Anti‑tumor effects of perampanel in malignant glioma cells

Glioblastoma has a poor prognosis even after multimodal treatment, such as surgery, chemotherapy and radiation therapy. Patients with glioblastoma frequently develop epileptic seizures during the clinical course of the disease and often require antiepileptic drugs. Therefore, agents with both antiepileptic and antitumoral effects may be very useful for glioblastoma treatment. Perampanel, an α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor antagonist, is an antiepileptic drug that is widely used for intractable epilepsy. The present study aimed to assess the potential antitumoral effects of perampanel using malignant glioma cell lines. The cell proliferation inhibitory effect was evaluated using six malignant glioma cell lines (A-172, AM-38, T98G, U-138MG, U-251MG and YH-13). A dose-dependent inhibitory effect of perampanel on cell viability was demonstrated; however, the sensitivity of cells to perampanel varied and further antitumoral effects were demonstrated in combination with temozolomide (TMZ) in certain malignant glioma cells. Furthermore, cell cycle distribution and apoptosis induction analyses were performed in T98G and U-251MG cells using a fluorescence activated cell sorter (FACS) and the expression levels of apoptosis-related proteins were evaluated using western blotting. No significant change was demonstrated in the proportions of cells in the G0/G1, S and G2/M phases under 1.0 µM perampanel treatment, whereas induction of apoptosis was demonstrated using FACS at 10 µM perampanel and western blotting at 1.0 µM perampanel in both glioma cell lines. Overexpression of SERPINE1 may be related to poor prognosis in patients with gliomas. The combination of 1.0 µM perampanel and 5.0 µM tiplaxtinin, a SERPINE1 inhibitor, demonstrated further reduced cell viability in perampanel-resistant U-138MG cells, which have high expression levels of SERPINE1. These results indicated that the antitumor effect of perampanel may not be expected for malignant gliomas with higher expression levels of SERPINE1. The findings of the present study suggested that the antiepileptic drug perampanel may also have an antitumor effect through the induction of apoptosis, which is increased when combined with TMZ in certain malignant glioma cells. These findings also suggested that SERPINE1 expression may be involved in perampanel susceptibility. These results may lead to new therapeutic strategies for malignant glioma.

Interleukin-6 sensitizes TNF-α and TRAIL/Apo2L dependent cell death through upregulation of death receptors in human cancer cells

Interleukin-6 (IL-6) enhanced TNF-α and TRAIL/Apo2L induced cell death in various human cancer cells derived from malignant glioma, melanoma, breast cancer and leukemia, although the effect was not detected with IL-6 alone. The effects of IL-6 using SKBR3 cells were associated with the generation of apoptotic cells as analyzed by fluorescence microscopy and flow cytometry. IL-6 activated p53 and upregulated TRAIL death receptors (DR-4 and DR-5) and stimulated the TNF-α and TRAIL dependent extrinsic apoptotic pathway without activation of the p53 mediated intrinsic apoptotic pathway. TNF-α and TRAIL induced cleavage of caspase-8 and caspase-3 was more enhanced by IL-6, although these caspases were not cleaved by IL-6 alone. The dead cell generation elicited by the combination with IL-6 was blocked by anti-human TRAIL R2/TNFRSF10B Fc chimera antibody which can neutralize the DR-5 mediated death signal. These findings indicate that IL-6 could contribute to the enhancement of TNF-α or TRAIL induced apoptosis through p53 dependent upregulation of DR-4 and DR-5. The data suggest that a favorable therapeutic interaction could occur between TNF-α or TRAIL and IL-6, and provide an experimental basis for rational clinical treatments in various cancers.

Antitumor effect of lenalidomide in malignant glioma cell lines

Glioblastoma is a malignant brain tumor exhibiting highly aggressive proliferation and invasion capacities. Despite treatment by aggressive surgical resection and adjuvant therapy including temozolomide and radiation therapy, patient prognosis remains poor. Lenalidomide, a derivative of thalidomide, is known to be an immunomodulatory agent that has been used to treat hematopoietic malignancies. There are numerous studies revealing an antitumor effect of lenalidomide in hematopoietic cells, but not in glioma cells. The present study aimed to demonstrate the antitumor effect of lenalidomide on malignant glioma cell lines. The growth inhibition of malignant glioma cells (A-172, AM-38, T98G, U-138MG, U-251MG, and YH-13) by lenalidomide was assessed using a Coulter counter. The mechanism of the antitumor effect of lenalidomide was examined employing a fluorescence-activated cell sorter, western blot analysis, and quantitative real-time reverse transcriptional polymerase chain reaction (RT-qPCR) in malignant glioma cell lines (A-172, AM-38). The results revealed that the number of malignant glioma cells was decreased in a concentration-dependent manner by lenalidomide. DNA flow cytometric analysis demonstrated an increase in the ratio of cells at the G₀/G₁ phase following lenalidomide treatment. Western blot analysis and RT-qPCR revealed that p53 activation and the expression of p21 were increased in glioma cells treated with lenalidomide. Western blot analysis revealed that cleavage of PARP did not occur; however, increased expression of Bax protein, cleavage of caspase-9 and cleavage of caspase-3 were confirmed. Analysis by FACS also supported the conclusion that little apoptosis induction occurred following lenalidomide treatment of malignant glioma cell lines. In conclusion, lenalidomide exerts an antitumor effect on glioma cells due to alterations in cell cycle distribution.

Indoleamine 2,3-dioxygenase 1 is highly expressed in glioma stem cells

Recent research has revealed that glioblastoma (GBM) avoids the immune system via strong expression of indoleamine 2,3-dioxygenase 1 (IDO1). IDO1, an enzyme involved in tryptophan metabolism, is now proposed as a new target in GBM treatment, since several reports have demonstrated that IDO1 expression is related to GBM malignancy. On the other hand, it is well known that glioma stem cells (GSCs) are strongly related to the malignancy of GBM. However, there is as yet no report evaluating the relationship between GSCs and IDO1. We therefore examined the expression levels of IDO1 in GSCs in order to identify a new therapeutic target for GBM based on the immune systems of GSCs. In the present study, we employed human GBM cell lines (U-138MG, U-251MG) and patient-derived GSC model cell lines (0125-GSC, 0222-GSC). GSC model cell lines Rev-U-138MG and Rev-U-251MG were established by culturing U-138MG and U-251MG in serum-free media, while differentiated GBM model cell lines 0125-DGC and 0222-DGC were established by culturing 0125-GSC and 0222-GSC in serum-containing media. The expression levels of stem cell markers (Nanog, Nestin, Oct4 and Sox2) and IDO1 protein and mRNA were determined. Rev-U-138MG and Rev-U-251MG formed spheres and their expression levels of stem cell markers were increased as compared to U-138MG and U-251MG. On the other hand, 0125-DGC and 0222-DGC suffered breakdown of sphere formation, despite the original 0125-GSC and 0222-GSC forming spheres, and their expression levels of the markers were decreased. IDO1 expressions were strongly recognized in Rev-U-138MG, Rev-U-251MG, 0125-GSC and 0222-GSC as compared to U-138MG, U-251MG, 0125-DGC and 0222-DGC. These findings demonstrate that GSCs exhibit treatment resistance with immunosuppression via high expression levels of IDO1, and could represent a novel target for GBM treatment.

IFN‑β sensitizes TRAIL‑induced apoptosis by upregulation of death receptor 5 in malignant glioma cells

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a member of the tumor necrosis factor (TNF) family, induces apoptosis in cancer cells by binding to its receptors, death receptor 4 (DR4) and DR5, without affecting normal cells, and is therefore considered to be a promising antitumor agent for use in cancer treatment. However, several studies have indicated that most glioma cell lines display resistance to TRAIL-induced apoptosis. To overcome such resistance and to improve the efficacy of TRAIL-based therapies, identification of ideal agents for combinational treatment is important for achieving rational clinical treatment in glioblastoma patients. The main aim of this study was to investigate whether interferon-β (IFN-β) (with its pleiotropic antitumor activities) could sensitize malignant glioma cells to TRAIL-induced apoptosis using glioma cell lines. TRAIL exhibited a dose-dependent antitumor effect in all of the 7 types of malignant glioma cell lines, although the intensity of the effect varied among the cell lines. In addition, combined treatment with TRAIL (low clinical dose: 1 ng/ml) and IFN-β (clinically relevant concentration: 10 IU/ml) in A-172, AM-38, T98G, U-138MG and U-251MG demonstrated a more marked antitumor effect than TRAIL alone. Furthermore, the antitumor effect of the combined treatment with TRAIL and IFN-β may be enhanced via an extrinsic apoptotic system, and upregulation of DR5 was revealed to play an important role in this process in U-138MG cells. These findings provide an experimental basis to suggest that combined treatment with TRAIL and IFN-β may offer a new therapeutic strategy for malignant gliomas.

Papillary glioblastoma exhibiting a neuroradiological cyst with a mural nodule: A case report

RATIONALE

Glioblastomas are malignant, infiltrating gliomas classified as grade IV by the World Health Organization. Genetically, most glioblastomas do not exhibit the isocitrate dehydrogenase (IDH) 1/2 gene mutation and rarely harbor the 1p/19q co-deletion. Neuroradiologically, glioblastomas rarely form a cyst with a mural nodule lesion.

PATIENT CONCERNS

In this study, a 78-year-old woman, with speech difficulty and forgetfulness, had a cystic tumor with a mural nodule in the right frontoparietal lobe. Therefore, partial tumor resection was performed.

DIAGNOSIS

Histopathology of the tumor, a glioblastoma, exhibited pseudopapillary features with non-hyalinized capillary cores and rich mini-gemistocytic cells. Genetic analysis of the tumor revealed co-deletion of 1p36/19q13, with wild-type IDH.

INTERVENTIONS

The patient underwent a combination of postoperative radiotherapy and temozolomide chemotherapy before leaving the hospital. After discharge, she was treated by 20 courses of temozolomide chemotherapy.

OUTCOMES

The patient is free from tumor recurrence 23 months after the operation.

LESSONS

We present a unique case of glioblastoma that exhibited novel neuroradiological, histopathological, and genetic features with a favorable prognosis for the patient. Therefore, a compilation of similar cases with clinicopathological and genetic analyses to characterize this unique glioblastoma is critical. Clinical evidence will help develop effective therapeutic approaches to improve prognosis in patients with glioblastoma.

A symptomatic large subependymoma with neuroradiological features mimicking a high-grade glioma: A case report

A subependymoma is a benign primary brain tumor classified as a World Health Organization grade I tumor; it is asymptomatic in most cases. We present the case of a 66-year-old Japanese man with a complaint of recurrent vomiting that led to the discovery of a large mass with hemorrhage, peritumoral edema, and a midline shift in the posterior horn of the right lateral ventricle. The patient was pathologically diagnosed with subependymoma after undergoing total tumor resection; a year after the surgery, he was free from tumor recurrence. Although symptomatic subependymomas are rare, they tend to show hemorrhage with peritumoral edema on neuroradiological tests and tend to be confused with high-grade brain tumors. In the present case, we highlight the importance of the appropriate diagnosis for subependymomas showing neuroradiological features that mimic high-grade gliomas. This diagnosis will help in providing suitable treatment for subependymomas.

Glioblastoma fed by middle meningeal artery and displaying cyst formation soon after repeated implantation of carmustine wafers: A case report

The present study reported an unusual case of temporal lobe glioblastoma (GBM) fed from the middle meningeal artery that progressed rapidly. A 66-year-old male was admitted to the Department of Neurosurgery at Nihon University Itabashi Hosipital (Tokyo, Japan) with epilepsy. Magnetic resonance imaging disclosed a small well-enhanced right middle fossa mass lesion, which was relatively boundary-clear and attached to the dura mater. An angiogram showed a stain fed from the right middle meningeal artery. The mass lesion was removed completely by surgery and diagnosed pathologically as GBM. Tumor recurrence was observed 6 months later and a second surgery was performed. Eight pieces of carmustine wafers were implanted in the tumor resection cavity at the first and second surgeries. The patient underwent a third surgery soon after the second surgery, as a cyst had formed in the resection cavity. The tumor became uncontrollable and the patient died at 11 months after the first surgery even though he had undergone multimodality treatment. Since GBM fed by the middle meningeal artery is rare, the timing of surgical treatment is difficult as it is easy to misdiagnose a case like the present one as a meningioma. Furthermore, repeated implantation of carmustine wafers should be considered carefully, since adverse events associated with such wafers may easily occur.

A case of symptomatic granular cell tumor of the sellar region with large calcification

We report here a rare case of symptomatic granular cell tumor (GCT) of the sellar region with a large calcification. A 70-year-old woman presented with a sellar mass, accompanied by bitemporal hemianopia. The patient was diagnosed preoperatively as having a craniopharyngioma or a pituitary adenoma, because of the large calcification. The patient underwent surgical tumor resection via endoscopic trans-sphenoidal surgery and was diagnosed pathologically as having GCT. The patient's postoperative course was uneventful and her visual field disturbance improved soon after the operation. We briefly discuss the pathological discrimination of GCT and other sellar tumors, since there are many unclear points concerning this rare tumor.