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The authors have withdrawn their manuscript owing to massive revision and data validation. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author.

In continuation of our previous efforts for the development of potent small molecules against brain cancer, herein we synthesized seventeen new compounds and tested their anti-gliomapotential against established glioblastoma cell lines, namely, D54MG, U251, and LN-229 as well as patient derived cell lines (DB70 and DB93). Among them, the carboxamide derivatives, BT-851 and BT-892 were found to be the most active leads in comparison to our established hit compound BT#9.The SAR studies of our hit BT#9 compound resulted in the development of two new lead compounds by hit to lead strategy. The detailed biological studies are currently underway. The active compounds could possibly act as template for the future development of newer anti-glioma agents.

Abstract: BACKGROUND: Brain tumors are the second most common type of pediatric cancer and are the leading cause of all cancer-related deaths in children. Medulloblastoma (MB) is the most common type of malignant pediatric brain tumor and has a five-year overall survival ranging from 40-75%, depending on the patient’s age and other prognostic features. There are current anti-cancer therapies against medulloblastoma, but the treatment of recurrent disease remains a challenge. Magmas (mitochondria-associated protein involved in granulocyte-macrophage colony-stimulating factor signal transduction) overexpression has been reported in multiple types of metabolically active tissue and cancer cells, including prostate cancer, pituitary adenoma, and glioma. Limited data suggest that specific subgroups of medulloblastoma may also overexpress Magmas. This study aims to examine whether Magmas inhibition by compound “BT#9” could be beneficial for the treatment of medulloblastoma. METHODS: We studied the ability of a Magmas inhibitor (BT#9) as a therapeutic agent in stable medulloblastoma cell lines (DAOY and D283) and patient-derived primary cultures with MTT assays, migration assays, and invasion assays. RESULTS: Similar to the adult GBM studies, Magmas inhibition by BT9 had significant cytotoxic effects, causing both decreased cell proliferation and blocked cell migration in medulloblastoma cell lines DAOY and D283. IC50s determined for each during different time points demonstrated an average range of less than 3μM compared to the average range seen in adult glioblastoma cell cultures (< 10 μM). These findings suggest that the inhibition of Magmas warrants further investigation as a potential therapeutic target to optimize clinical outcomes in medulloblastoma. Our future studies will include the determination of IC50s for primary cell cultures and in vitro testing with patient-derived xenograft models.

Abstract: Glioblastoma (WHO Grade IV glioma) is the most aggressive brain cancer. The current standard of care treatment includes surgery, radiation, and chemotherapy. Tumor recurrence is almost inevitable as less than 50% of patients survive more than two years. The low survival rate poses a dire need to develop an effective therapy for GBM patients. GBM cells are resistant to treatment, as they activate their DNA damage response mechanisms to overcome the effects of radiation and temozolomide (TMZ) treatments. Recurrent tumors can arise from slow cycling and self-renewing stem/tumor-initiating cells resistant to radiation and TMZ. No second-line therapy was proven to prolong survival after TMZ failure. Magmas (Mitochondria-associated protein involved in granulocyte-macrophage colony-stimulating factor signal transduction) is a subunit of the TIM23 complex regulating precursor protein trafficking into the mitochondrial matrix. Magmas is encoded by pam16, known to be upregulated in human pituitary adenomas, prostate cancer and GBM. Previous studies have demonstrated that Magmas negatively regulates the stimulatory activity of Pam18, which in turn stimulates the ATPase activity of mitochondrial heat shock protein 70 (mtHsp70). No small molecules targeting Magmas are in clinical use. We developed a novel small molecule inhibitor (BT9) that has been specifically designed to inhibit Magmas binding to Pam18. BT9 induces apoptosis through cleavage of caspase-3, reduced mitochondrial respiration and glycolysis. Our recent findings also demonstrate that BT9 treatment reduced protein trafficking of Lon protease into the mitochondrial matrix. Pretreatment of glioma cells with BT9 sensitizes cells to radiation treatment and enhances the TMZ activity. BT9 can cross the blood-brain-barrier and improve survival in intracranial glioma PDX models. BT9 has potential therapeutic value by directly dysregulating mitochondrial function in GBM, enhancing radiation and chemotherapy response, and improving survival in a relevant animal model.

Abstract Glioblastoma (GBM), a WHO grade IV brain cancer, exhibits strong treatment resistance and a high rate of reoccurrence, which gives it a dismal prognosis, a 5% survival rate in the first 5 years. LonP1, a mitochondrial master regulator, can drive metabolic transformation, cytokine production, EMT, and treatment resistance in various cancer types, but its role in GBM remains unexplored. Our research group has previously shown that LonP1 is overexpressed in human malignant gliomas, particularly glioblastoma, and that this is associated with disease prognosis. Here, we present findings that demonstrate that LonP1 seems to drive enhanced tumor progression, invasiveness, angiogenesis in different high grade glioblastomas based on TCGA-subtype. Furthermore, in collaboration with Professor Bhaskar Das, we have validated a lead compound, BT317, with on-target inhibition of LonP1 protease activity. BT317 has enhanced activity against glioma stem cell lines (GSC) and has demonstrated low toxicity and efficacy in an intracranial xenograft model. This preliminary data highlights the potential of using combinatorial, pharmacological LonP1 and proteasome inhibition as a novel strategy for targeting specific subtypes of GBM.

Abstract BACKGROUNDS Glioblastoma (GBM) is an aggressive infiltrative brain tumor, and has an extremely poor prognosis despite the use of multiple treatment modalities, including surgery, radiation, and chemotherapy. Meanwhile, mitochondrial changes represent a significant part of cancer cell biology since cancer cells must survive and adapt to challenging microenvironments, specifically in conditions where tumor growth makes oxygen and glucose scarce. As GBM is characterized by extensive hypoxia-induced phenotypic changes such as abnormal vascular proliferation and necrosis, regulation of mitochondrial function could be a novel approach for treating GBM that currently lacks effective therapies. Magmas (mitochondria-associated protein involved in granulocyte-macrophage colony-stimulating factor signal transduction) is a nuclear gene that encodes for the mitochondrial import inner membrane translocase subunit Tim16. We previously demonstrated that a novel Magmas inhibitor, BT#9, significantly exerted anti-tumor effect in glioma in vitro, and may cross the blood brain barrier in vivo, indicating that Magmas inhibitor may be a new chemotherapeutic agent for the treatment of GBM. METHODS In this study, the antitumor effect of Magmas inhibitor BT#9 was tested in an orthotopic xenograft model of human GBM. The molecular mechanism of BT#9 was investigated using glioma cell lines. RESULTS The mice were tolerated to BT#9, and there was no statistical difference in the weight of animals between the control and MTD (Maximum-tolerated Dose, 50mg/kg) groups. The immunocompromised mice, intracranially implanted with human D-54 GBM xenografts, survived significantly longer than the controls (P< 0.5) when treated with BT#9 at MTD. In vitro study showed that the MAP kinase pathways are involved in BT#9-induced tumor suppression. DISCUSSION This is the first study on the role of Magmas in glioma in vivo. Our findings suggested that Magmas plays a key role in glioma survival and targeting Magmas by Magmas inhibitor has the potential to become a therapeutic strategy in glioma patients.

PurposeMagmas (mitochondria-associated protein involved in granulocyte-macrophage colony-stimulating factor signal transduction) is a nuclear gene that encodes the mitochondrial import inner membrane translocase subunit Tim16. Magmas is highly conserved, ubiquitously expressed in mammalian cells, and is essential for cell viability. Magmas expression levels are increased in prostate cancers and pituitary adenomas. Moreover, silencing Magmas by RNAi sensitizes pituitary adenoma cells to pro-apoptotic stimuli and induces a G0/G1 accumulation. The aim of this study was to examine whether inhibition of Magmas by small molecule inhibitors could be beneficial for the treatment of malignant gliomas.MethodsWe evaluated the expression of Magmas in patient-derived glioblastoma tissue samples and xenograft models. We studied the feasibility of a small molecule Magmas inhibitor (BT#9) as a therapeutic agent in stable human glioma cell lines and high-grade patient derived glioma stem-like cells.ResultsMagmas was overexpressed in tissue sections from glioma patients and xenografts. In vivo studies revealed that BT#9 could cross the blood-brain barrier in the animal model. Magmas inhibition by BT#9 in glioma cell lines significantly decreased cell proliferation, induced apoptosis along with vacuole formation, and blocked migration and invasion. In addition, BT#9 treatment decreased the respiratory function of glioma cells, supporting the role that Magmas serves as a reactive oxygen species regulator.ConclusionsThis is the first study on the role of Magmas in glioma. Our findings suggest that Magmas plays a key role in glioma cell survival and targeting Magmas by small molecule inhibitors may be a therapeutic strategy in gliomas.