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INTRODUCTION Glioblastoma (GBM) is the most common primary malignant brain tumors. Despite aggressive therapies, median overall survival of patients who suffered from GBM is only 18 months. Furthermore, there is no effective therapy for glioma stem cells (GSCs), which act as forming tumors. Herein, we newly identified pentamidine, an antiprotozoal drug, is effective for GSCs by using drug repositioning approach. METHOD We used patient-derived glioma stem like cell lines KGS01, KGS07 which were established at Kanazawa University. We investigated proliferation ability, stemness and intracellular signal change by proliferation assay, sphere forming assay and western blotting, respectively. RESULT: Proliferation ability was prohibited by pentamidine in both cell lines. The half maximal inhibitory concentration was 1 - 5 μM. Sphere forming assay revealed that size and number of spheres were reduced in both cell lines, depending on concentration of pentamidine. Phosphorylation of extracellular signal-related kinase (ERK) and signal transducer and activator of transcription 3 (STAT3) were suppressed by pentamidine. DISCUSSION Pentamidine is known as the therapeutic drug for pneumocystis jirovecii. In this study, pentamidine suppressed proliferation activity and stemness in both glioma stem cell lines. Previous papers revealed pentamidine had anti-tumor effects for some types of tumor cell lines, however, therapeutic effect for tumor stem cells have never been mentioned. CONCLUSION These results suggest that pentamidine would be therapeutic drug for GSCs by suppressing phosphorylation of ERK and STAT3.

BACKGROUND Among potential glioblastoma (GBM) blood biomarkers that we identified recently, we focused on gelsolin (GSN), a key regulator of actin filament disassembly. GSN was significantly lower in the blood of patients with GBM than in that of healthy controls. In this study, we analyzed the function of GSN and identified microRNAs (miRs) involved in GSN expression in GBM. METHODS QRT-PCR and western blot were introduced to evaluate the expression level of GSN in normal brain and GBM tissue. The localization of GSN was examined by immunohistochemistry and immunocytochemistry using human samples. The association between the expression level of GSN and progression free survival (PFS) /overall survival (OS) in GBM was assessed by Kaplan-Meier analysis. The function of GSN and its signal transduction in glioma cell lines were analyzed using small interfering RNA (siRNA) knockdown of GSN. Additionally, miRs controlling GSN expression were retrieved from databases of miRs, and miRs related to GSN expression were identified in GBM tissues. RESULTS The expression level of GSN was significantly lower in GBM tissues compared to normal brains. Normal astrocytes mainly expressed GSN. High expressor of GSN showed longer PFS and OS than low expressor. Proliferation and invasion in glioma cell lines were significantly promoted by siRNA for GSN accompanied with the activation of glycogen synthase kinase 3β. In GBM tissues, the expression levels of GSN and miR-654-5p, 450b-5p showed an inverse correlation. The inhibitor for miR-654-5p and miR-450b-5p accelerated GSN expression resulting reduction of proliferation. CONCLUSION GSN plays a role as suppressor of proliferation and invasion in GBM. miR-654-5p and miR-450b-5p which control GSN expression can be targets against GBM.

PD-L1 and PD-L2 expression on tumor cells and tumor-infiltrating immune cells in primary central nervous system lymphoma (PCNSL) remains unclear. In the present study, we investigated the expressions of PD-L1 and PD-L2 in surgical specimens from needle biopsies and craniotomies to compare tumor tissue with surrounding tumor tissue (peritumoral tissue) and analyzed the correlation between expression of PD-L1/PD-L2 and survival in patients with PCNSL. We retrospectively analyzed the cases of 70 patients histologically diagnosed with PCNSL (diffuse large B-cell lymphoma). Immunohistochemistry for CD20, CD68, PD-L1, and PD-L2 was performed. In cases with specimens taken by craniotomy, the percentages of PD-L1- and PD-L2-positive macrophages were evaluated in both tumor and peritumoral tissue. The Kaplan-Meier method with log-rank test and Cox proportional hazard model were used for survival analysis. The tumor cells did not express very much PD-L1 and PD-L2, but macrophages expressed PD-L1 and PD-L2 in most of the patients. The median percentage of PD-L2-positive cells was significantly higher among peritumoral macrophages (32.5%; 95%CI: 0–94.6) than intratumoral macrophages (27.5%; 95%CI: 0–81.1, p=0.0014). There was a significant correlation between the percentages of PD-L2-positive intratumoral macrophages and PD-L2-positive peritumoral macrophages (p=0.0429), with very low coefficient correlation (ρ=0.098535). PD-L1 expression on macrophages was significantly associated with biological factors (intratumoral macrophages: better KPS, p=0.0008; better MSKCC score, p=0.0103; peritumoral macrophages: low proportion of LDH elevation, p=0.0064) and longer OS (for intratumoral macrophages: high PD-L1=60 months, 95%CI=30–132.6; low PD-L1=24 months, 95%CI=11–48; p=0.032; for peritumoral macrophages: high PD-L1=60 months, 95%CI=30.7-NR; low PD-L1=14 months, 95%CI=3–26). PD-L1 expression on peritumoral macrophages was strongly predictive of a favorable outcome (HR=0.30, 95%CI=0.12–0.77, p=0.0129). Macrophages in intratumoral and peritumoral tissue expressed PD-L1 and PD-L2 at a higher rate than tumor cells. PD-L1 expression, especially on peritumoral macrophages, seems to be an important prognostic factor in PCNSL.