ABSTRACT
Glioblastoma (GBM) is a common and malignant tumor with a poor prognosis. Glioblastoma stem cells (GSCs) have been reported to be involved in tumorigenesis, tumor maintenance and therapeutic resistance. Thus, to discover novel candidate therapeutic drugs for anti-GBM and anti-GSCs is an urgent need. We hypothesized that if treatment with a drug could reverse, at least in part, the gene expression signature of GBM and GSCs, this drug may have the potential to inhibit pathways essential in the formation of GBM and thereby treat GBM. Here, we collected 356 GBM gene signatures from public databases and queried the Connectivity Map. We systematically evaluated the in vitro antitumor effects of 79 drugs in GBM cell lines. Of the drugs screened, thioridazine was selected for further characterization because it has potent anti-GBM and anti-GSCs properties. When investigating the mechanisms underlying the cytocidal effects of thioridazine, we found that thioridazine induces autophagy in GBM cell lines, and upregulates AMPK activity. Moreover, LC3-II was upregulated in U87MG sphere cells treated with thioridazine. In addition, thioridazine suppressed GBM tumorigenesis and induced autophagy in vivo. We not only repurposed the antipsychotic drug thioridazine as a potent anti-GBM and anti-GSCs agent, but also provided a new strategy to search for drugs with anticancer and anticancer stem cell properties.
Subject(s)
Antipsychotic Agents/pharmacology , Brain Neoplasms/drug therapy , Glioblastoma/drug therapy , Neoplastic Stem Cells/drug effects , Thioridazine/pharmacology , Animals , Autophagy/drug effects , Brain Neoplasms/genetics , Brain Neoplasms/pathology , Cell Line, Tumor , Cell Survival/drug effects , Drug Screening Assays, Antitumor/methods , Gene Expression Profiling , Glioblastoma/genetics , Glioblastoma/pathology , Humans , Mice, Inbred NOD , Mice, SCID , Neoplastic Stem Cells/physiology , Random Allocation , Xenograft Model Antitumor AssaysABSTRACT
The adenovirus E1A protein has been shown to be involved in the potentiation of apoptosis induced by chemotherapeutic agents, yet the molecular events of E1A-mediated apoptosis are not very clear. A recent report has suggested that deamidation of the Bcl-X(L) protein inhibits its antiapoptotic ability and leads to apoptosis induced by alkylating agents in Rb-deficient tumor cells. Since Rb is known to interact with E1A, which interrupts Rb's normal function, we examined Bcl-X(L) deamidation and cell death induced by cisplatin in E1A transfectants. We found that the E1A transfectants became sensitive to cisplatin-induced apoptosis compared to the parental cells, SKOV3.ip1. Our data show that cisplatin treatment induced the modification of Bcl-X(L) in the E1A transfectants in dosage and time-dependent manner. Furthermore, phosphatase treatment had no effect on the level of Bcl-X(L) modification, whereas alkaline lysis buffer appeared to induce the same modification of Bcl-X(L). Ectopic expression of the deamidated forms of Bcl- X(L) in SKOV3.ip1 cells revealed that the modification to the Bcl- X(L) protein molecules was deamidation. Expression of the E1A mutant (dl1108) which contains deletion at CR2 domain suppressed Bcl-X(L) deamidation and apoptosis induced by cisplatin. We also found that expression of the nondeamidated Bcl-X(L) protected E1A transfectants from apoptosis. These findings suggest that Bcl-X(L) deamidation contributes to E1A-mediated cisplatin sensitization in SKOV3.ip1 cells.
