoperative pneumocephalus increases the recurrence rate of chronic subdural hematoma.

OBJECTIVES: Pneumocephalus is a common operative complication of chronic subdural hematoma. This study is to analyze the relationship between postoperative pneumocephalus and the recurrence and surgical outcomes. PATIENTS AND METHODS: This is a retrospective case-cohort study, including a pneumocephalus group (n = 46) and a control group (n = 181). Their recurrence rates, CT attenuation values, hospital stay, healing time and the neurological status were recorded and analyzed. RESULTS: The pneumocephalus group had a recurrence rate of 32.6%, significantly higher than the control (17.7%). In addition, the pneumocephalus group had a higher rate of postoperative epilepsy (21.7% vs 3.3%), longer hospital stay (11.5 ±â€¯2.8 vs 7.8 ±â€¯1.2 days), longer healing time (10.8 ±â€¯5.4 vs 6.5 ±â€¯2.3 months), and worse neurological scores than the control. CONCLUSION: Pneumocephalus increases the recurrence rate of chronic subdural hematoma, and it not only prolongs the hospital stay and healing time, but also leads to deterioration of the neurological status.

FM19G11 inhibits O6 -methylguanine DNA-methyltransferase expression under both hypoxic and normoxic conditions.

FM19G11 is a small molecular agent that inhibits hypoxia-inducible factor-1-alpha (HIF-1α) and other signaling pathways. In this study, we characterized the modulating effects of FM19G11 on O6 -methylguanine DNA-methyltransferase (MGMT), the main regulator of temozolomide (TMZ) resistance in glioblastomas. This study included 2 MGMT-positive cell lines (GBM-XD and T98G). MGMT promoter methylation status, mRNA abundance, and protein levels were determined before and after FM19G11 treatment, and the roles of various signaling pathways were characterized. Under hypoxic conditions, MGMT mRNA and protein levels were significantly downregulated by FM19G11 via the HIF-1α pathway in both GBM-XD and T98G cells. In normoxic culture, T98G cells were strongly positive for MGMT, and MGMT expression was substantially downregulated by FM19G11 via the NF-κB pathway. In addition, TMZ resistance was reversed by treatment with FM19G11. Meanwhile, FM19G11 has no cytotoxicity at its effective dose. FM19G11 could potentially be used to counteract TMZ resistance in MGMT-positive glioblastomas.

Inhibition of the CyclinD1 promoter in response to sonic hedgehog signaling pathway transduction is mediated by Gli1.

Medulloblastoma (MB) is the most common malignant tumor of the central nervous system in children. Accumulating evidence suggests a major role for the activation of the sonic hedgehog (SHH) signaling pathway in the development of MB cells; however, the mechanisms underlying the effect of this pathway on tumor survival and growth remain poorly understood. The Gli family zinc finger 1 (Gli1) transcription factor is considered as a mediator of the SHH signaling pathway in MB cells. Therefore, the present study investigated whether the SHH signaling pathway promotes the apoptosis of MB cells via downregulation of Gli1. GANT61, a novel Gli1 inhibitor, is known to have an in vitro activity against tumors. In the current study, Daoy cells were treated with different concentrations of GANT61 for 24 h, and the effect on cell proliferation was assayed by cell counting kit-8 assay. In addition, the cell cycle progression and apoptosis were assayed by flow cytometry analysis and hematoxylin-eosin (HE) staining. The effects of GANT61 treatment on SHH signaling pathway at the mRNA level were assayed by polymerase chain reaction (PCR). To further elucidate the inhibitory effects of GANT61 on the expression of Gli1 and CyclinD1, their protein levels were examined by western blot and immunofluorescence. The results indicated that GANT61 significantly inhibited the proliferation of Daoy cells in a dose-dependent manner, compared with the control group (P<0.05). HE staining revealed that cells had increasingly abnormal protuberance with increasing GANT61 concentration. Flow cytometry analysis also demonstrated that GANT61 induced G1/S arrest and apoptosis of Daoy cells in a dose-dependent manner (P<0.05). Gli1 and CyclinD1 mRNA expression levels were downregulated by GANT61 treatment (P<0.05); similarly, their protein levels were downregulated by GANT61 treatment in a dose-dependent manner (P<0.05). In conclusion, Gli1 expression was significantly associated with CyclinD1 expression in MB. These data demonstrated that Gli1 is an important mediator of the SHH pathway activity in MB, and may be a novel agent for use in combined chemotherapeutic regimens.

Good Surgical Outcomes of Hemifacial Spasm Patients with Obvious Facial Nerve Indentation and Color Change.

OBJECTIVES: Hemifacial spasm results from vascular compression of the facial nerve. It remains controversial whether severe compression and subsequent nerve indentation predict a good or a poor surgical outcome. Here, to illustrate the relationship between the degree of neurovascular compression and surgical outcome, we conducted a retrospective case-cohort study focused on patients whose facial nerve was seriously compressed. METHODS: This study included 2 groups. The nerve-indentation group included 48 patients with hemifacial spasm whose facial nerves had obvious indentation and color change at the site of neurovascular conflict. The control group included 48 randomly selected patients with hemifacial spasm without facial nerve indentation or color change who were surgically treated by the same team during the same period. The surgical findings, intraoperative lateral spread response results, and clinical outcomes were compared. RESULTS: Single-vessel compression was found more frequently in the nerve-indentation group (87.5%) than in the control group (60.4%, P < 0.05). The lateral spread response (LSR) resolution rate of the nerve-indentation group was 91.7%, and that of the control group was 87.5% (P > 0.05). The rates at which the microvascular decompression procedure was successful were equal in the nerve-indentation and the control groups (93.8% vs. 91.7%, P > 0.05). CONCLUSIONS: Severe vascular compression and subsequent nerve indentation were correlated with a greater possibility of single compression and a lower incidence of multiple neurovascular conflicts in patients with hemifacial spasm, making the microvascular decompression procedure more accurate and easier. Therefore nerve indentation might predict good surgical outcomes.