elafin and Brain-Neoplasms

Topics: Brain Neoplasms; Diabetes, Gestational; Elafin; Epigenesis, Genetic; Female; Fetal Macrosomia; Humans; Hyperinsulinism; Infant, Newborn; Insulin; Mothers; Pregnancy; Proto-Oncogene Proteins c-akt; Survivin

Small molecule inhibitors of phosphatidylinositol-3 kinase (PI3K) have been developed as molecular therapy for cancer, but their efficacy in the clinic is modest, hampered by resistance mechanisms.. We studied the effect of PI3K therapy in patient-derived tumor organotypic cultures (from five patient samples), three glioblastoma (GBM) tumor cell lines, and an intracranial model of glioblastoma in immunocompromised mice (n = 4-5 mice per group). Mechanisms of therapy-induced tumor reprogramming were investigated in a global metabolomics screening, analysis of mitochondrial bioenergetics and cell death, and modulation of protein phosphorylation. A high-throughput drug screening was used to identify novel preclinical combination therapies with PI3K inhibitors, and combination synergy experiments were performed. All statistical methods were two-sided.. PI3K therapy induces global metabolic reprogramming in tumors and promotes the recruitment of an active pool of the Ser/Thr kinase, Akt2 to mitochondria. In turn, mitochondrial Akt2 phosphorylates Ser31 in cyclophilin D (CypD), a regulator of organelle functions. Akt2-phosphorylated CypD supports mitochondrial bioenergetics and opposes tumor cell death, conferring resistance to PI3K therapy. The combination of a small-molecule antagonist of CypD protein folding currently in preclinical development, Gamitrinib, plus PI3K inhibitors (PI3Ki) reverses this adaptive response, produces synergistic anticancer activity by inducing mitochondrial apoptosis, and extends animal survival in a GBM model (vehicle: median survival = 28.5 days; Gamitrinib+PI3Ki: median survival = 40 days, P = .003), compared with single-agent treatment (PI3Ki: median survival = 32 days, P = .02; Gamitrinib: median survival = 35 days, P = .008 by two-sided unpaired t test).. Small-molecule PI3K antagonists promote drug resistance by repurposing mitochondrial functions in bioenergetics and cell survival. Novel combination therapies that target mitochondrial adaptation can dramatically improve on the efficacy of PI3K therapy in the clinic.

Topics: Animals; Antineoplastic Agents; Apoptosis; Brain Neoplasms; Cell Line, Tumor; Cell Survival; Cellular Reprogramming; Cyclophilins; Drug Resistance, Neoplasm; Drug Synergism; Elafin; Energy Metabolism; Glioblastoma; Guanidines; Humans; Immunocompromised Host; Mice; Mitochondria; Phosphorylation; Protein Folding; Proto-Oncogene Proteins c-akt; Xenograft Model Antitumor Assays

Deregulation of ErbB receptor-tyrosine kinases is a hallmark of many human cancers. Conserved in the ErbB family is a cluster of basic amino acid residues in the cytoplasmic juxtamembrane region. We found that charge-silencing mutagenesis within this juxtamembrane region of the epidermal growth factor receptor (EGFR) results in the generation of a mutant receptor (EGFR Mut R1-6) that spontaneously transforms NIH 3T3 cells in a ligand-independent manner. A similar mutant with one additional basic residue, EGFR Mut R1-5, fails to exhibit ligand-independent transformation. The capacity of EGFR Mut R1-6 to mediate this transformation is maintained when this mutant is retained in the endoplasmic reticulum via a single point mutation, L393H, which we describe. We show that EGFR Mut R1-6 with or without L393H exhibits enhanced basal tyrosine phosphorylation when ectopically expressed, and the ligand-independent transforming activity of EGFR Mut R1-6 is sensitive to inhibition of EGFR kinase activity and is particularly dependent on PI3K and mTOR activity. Similar to EGFR Mut R1-6/L393H in NIH 3T3 cells, EGFR variant type III, a highly oncogenic mutant form of EGFR linked to human brain cancers, confers transforming activity while it is wholly endoplasmic reticulum-retained in U87 cells. Our findings highlight the importance of the polybasic juxtamembrane sequence in regulating the oncogenic potential of EGFR signaling.

Topics: Animals; Brain Neoplasms; Cell Membrane; Cell Transformation, Neoplastic; Elafin; Endoplasmic Reticulum; ErbB Receptors; Humans; Ligands; Mice; Mutation; NIH 3T3 Cells; Signal Transduction

MicroRNAs (miRNAs) are small non-coding RNAs that negatively regulate gene expression at the post-transcriptional and/or translational level by binding loosely complimentary sequences in the 3'untranslated regions (UTRs) of target mRNAs. Increased expressions of several miRNAs, specifically hsa-miR-21, have been reported to modulate glioma development. Here we report downregulation of miR-451 in A172, LN229 and U251 human glioblastoma cells. Increased expression of miR-451 by administration of miR-451 mimics oligonucleotides reversed the biology of each of the three cell lines, inhibiting cell growth, inducing G0/G1 phase arrest and increasing cell apoptosis. Further, treatment with miR-451 mimics oligonucleotides diminished the invasive capacity of these cells, as the number of cells invading through matrigel was significantly decreased. Akt1, CyclinD1, MMP-2, MMP-9 and Bcl-2 protein expression decreased, and p27 expression increased in a dose-dependent manner with miR-451 mimics oligonucleotides. Taken together, these studies reveal miR-451 impacts glioblastoma cell proliferation, invasion and apoptosis, perhaps via regulation of the PI3K/AKT signaling pathway. We propose an essential role for miR-451 as a tumor-suppressor of human glioma.

Topics: Apoptosis; Blotting, Western; Brain Neoplasms; Cell Line, Tumor; Cell Proliferation; Elafin; Gene Expression; Gene Expression Regulation, Neoplastic; Genes, Tumor Suppressor; Glioma; Humans; MicroRNAs; Neoplasm Invasiveness; Proto-Oncogene Proteins c-akt; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Transfection; Up-Regulation

Vascular endothelial growth factor (VEGF) inhibitors are the most promising anti-angiogenic agents used increasingly in the clinic. However, to be efficient, anti-VEGF agents need to be associated with classic chemotherapy. Exploring gene regulation in tumor cells during anti-angiogenesis might help to comprehend the molecular basis of response to treatment. To generate a defined anti-angiogenic condition in vivo, we transfected human glioma cells with short-interfering RNAs against VEGF-A and implanted them on the chick chorio-allantoic membrane. Gene regulation in avascular tumors was studied using human Affymetrixtrade mark GeneChips. Potentially important genes were further studied in glioma patients. Despite strong VEGF inhibition, we observed recurrent formation of small, avascular tumors. CHI3L2, IL1B, PI3/elafin and CHI3L1, which encodes for YKL-40, a putative prognosticator for various diseases, including cancer, were strongly up-regulated in avascular glioma. In glioblastoma patients, these genes showed coregulation and their expression differed significantly from low-grade glioma. Importantly, high levels of CHI3L1 (p = 0.036) and PI3/elafin mRNA (p = 0.0004) were significantly correlated with poor survival. Cox regression analysis further confirmed that PI3 and CHI3L1 levels are survival markers independent from patient age and sex. Elafin-positive tumor cells were only found in glioblastoma, where they were clustered around necrotic areas. PI3/elafin is strongly induced by serum deprivation and hypoxia in U87 glioma cells in vitro. Our results indicate that anti-angiogenesis in experimental glioma drives expression of critical genes which relate to disease aggressiveness in glioblastoma patients. In particular, CHI3L1 and PI3/elafin may be useful as new prognostic markers and new therapeutic targets.

Topics: Adipokines; Adult; Astrocytoma; Biomarkers, Tumor; Brain; Brain Neoplasms; Cell Proliferation; Chitinase-3-Like Protein 1; Elafin; Female; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Glioblastoma; Glycoproteins; Humans; Immunoenzyme Techniques; Lectins; Male; Middle Aged; Neovascularization, Pathologic; Oligonucleotide Array Sequence Analysis; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; RNA, Small Interfering; Survival Rate; Up-Regulation; Vascular Endothelial Growth Factor A