Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P11021 (BiP)
 2,049 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

HSP70 chaperones mediate protein folding by ATP-dependent interaction with short linear peptide segments that are exposed on unfolded proteins. The mode of action of the Escherichia coli homolog DnaK is representative of all HSP70 chaperones, including the endoplasmic reticulum variant BiP/GRP78. DnaK has been shown to be effective in assisting refolding of a wide variety of prokaryotic and eukaryotic proteins, including the alpha-helical homodimeric secretory cytokine interferon-gamma (IFN-gamma). We screened solid-phase peptide libraries from human and mouse IFN-gamma to identify DnaK-binding sites. Conserved DnaK-binding sites were identified in the N-terminal half of helix B and in the C-terminal half of helix C, both of which are located at the IFN-gamma dimer interface. Soluble peptides derived from helices B and C bound DnaK with high affinity in competition assays. No DnaK-binding sites were found in the loops connecting the alpha-helices. The helix C DnaK-binding site appears to be conserved in most members of the superfamily of interleukin (IL)-10-related cytokines that comprises, apart from IL-10 and IFN-gamma, a series of recently discovered small secretory proteins, including IL-19, IL-20, IL-22/IL-TIF, IL-24/MDA-7 (melanoma differentiation-associated gene), IL-26/AK155, and a number of viral IL-10 homologs. These cytokines belong to a relatively small group of homodimeric proteins with highly interdigitated interfaces that exhibit the strongly hydrophobic character of the interior core of a single-chain folded domain. We propose that binding of DnaK to helix C in the superfamily of IL-10-related cytokines may constitute the hallmark of a novel conserved regulatory mechanism in which HSP70-like chaperones assist in the formation of a hydrophobic dimeric "folding" interface.
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PMID:The conserved helix C region in the superfamily of interferon-gamma /interleukin-10-related cytokines corresponds to a high-affinity binding site for the HSP70 chaperone DnaK. 1197 Sep 58

mda-7/IL-24 (HGMW-approved symbol IL24) is a tumor suppressor gene whose expression is lost during tumor progression. Gene transfer using adenoviral mda-7/IL-24 (Ad-mda7) exhibits minimal toxicity on normal cells while inducing potent apoptosis in a variety of cancer cell lines. Ad-mda7-transduced cells express high levels of MDA-7 protein intracellularly and also secrete a soluble form of MDA-7 protein. In this study, we sought to determine whether the intracellular or secreted MDA-7 protein was responsible for anti-tumor activity in H1299 lung tumor cells. Ad-mda7 transduction of lung tumor cells increased expression of stress-related proteins, including BiP, GADD34, PP2A, caspases 7 and 12, and XBP-1, consistent with activation of the UPR pathway, a key sensor of endoplasmic reticulum (ER)-mediated stress. Blocking secretion of MDA-7 did not inhibit apoptosis, demonstrating that intracellular MDA-7 was responsible for cytotoxicity. Consistent with this result, when applied directly to lung cancer cells, soluble MDA-7 protein exhibited minimal cytotoxic effect. We then generated mda-7 expression constructs using vectors that target the expressed protein to various subcellular compartments, including cytoplasm, nucleus, and ER. Only full-length and ER-targeted MDA-7 elicited cell death in tumor cells. Thus in lung cancer cells, Ad-mda7 activates the UPR stress pathway and induces apoptosis via intracellular MDA-7 expression in the secretory pathway.
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PMID:The tumor suppressor activity of MDA-7/IL-24 is mediated by intracellular protein expression in NSCLC cells. 1500 2

Melanoma differentiation-associated gene-7/interleukin-24 (mda-7/IL-24) is a unique member of the IL-10 gene family that induces cancer-selective growth suppression and apoptosis in a wide spectrum of human cancers in cell culture and animal models. Additionally, recent clinical trials confirm safety and document significant clinical activity of mda-7/IL-24 in patients with diverse solid cancers and melanomas. Despite intensive study the molecular basis of tumor-cell selectivity of mda-7/IL-24 is not well characterized. Using deletion analysis, a specific mutant of MDA-7/IL-24, M4, consisting of amino acids 104 to 206, is described that retains the cancer-specific growth-suppressive and apoptosis-inducing properties of the full-length protein. Employing rationally designed mutational analysis, we show that MDA-7/IL-24 and M4 physically interact with BiP/GRP78 through their C and F helices, localize in the endoplasmic reticulum, and activate p38 MAPK and GADD gene expression, culminating in cancer-selective apoptosis. These studies provide novel mechanistic insights into the discriminating antitumor activity of MDA-7/IL-24 by elucidating BiP/GRP78 as a defined intracellular target of action and present an unparalleled opportunity to develop improved therapeutic versions of this cancer-specific apoptosis-inducing cytokine.
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PMID:BiP/GRP78 is an intracellular target for MDA-7/IL-24 induction of cancer-specific apoptosis. 1691 97

Biochemical and genetic mutation-based analyses confirm that the MDA-7/IL-24 protein can induce transformed cell-specific apoptosis through a mechanism involving endoplasmic reticulum (ER) stress-associated pathways. Covalent modifications by N-linked glycans in the ER contribute to the conformational maturation and biological functions of many proteins. Because MDA-7/IL-24 is a glycosylated protein, we investigated the role of glycosylation in mediating the specific biological and "bystander" antitumor activities of this cytokine. An adenovirus vector expressing a nonsecreted and nonglycosylated version of MDA-7/IL-24 protein was generated via deletion of its signal peptide and point mutations of its three N-glycosylated sites. In this study, we showed that this intracellular nonglycosylated protein was as effective as wild-type MDA-7/IL-24 protein in inducing apoptosis in multiple tumor cell lines. Both constructs (a) displayed transformed cell specificity and localization to the ER compartment, (b) mediated apoptosis through JAK/STAT-independent and p38(MAPK)-dependent pathways, (c) induced sustained ER stress as evidenced by expression of ER stress markers (BiP/GRP78, GRP94, XBP-1, and eIF2alpha), and (d) generated proteins that physically interacted with BiP/GRP78. Additionally, an expression construct containing the mda-7/IL-24 signal peptide linked to the mutated nonglycosylated mda-7/IL-24 gene retained the ability to induce bystander antitumor activity. These studies reveal that MDA-7/IL-24 glycosylation is not mandatory for inducing cell death or bystander activities in different cancer cells, providing new insights into the mechanism by which MDA-7/IL-24 induces apoptosis and ER stress.
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PMID:N-glycosylation of MDA-7/IL-24 is dispensable for tumor cell-specific apoptosis and "bystander" antitumor activity. 1717 84

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.
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PMID:Caspase-, cathepsin-, and PERK-dependent regulation of MDA-7/IL-24-induced cell killing in primary human glioma cells. 1828 15

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.
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PMID:PERK-dependent regulation of MDA-7/IL-24-induced autophagy in primary human glioma cells. 1829 61

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.
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PMID:Autocrine regulation of mda-7/IL-24 mediates cancer-specific apoptosis. 1859 61

Melanoma differentiation associated gene-7/interleukin 24 (mda-7/IL-24) is a unique interleukin (IL)-10 family cytokine displaying selective apoptosis-inducing activity in transformed cells without harming normal cells. The present studies focused on defining the mechanism(s) by which recombinant adenoviral delivery of MDA-7/IL-24 inhibits cell survival of human ovarian carcinoma cells. Expression of MDA-7/IL-24 induced phosphorylation of protein kinase R-like endoplasmic reticulum kinase (PERK) and eukaryotic initiation factor2alpha (eIF2alpha). In a PERK-dependent fashion, MDA-7/IL-24 reduced ERK1/2 and AKT phosphorylation and activated c-Jun NH(2)-terminal kinase (JNK) 1/2 and p38 mitogen-activated protein kinase (MAPK). MDA-7/IL-24 reduced MCL-1 and BCL-XL and increased BAX levels via PERK signaling; cell-killing was mediated via the intrinsic pathway, and cell killing was primarily necrotic as judged using Annexin V/propidium iodide staining. Inhibition of p38 MAPK and JNK1/2 abolished MDA-7/IL-24 toxicity and blocked BAX and BAK activation, whereas activation of mitogen-activated extracellular-regulated kinase (MEK) 1/2 or AKT suppressed enhanced killing and JNK1/2 activation. MEK1/2 signaling increased expression of the MDA-7/IL-24 and PERK chaperone BiP/78-kDa glucose regulated protein (GRP78), and overexpression of BiP/GRP78 suppressed MDA-7/IL-24 toxicity. MDA-7/IL-24-induced LC3-green fluorescent protein vesicularization and processing of LC3; and knockdown of ATG5 suppressed MDA-7/IL-24-mediated toxicity. MDA-7/IL-24 and cisplatin interacted in a greater than additive fashion to kill tumor cells that was dependent on a further elevation of JNK1/2 activity and recruitment of the extrinsic CD95 pathway. MDA-7/IL-24 toxicity was enhanced in a weak additive fashion by paclitaxel; paclitaxel enhanced MDA-7/IL-24 + cisplatin lethality in a greater than additive fashion via BAX. Collectively, our data demonstrate that MDA-7/IL-24 induces an endoplasmic reticulum stress response that activates multiple proapoptotic pathways, culminating in decreased ovarian tumor cell survival.
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PMID:Cisplatin enhances protein kinase R-like endoplasmic reticulum kinase- and CD95-dependent melanoma differentiation-associated gene-7/interleukin-24-induced killing in ovarian carcinoma cells. 1991 Apr 52

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.
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PMID:Ceramide plays a prominent role in MDA-7/IL-24-induced cancer-specific apoptosis. 1993 35

Conditionally replication competent adenoviruses (Ads) that selectively replicate in cancer cells and simultaneously express a therapeutic cytokine, such as melanoma differentiation associated gene- 7/Interleukin-24 (mda-7/IL-24), a Cancer Terminator Virus (CTV-M7), hold potential for treating human cancers. To enhance the efficacy of the CTV-M7, we generated a chimeric Ad.5 and Ad.3 modified fiber bipartite CTV (Ad.5/3-CTV-M7) that can infect tumor cells in a Coxsackie Adenovirus receptor (CAR) independent manner, while retaining high infectivity in cancer cells containing high CAR. Although mda-7/IL-24 displays broad-spectrum anticancer properties, pancreatic ductal adenocarcinoma (PDAC) cells display an intrinsic resistance to mda-7/IL-24-mediated killing due to an mda-7/IL-24 mRNA translational block. However, using a chemoprevention gene therapy (CGT) approach with perillyl alcohol (POH) and a replication incompetent Ad to deliver mda-7/IL-24 (Ad.mda-7) there is enhanced conversion of mda-7/IL-24 mRNA into protein resulting in pancreatic cancer cell death in vitro and in vivo in nude mice containing human PDAC xenografts. This combination synergistically induces mda-7/IL-24-mediated cancer-specific apoptosis by inhibiting anti-apoptotic Bcl-xL and Bcl-2 protein expression and inducing an endoplasmic reticulum (ER) stress response through induction of BiP/GRP-78, which is most evident in chimeric-modified non-replicating Ad.5/3- mda-7- and CTV-M7-infected PDAC cells. Moreover, Ad.5/3-CTV-M7 in combination with POH sensitizes therapy-resistant MIA PaCa-2 cell lines over-expressing either Bcl-2 or Bcl-xL to mda-7/IL-24-mediated apoptosis. Ad.5/3-CTV-M7 plus POH also exerts a significant antitumor 'bystander' effect in vivo suppressing both primary and distant site tumor growth, confirming therapeutic utility of Ad.5/3-CTV-M7 plus POH in PDAC treatment, where all other current treatment strategies in clinical settings show minimal efficacy.
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PMID:Chemoprevention gene therapy (CGT) of pancreatic cancer using perillyl alcohol and a novel chimeric serotype cancer terminator virus. 2423 57


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