Molecular profiling of MPS1 gene silencing in U251 glioma cell line

Aneuploidy has been recognized as a common characteristic of cancers. Aneuploidy frequently results from errors of the mitotic checkpoint, the major cell cycle control mechanism that acts to prevent chromosome missegregation. Mutation of the genes that control chromosome segregation during mitosis may explain the high rate of chromosomal instability and aneuploidy, a characteristic of most solid tumors, including glioblastoma (GBM) (Gordon et al., 2012 [1]; Singh et al., 2012 [2]). Monopolar spindle 1 (MPS1) is an essential spindle assembly checkpoint kinase that is overexpressed in several human cancers (Kilpinen et al., 2010 [3]; Mills et al., 1992 [4]; Yuan et al., 2006 [5]). In our previous publication, we have shown the role of MPS1 kinase in DNA repair and enhanced radiosensitivity in GBM (Maachani et al., 2015 [6]). Here, we provide methodological and analytical details of that study, to compare mRNA expression profile of siMPS1-silenced U251 cells with untransfected control, and siRNA control (siNeg) at 6, 24, and 48 h after transfection. The raw data of this study is deposited in Gene Expression Omnibus under the accession number GSE57091

Dual Inhibition of PI3K/AKT and MEK/ERK Pathways Induces Synergistic Antitumor Effects in Diffuse Intrinsic Pontine Glioma Cells

Diffuse intrinsic pontine glioma (DIPG) is a devastating disease with an extremely poor prognosis. Recent studies have shown that platelet-derived growth factor receptor (PDGFR) and its downstream effector pathway, PI3K/AKT/mTOR, are frequently amplified in DIPG, and potential therapies targeting this pathway have emerged. However, the addition of targeted single agents has not been found to improve clinical outcomes in DIPG, and targeting this pathway alone has produced insufficient clinical responses in multiple malignancies investigated, including lung, endometrial, and bladder cancers. Acquired resistance also seems inevitable. Activation of the Ras/Raf/MEK/ERK pathway, which shares many nodes of cross talk with the PI3K/AKT pathway, has been implicated in the development of resistance. In the present study, perifosine, a PI3K/AKT pathway inhibitor, and trametinib, a MEK inhibitor, were combined, and their therapeutic efficacy on DIPG cells was assessed. Growth delay assays were performed with each drug individually or in combination. Here, we show that dual inhibition of PI3K/AKT and MEK/ERK pathways synergistically reduced cell viability. We also reveal that trametinib induced AKT phosphorylation in DIPG cells that could not be effectively attenuated by the addition of perifosine, likely due to the activation of other compensatory mechanisms. The synergistic reduction in cell viability was through the pronounced induction of apoptosis, with some effect from cell cycle arrest. We conclude that the concurrent inhibition of the PI3K/AKT and MEK/ERK pathways may be a potential therapeutic strategy for DIPG

Advances in Molecular Imaging of Locally Delivered Targeted Therapeutics for Central Nervous System Tumors

Thanks to the recent advances in the development of chemotherapeutics, the morbidity and mortality of many cancers has decreased significantly. However, compared to oncology in general, the field of neuro-oncology has lagged behind. While new molecularly targeted chemotherapeutics have emerged, the impermeability of the blood–brain barrier (BBB) renders systemic delivery of these clinical agents suboptimal. To circumvent the BBB, novel routes of administration are being applied in the clinic, ranging from intra-arterial infusion and direct infusion into the target tissue (convection enhanced delivery (CED)) to the use of focused ultrasound to temporarily disrupt the BBB. However, the current system depends on a “wait-and-see” approach, whereby drug delivery is deemed successful only when a specific clinical outcome is observed. The shortcomings of this approach are evident, as a failed delivery that needs immediate refinement cannot be observed and corrected. In response to this problem, new theranostic agents, compounds with both imaging and therapeutic potential, are being developed, paving the way for improved and monitored delivery to central nervous system (CNS) malignancies. In this review, we focus on the advances and the challenges to improve early cancer detection, selection of targeted therapy, and evaluation of therapeutic efficacy, brought forth by the development of these new agents

¹⁸F‑Radiolabeled Panobinostat Allows for Positron Emission Tomography Guided Delivery of a Histone Deacetylase Inhibitor

Histone deacetylase (HDAC) inhibition is becoming an increasingly popular approach to treat cancer, as HDAC overexpression is common in many malignancies. The blood–brain barrier (BBB) prevents systemically delivered drugs from reaching brain at effective concentration, making small-molecule-HDAC inhibition in brain tumors particularly challenging. To circumvent the BBB, novel routes for administering therapeutics are being considered in the clinic, and a need exists for drugs whose deliveries can be directly imaged, so that effective delivery across the BBB can be monitored. We report chemistry for radiolabeling the HDAC inhibitor, panobinostat, with fluoride-18 (compound-<b>1</b>). Like panobinostat, compound <b>1</b> retains nanomolar efficacy in diffuse intrinsic pontine glioma (DIPG IV and XIII) cells (IC₅₀ = 122 and 108 nM, respectively), with lesser activity against U87 glioma. With a favorable therapeutic ratio, <b>1</b> is highly selective to glioma and demonstrates considerably less toxicity toward healthy astrocyte controls (IC₅₀ = 5265 nM). Compound <b>1</b> is stable in aqueous solution at physiological pH (>7 days, fetal bovine serum), and its delivery can be imaged by positron emission tomography (PET). Compound <b>1</b> is synthesized in two steps, and employs rapid, late-stage aqueous isotopic exchange ¹⁸F-radiochemistry. PET is used to image the in vivo delivery of [¹⁸F]-<b>1</b> to the murine central nervous system via convection enhanced delivery