Prostaglandin E2 (PGE2) is known to increase glioblastoma (GBM) cell proliferation and migration while cyclooxygenase (COX) inhibition decreases proliferation and migration. The present study investigated the effects of COX inhibitors and PGE2 receptor antagonists on GBM cell biology. Cells were grown with inhibitors and dose response, viable cell counting, flow cytometry, cell migration, gene expression, Western blotting, and gelatin zymography studies were performed. The stimulatory effects of PGE2 and the inhibitory effects of ibuprofen (IBP) were confirmed in GBM cells. The EP2 and EP4 receptors were identified as important mediators of the actions of PGE2 in GBM cells. The concomitant inhibition of EP2 and EP4 caused a significant decrease in cell migration which was not reverted by exogenous PGE2. In T98G cells exogenous PGE2 increased latent MMP2 gelatinolytic activity. The inhibition of COX1 or COX2 caused significant alterations in MMP2 expression and gelatinolytic activity in GBM cells. These findings provide further evidence for the importance of PGE2 signalling through the EP2 and the EP4 receptor in the control of GBM cell biology. They also support the hypothesis that a relationship exists between COX1 and MMP2 in GBM cells which merits further investigation as a novel therapeutic target for drug development.

OBJECTIVE:To analyze the associated expression of STMN1, MELK and FOXM1 in search of alternative drugable target in glioblastoma (GBM) and to review relevant functional roles of STMN1 in cancer biology. METHOD: STMN1, MELK and FOXM1 expressions were studied by quantitative PCR and their coexpressions were analyzed in two independent glioblastoma cohorts. A review of articles in indexed journals that addressed the multiple functional aspects of STMN1 was conducted, focusing on the most recent reports discussing its role in cancer, in chemoresistance and in upstream pathways involving MELK and FOXM1. RESULTS: Significant associated expressions of MELK and FOXM1 were observed with STMN1 in GBM. Additionally, the literature review highlighted the relevance of STMN1 in cancer progression. CONCLUSION: STMN1 is very important to induce events in cancer development and progression, as cellular proliferation, migration, and drug resistance. Therefore, STMN1 can be an important therapeutic target for a large number of human cancers. In glioblastoma, the most aggressive brain tumor, the MELK/FOXM1/STMN1 presented significant associated expressions, thus pointing MELK and FOXM1 as alternative targets for therapy instead of STMN1, which is highly expressed in normal brain tissue. Continuous functional research to understand the STMN1 signaling pathway is worthwhile to improve the therapeutic approaches in cancer.

Glioblastoma (GBM) is the most common and aggressive malignant brain tumor in adults and standard treatment consists of surgical resection of the tumor, followed by radiation and chemotherapy with temozolomide. Our group performed the analysis of differently expressed genes between GBM and pilocytic astrocytoma. One of the genes with increased expression in GBMs was MELK (maternal embryonic leucine zipper kinase), which encodes a serine / threonine kinase protein that plays an important role in various cellular processes, such as proliferation, cell cycle, apoptosis, and oncogenesis. A siRNA silenced GBM cell analysis was performed to identify possible genes associated with the MELK pathway. One of the genes identified was STMN1, which encodes stathmin 1, an important cytosolic protein that plays a critical role in mitosis by regulating microtubule dynamics during cell cycle progression and migration. In addition, STMN1 is also involved in other biological processes, such as migrating and differentiating, through the phosphorylation of four serines (S16, S25, S38 and S63) triggers protein activation, weakening its binding to tubulin molecules. FOXM1, an important transcription factor, identified as regulator in the expression of several genes essential for cell cycle progression, including STMN1, was also a target of this study. In addition, FOXM1 is phosphorylated by MELK, regulating mitosis. MELK, STMN1 and FOXM1 are still related to tumor cell resistance to chemotherapy treatment. The aim of this study was to analysize expression levels of MELK, STMN1 and FOXM1 in our cohort astrocytomas of different degrees of malignancy. In addition, these data were validated in silico in larger cohorts of The Cancer Genome Atlas (TCGA). The expression of the three genes increased according to the malignancy of astrocytomas in our cases and in TCGA cases. MELK and STMN1, MELK and FOXM1 and STMN1 and FOXM1 expression levels were positively correlated in our GBM series, as well as in the TCGA series. In addition, the three genes showed higher expression in the proneural GBM subtype than in the Mesenquimal and Clássico subtypes in the case series of TCGA. U87MG and A172 cells silenced with MELK siRNA showed a similar decrease in MELK and STMN1 expression (~90%), but with a lower level of FOXM1 decrease (~50%). Phosphorylated serines of STMN1 were also analyzed after MELK silencing, and there was a decrease in phosphorylation compared to the control. On the other hand, when STMN1 expression was silenced with siRNA, MELK expression did not change and FOXM1 expression decreased by 40%. Silenced cells showed a reduction in cell viability and migration. Additionally, GBM cases were divided based on the expression of high and low STMN1. Of the cases with increased STMN1 expression, 79% showed increased FOXM1 expression, compared to 25% in the low STMN1 expression group. However, these groups showed no difference in survival of patients. The relationship between the three genes and drug resistance was analyzed in temozolamide and vinc...

Serachi OF. Analysis of the effect of cyclooxygenase on the expression and activity of Multiple Drug Resistance Proteins (MDRP) in human glioma. [Masters thesis (Cell and

Abstracts iii55NEURO-ONCOLOGY • MAY 2017 agent for distribution monitoring under MRI, and evaluate the possibility of their use as a drug-loaded vehicle to monitor the infused drug directly. MATERIAL AND METHODS: lipid-based microbubbles loaded with doxorubicin (MB-Dox) were synthesized. Cytotoxicity of MB-Dox was evaluated both in vitro and in vivo. Optimized R2 relaxometry of MRI was accomplished to reveal the contrast capacity and pharmacokinetics of MBDox through CED in brain. U87MG xenograft-bearing mice were organized for efficacy study. RESULTS: It shows that MB-Dox can provide great detectability through MRI relaxometry and correctly represent drug distribution after CED infusion. Compared with the short half-life of Gd-DTPA (1-2 hours), microbubbles allow an elongated observation period of up to 12 hours. Moreover, microbubbles provide a sufficiently high drug payload, Thus glioma mice that underwent a CED infusion of MB-dox presented significant tumor growth suppression and a appreciably improved survival rate. CONCLUSIONS: This study recommends drug-loaded microbubbles is a great theranostic tool for CED procedures. This study is supported by Center for Advanced Molecular Imaging and Translation, Chang Gung