bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diphtheria toxin-murine granulocyte-macrophage colony-stimulating factor–induced hepatotoxicity is mediated by Kupffer cells
Authors: Westcott Marlena M. , Abi-Habib Ralph J. , Cohen Kimberley A. , Willingham Mark C. , Liu Shihui , Bugge Thomas H. , Leppla Stephen H. , Frankel Arthur E. 
Published: June 2022

Abstract
DT388GMCSF, a fusion toxin composed of the NH2-terminal region of diphtheria toxin (DT) fused to human granulocyte-macrophage colony-stimulating factor (GMCSF) has shown efficacy in the treatment of acute myeloid leukemia. However, the primary dose-limiting side effect is liver toxicity. We have reproduced liver toxicity in rats using the rodent cell-tropic DT-murine GMCSF (DT390mGMCSF). Serum aspartate aminotransferase and alanine aminotransferase were elevated 15- and 4-fold, respectively, in DT390mGMCSF-treated rats relative to controls. Histologic analysis revealed hepatocyte swelling; however, this did not lead to hepatic necrosis or overt histopathologic changes in the liver. Immunohistochemical staining showed apoptotic cells in the sinusoids, and depletion of cells expressing the monocyte/macrophage markers, ED1 and ED2, indicating that Kupffer cells (KC) are targets of DT390mGMCSF. In contrast, sinusoidal endothelial cells seemed intact. In vitro, DT390mGMCSF was directly cytotoxic to primary KC but not hepatocytes. Two related fusion toxins, DT388GMCSF, which targets the human GMCSF receptor, and DT390mIL-3, which targets the rodent IL-3 receptor, induced a less than 2-fold elevation in serum transaminases and did not deplete KC in vivo. In addition, DTU2mGMCSF, a modified form of DT390mGMCSF with enhanced tumor cell specificity, was not hepatotoxic and was significantly less toxic to KC in vivo and in vitro. These results show that DT390mGMCSF causes liver toxicity by targeting KC, and establish a model for studying how this leads to hepatocyte injury. Furthermore, alternative fusion toxins with potentially reduced hepatotoxicity are presented.
Src inhibition enhances paclitaxel cytotoxicity in ovarian cancer cells by caspase-9-independent activation of caspase-3
Authors: Chen Ting , Pengetnze Yolande , Taylor Christopher C. 
Published: June 2022

Abstract
Src tyrosine kinase has been found to be overexpressed and activated in a high proportion of ovarian cancers and ovarian cancer cell lines. Furthermore, Src activation is associated with activation of growth and survival signaling pathways. The present study was conducted in order to determine the effects of Src inhibition on ovarian cancer cell survival in response to chemotherapeutic agents. Inhibition of Src, either pharmacologically or through expression of a Src dominant-negative fusion construct, enhanced the cytotoxicity of two different classes of chemotherapeutics: paclitaxel and cisplatinum, in both mouse and human ovarian cancer cells. Interestingly, Src inhibition also restored sensitivity to drug-resistant ovarian cancer cells. The increased cytotoxicity in response to Src inhibition was associated with a large increase in processing and activation of caspase-3. The activation of caspase-3 seems to be independent of cytochrome c release and caspase-9 activation. The present study indicates that Src tyrosine kinase may provide an important target for small molecule inhibition in ovarian cancer.
Novel peptidomimetic inhibitors of signal transducer and activator of transcription 3 dimerization and biological activity
Authors: Turkson James , Kim Joon S. , Zhang Shumin , Yuan Jing , Huang Mei , Glenn Matthew , Haura Eric , Sebti Said , Hamilton Andrew D. , Jove Richard 
Published: June 2022

Abstract
The critical role of signal transducer and activator of transcription 3 (Stat3) in the growth and survival of human tumor cells identifies it as a promising target for cancer drug discovery. We previously identified a Stat3 SH2 domain-binding phosphopeptide, PY*LKTK, and its tripeptide derivatives, PY*L and AY*L (where Y* represents phosphotyrosine), which inhibit Stat3 biochemical activity and biological function. Here, we report novel peptidomimetic compounds based on PY*L (or AY*L) with substitution of the Y-1 residue by benzyl, pyridyl, or pyrazinyl derivatives that are selective and greater than 5-fold more potent in disrupting Stat3 activity in vitro than lead tripeptides. The biological activities of these derivatives mirror that originally observed for peptides. In this context, the representative peptidomimetic ISS 610 with 4-cyanobenzoate substitution inhibits constitutive Stat3 activity in Src-transformed mouse fibroblasts and human breast and lung carcinoma cells. This effect is not evident with the non-phosphorylated counterpart, ISS 610NP, consistent with interaction of peptidomimetics with the SH2 domain of Stat3. Moreover, ISS 610 induces cell growth inhibition and apoptosis of Src-transformed fibroblasts that contain persistently active Stat3. We present the first report of a peptidomimetic approach to design of small-molecule inhibitors of Stat3 that are also among the first examples of disruptors of transcription factor dimerization with the potential for novel cancer therapy.
Sulindac enhances adenoviral vector expressing mda-7/IL-24–mediated apoptosis in human lung cancer
Authors: Oida Yasuhisa , Gopalan Began , Miyahara Ryo , Inoue Satoshi , Branch Cynthia D. , Mhashilkar Abner M. , Lin E. , Bekele B. Nebiyou , Roth Jack A. , Chada Sunil , Ramesh Rajagopal 
Published: June 2022

Abstract
Several studies have shown antitumor activities of the melanoma differentiation–associated gene 7 (mda-7) and the nonsteroidal anti-inflammatory drug sulindac when used as a monotherapies against a wide variety of human cancers. However, the combined effects of mda-7 and sulindac have not previously been tested. Therefore, we tested the antitumor activity of an adenoviral vector expressing mda-7 (Ad-mda7) in combination with sulindac against non–small cell lung cancer cells in vitro and in vivo. When treated with Ad-mda7 in combination with sulindac, human lung cancer cells (A549 and H1299) underwent growth suppression resulting in apoptosis. The growth inhibition induced by Ad-mda7 in combination with sulindac was significantly greater than that observed with Ad-mda7 or sulindac alone. Furthermore, the degree of growth inhibition induced using this combination was dose-dependent for sulindac. Treatment with Ad-mda7 in combination with sulindac had no growth inhibitory effects on human normal lung (CCD-16) fibroblasts. We then investigated the mechanism by which sulindac enhances Ad-mda7-mediated apoptosis. Sulindac increased expression of ectopic MDA-7 protein in tumor cells, thereby increasing the expression of downstream effectors RNA-dependent protein kinase, p38MAPK, caspase-9, and caspase-3 and enhancing apoptosis of non–small cell lung cancer cells. Pulse-chase experiments showed that the increased expression of MDA-7 protein in sulindac-treated cells was due to increased half-life of the MDA-7 protein. Finally, treatment of human lung tumor xenografts in nude mice with Ad-mda7 plus sulindac significantly suppressed growth (P = 0.001) compared with Ad-mda7 or sulindac alone. Our results show for the first time that combined treatment with Ad-mda7 plus sulindac enhances growth inhibition and apoptosis of human lung cancer cells. The increased antitumor activity observed with the combination treatment is a result of increased half-life of MDA-7 protein. Regulation of protein turnover is a heretofore-unrecognized mechanism of this nonsteroidal anti-inflammatory drug.
Flavopiridol enhances human tumor cell radiosensitivity and prolongs expression of γH2AX foci
Authors: Camphausen Kevin , Brady Kristin J. , Burgan William E. , Cerra Michael A. , Russell Jeffery S. , Bull Elizabeth E.A. , Tofilon Philip J. 
Published: June 2022

Abstract
Flavopiridol is a cyclin-dependent kinase (CDK) inhibitor, which has recently entered clinical trials. However, when administered as a single agent against solid tumors, the antitumor actions of flavopiridol have been primarily cytostatic. Given its reported effects on cell cycle regulation, transcription, and apoptosis, flavopiridol may also influence cellular radioresponse. Thus, to evaluate the potential for combining this cyclin-dependent kinase inhibitor with radiation as a cancer treatment strategy, we have investigated the effects of flavopiridol on the radiation sensitivity of two human prostate cancer cell lines (DU145 and PC3). The data presented here indicate that exposure to flavopiridol (60–90 nm) after irradiation enhanced the radiosensitivity of both DU145 and PC3 cells. This sensitization occurred in the absence of significant reductions in cell proliferation, retinoblastoma protein phosphorylation, or P-TEFb activity. Moreover, the post-irradiation addition of flavopiridol had no effect on radiation-induced apoptosis or the activation of the G2 cell cycle checkpoint. However, flavopiridol did modify the time course of γH2AX expression in irradiated cells. Whereas there was no significant difference in radiation-induced γH2AX foci at 6 h, at 24 h after irradiation, the number of cells expressing γH2AX foci was significantly greater in the flavopiridol-treated cells. These results indicate that flavopiridol can enhance radiosensitivity of human tumor cells and suggest that this effect may involve an inhibition of DNA repair.
Up-regulation of c-Jun-NH2-kinase pathway contributes to the induction of mitochondria-mediated apoptosis by α-tocopheryl succinate in human prostate cancer cells
Authors: Zu Ke , Hawthorn Lesleyann , Ip Clement 
Published: June 2022

Abstract
Previously, α-tocopheryl succinate (α-TOS) has been reported to induce caspase-mediated apoptosis in PC-3 human prostate cancer cells. Caspase-9 was among several initiator caspases activated by α-TOS, suggesting a potential contribution of the intrinsic apoptotic pathway in mediating the response to α-TOS. Gene expression microarray was carried out as a screen to identify novel signaling molecules modulated by α-TOS, with a special focus on those known to play a role in mitochondria-mediated apoptosis. We discovered that Ask1, GADD45β, and Sek1, three key components of the stress-activated mitogen-activated protein kinase pathway, are novel targets of α-TOS. Western blot analysis showed increased levels of phospho-Sek1 and phospho-c-Jun-NH2-kinase (JNK) in addition to total Ask1, GADD45β, and Sek1. α-TOS also altered JNK-specific phosphorylation of Bcl-2 and Bim in a manner consistent with enhanced mitochondrial translocation of Bax and Bim. Because the expression level of most Bcl-2 family members remained unchanged, the posttranslational modification of Bcl-2 and Bim by JNK is likely to be a driving force in α-TOS activation of the intrinsic apoptotic pathway. Based on our findings, we propose a working model to capture the salient features of the apoptotic signaling circuitry of α-TOS.
Biological characterization of MLN944: A potent DNA binding agent
Authors: Sappal Darshan S. , McClendon A. Kathleen , Fleming James A. , Thoroddsen Vala , Connolly Kelly , Reimer Corinne , Blackman Ronald K. , Bulawa Christine E. , Osheroff Neil , Charlton Peter , Rudolph-Owen Laura A. 
Published: June 2022

Abstract
MLN944 (XR5944) is a novel bis-phenazine that has demonstrated exceptional efficacy against a number of murine and human tumor models. The drug was reported originally as a dual topoisomerase I/II poison, but a precise mechanism of action for this compound remains to be determined. Several lines of evidence, including the marginal ability of MLN944 to stabilize topoisomerase-dependent cleavage, and the sustained potency of MLN944 in mammalian cells with reduced levels of both topoisomerases, suggest that other activities of the drug exist. In this study, we show that MLN944 intercalates into DNA, but has no effect on the catalytic activity of either topoisomerase I or II. MLN944 displays no significant ability to stimulate DNA scission mediated by either topoisomerase I or II compared with camptothecin or etoposide, respectively. In addition, yeast genetic models also point toward a topoisomerase-independent mechanism of action. To examine cell cycle effects, synchronized human HCT116 cells were treated with MLN944, doxorubicin, camptothecin, or a combination of the latter two to mimic a dual topoisomerase poison. MLN944 treatment was found to induce a G1 and G2 arrest in cells that is unlike the typical G2-M arrest noted with known topoisomerase poisons. Finally, transcriptional profiling analysis of xenograft tumors treated with MLN944 revealed clusters of regulated genes distinct from those observed in irinotecan hydrochloride (CPT-11)-treated tumors. Taken together, these findings suggest that the primary mechanism of action of MLN944 likely involves DNA binding and intercalation, but does not appear to involve topoisomerase inhibition.
Transcriptional targeting in renal cancer cell lines via the human CXCR4 promoter
Authors: Haviv Yosef S. , van Houdt Winan J. , Lu Baogen , Curiel David T. , Zhu Zeng B. 
Published: June 2022

AbstractMetastatic renal cell carcinoma (RCC) is often resistant to standard treatment, thereby requiring new therapeutic strategies. In this regard, tumor cell migration and metastasis have recently been shown to be regulated by chemokines and their respective receptors (e.g., SDF-1α/CXCR4). In the context of RCC, up-regulation of CXCR4 expression is closely related to the development of invasive cancer. Thus, we hypothesized that the CXCR4 pathway could be exploited for RCC targeting with gene therapy vectors. In this regard, targeting adenoviral vectors to tumor cells is critically dependent on tumor-specific gene expression. Toward the end of RCC tumor targeting, we evaluated the utility of the CXCR4 promoter in an adenoviral context. First, overexpression of CXCR4 was confirmed in several RCC cell lines. Next, an adenoviral vector was constructed, whereby the human CXCR4 promoter drives the expression of a reporter gene. We tested the activity of the CXCR4 promoter in vitro and in vivo in relevant models. Our data indicate that the human CXCR4 promoter is highly active in RCC cells but not in normal human cells. Finally, biodistribution studies in mice demonstrated dramatic repression of the CXCR4 promoter in the liver but not in the kidney. In conclusion, the unique activity of the CXCR4 promoter in RCC lines and its repression in normal human cells and in the murine liver underscore its potential utility as a novel candidate for transcriptional targeting of RCC.
Identification of 4-anilino-3-quinolinecarbonitrile inhibitors of mitogen-activated protein/extracellular signal-regulated kinase 1 kinase
Authors: Mallon Robert , Feldberg Larry , Kim Steven , Collins Karen , Wojciechowicz Donald , Kohler Constance , Kovacs Diana , Discafani Carolyn , Zhang Nan , Wu Biqi , Floyd Brawner , Powell Dennis , Berger Dan 
Published: June 2022

Abstract
A high-throughput screen for Ras–mitogen-activated protein kinase (MAPK) signaling inhibitors identified two series (class 1 and 2) of substituted 4-anilino-3-quinolinecarbonitriles as potent (IC50s &lt;10 nmol/L) mitogen-activated protein/extracellular signal-regulated kinase 1 (MEK1) kinase inhibitors. These compounds had cyanoquinoline cores, but differed in their respective aniline groups [1a, 1b: 4-phenoxyphenylaniline; 2a, 2b: 3-chloro-4-(1-methylimidazol-2-sulfanyl)aniline]. These compounds were competitive inhibitors of ATP binding by MEK1 kinase, and they had minimal or no effect on Raf, epidermal growth factor receptor (EGFR), Akt, cyclin-dependent kinase 4 (CDK4), or MK2 kinases at concentrations &gt;100-fold higher than those that inhibited MEK1 kinase. Both class 1 and 2 compounds inhibited in vitro growth of human tumor cell lines. A class 2 compound (2b) was the most potent inhibitor of human tumor cell growth in vitro, and this effect was linked to distinct suppression of MAPK phosphorylation in cells. Compound 2b did not affect phosphorylation status of other kinases, such as EGFR, Akt, and stress-activated protein (SAP)/c-jun-NH kinase (Jnk); nor did it affect overall tyrosine phosphorylation level in cells. However, compound 2b did inhibit MEK1 phosphorylation in cells. Inhibition of MEK1 phosphorylation by 2b was not due to a major effect on Raf kinase activity, because enzyme assays showed minimal Raf kinase inhibition. We believe compound 2b inhibits kinase activity upstream of Raf, and thereby affects MEK1 phosphorylation in cells. Even with the dual effect of 2b on MEK and MAPK phosphorylation, this compound was well tolerated and significantly inhibited growth of the human colon tumor cell line LoVo (at 50 and 100 mg/kg BID, i.p.) in a nude mouse xenograft model.
Down-regulation of protein kinase Cη potentiates the cytotoxic effects of exogenous tumor necrosis factor–related apoptosis-inducing ligand in PC-3 prostate cancer cells
Authors: Sonnemann Jürgen , Gekeler Volker , Sagrauske Antje , Müller Cornelia , Hofmann Hans-Peter , Beck James F. 
Published: June 2022

Abstract
Tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) is a highly promising candidate for the treatment of cancer because it elicits cell death in the majority of tumor cells while sparing most normal cells. Some cancers, however, display resistance to TRAIL, suggesting that treatment with TRAIL alone may be insufficient for cancer therapy. In the present study, we explored whether the apoptotic responsiveness of PC-3 prostate cancer cells to TRAIL could be enhanced by targeting the novel protein kinase C (PKC) isoform η. Transfection of PC-3 cells with second-generation chimeric antisense oligonucleotides against PKCη caused a time- and dose-dependent knockdown of PKCη, as revealed by real-time RT-PCR and Western blot analyses. Knockdown of PKCη resulted in a marked amplification of TRAIL's cytotoxic activity. Cell killing could be substantially prevented by the pan-caspase inhibitor z-VAD-fmk. In addition, PKCη knockdown and administration of TRAIL significantly synergized in activation of caspase-3 and internucleosomal DNA fragmentation. Knockdown of PKCη augmented TRAIL-induced dissipation of the mitochondrial transmembrane potential and release of cytochrome c from mitochondria into the cytosol, indicating that PKCη acts upstream of mitochondria. We conclude that PKCη represents a considerable resistance factor with respect to TRAIL and a promising target to exploit the therapeutic potential of TRAIL.
Role of polymorphonuclear leukocytes, nitric oxide synthase, and cyclooxygenase in vascular permeability changes induced by C5a agonist peptides
Authors: Kurizaki Takashi , Abe Michio , Sanderson Sam D. , Enke Charles A. , Baranowska-Kortylewicz Janina 
Published: June 2022

Abstract
Tumor responses to radioimmunotherapy combined with peptide agonists of human C5a anaphylatoxin such as GCGYSFKPMPLaR (C5aAP) are two- to four-fold better, depending on the dose of C5aAP, than responses to radioimmunotherapy alone. The enhanced tumor vascular permeability (VP) is the key factor responsible for this improvement. These studies were designed to identify the sequence of events leading to the improved extravasation of immunoglobulin in response to C5aAP. The VP changes were measured in mice after administration of C5aAP alongside of various mediators. The depletion of circulating polymorphonuclear neutrophils (PMN) in mice abolished the C5aAP-induced VP increase. Blocking of P-selectin also returned VP to its basal levels after the C5aAP treatment, indicating that C5aAP-induced VP changes are initiated by interactions of C5aAP with PMNs. Aminoguanidine, an inducible nitric oxide synthase (NOS) inhibitor, given before C5aAP returned VP to control levels. Nω-nitro-l-arginine methyl ester, a nonselective NOS inhibitor, had a marginal effect on the activity of C5aAP. Indomethacin, a nonselective cyclooxygenase inhibitor, suppressed C5aAP-induced increases in VP, whereas N-(2-cyclohexyloxy-4-nitrophenyl)-methanesulfonamide, a selective cyclooxygenase-2 inhibitor, was active only at high doses. While C5aAP given i.p. did not alter tumor uptake of 125I-B72.3, the i.v. administration resulted in ∼40% increase, confirming the prerequisite interaction of C5aAP with PMNs. The sequence leading to the increased VP appears to be initiated by the interaction of C5aAP with C5a receptor expressed on PMNs followed by binding to endothelial cells of blood vessels. The interaction with P-selectin is responsible for the initiation of the nitric oxide cascade as evidenced by inducible NOS activation. Additionally, prostaglandins are required for expression of the full magnitude of the C5aAP activities.
Characterization of inhibitors of specific carboxylesterases: Development of carboxylesterase inhibitors for translational application
Authors: Yoon Kyoung Jin P. , Hyatt Janice L. , Morton Christopher L. , Lee Richard E. , Potter Philip M. , Danks Mary K. 
Published: June 2022

Abstract
Carboxylesterases, expressed at high levels in human liver and intestine, are thought to detoxify xenobiotics. The anticancer prodrug 7-ethyl-10-[4-1-piperidino)-1-piperidino]carbonyloxycamptothecin (CPT-11) is also metabolized by carboxylesterases to produce the active drug 7-ethyl-10-hydroxycamptothecin. Activation of CPT-11 by human intestinal carboxylesterase (hiCE) in the human intestine may contribute to delayed onset diarrhea, a dose-limiting side effect of this drug. The goal of this study was to develop small molecule inhibitors selective for hiCE to circumvent or treat the toxic side effects of CPT-11. A secondary goal was to develop molecules that specifically inhibit activation of CPT-11 by a rabbit liver carboxylesterase (rCE). rCE is the most efficient CPT-11–activating enzyme thus far identified, and this enzyme is being developed for viral-directed enzyme prodrug therapy applications. Based on in vitro assays with partially purified hiCE and rCE proteins and on growth inhibition assays using U373MG human glioma cells transfected to express hiCE or rCE (U373pIREShiCE or U373pIRESrCE), we identified specific inhibitors of each enzyme. Lead compounds are derivatives of nitrophenol having 4-(furan-2-carbonyl)-piperazine-1-carboxylic acid or 4-[(4-chlorophenyl)-phenylmethyl]-piperazine-1-carboxylic acid substitutions in the p position. Kinetic analysis of each compound for hiCE compared with rCE showed that the Ki values of the most selective of these inhibitors differed by 6- to 10-fold. In growth inhibition assays, nontoxic, low micromolar concentrations of these inhibitors increased the EC50 of CPT-11 for U373pIREShiCE or U373pIRESrCE cells by 13- to &gt;1,500-fold. The four compounds characterized in this study will serve as lead compounds for a series of inhibitors to be constructed using a combinatorial approach.