Article

Identification of novel synergistic targets for rational drug combinations with PI3 kinase inhibitors using siRNA synthetic lethality screening against GBM

Brain Tumor Center, Department of Neuro-Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
Neuro-Oncology (Impact Factor: 5.29). 04/2011; 13(4):367-75. DOI: 10.1093/neuonc/nor012
Source: PubMed

ABSTRACT Several small molecules that inhibit the PI3 kinase (PI3K)-Akt signaling pathway are in clinical development. Although many of these molecules have been effective in preclinical models, it remains unclear whether this strategy alone will be sufficient to interrupt the molecular events initiated and maintained by signaling along the pathways because of the activation of other pathways that compensate for the inhibition of the targeted kinase. In this study, we performed a synthetic lethality screen to identify genes or pathways whose inactivation, in combination with the PI3K inhibitors PX-866 and NVPBEZ-235, might result in a lethal phenotype in glioblastoma multiforme (GBM) cells. We screened GBM cells (U87, U251, and T98G) with a large-scale, short hairpin RNA library (GeneNet), which contains 43 800 small interfering RNA sequences targeting 8500 well-characterized human genes. To decrease off-target effects, we selected overlapping genes among the 3 cell lines that synergized with PX-866 to induce cell death. To facilitate the identification of potential targets, we used a GSE4290 dataset and The Cancer Genome Atlas GBM dataset, identifying 15 target genes overexpressed in GBM tissues. We further analyzed the selected genes using Ingenuity Pathway Analysis software and showed that the 15 genes were closely related to cancer-promoting pathways, and a highly interconnected network of aberrations along the MYC, P38MAPK, and ERK signaling pathways were identified. Our findings suggest that inhibition of these pathways might increase tumor sensitivity to PX-866 and therefore represent a potential clinical therapeutic strategy.

Download full-text

Full-text

Available from: Jing Wang, Sep 03, 2015
0 Followers
 · 
158 Views
 · 
57 Downloads
  • Source
    • "Together, a number of recent studies have provided the molecular basis for the observation that small-molecule inhibitors of PI3K/Akt/mTOR signaling represent a potent strategy to enhance the sensitivity of cancer cells toward cell death induction via the mitochondrial pathway of apoptosis. Accordingly, smallmolecule inhibitors of PI3K/mTOR were shown to chemosensitize various cancers to a large variety of anticancer drugs, e.g., topoisomerase-1 or -2 inhibitors, platinum compounds, or microtubule interfering agents (Wallin et al., 2010; Bender et al., 2011; Kim et al., 2011; Mueller et al., 2012). This PI3K/mTOR-mediated chemosensitization may involve a shifted ratio between pro-and antiapoptotic Bcl-2 proteins, thereby engaging mitochondrial outer membrane permeabilization and the mitochondrial pathway of apoptosis. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Signaling via the intrinsic (mitochondrial) pathway of apoptosis represents one of the critical signal transduction cascades that control the regulation of cell death. This pathway is typically altered in human cancers, thereby providing a suitable target for therapeutic intervention. Members of the Bcl-2 family of proteins as well as cell survival signaling cascades such as the PI3K/Akt/mTOR pathway are involved in the regulation of mitochondria-mediated apoptosis. Therefore, further insights into the molecular mechanisms that form the basis for the control of mitochondria-mediated apoptosis will likely open new perspectives to bypass evasion of apoptosis and treatment resistance in human cancers.
    Frontiers in Oncology 10/2012; 2:121. DOI:10.3389/fonc.2012.00121
  • Source
    • "Although many of these molecules have been effective in preclinical models, it remains unclear whether this strategy alone will be sufficient to interrupt the molecular events initiated and maintained by signaling along the pathways because of the activation of other pathways that compensate for the inhibition of the targeted kinase. Attempts have recently been made to identify genes or pathways whose inactivation, in combination with the PI3K inhibitors PX-866 and NVPBEZ-235, might result in a lethal phenotype in glioblastoma multiforme cells [48]. The identified shRNA22, when expressed in CSCs from glioblastoma patients, inhibits cell proliferation and self-renewal, induces apoptosis and significantly reduces their tumorigenic potential when xenotransplanted into the brains of nude rats. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Glioblastomas (GBM) may contain a variable proportion of active cancer stem cells (CSCs) capable of self-renewal, of aggregating into CD133(+) neurospheres, and to develop intracranial tumors that phenocopy the original ones. We hypothesized that nucleostemin may contribute to cancer stem cell biology as these cells share characteristics with normal stem cells. Here we report that nucleostemin is expressed in GBM-CSCs isolated from patient samples, and that its expression, conversely to what it has been described for ordinary stem cells, does not disappear when cells are differentiated. The significance of nucleostemin expression in CSCs was addressed by targeting the corresponding mRNA using lentivirally transduced short hairpin RNA (shRNA). In doing so, we found an off-target nucleostemin RNAi (shRNA22) that abolishes proliferation and induces apoptosis in GBM-CSCs. Furthermore, in the presence of shRNA22, GBM-CSCs failed to form neurospheres in vitro or grow on soft agar. When these cells are xenotransplanted into the brains of nude rats, tumor development is significantly delayed. Attempts were made to identify the primary target/s of shRNA22, suggesting a transcription factor involved in one of the MAP-kinases signaling-pathways or multiple targets. The use of this shRNA may contribute to develop new therapeutic approaches for this incurable type of brain tumor.
    PLoS ONE 12/2011; 6(12):e28753. DOI:10.1371/journal.pone.0028753 · 3.23 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The expression of an array of signaling molecules, along with the assessment of real-time cell proliferation, has been performed in U87 glioma cell line and in patients' glioblastoma established cell cultures in order to provide a better understanding of cellular and molecular events involved in glioblastoma pathogenesis. Experimental therapy was performed using a phosphatidylinositol-3'-kinase (PI3K) inhibitor. xMAP technology was employed to assess expression levels of several signal transduction molecules and real-time xCELLigence platform for cell behavior. PI3K inhibition induced the most significant effects on global signaling pathways in patient-derived cell cultures, especially on members of the mitogen-activated protein-kinase family, P70S6 serine-threonine kinase, and cAMP response element-binding protein expression and further prevented tumor cell proliferation. The PI3K pathway might be a prime target for glioblastoma treatment.
    OncoTargets and Therapy 11/2013; 6:1737-1749. DOI:10.2147/OTT.S52365 · 2.31 Impact Factor
Show more