Zao-Zhong Su

Virginia Commonwealth University, Richmond, VA, United States

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Publications (70)485.73 Total impact

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    ABSTRACT: Pancreatic cancer remains one of the deadliest of all cancers despite aggressive surgical treatment combined with adjuvant radiotherapy and chemotherapy. Chemoresistance and radioresistance are the principal causes of failure of pancreatic cancer patients to respond to therapy. Conditionally replication-competent adenovirus (CRCA)-based cancer gene therapy is an innovative strategy for treating cancers displaying inherent resistance to treatment. Limitations of current adenovirus (Ad)-based gene therapies for malignant tumors include lack of cancer-specificity, and effective and targeted delivery. To remedy this situation, CRCAs has been designed that express E1A, necessary for Ad replication, under the control of a cancer-specific progression elevated gene-3 promoter (PEG-Prom) with concomitant expression of an immunomodulatory cytokine, such as mda-7/IL-24 or interferon-γ (IFN- γ), under the control of a ubiquitous and strong cytomegalovirus promoter (CMV-Prom) from the E3 region. These bipartite CRCAs, when armed with a transgene, are called cancer terminator viruses (CTVs), i.e., Ad.PEG-E1A-CMV-mda-7 (CTV-M7) and Ad.PEG-E1A-CMV-IFN- γ (CTV-γ), because of their universal effectiveness in cancer treatment irrespective of p53/pRb/p16 or other genetic alterations in tumor cells. In addition to their selective oncolytic effects in tumor cells, the potent 'bystander antitumor' properties of MDA-7/IL-24 and IFN-γ embody the CTVs with expanded treatment properties for both primary and distant cancers. Pancreatic cancer cells display a "translational block" of mda-7/IL-24 mRNA, limiting production of MDA-7/IL-24 protein and cancer-specific apoptosis. Specific chemopreventive agents abrogate this "translational block" resulting in pancreatic cancer-specific killing. This novel chemoprevention gene therapy (CGT) strategy holds promise for both prevention and treatment of pancreatic cancers where all other strategies have proven ineffectual.
    Current Molecular Medicine 11/2012; · 4.20 Impact Factor
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    ABSTRACT: Melanoma differentiation associated gene-9 (MDA-9), also known as syntenin, functions as a positive regulator of melanoma progression and metastasis. In contrast, the Raf kinase inhibitor RKIP, a negative modulator of RAF-stimulated MEKK activation, is strongly downregulated in metastatic melanoma cells. In this study, we explored an hypothesized inverse relationship between MDA-9 and RKIP in melanoma. Tumor array and cell line analyses confirmed an inverse relationship between expression of MDA-9 and RKIP during melanoma progression. We found that MDA-9 transcriptionally downregulated RKIP in support of a suggested crosstalk between these two proteins. Further, MDA-9 and RKIP physically interacted in a manner that correlated with a suppression of FAK and c-Src phosphorylation, crucial steps necessary for MDA-9 to promote FAK/c-Src complex formation and initiate signaling cascades that drive the MDA-9-mediated metastatic phenotype. Lastly, ectopic RKIP expression in melanoma cells overrode MDA-9-mediated signaling, inhibiting cell invasion, anchorage-independent growth and in vivo dissemination of tumor cells. Taken together, these findings establish RKIP as an inhibitor of MDA-9-dependent melanoma metastasis, with potential implications for targeting this process therapeutically.
    Cancer Research 10/2012; · 9.28 Impact Factor
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    ABSTRACT: Hepatocellular carcinoma (HCC) is a highly virulent malignancy with no effective treatment, thus requiring innovative and effective targeted therapies. The oncogene astrocyte-elevated gene-1 (AEG-1) plays a seminal role in hepatocarcinogenesis and profoundly downregulates insulin-like growth factor-binding protein-7 (IGFBP7). The present study focuses on analyzing potential tumor suppressor functions of IGFBP7 in HCC and the relevance of IGFBP7 downregulation in mediating AEG-1 function. IGFBP7 expression was detected by immunohistochemistry in HCC tissue microarray and real-time PCR and ELISA in human HCC cell lines. Dual FISH was done to detect LOH at IGFBP7 locus. Stable IGFBP7-overexpressing clones were established in the background of AEG-1-overexpressing human HCC cells and were analyzed for in vitro proliferation and senescence and in vivo tumorigenesis and angiogenesis. IGFBP7 expression is significantly downregulated in human HCC samples and cell lines compared with normal liver and hepatocytes, respectively, and inversely correlates with the stages and grades of HCC. Genomic deletion of IGFBP7 was identified in 26% of patients with HCC. Forced overexpression of IGFBP7 in AEG-1-overexpressing HCC cells inhibited in vitro growth and induced senescence, and profoundly suppressed in vivo growth in nude mice that might be an end result of inhibition of angiogenesis by IGFBP7. The present findings provide evidence that IGFBP7 functions as a novel putative tumor suppressor for HCC and establish the corollary that IGFBP7 downregulation can effectively modify AEG-1 function. Accordingly, targeted overexpression of IGFBP7 might be a potential novel therapy for HCC.
    Clinical Cancer Research 09/2011; 17(21):6693-701. · 7.84 Impact Factor
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    ABSTRACT: Since its initial identification and cloning in 2002, Astrocyte Elevated Gene-1 (AEG-1), also known as metadherin (MTDH), 3D3 and LYsine-RIch CEACAM1 co-isolated (LYRIC), has emerged as an important oncogene that is overexpressed in all cancers analyzed so far. Examination of a large cohort of patient samples representing diverse cancer indications has revealed progressive increase in AEG-1 expression with stages and grades of the disease and an inverse relationship between AEG-1 expression level and patient prognosis. AEG-1 functions as a bona fide oncogene by promoting transformation. In addition, it plays a significant role in invasion, metastasis, angiogenesis and chemoresistance, all important hallmarks of an aggressive cancer. AEG-1 is also implicated in diverse physiological and pathological processes, such as development, inflammation, neurodegeneration, migraine and Huntington's disease. AEG-1 is a highly basic protein with a transmembrane domain and multiple nuclear localization signals and it is present in the cell membrane, cytoplasm, nucleus, nucleolus and endoplasmic reticulum. In each location, AEG-1 interacts with specific proteins thereby modulating diverse intracellular processes the combination of which contributes to its pleiotrophic properties. The present review provides a snapshot of the current literature along with future perspectives on this unique molecule.
    Pharmacology [?] Therapeutics 04/2011; 130(1):1-8. · 7.79 Impact Factor
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    ABSTRACT: Hepatocellular carcinoma (HCC) is a highly aggressive cancer with no currently available effective treatment. Understanding of the molecular mechanism of HCC development and progression is imperative for developing novel, effective, and targeted therapies for this lethal disease. In this article, we document that the cellular transcription factor Late SV40 Factor (LSF) plays an important role in HCC pathogenesis. LSF protein was significantly overexpressed in human HCC cells compared to normal hepatocytes. In 109 HCC patients, LSF protein was overexpressed in >90% cases, compared to normal liver, and LSF expression level showed significant correlation with the stages and grades of the disease. Forced overexpression of LSF in less aggressive HCC cells resulted in highly aggressive, angiogenic, and multiorgan metastatic tumors in nude mice. Conversely, inhibition of LSF significantly abrogated growth and metastasis of highly aggressive HCC cells in nude mice. Microarray studies revealed that as a transcription factor, LSF modulated specific genes regulating invasion, angiogenesis, chemoresistance, and senescence. The expression of osteopontin (OPN), a gene regulating every step in tumor progression and metastasis, was robustly up-regulated by LSF. It was documented that LSF transcriptionally up-regulates OPN, and loss-of-function studies demonstrated that OPN plays an important role in mediating the oncogenic functions of LSF. Together, these data establish a regulatory role of LSF in cancer, particularly HCC pathogenesis, and validate LSF as a viable target for therapeutic intervention.
    Proceedings of the National Academy of Sciences 05/2010; 107(18):8357-62. · 9.81 Impact Factor
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    ABSTRACT: Melanoma differentiation associated gene-7/interleukin-24 (mda-7/IL-24) uniquely displays broad cancer-specific apoptosis-inducing activity through induction of endoplasmic reticulum (ER) stress. We hypothesize that ceramide, a promoter of apoptosis, might contribute to mda-7/IL-24 induction of apoptosis. Ad.mda-7-infected tumor cells, but not normal cells, showed increased ceramide accumulation. Infection with Ad.mda-7 induced a marked increase in various ceramides (C16, C24, C24:1) selectively in prostate cancer cells. Inhibiting the enzyme serine palmitoyltransferase (SPT) using the potent SPT inhibitor myriocin (ISP1), impaired mda-7/IL-24-induced apoptosis and ceramide production, suggesting that ceramide formation caused by Ad.mda-7 occurs through de novo synthesis of ceramide and that ceramide is required for mda-7/IL-24-induced cell death. Fumonisin B1 (FB1) elevated ceramide formation as well as apoptosis induced by Ad.mda-7, suggesting that ceramide formation may also occur through the salvage pathway. Additionally, Ad.mda-7 infection enhanced expression of acid sphingomyelinase (ASMase) with a concomitant increase in ASMase activity and decreased sphingomyelin in cancer cells. ASMase silencing by RNA interference inhibited the decreased cell viability and ceramide formation after Ad.mda-7 infection. Ad.mda-7 activated protein phosphatase 2A (PP2A) and promoted dephosphorylation of the anti-apoptotic molecule BCL-2, a downstream ceramide-mediated pathway of mda-7/IL-24 action. Pretreatment of cells with FB1 or ISP-1 abolished the induction of ER stress markers (BiP/GRP78, GADD153 and pospho-eIF2alpha) triggered by Ad.mda-7 infection indicating that ceramide mediates ER stress induction by Ad.mda-7. Additionally, recombinant MDA-7/IL-24 protein induced cancer-specific production of ceramide. These studies define ceramide as a key mediator of an ER stress pathway that may underlie mda-7/IL-24 induction of cancer-specific killing.
    Journal of Cellular Physiology 11/2009; 222(3):546-55. · 4.22 Impact Factor
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    ABSTRACT: Since its original cloning by subtraction hybridization in 2002, it is now evident that Astrocyte elevated gene-1 (AEG-1) is a key contributor to the carcinogenic process in diverse organs. AEG-1 protein expression is elevated in advanced stages of many cancers, which correlates with poor survival. In specific cancers, such as breast and liver cancer, the AEG-1 gene itself is amplified, further supporting a seminal role in tumorigenesis. Overexpression and inhibition studies both in in vitro and in in vivo models reveal the importance of AEG-1 in regulating multiple physiologically and pathologically relevant processes including proliferation, invasion, metastasis, and gene expression. AEG-1 is a single-pass transmembrane protein with multiple nuclear localization signals and no known domains or motifs. Although pertinent roles of AEG-1 in the carcinogenic process are established, its potential function (promotion of metastasis only versus functioning as a bona fide oncogene) as well as localization (cell surface versus nucleus) remain areas requiring further clarification. The present review critically evaluates what is currently known about AEG-1 and provides new perspectives relative to this intriguing molecule that may provide a rational target for intervening in the cancer phenotype.
    Cancer Research 11/2009; 69(22):8529-35. · 9.28 Impact Factor
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    ABSTRACT: The innate immune system responds within minutes of infection to produce type I interferons and pro-inflammatory cytokines. Interferons induce the synthesis of cell proteins with antiviral activity, and also shape the adaptive immune response by priming T cells. Despite the discovery of interferons over 50 years ago, only recently have we begun to understand how cells sense the presence of a virus infection. Two families of pattern recognition receptors have been shown to distinguish unique molecules present in pathogens, such as bacterial and fungal cell wall components, viral RNA and DNA, and lipoproteins. The first family includes the membrane-bound toll-like receptors (TLRs). Studies of the signaling pathways that lead from pattern recognition to cytokine induction have revealed extensive and overlapping cascades that involve protein-protein interactions and phosphorylation, and culminate in activation of transcription proteins that control the transcription of genes encoding interferons and other cytokines. A second family of pattern recognition receptors has recently been identified, which comprises the cytoplasmic sensors of viral nucleic acids, including MDA-5, RIG-I, and LGP2. In this review we summarize the discovery of these cytoplasmic sensors, how they recognize nucleic acids, the signaling pathways leading to cytokine synthesis, and viral countermeasures that have evolved to antagonize the functions of these proteins. We also consider the function of these cytoplasmic sensors in apoptosis, development and differentiation, and diabetes.
    Pharmacology [?] Therapeutics 08/2009; 124(2):219-34. · 7.79 Impact Factor
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    ABSTRACT: Astrocyte elevated gene-1 (AEG-1) is overexpressed in >90% of human hepatocellular carcinoma (HCC) patients and plays a significant role in mediating aggressive progression of HCC. AEG-1 is known to augment invasion, metastasis, and angiogenesis, and we now demonstrate that AEG-1 directly contributes to another important hallmark of aggressive cancers, that is, resistance to chemotherapeutic drugs, such as 5-fluorouracil (5-FU). AEG-1 augments expression of the transcription factor LSF that regulates the expression of thymidylate synthase (TS), a target of 5-FU. In addition, AEG-1 enhances the expression of dihydropyrimidine dehydrogenase (DPYD) that catalyzes the initial and rate-limiting step in the catabolism of 5-FU. siRNA-mediated inhibition of AEG-1, LSF, or DPYD significantly increased the sensitivity of HCC cells to 5-FU in vitro and a lentivirus delivering AEG-1 siRNA in combination with 5-FU markedly inhibited growth of HCC cells xenotransplanted in athymic nude mice when compared to either agent alone. The present studies highlight 2 previously unidentified genes, AEG-1 and LSF, contributing to chemoresistance. Inhibition of AEG-1 might be exploited as a therapeutic strategy along with 5-FU-based combinatorial chemotherapy for HCC, a highly fatal cancer with currently very limited therapeutic options.
    Proceedings of the National Academy of Sciences 08/2009; 106(31):12938-43. · 9.81 Impact Factor
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    ABSTRACT: Hepatocellular carcinoma (HCC) is a highly aggressive vascular cancer characterized by diverse etiology, activation of multiple signal transduction pathways, and various gene mutations. Here, we have determined a specific role for astrocyte elevated gene-1 (AEG1) in HCC pathogenesis. Expression of AEG1 was extremely low in human hepatocytes, but its levels were significantly increased in human HCC. Stable overexpression of AEG1 converted nontumorigenic human HCC cells into highly aggressive vascular tumors, and inhibition of AEG1 abrogated tumorigenesis by aggressive HCC cells in a xenograft model of nude mice. In human HCC, AEG1 overexpression was associated with elevated copy numbers. Microarray analysis revealed that AEG1 modulated the expression of genes associated with invasion, metastasis, chemoresistance, angiogenesis, and senescence. AEG1 also was found to activate Wnt/beta-catenin signaling via ERK42/44 activation and upregulated lymphoid-enhancing factor 1/T cell factor 1 (LEF1/TCF1), the ultimate executor of the Wnt pathway, important for HCC progression. Inhibition studies further demonstrated that activation of Wnt signaling played a key role in mediating AEG1 function. AEG1 also activated the NF-kappaB pathway, which may play a role in the chronic inflammatory changes preceding HCC development. These data indicate that AEG1 plays a central role in regulating diverse aspects of HCC pathogenesis. Targeted inhibition of AEG1 might lead to the shutdown of key elemental characteristics of HCC and could lead to an effective therapeutic strategy for HCC.
    The Journal of clinical investigation 03/2009; 119(3):465-77. · 15.39 Impact Factor
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    ABSTRACT: We describe a novel basic leucine zipper containing type I IFN-inducible early response gene SARI (Suppressor of AP-1, Regulated by IFN). Steady-state SARI mRNA expression was detected in multiple lineage-specific normal cells, but not in their transformed/tumorigenic counterparts. In normal and cancer cells, SARI expression was induced 2 h after fibroblast IFN (IFN-beta) treatment with 1 U/ml of IFN-beta. Antisense inhibition of SARI protected HeLa cells from IFN-beta-mediated growth inhibition. As a corollary, overexpression of SARI inhibited growth and induced apoptosis in cancer cells, but not in normal cells. SARI interacted with c-Jun via its leucine zipper, resulting in inhibition of DNA binding of activator protein (AP-1) complex and consequently AP-1-dependent gene expression. Transformed cells relying on AP-1 activity for proliferative advantage demonstrated increased susceptibility to SARI-mediated growth inhibition. These findings uncover a novel mode of IFN-induced anti-tumor growth suppression and suggest potential gene therapy applications for SARI.
    Proceedings of the National Academy of Sciences 01/2009; 105(52):20906-11. · 9.81 Impact Factor
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    ABSTRACT: The scaffold PDZ-domain containing protein mda-9/syntenin functions as a positive regulator of cancer cell progression in human melanoma and other tumors. mda-9/Syntenin regulates cell motility and invasion by altering defined biochemical and signaling pathways, including focal adhesion kinase (FAK), p38 mitogen-activated protein kinase (MAPK) and NF-kappaB, but precisely how mda-9/syntenin organizes these multiprotein signaling complexes is not well understood. Using a clinically relevant human melanoma model, we demonstrate that mda-9/syntenin physically interacts with c-Src and this communication correlates with an increase in FAK/c-Src complex formation and c-Src activation. Inhibiting mda-9/syntenin, using an adenovirus expressing antisense mda-9/syntenin or addition of c-Src siRNA, suppresses melanoma cell migration, anchorage-independent growth, and spontaneous tumor cell dissemination in vivo in a human melanoma animal metastasis model. These data are compatible with a model wherein interaction of MDA-9/syntenin with c-Src promotes the formation of an active FAK/c-Src signaling complex, leading to enhanced tumor cell invasion and metastatic spread. These provocative findings highlight mda-9/syntenin and its interacting partners as promising therapeutic targets for intervention of metastasis.
    Proceedings of the National Academy of Sciences 11/2008; 105(41):15914-9. · 9.81 Impact Factor
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    ABSTRACT: A noteworthy aspect of melanoma differentiation-associated gene-7/interleukin-24 (mda-7/IL-24) as a cancer therapeutic is its ability to selectively kill cancer cells without harming normal cells. Intracellular MDA-7/IL-24 protein, generated from an adenovirus expressing mda-7/IL-24 (Ad.mda-7), induces cancer-specific apoptosis by inducing an endoplasmic reticulum (ER) stress response. Secreted MDA-7/IL-24 protein, generated from cells infected with Ad.mda-7, induces growth inhibition and apoptosis in surrounding noninfected cancer cells but not in normal cells, thus exerting an anti-tumor "bystander" effect. The present studies reveal a provocative finding that recombinant MDA-7/IL-24 protein can robustly induce expression of endogenous mda-7/IL-24, which generates the signaling events necessary for bystander killing. To evaluate the mechanism underlying this positive autocrine feedback loop, we show that MDA-7/IL-24 protein induces stabilization of its own mRNA without activating its promoter. Furthermore, this posttranscriptional effect depends on de novo protein synthesis. As a consequence of this autocrine feedback loop MDA-7/IL-24 protein induces sustained ER stress as evidenced by expression of ER stress markers (BiP/GRP78, GRP94, GADD153, and phospho-eIF2alpha) and reactive oxygen species production, indicating that both intracellular and secreted proteins activate similar signaling pathways to induce apoptosis. Thus, our results clarify the molecular mechanism by which secreted MDA-7/IL-24 protein (generated from Ad.mda-7-infected cells) exerts cancer-specific killing.
    Proceedings of the National Academy of Sciences 08/2008; 105(28):9763-8. · 9.81 Impact Factor
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    ABSTRACT: Cancer is a progressive disease that, in many instances, if untreated, can culminate in metastatic spread of primary tumor cells to distant sites in the body. Metastasis frequently confers virulence and therapy resistance to cancer cells, and defining the molecular events that control metastasis will be mandatory to develop rational, targeted therapies for effective intervention, prevention of recurrence, and the "holy grail" of engendering a cure. Adapter proteins are physiologically pertinent molecules that, through interactions with key regulatory proteins via specific conserved domains, control important cellular events. Melanoma differentiation associated gene-9 (mda-9), also known as syntenin, is a PDZ domain-containing adapter protein that is involved in organization of protein complexes in the plasma membranes, regulation of B-cell development, intracellular trafficking and cell-surface targeting, synaptic transmission, and axonal outgrowth. Recent studies now define a seminal role for mda-9/syntenin in cancer metastasis. The present review provides a current perspective of our understanding of this important aspect of mda-9/syntenin, suggesting that this gene and its encoded protein and interacting protein partners may provide viable targets for intervening in the final and invariably the most lethal stage of cancer progression, namely, cancer metastasis.
    Cancer Research 06/2008; 68(9):3087-93. · 9.28 Impact Factor
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    ABSTRACT: The poor prognosis of pancreatic cancer patients using currently available therapies mandates novel therapeutics that combine anti-neoplastic potency with toxicity-minimizing cancer specificity. Employing an overlapping pathway screen to identify genes exhibiting coordinated expression as a consequence of terminal cell differentiation and replicative senescence, we identified human polynucleotide phosphorylase (hPNPase(old-35)), a 3',5'-exoribonuclease that exhibits robust growth-suppressing effects in a wide spectrum of human cancers. A limitation to the anti-neoplastic efficacy of hPNPase(old-35) relates to its lack of cancer specificity. The promoter of Progression Elevated Gene-3 (PEG-Prom), discovered in our laboratory via subtraction hybridization in a transformation progression rodent tumor model functions selectively in a diverse array of human cancer cells, with limited activity in normal cells. An adenovirus constructed with the PEG-Prom driving expression of hPNPase(old-35) containing a C-terminal Hemaglutinin (HA)-tag (Ad.PEG.hPNPase(old-35)) was shown to induce robust transgene expression, growth suppression, apoptosis, and cell-cycle arrest in a broad panel of pancreatic cancer cells, with minimal effects in normal immortalized pancreatic cells. hPNPase(old-35) expression correlated with arrest in the G(2)/M phase of the cell cycle and up-regulation of the cyclin-dependent kinase inhibitors (CDKI) p21(CIP1/WAF-1/MDA-6) and p27(KIP1). In a nude mouse xenograft model, Ad.PEG.hPNPase(old-35) injections effectively inhibited growth of human pancreatic cancer cells in vivo. These findings support the potential efficacy of combining a cancer-specific promoter, such as the PEG-Prom, with a novel anti-neoplastic agent, such as hPNPase(old-35), to create a potent, targeted cancer therapeutic, especially for a devastating disease like pancreatic cancer.
    Journal of Cellular Physiology 05/2008; 215(2):401-409. · 4.22 Impact Factor
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    ABSTRACT: Malignant glioma is a consistently fatal brain cancer. The tumor invades the surrounding tissue, limiting complete surgical removal and thereby initiating recurrence. Identifying molecules critical for glioma invasion is essential to develop targeted, effective therapies. The expression of astrocyte elevated gene-1 (AEG-1) increases in malignant glioma and AEG-1 regulates in vitro invasion and migration of malignant glioma cells by activating the nuclear factor-kappaB (NF-kappaB) signaling pathway. The present studies elucidate the domains of AEG-1 important for mediating its function. Serial NH(2)-terminal and COOH-terminal deletion mutants were constructed and functional analysis revealed that the NH(2)-terminal 71 amino acids were essential for invasion, migration, and NF-kappaB-activating properties of AEG-1. The p65-interaction domain was identified between amino acids 101 to 205, indicating that p65 interaction alone is not sufficient to mediate AEG-1 function. Coimmunoprecipitation assays revealed that AEG-1 interacts with cyclic AMP-responsive element binding protein-binding protein (CBP), indicating that it might act as a bridging factor between NF-kappaB, CBP, and the basal transcription machinery. Chromatin immunoprecipitation assays showed that AEG-1 is associated with the NF-kappaB binding element in the interleukin-8 promoter. Thus, AEG-1 might function as a coactivator for NF-kappaB, consequently augmenting expression of genes necessary for invasion of glioma cells. In these contexts, AEG-1 represents a viable potential target for the therapy of malignant glioma.
    Cancer Research 04/2008; 68(5):1478-84. · 9.28 Impact Factor
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    ABSTRACT: Retinoic acid inducible gene-I (RIG-I) functions as the first line of defense against viral infection by sensing dsRNA and inducing type I interferon (IFN) production. The expression of RIG-I itself is induced by IFN-alpha/beta and dsRNA. To comprehend the molecular mechanism of expression regulation, we cloned the RIG-I promoter and analyzed its activity upon IFN-beta and dsRNA treatment. Under basal condition, RIG-I mRNA level and promoter activity were significantly higher in normal cells versus their tumor counterparts. In both normal and cancer cells, RIG-I expression was induced by IFN-beta and dsRNA. A single IRF-1 binding site in the proximal promoter functioned as a crucial regulator of basal, IFN-beta- and dsRNA-mediated induction of the RIG-I promoter. IFN-beta and dsRNA treatment increased IRF-1 binding to the RIG-I promoter. IRF-1 expression was also higher in normal cells than in cancer cells and it was induced by IFN-beta with similar kinetics as RIG-I. These results confirm that by controlling RIG-I expression, IRF-1 plays an essential role in anti-viral immunity. IRF-1 is a tumor suppressor and the expression profile of RIG-I together with its regulation by IRF-1 and the presence of a caspase-recruitment domain in RIG-I suggest that RIG-I might also possess tumor suppressor properties.
    Journal of Cellular Physiology 12/2007; 213(2):502-10. · 4.22 Impact Factor
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    ABSTRACT: A potentially less toxic approach for cancer therapy comprises induction of tumor cells to lose growth potential irreversibly and terminally differentiate. Combining this scheme termed 'differentiation therapy of cancer' with subtraction hybridization to human melanoma cells resulted in the cloning of melanoma differentiation associated (mda) genes displaying elevated expression as a consequence of induction of terminal differentiation. One originally novel gene, mda-7, was found to display elevated expression in normal melanocytes and nevi with progressive loss of expression as a consequence of melanoma development and progression to metastasis. Based on structure, biochemical properties and chromosomal location, mda-7 has now been reclassified as interleukin (IL)-24, a member of the expanding IL-10 family of cytokines. In vitro cell culture and in vivo animal studies indicate that mda-7/IL-24 selectively induces programmed cell death (apoptosis) in multiple human cancers (including melanomas), without harming normal cells, and promotes profound anti-tumor activity in nude mice containing human tumor xenografts. Based on these remarkable properties, a Phase I clinical trial was conducted to test the safety of administration of mda-7/IL-24 by a replication incompetent adenovirus (Ad.mda-7; INGN 241) in patients with advanced solid cancers including melanoma. mda-7/IL-24 was found to be safe and to promote significant clinical activity, particularly in the context of patients with metastatic melanoma. These results provide an impetus for further clinical studies and document a central paradigm of cancer therapy, namely translation of basic science from the "bench to the bedside."
    Toxicology and Applied Pharmacology 12/2007; 224(3):300-7. · 3.98 Impact Factor
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    ABSTRACT: Overexpression of the multidrug resistance 1 (MDR1) gene, encoding P-glycoprotein (P-gp), facilitates resistance to diverse chemotherapeutic drugs and current P-gp inhibitors display high toxicity. We studied the effects of melanoma differentiation associated gene-7/interleukin-24 (mda-7/IL-24), which exhibits cancer-specific apoptosis-inducing properties, in drug-sensitive (SW620) and drug-resistant (SW620/Dox) colorectal carcinoma cells. Adenovirus administered mda-7/IL-24, Ad.mda-7, effectively reversed resistance to doxorubicin-induced apoptosis in SW620/Dox cells by increased intracellular accumulation and decreased efflux of doxorubicin. Unexpectedly, P-gp-overexpressing cells (SW620/Dox) displayed increased apoptosis following Ad.mda-7 infection compared with parental SW620 cells, which correlated with more MDA-7/IL-24 protein in SW620/Dox than SW620 cell and potentially explains the increased sensitivity of P-gp-overexpressing cells to mda-7/IL-24. Transient overexpression of MDR1 in SW620 cells significantly increased apoptosis, decreased anchorage-independent growth, and increased MDA-7/IL-24 protein following Ad.mda-7 infection, whereas down-modulation of MDR1 in SW620/Dox cells by small interfering RNA decreased apoptosis following Ad.mda-7 infection. The increased mda-7/IL-24 sensitivity observed in SW620/Dox cells was partly due to increased reactive oxygen species generation and lower mitochondrial membrane potential. These findings confirm that mda-7/IL-24 is a potent MDR reversal agent, preferentially causing apoptosis in P-gp-overexpressing MDR cells, suggesting significant expanded clinical implications for the use of mda-7/IL-24 in treating neoplasms that have failed chemotherapy mediated by the P-gp MDR mechanism.
    Molecular Cancer Therapeutics 12/2007; 6(11):2985-94. · 5.60 Impact Factor
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    ABSTRACT: Subtraction hybridization applied to a 'differentiation therapy' model of cancer employing human melanoma cells resulted in the cloning of melanoma differentiation associated gene-7/interleukin-24 (mda-7/IL-24). Initial studies confirm an inverse correlation between mda-7 expression and melanoma development and progression. Forced expression of mda-7 by means of a plasmid or via a replication incompetent adenovirus (Ad.mda-7) promotes growth suppression and induces apoptosis in a broad array of human cancers. In contrast, mda-7 does not induce growth suppressive or toxic effects in normal cells. Based on structure (containing an IL-10 signature motif), secretion by cells (including subsets of T-cells) and location on chromosome 1q (in an area containing IL-10-family genes), mda-7 has now been renamed mda-7/IL-24. Studies by several laboratories have uncovered many of mda-7/IL-24's unique properties, including cancer-specific apoptosis-induction, cell cycle regulation, an ability to inhibit angiogenesis, potent 'bystander antitumor activity' and a capacity to enhance the sensitivity of tumor cells to radiation, chemotherapy and monoclonal antibody therapy. Moreover, based on its profound cancer tropism, substantiated by in vivo human xenograft studies in nude mice, mda-7/IL-24 (administered as Ad.mda-7) was evaluated in a phase I clinical trial in patients with melanomas and solid cancers. These studies document that mda-7/IL-24 is well tolerated and demonstrates evidence of significant clinical activity. In these contexts, mda-7/IL-24 represents a unique cytokine gene with potential for therapy of human cancers. The present review focuses on three unique properties of mda-7/IL-24, namely its potent 'bystander antitumor activity', ability to sensitize tumor cells to radiation, and its antiangiogenesis properties. Additionally, an overview of the phase I clinical trial is provided. These studies affirm that mda-7/IL-24 has promise for the management of diverse cancers.
    International Journal of Oncology 12/2007; 31(5):985-1007. · 2.66 Impact Factor

Publication Stats

3k Citations
485.73 Total Impact Points

Institutions

  • 2008–2012
    • Virginia Commonwealth University
      • Department of Human and Molecular Genetics
      Richmond, VA, United States
  • 1991–2008
    • Columbia University
      • • College of Physicians and Surgeons
      • • Department of Urology
      New York City, NY, United States
  • 2005
    • Hallym University
      Sŏul, Seoul, South Korea
    • Johns Hopkins University
      • Department of Neurology
      Baltimore, MD, United States
  • 1998
    • CUNY Graduate Center
      New York City, New York, United States