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Melanoma differentiation-associated gene-7/IL-24 ( mda-7/IL-24 ) displays broad-spectrum anticancer activity in vitro, in vivo in preclinical animal models, and in a phase I/II clinical trial in patients with advanced cancers without harming normal cells or tissues. Here we demonstrate that mda-7/IL-24 regulates a specific subset of miRNAs, including cancer-associated miR-221. Either ectopic expression of mda-7/IL-24 or treatment with recombinant His-MDA-7 protein resulted in downregulation of miR-221 and upregulation of p27 and PUMA in a panel of cancer cells, culminating in cell death. Mda-7/IL-24 -induced cancer cell death was dependent on reactive oxygen species induction and was rescued by overexpression of miR-221. Beclin-1 was identified as a new transcriptional target of miR-221, and mda-7/IL-24 regulated autophagy through a miR-221/beclin-1 feedback loop. In a human breast cancer xenograft model, miR-221-overexpressing MDA-MB-231 clones were more aggressive and resistant to mda-7/IL-24 -mediated cell death than parental clones. This is the first demonstration that mda-7/IL-24 directly regulates miRNA expression in cancer cells and highlights the novelty of the mda-7/IL-24 -miR-221-beclin-1 loop in mediating cancer cell-specific death. Cancer Res; 77(4); 949-59. ©2016 AACR ., (©2016 American Association for Cancer Research.)

Advanced stages of neuroblastoma, the most common extracranial malignant solid tumor of the central nervous system in infants and children, are refractive to therapy. Ectopic expression of melanoma differentiation-associated gene-7/interleukin-24 (mda-7/IL-24) promotes broad-spectrum antitumor activity in vitro, in vivo in preclinical animal models, and in a phase I clinical trial in patients with advanced cancers without harming normal cells. mda-7/IL-24 exerts cancer-specific toxicity (apoptosis or toxic autophagy) by promoting endoplasmic reticulum stress and modulating multiple signal transduction pathways regulating cancer cell growth, invasion, metastasis, survival, and angiogenesis. To enhance cancer-selective expression and targeted anticancer activity of mda-7/IL-24, we created a tropism-modified cancer terminator virus (Ad.5/3-CTV), which selectively replicates in cancer cells producing robust expression of mda-7/IL-24 We now show that Ad.5/3-CTV induces profound neuroblastoma antiproliferative activity and apoptosis in a caspase-3/9-independent manner, both in vitro and in vivo in a tumor xenograft model. Ad.5/3-CTV promotes these effects through a unique pathway involving apoptosis-inducing factor (AIF) translocation into the nucleus. Inhibiting AIF rescued neuroblastoma cells from Ad.5/3-CTV-induced cell death, whereas pan-caspase inhibition failed to promote survival. Ad.5/3-CTV infection of neuroblastoma cells increased ATM phosphorylation instigating nuclear translocation and increased γ-H2AX, triggering nuclear translocation and intensified expression of AIF. These results were validated further using two ATM small-molecule inhibitors that attenuated PARP cleavage by inhibiting γ-H2AX, which in turn inhibited AIF changes in Ad.5/3-CTV-infected neuroblastoma cells. Taken together, we elucidate a novel pathway for mda-7/IL-24-induced caspase-independent apoptosis in neuroblastoma cells mediated through modulation of AIF, ATM, and γ-H2AX. Cancer Res; 76(12); 3572-82. ©2016 AACR., (©2016 American Association for Cancer Research.)

Polyinosine-polycytidylic acid [pIC] is a synthetic dsRNA that acts as an immune agonist of TLR3 and RLR to activate dendritic and natural killer cells that can kill tumor cells. pIC can also trigger apoptosis in pancreatic ductal adenocarcinoma cells (PDAC) but its mechanism of action is obscure. In this study, we investigated the potential therapeutic activity of a formulation of pIC with polyethylenimine ([pIC](PEI)) in PDAC and investigated its mechanism of action. [pIC](PEI) stimulated apoptosis in PDAC cells without affecting normal pancreatic epithelial cells. Mechanistically, [pIC](PEI) repressed XIAP and survivin expression and activated an immune response by inducing MDA-5, RIG-I, and NOXA. Phosphorylation of AKT was inhibited by [pIC](PEI) in PDAC, and this event was critical for stimulating apoptosis through XIAP and survivin degradation. In vivo administration of [pIC](PEI) inhibited tumor growth via AKT-mediated XIAP degradation in both subcutaneous and quasi-orthotopic models of PDAC. Taken together, these results offer a preclinical proof-of-concept for the evaluation of [pIC](PEI) as an immunochemotherapy to treat pancreatic cancer., (©2014 American Association for Cancer Research.)

Subtraction hybridization combined with induction of cancer cell terminal differentiation in human melanoma cells identified melanoma differentiation-associated gene-7/interleukin-24 (mda-7/IL-24) and SARI (suppressor of AP-1, induced by IFN) that display potent antitumor activity. These genes are not constitutively expressed in cancer cells and forced expression of mda-7/IL-24 (Ad.mda-7) or SARI (Ad.SARI) promotes cancer-specific cell death. Ectopic expression of mda-7/IL-24 induces SARI mRNA and protein in a panel of different cancer cells, leading to cell death, without harming corresponding normal cells. Simultaneous inhibition of K-ras downstream extracellular signal-regulated kinase 1/2 signaling in pancreatic cancer cells reverses the translational block of MDA-7/IL-24 and induces SARI expression and cell death. Using SARI-antisense-based approaches, we demonstrate that SARI expression is necessary for mda-7/IL-24 antitumor effects. Secreted MDA-7/IL-24 protein induces antitumor "bystander" effects by promoting its own expression. Recombinant MDA-7/IL-24 (His-MDA-7) induces SARI expression, supporting the involvement of SARI in the MDA-7/IL-24-driven autocrine loop, culminating in antitumor effects. Moreover, His-MDA-7, after binding to its cognate receptors (IL-20R1/IL-20R2 or IL-22R/IL-20R2), induces intracellular signaling by phosphorylation of p38 MAPK, leading to transcription of a family of growth arrest and DNA damage inducible (GADD) genes, culminating in apoptosis. Inhibition of p38 MAPK fails to induce SARI following Ad.mda-7 infection. These findings reveal the significance of the mda-7/IL-24-SARI axis in cancer-specific killing and provide a potential strategy for treating both local and metastatic disease.

X-linked inhibitor of apoptosis protein (XIAP) is constitutively expressed endogenous inhibitor of apoptosis, exhibit its antiapoptotic effect by inactivating key caspases such as caspase-3, caspase-7 and caspase-9 and also play pivotal role in rendering cancer chemoresistance. Our studies showed the coadministration of TQ and TAM resulting in a substantial increase in breast cancer cell apoptosis and marked inhibition of cell growth both in vitro and in vivo. Anti-angiogenic and anti-invasive potential of TQ and TAM was assessed through in vitro studies. This novel combinatorial regimen leads to regulation of multiple cell signaling targets including inactivation of Akt and XIAP degradation. At molecular level, TQ and TAM synergistically lowers XIAP expression resulting in binding and activation of caspase-9 in apoptotic cascade, and interfere with cell survival through PI3-K/Akt pathway by inhibiting Akt phosphorylation. Cleaved caspase-9 further processes other intracellular death substrates such as PARP thereby shifting the balance from survival to apoptosis, indicated by rise in the sub-G1 cell population. This combination also downregulates the expression of Akt-regulated downstream effectors such as Bcl-xL, Bcl-2 and induce expression of Bax, AIF, cytochrome C and p-27. Consistent with these results, overexpression studies further confirmed the involvement of XIAP and its regulatory action on Akt phosphorylation along with procaspase-9 and PARP cleavage in TQ-TAM coadministrated induced apoptosis. The ability of TQ and TAM in inhibiting XIAP was confirmed through siRNA-XIAP cotransfection studies. This novel modality may be a promising tool in breast cancer treatment.

The prognosis of patients with human high-grade gliomas (HGGs) remains dismal despite major advances in their management, due mainly to the high resistance of these infiltrative tumor cells to programmed cell death (PCD). Most therapeutic strategies for HGGs are aimed to maximize PCD type I, apoptosis or type II, autophagy. These are predominantly distinctive processes, but many studies suggest a cross-talk between the two. A better understanding of the link between PCD types I and II might allow development of more effective therapies for HGGs. In this study, we examined whether there is a common upstream signaling event responsible for both apoptotic and autophagic PCD using 3 chemotherapeutic agents in human HGG cells. Our study shows that each agent caused a significant decrease in cell viability in each of the HGG cell lines tested. The increase rate of apoptosis and autophagy varied among cell lines and chemotherapeutic agents used. Increased expression of cytidine-cytidine-adenosine-adenosine-thymidine (C)/enhancer binding protein (EBP) homologous transcription factor C/EBP homologous protein (CHOP)/growth arrest and DNA damage-inducible gene 153 (GADD153) was documented after use of either pro-autophagic or pro-apoptotic agents. The involvement of CHOP/GADD153 in both type I and type II PCD was confirmed by overexpression and gene-silencing studies. Gene silencing by small-interfering RNA-mediated CHOP/GADD153 resulted in increased cell viability, decreased upregulation of microtubule-associated protein light-chain 3' type II (LC3II) and cleaved caspase-3, and inhibition of apoptosis and autophagy. Exogenous expression of CHOP/GADD153 triggered apoptosis and autophagy in the absence of other stimuli. The clinical significance of these findings was supported by the evidence that celecoxib, a nonsteroidal anti-inflammatory drug known to induce GADD153-mediated apoptosis, strongly increases both type I and type II PCD in HGG cells when combined with another inducer of GADD153. These data suggest that CHOP/GADD153 should be investigated as a novel targetable signaling step to improve therapies for HGGs.

A subtraction hybridization approach combined with a differentiation therapy model of human melanoma identified melanoma differentiation associated gene-7 (mda-7) as a gene upregulated during induction of terminal differentiation. Based on conserved structure, chromosomal location and cytokine-like properties, mda-7, has now been classified as a member of the expanding interleukin (IL)-10 gene family and designated as mda-7/IL-24. Extensive in vitro and in vivo human tumor xenograft studies confirm that mda-7/IL-24 induces apoptosis specifically in tumor cells without harming normal cells. Unique properties of mda-7/IL-24 action also include potent "bystander antitumor" activity, an ability to exert anti-angiogenic effects, immune modulating ability and a capacity to enhance the sensitivity of tumor cells to radiotherapy, chemotherapy and monoclonal antibody therapy. Very recent studies from our groups further reveal autocrine regulation and chemoprevention facilitating properties of mda-7/IL-24. Based on these remarkable antitumor attributes, mda-7/IL-24 was evaluated by intratumoral injection with a replication incompetent adenovirus expressing this gene (Ad.mda-7; INGN 241) in a phase I clinical trial in patients with metastatic melanomas and other advanced solid cancers. mda-7/IL-24 was well tolerated with significant clinical activity. This review highlights our current understanding of the molecular and biochemical basis of mda-7/IL-24 antitumor properties and highlights its potential as a viable gene-based therapy for a wide spectrum of primary and advanced cancers.

Melanoma differentiation associated gene-7/interleukin 24 (mda-7/IL-24) is a novel cytokine displaying selective apoptosis-inducing activity in transformed cells without harming normal cells. The studies by Yacoub et al. (Mol Cancer Ther 2008; 7:314-29) further defines the mechanism(s) by which a GST-MDA-7 fusion protein inhibits cell survival of primary human glioma cells in vitro. GST-MDA-7 killed glioma cells with diverse genetic characteristics that were dependent on activation of JNK1-3 with subsequent activation of BAX and the induction of mitochondrial dysfunction. Activation of JNK1-3 was dependent upon protein kinase R-like endoplasmic reticulum kinase (PERK) and GST-MDA-7 lethality was suppressed in PERK(-/-) cells. GST-MDA-7 caused PERK-dependent vacuolization of LC3-expressing endosomes whose formation was suppressed by incubation with 3-methyladenine, expression of HSP70 or of BiP/GRP78, or by knockdown of ATG5 or Beclin 1 expression, but not by inhibition of the JNK1-3 pathway. Knockdown of ATG5 or Beclin 1 expression or overexpression of HSP70 reduced GST-MDA-7 lethality. Our data demonstrate that GST-MDA-7 induces an ER stress response that, via the induction of autophagy, is causal in the activation of pro-apoptotic pathways that converge on the mitochondrion and ultimately culminate in decreased glioma cell survival.

The present studies defined the biological effects of a GST fusion protein of melanoma differentiation-associated gene-7 (mda-7), GST-MDA-7 (1 and 30 nmol/L), on cell survival and cell signaling in primary human glioma cells in vitro. GST-MDA-7, in a dose- and time-dependent fashion killed glioma cells with diverse genetic characteristics; 1 nmol/L caused arrest without death, whereas 30 nmol/L caused arrest and killing after exposure. Combined inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) and AKT function was required to enhance 1 nmol/L GST-MDA-7 lethality in all cell types, whereas combined activation of MEK1 and AKT was required to suppress 30 nmol/L GST-MDA-7 lethality; both effects are mediated in part by modulating c-Jun NH(2)-terminal kinase (JNK) 1-3 activity. The geldanamycin 17AAG inhibited AKT and ERK1/2 in GBM cells and enhanced GST-MDA-7 lethality. JNK1-3 signaling promoted BAX activation and mitochondrial dysfunction. In GBM6 cells, GST-MDA-7 (30 nmol/L) transiently activated p38 mitogen-activated protein kinase, which was modestly protective against JNK1-3-induced toxicity, whereas GST-MDA-7 (300 nmol/L) caused prolonged intense p38 mitogen-activated protein kinase activation, which promoted cell death. In GBM12 cells that express full-length mutant activated ERBB1, inhibition of ERBB1 did not modify GST-MDA-7 lethality; however, in U118 established glioma cells, stable overexpression of wild-type ERBB1 and/or truncated active ERBB1vIII suppressed GST-MDA-7 lethality. Our data argue that combined inhibition of ERK1/2 and AKT function, regardless of genetic background, promotes MDA-7 lethality in human primary human glioma cells via JNK1-3 signaling and is likely to represent a more ubiquitous approach to enhancing MDA-7 toxicity in this cell type than inhibition of ERBB1 function.

Melanoma differentiation-associated gene-7/interleukin-24 (mda-7/IL-24) is a novel cytokine displaying selective apoptosis-inducing activity in transformed cells without harming normal cells. The present studies focused on defining the mechanism(s) by which a GST-MDA-7 fusion protein inhibits cell survival of primary human glioma cells in vitro. GST-MDA-7 killed glioma cells with diverse genetic characteristics that correlated with inactivation of ERK1/2 and activation of JNK1-3. Activation of JNK1-3 was dependent on protein kinase R-like endoplasmic reticulum kinase (PERK), and GST-MDA-7 lethality was suppressed in PERK-/- cells. JNK1-3 signaling activated BAX, whereas inhibition of JNK1-3, deletion of BAX, or expression of dominant-negative caspase-9 suppressed lethality. GST-MDA-7 also promoted a PERK-, JNK-, and cathepsin B-dependent cleavage of BID; loss of BID function promoted survival. GST-MDA-7 suppressed BAD and BIM phosphorylation and heat shock protein 70 (HSP70) expression. GST-MDA-7 caused PERK-dependent vacuolization of LC3-expressing endosomes whose formation was suppressed by incubation with 3-methyladenine, expression of HSP70 or BiP/GRP78, or knockdown of ATG5 or Beclin-1 expression but not by inhibition of the JNK1-3 pathway. Knockdown of ATG5 or Beclin-1 expression or overexpression of HSP70 reduced GST-MDA-7 lethality. Our data show that GST-MDA-7 induces an endoplasmic reticulum stress response that is causal in the activation of multiple proapoptotic pathways, which converge on the mitochondrion and highlight the complexity of signaling pathways altered by mda-7/IL-24 in glioma cells that ultimately culminate in decreased tumor cell survival.

Melanoma differentiation associated gene-7 (mda-7) was cloned using subtraction hybridization from terminally differentiated human melanoma cells. Based on structural and functional properties, mda-7 is now recognized as interleukin-24 (IL-24), a new member of the expanding IL-10 gene family. Unique properties of mda-7/IL-24 include its ability to selectively induce growth suppression, apoptosis and radiosensitization in diverse human cancer cells, without causing similar effects in normal cells. The utility of mda-7/IL-24, administered by means of a replication-incompetent adenovirus, as a gene therapy for cancer has recently received validation in patients, highlighting an important phenomenon initially observed in pancreatic tumor cells, namely a 'potent bystander apoptosis-inducing effect' in adjacent tumor cells not initially receiving this gene product. We presently investigated the contribution of mda-7/IL-24 secreted by normal cells in mediating this 'bystander effect', and document that normal cells induced to produce mda-7/IL-24 following infection with recombinant adenoviruses expressing this cytokine secrete mda-7/IL-24, which modifies the anchorage-independent growth, invasiveness, survival and sensitivity to radiation of cancer cells that contain functional IL-20/IL-22 receptors, but not in cancer cells that lack a complete set of receptors. Moreover, the combination of secreted mda-7/IL-24 and radiation engenders a 'bystander antitumor effect' not only in inherently mda-7/IL-24 or radiation-sensitive cancer cells, but also in tumor cells overexpressing the antiapoptotic proteins bcl-2 or bcl-x(L) and displaying resistance to either treatment alone. The present studies provide definitive evidence that secreted mda-7/IL-24 from normal cells can induce direct antitumor and radiation-enhancing effects that are dependent on the presence of canonical receptors for this cytokine on tumor cells. Moreover, we now describe a novel means of enhancing mda-7/IL-24's therapeutic potential by targeting normal cells to produce and release this cancer-specific apoptosis-inducing cytokine, a strategy that could be employed as an innovative way of using this unique gene product for treating metastatic disease.

Melanoma differentiation-associated gene-7/interleukin-24 (mda-7/IL-24) is a multifunctional cytokine displaying broad-spectrum anticancer activity in vitro or in vivo in preclinical animal cancer models and in a phase 1/2 clinical trial in patients with advanced cancers. mda-7/IL-24 targets specific miRNAs, including miR-221 and miR-320, for down-regulation in a cancer-selective manner. We demonstrate that mda-7/IL-24, administered through a replication incompetent type 5 adenovirus (Ad.mda-7) or with His-MDA-7/IL-24 protein, down-regulates DICER, a critical regulator in miRNA processing. This effect is specific for mature miR-221, as it does not affect Pri-miR-221 expression, and the DICER protein, as no changes occur in other miRNA processing cofactors, including DROSHA, PASHA, or Argonaute. DICER is unchanged by Ad.mda-7/IL-24 in normal immortal prostate cells, whereas Ad.mda-7 down-regulates DICER in multiple cancer cells including glioblastoma multiforme and prostate, breast, lung, and liver carcinoma cells. MDA-7/IL-24 protein down-regulates DICER expression through canonical IL-20/IL-22 receptors. Gain- and loss-of-function studies confirm that overexpression of DICER rescues deregulation of miRNAs by mda-7/IL-24, partially rescuing cancer cells from mda-7/IL-24-mediated cell death. Stable overexpression of DICER in cancer cells impedes Ad.mda-7 or His-MDA-7/IL-24 inhibition of cell growth, colony formation, PARP cleavage, and apoptosis. In addition, stable overexpression of DICER renders cancer cells more resistant to Ad.mda-7 inhibition of primary and secondary tumor growth. MDA-7/IL-24-mediated regulation of DICER is reactive oxygen species-dependent and mediated by melanogenesis-associated transcription factor. Our research uncovers a distinct role of mda-7/IL-24 in the regulation of miRNA biogenesis through alteration of the MITF-DICER pathway.

Melanoma differentiation associated gene-7/interleukin-24 (MDA-7/IL-24), a secreted protein of the IL-10 family, was first identified more than two decades ago as a novel gene differentially expressed in terminally differentiating human metastatic melanoma cells. MDA-7/IL-24 functions as a potent tumor suppressor exerting a diverse array of functions including the inhibition of tumor growth, invasion, angiogenesis, and metastasis, and induction of potent "bystander" antitumor activity and synergy with conventional cancer therapeutics. MDA-7/IL-24 induces cancer-specific cell death through apoptosis or toxic autophagy, which was initially established in vitro and in preclinical animal models in vivo and later in a Phase I clinical trial in patients with advanced cancers. This review summarizes the history and our current understanding of the molecular/biological mechanisms of MDA-7/IL-24 action rendering it a potent cancer suppressor. [ABSTRACT FROM AUTHOR]

Melanoma differentiation associated gene-7 (mda-7) was cloned using subtraction hybridization from terminally differentiated human melanoma cells. Based on structural and functional properties, mda-7 is now recognized as interleukin-24 (IL-24), a new member of the expanding IL-10 gene family. Unique properties of mda-7/IL-24 include its ability to selectively induce growth suppression, apoptosis and radiosensitization in diverse human cancer cells, without causing similar effects in normal cells. The utility of mda-7/IL-24, administered by means of a replication-incompetent adenovirus, as a gene therapy for cancer has recently received validation in patients, highlighting an important phenomenon initially observed in pancreatic tumor cells, namely a ‘potent bystander apoptosis-inducing effect’ in adjacent tumor cells not initially receiving this gene product. We presently investigated the contribution of mda-7/IL-24 secreted by normal cells in mediating this ‘bystander effect’, and document that normal cells induced to produce mda-7/IL-24 following infection with recombinant adenoviruses expressing this cytokine secrete mda-7/IL-24, which modifies the anchorage-independent growth, invasiveness, survival and sensitivity to radiation of cancer cells that contain functional IL-20/IL-22 receptors, but not in cancer cells that lack a complete set of receptors. Moreover, the combination of secreted mda-7/IL-24 and radiation engenders a ‘bystander antitumor effect’ not only in inherently mda-7/IL-24 or radiation-sensitive cancer cells, but also in tumor cells overexpressing the antiapoptotic proteins bcl-2 or bcl-xL and displaying resistance to either treatment alone. The present studies provide definitive evidence that secreted mda-7/IL-24 from normal cells can induce direct antitumor and radiation-enhancing effects that are dependent on the presence of canonical receptors for this cytokine on tumor cells. Moreover, we now describe a novel means of enhancing mda-7/IL-24's therapeutic potential by targeting normal cells to produce and release this cancer-specific apoptosis-inducing cytokine, a strategy that could be employed as an innovative way of using this unique gene product for treating metastatic disease.Oncogene (2005) 24, 7552–7566. doi:10.1038/sj.onc.1208911; published online 25 July 2005 [ABSTRACT FROM AUTHOR]

Progression Elevated Gene-3 (PEG-3) was cloned using subtraction hybridization as an upregulated transcript associated with transformation and tumor progression of rat embryo fibroblast cells. PEG-3 is a unique gene facilitating tumor progression by modulating multiple pathways in transformed cells, including genomic stability, angiogenesis and invasion. PEG-3 originates from mutation in the growth arrest and DNA damage inducible gene GADD34. A one base deletion in rat GADD34 results in a frame-shift and premature appearance of a stop-codon resulting in a C-terminally truncated molecule that is PEG-3. We now document that mutation in the GADD34 gene is a frequent event during transformation and/or immortalization of rodent cells. Sequencing of the GADD34 gene in a number of independent rat tumor cell lines revealed that in a majority of these the GADD34 gene is mutated to either PEG-3 or a PEG-3-like gene with similar C-terminal truncations. An important function of GADD34 is to inhibit cell growth, predominantly by apoptosis, and we demonstrate that PEG-3 or C-terminal truncations of human GADD34 resembling PEG-3 prevent growth inhibition by both human and rat GADD34. Phosphorylation of p53 by GADD34 is one mechanism by which it inhibits growth and PEG-3 could prevent GADD34-induced p53 phosphorylation. In contrast, PEG-3 was unable to block other GADD34-induced changes, including eIF2adephosphorylation, indicating that its effects on GADD34 may be related more to its effect on cell growth rather than a global inhibitor of all GADD34 functions. We hypothesize that mutational generation of PEG-3 or a similar molecule is a critical event during rodent carcinogenesis. The inherent property of PEG-3 to function as a dominant negative of the growth inhibitory property of GADD34 might rescue cells from DNA damage-induced apoptosis leading to growth independence and tumorigenesis.Oncogene (2005) 24, 2247-2255. doi:10.1038/sj.onc.1208420 Published online 17 January 2005 [ABSTRACT FROM AUTHOR]

Simple Summary: An optimum cancer therapeutic virus should embody unique properties, including an ability to: Selectively procreate and kill tumor but not normal cells; produce a secreted therapeutic molecule (with broad-acting anti-cancer effects on primary and distant metastatic cells because of potent "bystander" activity); and monitor therapy non-invasively by imaging primary and distant metastatic cancers. We previously created a broad-spectrum, cancer-selective and replication competent therapeutic adenovirus that embodies two of these properties, i.e., specifically reproduces in cancer cells and produces a therapeutic cytokine, MDA-7/IL-24, a "cancer terminator virus" (CTV). We now expand on this concept and demonstrate the feasibility of producing a tripartite CTV (TCTV) selectively expressing three genes from three distinct promoters that replicate in the cancer cells while producing MDA-7/IL-24 and an imaging gene (i.e., luciferase). This novel first-in-class tripartite "theranostic" TCTV expands the utility of therapeutic viruses to non-invasively image and selectively destroy primary tumors and metastases. Combining cancer-selective viral replication and simultaneous production of a therapeutic cytokine, with potent "bystander" anti-tumor activity, are hallmarks of the cancer terminator virus (CTV). To expand on these attributes, we designed a next generation CTV that additionally enables simultaneous non-invasive imaging of tumors targeted for eradication. A unique tripartite CTV "theranostic" adenovirus (TCTV) has now been created that employs three distinct promoters to target virus replication, cytokine production and imaging capabilities uniquely in cancer cells. Conditional replication of the TCTV is regulated by a cancer-selective (truncated PEG-3) promoter, the therapeutic component, MDA-7/IL-24, is under a ubiquitous (CMV) promoter, and finally the imaging capabilities are synchronized through another cancer selective (truncated tCCN1) promoter. Using in vitro studies and clinically relevant in vivo models of breast and prostate cancer, we demonstrate that incorporating a reporter gene for imaging does not compromise the exceptional therapeutic efficacy of our previously reported bipartite CTV. This TCTV permits targeted treatment of tumors while monitoring tumor regression, with potential to simultaneously detect metastasis due to the cancer-selective activity of reporter gene expression. This "theranostic" virus provides a new genetic tool for distinguishing and treating localized and metastatic cancers. [ABSTRACT FROM AUTHOR]

Despite some progress, treating advanced prostate cancer remains a major clinical challenge. Recent studies have shown that prostate cancer can originate from undifferentiated, rare, stem cell-like populations within the heterogeneous tumor mass, which play seminal roles in tumor formation, maintenance of tumor homeostasis and initiation of metastases. These cells possess enhanced propensity toward chemoresistance and may serve as a prognostic factor for prostate cancer recurrence. Despite extensive studies, selective targeted therapies against these stem cell-like populations are limited and more detailed experiments are required to develop novel targeted therapeutics. We now show that MDA-9/Syntenin/SDCBP (MDA-9) is a critical regulator of survival, stemness and chemoresistance in prostate cancer stem cells (PCSCs). MDA-9 regulates the expression of multiple stem-regulatory genes and loss of MDA-9 causes a complete collapse of the stem-regulatory network in PCSCs. Loss of MDA-9 also sensitizes PCSCs to multiple chemotherapeutics with different modes of action, such as docetaxel and trichostatin-A, suggesting that MDA-9 may regulate multiple drug resistance. Mechanistically, MDA-9-mediated multiple drug resistance, stemness and survival are regulated in PCSCs through activation of STAT3. Activated STAT3 regulates chemoresistance in PCSCs through protective autophagy as well as regulation of MDR1 on the surface of the PCSCs. We now demonstrate that MDA-9 is a critical regulator of PCSC survival and stemness via exploiting the inter-connected STAT3 and c-myc pathways. [ABSTRACT FROM AUTHOR]