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 survival of prostate cancer (PrCa) patients is associated with the transition to hormone-independent tumor growth and metastasis. Clinically, the dysregulation of androgen action has been associated with the formation of PrCa and the outcome of androgen deprivation therapy in PrCa. CCAAT/enhancer binding protein delta (CEBPD) is a transcription factor that has been reported to act as an oncogene or tumor suppressor, depending on the extra- and intracellular environments following tumorigenesis. We found that androgen can activate CEBPD transcription by direct binding of the androgen receptor (AR) to the CEBPD promoter region. Increases of suppressor of zeste 12 (SUZ12) and enhancer of zeste homolog 2 (EZH2) attenuated the androgen-induced transcription of CEBPD. Importantly, the increases in E2F1, SUZ12 and EZH2 as well as the inactivation of CEBPD were associated with the clinicopathological variables and survival of PrCa patients. We revealed that caspase 8 (CASP8), an apoptotic initiator, is responsive to CEBPD induction. Reporter and in vivo DNA-binding assays revealed that CEBPD directly binds to and activates CASP8 reporter activity. A prodrug system was developed for therapeutic application in AR-independent or androgen-insensitive PrCa to avoid the epigenetic effects on the suppression of CEBPD expression. Our results showed that the combination of a perforin (PF)-CEBPD prodrug (which increases the level of procaspase-8) and a PF-granzyme B prodrug (which activates CASP8 and caspase 3 (CASP3)) showed an additive effect in triggering the apoptotic pathway and enhancing apoptosis in PrCa cells.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/pharmacology , Apoptosis/drug effects , CCAAT-Enhancer-Binding Protein-delta/pharmacology , Caspase 3/metabolism , Caspase 8/metabolism , Granzymes/pharmacology , Perforin/pharmacology , Prodrugs/pharmacology , Prostatic Neoplasms/enzymology , Recombinant Fusion Proteins/pharmacology , Animals , BALB 3T3 Cells , Binding Sites , Caspase 8/genetics , Cell Line, Tumor , Cell Proliferation/drug effects , E2F1 Transcription Factor/genetics , E2F1 Transcription Factor/metabolism , Enhancer of Zeste Homolog 2 Protein , Enzyme Activation , Gene Expression Regulation, Neoplastic , Genes, Reporter , Humans , Male , Mice , Neoplasm Proteins , Polycomb Repressive Complex 2/genetics , Polycomb Repressive Complex 2/metabolism , Prodrugs/metabolism , Promoter Regions, Genetic , Prostatic Neoplasms/genetics , Prostatic Neoplasms/pathology , Receptors, Androgen/drug effects , Receptors, Androgen/metabolism , Signal Transduction/drug effects , Time Factors , Transcription Factors , TransfectionABSTRACT
The androgen receptor (AR) has a critical role in promoting androgen-dependent and -independent apoptosis in testicular cells. However, the molecular mechanisms that underlie the ligand-independent apoptosis, including the activity of AR in testicular stem cells, are not completely understood. In the present study, we generated induced pluripotent stem cells (iPSCs) from bovine testicular cells by electroporation of octamer-binding transcription factor 4 (OCT4). The cells were supplemented with leukemia inhibitory factor and bone morphogenetic protein 4, which maintained and stabilized the expression of stemness genes and pluripotency. The iPSCs were used to assess the apoptosis activity following exposure to phthalate esters, including di (2-ethyhexyl) phthalates, di (n-butyl) phthalate, and butyl benzyl phthalate. Phthalate esters significantly reduced the expression of AR in iPSCs and induced a higher ratio of BAX/BCL-2, thereby favoring apoptosis. Phthalate esters also increased the expression of cyclin-dependent kinase inhibitor 1 (p21(Cip1)) in a p53-dependent manner and enhanced the transcriptional activity of p53. The forced expression of AR and knockdown of p21(Cip1) led to the rescue of the phthalate-mediated apoptosis. Overall, this study suggests that testicular iPSCs are a useful system for screening the toxicity of environmental disruptors and examining their effect on the maintenance of stemness and pluripotency, as well as for identifying the iPSC signaling pathway(s) that are deregulated by these chemicals.
