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.

High-dose-infliximab-associated Cerebral Venous Sinus Thrombosis: A Case Report and Review of the Literature

A 28-year-old woman experienced severe headache and right homonymous hemianopia after receiving high-dose infliximab for Crohn's disease. Computed tomography showed hemorrhagic infarction in the left temporal and parietal lobes. An angiogram revealed left transverse to sigmoid sinus occlusion and a stagnated Labbe vein. The patient was treated surgically and achieved a good outcome. Inflammatory bowel diseases are known to accompany venous and arterial thrombosis in 1-2% of cases. Recently, infliximab has been suggested to increase this possibility. A case of Crohn's disease presenting with cerebral sinus thrombosis in the remission period during long-term/high-dose use of infliximab is presented. In addition, infliximab-associated thrombosis cases were reviewed.

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.