Targeting the epithelial to mesenchymal transition in glioblastoma: the emerging role of MET signaling

Glioblastoma multiforme (GBM) is the most common human primary brain malignancy and has a dismal prognosis. Aggressive treatments using maximal surgical resection, radiotherapy, and temozolomide result in median survival of only 14.6 months in patients with GBM. Numerous clinical approaches using small molecule inhibitors have shown disappointing results because of the genetic heterogeneity of GBM. The epithelial to mesenchymal transition (EMT) is a crucial biological process occurring in the early development stages of many species. However, cancer cells often obtain the ability to invade and metastasize through the EMT, which triggers the scattering of cells. The hepatocyte growth factor (HGF)/MET signaling pathway is indicative of the EMT during both embryogenesis and the invasive growth of tumors, because HGF potently induces mesenchymal transition in epithelial-driven cells. Activation of MET signaling or co-overexpression of HGF and MET frequently represents aggressive growth and poor prognosis of various cancers, including GBM. Thus, efforts to treat cancers by inhibiting MET signaling using neutralizing antibodies or small molecule inhibitors have progressed during the last decade. In this review, we discuss HGF/MET signaling in the development of diseases, including cancers, as well as updates on MET inhibition therapy.Y

Enhanced anti-tumor effect of combination therapy with gemcitabine and apigenin in pancreatic cancer

Apigenin is a dietary flavonoid possessing therapeutic potential against cancers. This study was designed to investigate whether combination therapy with gemcitabine and apigenin enhanced anti-tumor efficacy in pancreatic cancer. In vitro, the combination treatment resulted in more growth inhibition and apoptosis through the down-regulation of NF-kappa B activity with suppression of Akt activation in pancreatic cancer cell lines (MiaPaca-2, AsPC-1). In vivo, the combination therapy augmented tumor growth inhibition through the down-regulation of NF-kappa B activity with the suppression of Akt in tumor tissue. The combination of gemcitabine and apigenin enhanced anti-tumor efficacy through Akt and NF-kappa B activity suppression and apoptosis induction

Polymorphisms of the MCP-1 and HSP70-2 genes in Korean patients with alcoholic chronic pancreatitis

Alcoholic chronic pancreatitis (ACP) develops in only a small number of alcoholics. Monocyte chemotactic protein-1 (MCP-1) and heat-shock protein 70-2 (HSP70-2) polymorphisms have been reported to be associated with the severity of acute pancreatitis. However, their role in pathogenesis of ACP has not been investigated. A genetic association study for susceptibility and severity was performed on 79 male Korean ACP patients and 82 male controls. MCP-1 and HSP70-2 genotypes were determined using a fluorescence polarization detection method. The genotypes and G allele frequencies were no different in patients and controls. However, MCP-1 G allele had an effect on the development of severe ACP, when its frequency was compared in mild to moderate and severe ACP (29.6 vs. 56.0%, P = 0.02). The MCP-1 and HSP70-2 polymorphisms do not play a major role in the development of ACP in Koreans. However, MCP-1 polymorphism may be associated with the severity of ACP

USP1 targeting impedes GBM growth by inhibiting stem cell maintenance and radioresistance

Clinical benefits from standard therapies against glioblastoma (GBM) are limited in part due to intrinsic radio- and chemoresistance of GBM and inefficient targeting of GBM stem-like cells (GSCs). Novel therapeutic approaches that overcome treatment resistance and diminish stem-like properties of GBM are needed. We determined the expression levels of ubiquitination-specific proteases (USPs) by transcriptome analysis and found that USP1 is highly expressed in GBM. Using the patient GBM-derived primary tumor cells, we inhibited USP1 by shRNA-mediated knockdown or its specific inhibitor pimozide and evaluated the effects on stem cell marker expression, proliferation, and clonogenic growth of tumor cells. USP1 was highly expressed in gliomas relative to normal brain tissues and more preferentially in GSC enrichment marker (CD133 or CD15) positive cells. USP1 positively regulated the protein stability of the ID1 and CHEK1, critical regulators of DNA damage response and stem cell maintenance. Targeting USP1 by RNA interference or treatment with a chemical USP1 inhibitor attenuated clonogenic growth and survival of GSCs and enhanced radiosensitivity of GBM cells. Finally, USP1 inhibition alone or in combination with radiation significantly prolonged the survival of tumor-bearing mice. USP1-mediated protein stabilization promotes GSC maintenance and treatment resistance, thereby providing a rationale for USP1 inhibition as a potential therapeutic approach against GBM.Y

In vivo RNAi screen identifies NLK as a negative regulator of mesenchymal activity in glioblastoma

Glioblastoma (GBM) is the most lethal brain cancer with profound genomic alterations. While the bona fide tumor suppressor genes such as PTEN, NF1, and TP53 have high frequency of inactivating mutations, there may be the genes with GBM-suppressive roles for which genomic mutation is not a primary cause for inactivation. To identify such genes, we employed in vivo RNAi screening approach using the patient-derived GBM xenograft models. We found that Nemo-Like Kinase (NLK) negatively regulates mesenchymal activities, a characteristic of aggressive GBM, in part via inhibition of WNT/beta-catenin signaling. Consistent with this, we found that NLK expression is especially low in a subset of GBMs that harbors high WNT/mesenchymal activities. Restoration of NLK inhibited WNT and mesenchymal activities, decreased clonogenic growth and survival, and impeded tumor growth in vivo. These data unravel a tumor suppressive role of NLK and support the feasibility of combining oncogenomics with in vivo RNAi screen.Y

Additional file 1: of Natural killer (NK) cells inhibit systemic metastasis of glioblastoma cells and have therapeutic effects against glioblastomas in the brain

The ARRIVE Guidelines Checklist Animal Research: Reporting In Vivo Experiments. (PDF 813 kb

Dopamine receptor D2 regulates glioblastoma survival and death through MET and death receptor 4/5

Recent studies indicate that signaling molecules traditionally associated with central nervous system function play critical roles in cancer. Dopamine receptor signaling is implicated in various cancers including glioblastoma (GBM) and it is a recognized therapeutic target, as evidenced by recent clinical trials with a selective dopamine receptor D2 (DRD2) inhibitor ONC201. Understanding the molecular mechanism(s) of the dopamine receptor signaling will be critical for development of potent therapeutic options. Using the human GBM patient-derived tumors treated with dopamine receptor agonists and antagonists, we identified the proteins that interact with DRD2. DRD2 signaling promotes glioblastoma (GBM) stem-like cells and GBM growth by activating MET. In contrast, pharmacological inhibition of DRD2 induces DRD2-TRAIL receptor interaction and subsequent cell death. Thus, our findings demonstrate a molecular circuitry of oncogenic DRD2 signaling in which MET and TRAIL receptors, critical factors for tumor cell survival and cell death, respectively, govern GBM survival and death. Finally, tumor-derived dopamine and expression of dopamine biosynthesis enzymes in a subset of GBM may guide patient stratification for DRD2 targeting therapy

Translational Validation of Personalized Treatment Strategy Based on Genetic Characteristics of Glioblastoma

<div><p>Glioblastoma (GBM) heterogeneity in the genomic and phenotypic properties has potentiated personalized approach against specific therapeutic targets of each GBM patient. The Cancer Genome Atlas (TCGA) Research Network has been established the comprehensive genomic abnormalities of GBM, which sub-classified GBMs into 4 different molecular subtypes. The molecular subtypes could be utilized to develop personalized treatment strategy for each subtype. We applied a classifying method, NTP (Nearest Template Prediction) method to determine molecular subtype of each GBM patient and corresponding orthotopic xenograft animal model. The models were derived from GBM cells dissociated from patient's surgical sample. Specific drug candidates for each subtype were selected using an integrated pharmacological network database (PharmDB), which link drugs with subtype specific genes. Treatment effects of the drug candidates were determined by <i>in vitro</i> limiting dilution assay using patient-derived GBM cells primarily cultured from orthotopic xenograft tumors. The consistent identification of molecular subtype by the NTP method was validated using TCGA database. When subtypes were determined by the NTP method, orthotopic xenograft animal models faithfully maintained the molecular subtypes of parental tumors. Subtype specific drugs not only showed significant inhibition effects on the <i>in vitro</i> clonogenicity of patient-derived GBM cells but also synergistically reversed temozolomide resistance of MGMT-unmethylated patient-derived GBM cells. However, inhibitory effects on the clonogenicity were not totally subtype-specific. Personalized treatment approach based on genetic characteristics of each GBM could make better treatment outcomes of GBMs, although more sophisticated classifying techniques and subtype specific drugs need to be further elucidated.</p></div

Network for GBM subtype-specific drug candidates.

<p>Eight drug candidates were directly/indirectly liked to a number of subtype-specific genes; Clomipramine: 57 proneural-specific genes; Gefitinib: 64 proneural-specific genes; Beta-Nicotinamide Adenine Dinucleotide Hydrate: 35 neural-specific genes; Bicuculline: 5 neural-specific genes; Pravastatin: 100 mesenchymal-specific genes; Resveratrol: 86 mesenchymal-specific genes; Irinotecan: 20 classical-specific genes; Paclitaxel: 79 classical-specific genes.</p