bluuebunny/crossref_metadata_2025 huggingface dataset:
Mineralocorticoid receptor antagonists attenuate exaggerated exercise pressor reflex responses in hypertensive rats
Authors: Downey Ryan M. , Mizuno Masaki , Mitchell Jere H. , Vongpatanasin Wanpen , Smith Scott A.
Published: July 2017

Exaggerated heart rate (HR) and blood pressure responses to exercise in hypertension are mediated, in part, by overactivity of the exercise pressor reflex (EPR). The mechanisms underlying this EPR dysfunction have not been fully elucidated. Previous studies have shown that stimulation of mineralocorticoid receptors (MRs) with exogenous administration of aldosterone in normal, healthy rats reproduces the EPR overactivity characteristic of hypertensive animals. Conversely, the purpose of this study was to examine whether antagonizing MR with spironolactone (SPIR) or eplerenone (EPL) in decerebrated hypertensive rats ameliorates abnormal EPR function. Changes in mean arterial pressure (MAP) and HR induced by EPR or muscle mechanoreflex (a component of EPR) activation were assessed in normotensive Wistar-Kyoto rats and spontaneously hypertensive rats (SHRs) fed normal chow (NC) or a customized diet containing either SPIR or EPL for 3 wk. SHRs treated with SPIR or EPL had significantly attenuated MAP responses to EPR (NC: 45 ± 7 mmHg, SPIR: 26 ± 4 mmHg, and EPL: 24 ± 5 mmHg, P = 0.02) and mechanoreflex (NC: 34 ± 9 mmHg, SPIR: 17 ± 3 mmHg, and EPL: 15 ± 3 mmHg, P = 0.03) activation. SHRs treated with SPIR or EPL also showed significantly attenuated HR responses to EPR (NC: 17 ± 3 beats/min, SPIR: 9 ± 1 beats/min, and EPL: 9 ± 2 beats/min, P = 0.01) and mechanoreflex (NC: 15 ± 3 beats/min, SPIR: 6 ± 1 beats/min, and EPL: 7 ± 1 beats/min, P = 0.01) activation. Wistar-Kyoto rats treated with SPIR did not demonstrate significant differences in MAP or HR responses to EPR or mechanoreflex activation. The data suggest that antagonizing MRs may be an effective strategy for the treatment of EPR overactivity in hypertension.

NEW & NOTEWORTHY Exaggerated cardiovascular responses to exercise in hypertensive patients are linked with overactive exercise pressor reflexes (EPRs). Administration of low-dose mineralocorticoid receptor antagonists (spironolactone or eplerenone) effectively ameliorates abnormal EPR function in hypertension. Effective treatment of EPR overactivity may reduce the cardiovascular risks associated with physical activity in hypertension.
Tumorigenic Heterogeneity in Cancer Stem Cells Evolved from Long-term Cultures of Telomerase-Immortalized Human Mesenchymal Stem Cells
Authors: Burns Jorge S. , Abdallah Basem M. , Guldberg Per , Rygaard Jørgen , Schrøder Henrik D. , Kassem Moustapha
Published: July 2017

Long-term cultures of telomerase-transduced adult human mesenchymal stem cells (hMSC) may evolve spontaneous genetic changes leading to tumorigenicity in immunodeficient mice (e.g., hMSC-TERT20). We wished to clarify whether this unusual phenotype reflected a rare but dominant subpopulation or if the stem cell origin allowed most cells to behave as cancer stem cells. Cultures of the hMSC-TERT20 strain at population doubling 440 were highly clonogenic (94%). From 110 single-cell clones expanded by 20 population doublings, 6 underwent detailed comparison. Like the parental population, each clone had ≈1.2 days doubling time with loss of contact inhibition. All retained 1,25-(OH)2 vitamin D3–induced expression of osteoblastic markers: collagen type I, alkaline phosphatase, and osteocalcin. All shared INK4a/ARF gene locus deletion and epigenetic silencing of the DBCCR1 tumor suppressor gene. Despite in vitro commonality, only four of six clones shared the growth kinetics and 100% tumorigenicity of the parental population. In contrast, one clone consistently formed latent tumors and the other established tumors with only 30% penetrance. Changing the in vitro microenvironment to mimic in vivo growth aspects revealed concordant clonal heterogeneity. Latent tumor growth correlated with extracellular matrix entrapment of multicellular spheroids and high procollagen type III expression. Poor tumorigenicity correlated with in vitro serum dependence and high p27Kip1 expression. Aggressive tumorigenicity correlated with good viability plus capillary morphogenesis on serum starvation and high cyclin D1 expression. Thus, hMSC-TERT20 clones represent cancer stem cells with hierarchical tumorigenicity, providing new models to explore the stem cell hypothesis for cancer.
Phenoxodiol, a Novel Isoflavone, Induces G1 Arrest by Specific Loss in Cyclin-Dependent Kinase 2 Activity by p53-Independent Induction of p21WAF1/CIP1
Authors: Aguero Martin F. , Facchinetti Maria M. , Sheleg Zhanna , Senderowicz Adrian M.
Published: July 2017

Phenoxodiol, an isoflavone derivative of genistein with unknown mechanism of action, is currently being evaluated in early human cancer clinical trials. To determine the mechanism of antiproliferative effects of phenoxodiol, we examined its effects in a battery of human cell lines. Although we observed caspase-dependent apoptosis in HN12 cells as early as 24 hours after exposure, clonogenic death occurred only after 48-hour exposure despite caspase blockade by the general caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone (ZVAD)-fmk. Moreover, clear evidence of cell death as determined by nuclear morphology and plasmatic membrane damage occur despite ZVAD, suggesting that another mechanism besides caspase-dependent apoptosis is required for clonogenic death induced by phenoxodiol. In search for other potential antiproliferative effects, we assessed the effects of phenoxodiol in the cell cycle progression of human carcinoma cell lines. A significant G1-S arrest was observed by 12 hours of exposure in HN12 cell lines at concentrations ≥5 μg/mL. Cell cycle arrest occurred several hours (∼12 hours) before induction of apoptosis. Analysis of in vitro purified cyclin-dependent kinase (cdk) activity showed that phenoxodiol did not inhibit cdk activity. In contrast, cellular cdk2 activity obtained from HN12 cell lines exposed to phenoxodiol for 12 hours decreased by 60%, whereas cdk6 activity remained unaltered, suggesting that the loss of cdk2 activity was specific. Loss in cdk2 activity was preceded by the accumulation of the endogenous cdk inhibitor p21WAF1. To assess the role of p21WAF1 induction by phenoxodiol, we used HCT116 isogenic cell lines and showed that phenoxodiol induced G1 arrest together with p21WAF1 expression in wild-type clones. In contrast, p21−/− variants failed to show G1 arrest. Finally, induction of p21 by phenoxodiol is p53 independent, as phenoxodiol induced p21 in HCT116 lacking p53. These data therefore indicate that phenoxodiol promotes G1-S arrest by the specific loss in cdk2 activity due to p53-independent p21WAF1 induction. This novel feature of phenoxodiol may have clinical implications, as the majority of human malignancies have aberrations in cell cycle progression regulation.
C-C Chemokine Receptor 5 on Stromal Cells Promotes Pulmonary Metastasis
Authors: van Deventer Hendrik W. , O'Connor William , Brickey W. June , Aris Robert M. , Ting Jenny P.Y. , Serody Jonathan S.
Published: July 2017

We have shown that mice that express the C-C chemokine receptor 5 (CCR5) have enhanced local tumor growth and an impaired response to vaccine therapy compared with CCR5 knockout (CCR5−/−) mice. Here, we extend these observations to evaluate the function of CCR5 in pulmonary metastasis and the mechanism underlying the diminished tumor growth in CCR5−/− mice. Lung metastases were counted in wild-type (WT) and CCR5−/− mice following the injection of 1 × 106 B16-F10 melanoma cells. These results were compared with those from syngeneic bone marrow chimeric mice formed by the transfer of WT bone marrow into irradiated CCR5−/− and CCR5−/− marrow into irradiated WT mice. Intact CCR5−/− mice developed fewer metastases than WT mice (40.2 versus 70.6; P < 0.05). Bone marrow chimeras formed by the transfer of WT bone marrow into CCR5−/− hosts had fewer metastases than WT hosts injected with knockout marrow (46.6 versus 98.6; P < 0.01). Adoptive transfer of CCR5-expressing leukocytes also failed to promote metastasis in CCR5−/− mice. However, the i.v. transfer of WT pulmonary stromal cells into CCR5−/− mice increased the number of metastases compared with transfer of CCR5−/− stromal cells (102.8 versus 26.0; P < 0.05). These results show for the first time that CCR5 expression on stromal and not hematopoietic cells contributes to tumor metastasis. Therefore, recently developed CCR5 inhibitors may have a novel benefit in cancer therapy.
Target Cell–Restricted Apoptosis Induction of Acute Leukemic T Cells by a Recombinant Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand Fusion Protein with Specificity for Human CD7
Authors: Bremer Edwin , Samplonius Douwe F. , Peipp Matthias , van Genne Linda , Kroesen Bart-Jan , Fey Georg H. , Gramatzki Martin , de Leij Lou F.M.H. , Helfrich Wijnand
Published: July 2017

Current treatment of human T-cell leukemia and lymphoma is predominantly limited to conventional cytotoxic therapy and is associated with limited therapeutic response and significant morbidity. Therefore, more potent and leukemia-specific therapies with favorable toxicity profiles are urgently needed. Here, we report on the construction of a novel therapeutic fusion protein, scFvCD7:sTRAIL, designed to induce target antigen-restricted apoptosis in human T-cell tumors. ScFvCD7:sTRAIL consists of the death-inducing tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) genetically linked to an scFv antibody fragment specific for the T-cell surface antigen CD7. Treatment with scFvCD7:sTRAIL induced potent CD7-restricted apoptosis in a series of malignant T-cell lines, whereas normal resting leukocytes, activated T cells, and vascular endothelial cells (human umbilical vein endothelial cells) showed no detectable apoptosis. The apoptosis-inducing activity of scFvCD7:sTRAIL was stronger than that of the immunotoxin scFvCD7:ETA. In mixed culture experiments with CD7-positive and CD7-negative tumor cells, scFvCD7:sTRAIL induced very potent bystander apoptosis of CD7-negative tumor cells. In vitro treatment of blood cells freshly derived from T-acute lymphoblastic leukemia patients resulted in marked apoptosis of the malignant T cells that was strongly augmented by vincristin. In conclusion, scFvCD7:sTRAIL is a novel recombinant protein causing restricted apoptosis in human leukemic T cells with low toxicity for normal human blood and endothelial cells.
The Serine/Threonine Protein Kinase, p90 Ribosomal S6 Kinase, Is an Important Regulator of Prostate Cancer Cell Proliferation
Authors: Clark D.E. , Errington T.M. , Smith J.A. , Frierson H.F. , Weber M.J. , Lannigan D.A.
Published: July 2017

An increase in the activity of mitogen-activated protein kinase (MAPK) has been correlated with the progression of prostate cancer to advanced disease in humans. The serine/threonine protein kinase p90-kDa ribosomal S6 kinase (RSK) is an important downstream effector of MAPK but its role in prostate cancer has not previously been examined. Increasing RSK isoform 2 (RSK2) levels in the human prostate cancer line, LNCaP, enhanced prostate-specific antigen (PSA) expression, an important diagnostic marker for prostate cancer, whereas inhibiting RSK activity using a RSK-specific inhibitor, 3Ac-SL0101, decreased PSA expression. The RSK2 regulation of PSA expression occurred via a mechanism involving both RSK2 kinase activity and its ability to associate with the coactivator, p300. RNA interference of the androgen receptor (AR) showed that the AR was important in the RSK2-mediated increase in PSA expression. RSK levels are higher in ∼50% of human prostate cancers compared with normal prostate tissue, which suggests that increased RSK levels may participate in the rise in PSA expression that occurs in prostate cancer. Furthermore, 3Ac-SL0101 inhibited proliferation of the LNCaP line and the androgen-independent human prostate cancer line, PC-3. These results suggest that proliferation of some prostate cancer cells is dependent on RSK activity and support the hypothesis that RSK may be an important chemotherapeutic target for prostate cancer.
Immortal DNA Strand Cosegregation Requires p53/IMPDH–Dependent Asymmetric Self-renewal Associated with Adult Stem Cells
Authors: Rambhatla Lakshmi , Ram-Mohan Sumati , Cheng Jennifer J. , Sherley James L.
Published: July 2017

Because they are long-lived and cycle continuously, adult stem cells (ASCs) are predicted as the most common precursor for cancers in adult mammalian tissues. Two unique attributes have been proposed to restrict the carcinogenic potential of ASCs. These are asymmetric self-renewal that limits their number and immortal DNA strand cosegregation that limits their accumulation of mutations due to DNA replication errors. Until recently, the molecular basis and regulation of these important ASC-specific functions were unknown. We developed engineered cultured cells that exhibit asymmetric self-renewal and immortal DNA strand cosegregation. These model cells were used to show that both ASC-specific functions are regulated by the p53 cancer gene. Previously, we proposed that IMP dehydrogenase (IMPDH) was an essential factor for p53-dependent asymmetric self-renewal. We now confirm this proposal and provide quantitative evidence that asymmetric self-renewal is acutely sensitive to even modest changes in IMPDH expression. These analyses reveal that immortal DNA strand cosegregation is also regulated by IMPDH and confirm the original implicit precept that immortal DNA strand cosegregation is specific to cells undergoing asymmetric self-renewal (i.e., ASCs). With IMPDH being the rate-determining enzyme for guanine ribonucleotide (rGNP) biosynthesis, its requirement implicates rGNPs as important regulators of ASC asymmetric self-renewal and immortal DNA strand cosegregation. An in silico analysis of global gene expression data from human cancer cell lines underscored the importance of p53-IMPDH-rGNP regulation for normal tissue cell kinetics, providing further support for the concept that ASCs are key targets for adult tissue carcinogenesis.
Meat, Meat Cooking Methods and Preservation, and Risk for Colorectal Adenoma
Authors: Sinha Rashmi , Peters Ulrike , Cross Amanda J. , Kulldorff Martin , Weissfeld Joel L. , Pinsky Paul F. , Rothman Nathaniel , Hayes Richard B. ,   Prostate, Lung, Colorectal, and Ovarian Cancer Project Team
Published: July 2017

Cooking meat at high temperatures produces heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs). Processed meats contain N-nitroso compounds. Meat intake may increase cancer risk as HCAs, PAHs, and N-nitroso compounds are carcinogenic in animal models. We investigated meat, processed meat, HCAs, and the PAH benzo(a)pyrene and the risk of colorectal adenoma in 3,696 left-sided (descending and sigmoid colon and rectum) adenoma cases and 34,817 endoscopy-negative controls. Dietary intake was assessed using a 137-item food frequency questionnaire, with additional questions on meats and meat cooking practices. The questionnaire was linked to a previously developed database to determine exposure to HCAs and PAHs. Intake of red meat, with known doneness/cooking methods, was associated with an increased risk of adenoma in the descending and sigmoid colon [odds ratio (OR), 1.26; 95% confidence interval (95% CI), 1.05-1.50 comparing extreme quintiles of intake] but not rectal adenoma. Well-done red meat was associated with increased risk of colorectal adenoma (OR, 1.21; 95% CI, 1.06-1.37). Increased risks for adenoma of the descending colon and sigmoid colon were observed for the two HCAs: 2-amino-3,8-dimethylimidazo[4,5]quinoxaline and 2-amino-1-methyl-6-phenylimidazo[4,5]pyridine (OR, 1.18; 95% CI, 1.01-1.38 and OR, 1.17, 95% CI, 1.01-1.35, respectively) as well as benzo(a)pyrene (OR, 1.18; 95% CI, 1.02-1.35). Greater intake of bacon and sausage was associated with increased colorectal adenoma risk (OR, 1.14; 95% CI, 1.00-1.30); however, total intake of processed meat was not (OR, 1.04; 95% CI, 0.90-1.19). Our study of screening-detected colorectal adenomas shows that red meat and meat cooked at high temperatures are associated with an increased risk of colorectal adenoma.
Epidermal Growth Factor Receptor Dynamics Influences Response to Epidermal Growth Factor Receptor Targeted Agents
Authors: Jimeno Antonio , Rubio-Viqueira Belen , Amador Maria L. , Oppenheimer Darin , Bouraoud Nadia , Kulesza Peter , Sebastiani Valeria , Maitra Anirban , Hidalgo Manuel
Published: July 2017

Analysis of gene expression of cancer cell lines exposed to erlotinib, a small molecule inhibitor of the epidermal growth factor receptor (EGFR), showed a marked increase in EGFR mRNA in resistant cell lines but not in susceptible ones. Because cetuximab induces EGFR down-regulation, we explored the hypothesis that treatment with cetuximab would interfere with erlotinib-induced EGFR up-regulation and result in antitumor effects. Exposure of the resistant biliary tract cancer cell line HuCCT1 but not the susceptible A431 epidermoid cell line to erlotinib induced EGFR mRNA and protein expression. Combined treatment with cetuximab blunted the erlotinib-induced EGFR up-regulation and resulted in inhibition of cell proliferation and apoptosis in the HuCCT1 cells. Blockage of erlotinib-induced EGFR synthesis in HuCCT1 cells by small interfering RNA resulted in identical antitumor effects as cetuximab, providing mechanistic specificity. In mice xenografted with A431, HuCCT1, and the pancreatic cancer cell line Panc430, maximal growth arrest and decrease in Ki67 proliferation index were documented with combined therapy, and EGFR down-regulation was observed in cetuximab-treated tumors. These results may indicate that resistance to EGFR kinase inhibition may be, at least in part, mediated by a highly dynamic feedback loop consisting of up-regulation of the EGFR upon exposure to EGFR kinase inhibitors. Abrogation of this response by small interfering RNA-mediated EGFR mRNA down-regulation and/or by cetuximab-mediated protein clearance induced tumor arrest across several cancer models with different EGFR expression levels, suggesting that resistance and sensitivity are dynamic events where proportional decrease in the target rather than absolute content dictates outcome.
Extracellular Matrix Metalloproteinase Inducer Stimulates Tumor Angiogenesis by Elevating Vascular Endothelial Cell Growth Factor and Matrix Metalloproteinases
Authors: Tang Yi , Nakada Marian T. , Kesavan Prabakaran , McCabe Francis , Millar Hillary , Rafferty Patricia , Bugelski Peter , Yan Li
Published: July 2017

Matrix metalloproteinases (MMPs) are endopeptidases that play pivotal roles in promoting tumor disease progression, including tumor angiogenesis. In many solid tumors, MMP expression could be attributed to tumor stromal cells and is partially regulated by tumor-stroma interactions via tumor cell–associated extracellular matrix metalloproteinase inducer (EMMPRIN). The role of EMMPRIN during tumor angiogenesis and growth was explored by modulating EMMPRIN expression and activity using recombinant DNA engineering and neutralizing antibodies. In human breast cancer cells, changes in EMMPRIN expression influenced vascular endothelial growth factor (VEGF) production at both RNA and protein levels. In coculture of tumor cells and fibroblasts mimicking tumor-stroma interactions, VEGF expression was induced in an EMMPRIN- and MMP-dependent fashion, and was further enhanced by overexpressing EMMPRIN. Conversely, VEGF expression was inhibited by suppressing EMMPRIN expression in tumor cells, by neutralizing EMMPRIN activity, or by inhibiting MMPs. In vivo, EMMPRIN overexpression stimulated tumor angiogenesis and growth; both were significantly inhibited by antisense suppression of EMMPRIN. Expression of both human and mouse VEGF and MMP, derived from tumor and host cells, respectively, was regulated by EMMPRIN. These results suggest a novel tumor angiogenesis mechanism in which tumor-associated EMMPRIN functionally mediates tumor-stroma interactions and directly contributes to tumor angiogenesis and growth by stimulating VEGF and MMP expression.
Linking Transcriptional Elongation and Messenger RNA Export to Metastatic Breast Cancers
Authors: Guo Shanchun , Hakimi Mohamed-Ali , Baillat David , Chen Xiaowei , Farber Michele J. , Klein-Szanto Andres J.P. , Cooch Neil S. , Godwin Andrew K. , Shiekhattar Ramin
Published: July 2017

The biochemical pathways that are disrupted in the genesis of sporadic breast cancers remain unclear. Moreover, the present prognosticating markers used to determine the prognosis of node-negative patient leads to probabilistic results, and the eventual clinical course is far from certain. Here we identified the human TREX complex, a multiprotein complex that links transcription elongation to mRNA transport, as culprit of aggressive human breast cancers. We show that whereas p84N5 (called hTREX84) is expressed at very low levels in normal breast epithelial cells, it is highly expressed in breast tumors. Importantly, hTREX84 expression correlates with tumor size and the metastatic state of the tumor progression. Reduction of hTREX84 levels in breast cancer cell lines by small interfering RNA result in inhibition of cellular proliferation and abrogation of mRNA export. These results not only identify hTREX84 as a prognosticator of breast cancer but also delineate human TREX complex as a target for therapeutic drugs against breast cancer.
Molecular Basis of Incomplete O-Glycan Synthesis in MCF-7 Breast Cancer Cells: Putative Role of MUC6 in Tn Antigen Expression
Authors: Freire Teresa , Bay Sylvie , von Mensdorff-Pouilly Silvia , Osinaga Eduardo
Published: July 2017

An incomplete elongation of O-glycan saccharide chains in mucins have been found in epithelial cancers, leading to the expression of shorter carbohydrate structures, such as the Tn antigen (GalNAc-O-Ser/Thr). This antigen is one of the most specific human cancer–associated structures and is capable of inducing effective immune responses against cancer cells. We aimed to investigate the causes of the expression of Tn antigen in the Tn-rich MCF-7 breast cancer cell line focusing on the first step of the O-glycosylation process. Interestingly, amino acid sequences derived from “nonmammary” apomucins (MUC5B and MUC6) were very good acceptor substrates for ppGalNAc-Ts, which are the enzymes catalyzing the Tn antigen synthesis. MUC6 peptide glycosylation with MCF-7 microsome extracts as source of ppGalNAc-T activity yielded 95% conversion of the peptide into MUC6-Tn. In addition, the MUC6-Tn glycopeptide was a poor acceptor substrate for core 1 β3Gal-T, the next enzyme involved in the saccharide chain biosynthesis, yielding only 5% conversion of MUC6-Tn into MUC6-TF. These results indicate that nonmammary apomucin expression could be responsible, at least in part, for Tn antigen expression in MCF-7 breast cancer cells due to a combined action on glycosyltransferases: an increase of ppGalNAc-T activity and a decrease of core 1 β3Gal-T activity. Our hypothesis is supported by experiments in vivo showing that (a) native MUC6 glycoproteins express the Tn antigen in MCF-7 cells and (b) Tn antigen expression is increased after transfection with a construct encoding for a MUC6 recombinant protein into the low Tn-expressing breast cancer cell T47D. These results open new horizons in breast cancer glycoimmunology, stressing the potential role of nonmammary apomucins.
The Contribution of Bone Marrow–Derived Cells to the Tumor Vasculature in Neuroblastoma Is Matrix Metalloproteinase-9 Dependent
Authors: Jodele Sonata , Chantrain Christophe F. , Blavier Laurence , Lutzko Carolyn , Crooks Gay M. , Shimada Hiroyuki , Coussens Lisa M. , DeClerck Yves A.
Published: July 2017

The contribution of the tumor stroma to cancer progression has been increasingly recognized. We had previously shown that in human neuroblastoma tumors orthotopically implanted in immunodeficient mice, stromal-derived matrix metalloproteinase-9 (MMP-9) contributes to the formation of a mature vasculature by promoting pericyte recruitment along endothelial cells. Here we show that MMP-9 is predominantly expressed by bone marrow–derived CD45-positive leukocytes. Using a series of bone marrow transplantation experiments in MMP-9+/+ and MMP-9−/− mice xenotransplanted with human neuroblastoma tumors, we show that bone marrow–derived MMP-9 is critical for the recruitment of leukocytes from bone marrow into the tumor stroma and for the integration of bone marrow–derived endothelial cells into the tumor vasculature. Expression of MMP-9 by bone marrow–derived cells in the tumor stroma is also critical for the formation of a mature vasculature and coverage of endothelial cells with pericytes. Furthermore, in primary human neuroblastoma tumor specimens of unfavorable histology, we observed a higher level of tumor infiltration with MMP-9 expressing phagocytic cells and a higher degree of coverage of endothelial cells by pericytes when compared with tumor specimens with a favorable histology. Taken together, the data show that in neuroblastoma, MMP-9 plays a critical role in the recruitment of bone marrow–derived cells to the tumor microenvironment where they positively contribute to angiogenesis and tumor progression.
Flavokawain A, a Novel Chalcone from Kava Extract, Induces Apoptosis in Bladder Cancer Cells by Involvement of Bax Protein-Dependent and Mitochondria-Dependent Apoptotic Pathway and Suppresses Tumor Growth in Mice
Authors: Zi Xiaolin , Simoneau Anne R.
Published: July 2017

Consumption of the traditional kava preparation was reported to correlate with low and uncustomary gender ratios (more cancer in women than men) of cancer incidences in three kava-drinking countries: Fiji, Vanuatu, and Western Samoa. We have identified flavokawain A, B, and C but not the major kavalactone, kawain, in kava extracts as causing strong antiproliferative and apoptotic effect in human bladder cancer cells. Flavokawain A results in a significant loss of mitochondrial membrane potential and release of cytochrome c into the cytosol in an invasive bladder cancer cell line T24. These effects of flavokawain A are accompanied by a time-dependent decrease in Bcl-xL, a decrease in the association of Bcl-xL to Bax, and an increase in the active form of Bax protein. Using the primary mouse embryo fibroblasts Bax knockout and wild-type cells as well as a Bax inhibitor peptide derived from the Bax-binding domain of Ku70, we showed that Bax protein was, at least in part, required for the apoptotic effect of flavokawain A. In addition, flavokawain A down-regulates the expression of X-linked inhibitor of apoptosis and survivin. Because both X-linked inhibitor of apoptosis and survivin are main factors for apoptosis resistance and are overexpressed in bladder tumors, our data suggest that flavokawain A may have a dual efficacy in induction of apoptosis preferentially in bladder tumors. Finally, the anticarcinogenic effect of flavokawain A was evident in its inhibitory growth of bladder tumor cells in a nude mice model (57% of inhibition) and in soft agar.
Restoration of the Expression of Transporters Associated with Antigen Processing in Lung Carcinoma Increases Tumor-Specific Immune Responses and Survival
Authors: Lou Yuanmei , Vitalis Timothy Z. , Basha Genc , Cai Bing , Chen Susan S. , Choi Kyung Bok , Jeffries Andrew P. , Elliott W. Mark , Atkins Derek , Seliger Barbara , Jefferies Wilfred A.
Published: July 2017

A wide variety of human carcinomas have low expression of tumor-associated antigen presentation in the context of MHC class I antigens due to defects in the antigen presentation pathway. This immune evasion mechanism renders many tumors unrecognizable by host immune surveillance mechanisms. The present study examines the expression of HLA, tapasin, transporter associated with antigen processing 1 (TAP1), and β2 microglobulin in human small cell lung carcinoma and non–small cell lung carcinoma. Immunohistochemical staining showed severe impairment of the antigen presentation pathway in all patients. In order to recover tumor immunogenicity, a nonreplicating adenovirus expressing human TAP1 (AdhTAP1) was used to restore the expression of TAP1 in the antigen presentation pathway–deficient mouse lung carcinoma cell line, CMT.64. Infection of CMT.64 cells with AdhTAP1 increased MHC class I antigen surface expression, antigen presentation, and susceptibility to antigen-specific CTLs. Fluorescence-activated cell sorting and ELISPOT analysis showed that AdhTAP1 treatment significantly increased dendritic cell cross-presentation and cross-priming of tumor antigens. Furthermore, ex vivo and in vivo AdhTAP1 treatment significantly retarded tumor growth and increased survival of mice bearing CMT.64 tumors. Fluorescence-activated cell sorting analysis and immunohistochemical staining showed a significant increase in CD8+ and CD4+ T cells and CD11c+ dendritic cells infiltrating the tumors. The results show that TAP should be considered as a part of the immunotherapies for various cancers because it is likely to provide a general method for increasing immune responses against tumors regardless of the antigenic composition of the tumor or the MHC haplotypes of the host.
Effect of Platelet-Derived Growth Factor Receptor-β Inhibition with STI571 on Radioimmunotherapy
Authors: Baranowska-Kortylewicz Janina , Abe Michio , Pietras Kristian , Kortylewicz Zbigniew P. , Kurizaki Takashi , Nearman Jessica , Paulsson Janna , Mosley R. Lee , Enke Charles A. , Östman Arne
Published: July 2017

Whereas radioimmunotherapy of hematologic malignancies has evolved into a viable treatment option, the responses of solid tumors to radioimmunotherapy are discouraging. The likely cause of this problem is the interstitial hypertension inherent to all solid tumors. Remarkable improvements in tumor responses to radioimmunotherapy were discovered after the inclusion of STI571 in the therapy regimen. A combination of the tumor stroma–reactive STI571, a potent platelet-derived growth factor receptor-β (PDGFr-β) antagonist, and the tumor-seeking radiolabeled antibody B72.3 yielded long-lasting growth arrest of the human colorectal adenocarcinoma LS174T grown as s.c. xenografts in athymic mice. The interaction of STI571 with the stromal PDGFr-β reduced tumor interstitial fluid pressure (PIF) by >50% and in so doing improved the uptake of B72.3. The attenuation of PIF also had a positive effect on the homogeneity of antibody distribution. These effects were dose-dependent and under optimized dosing conditions allowed for a 2.45 times increase in the tumor uptake of B72.3 as determined in the biodistribution studies. Single-photon emission computed tomography imaging studies substantiated these results and indicated that the homogeneity of the radioisotope distribution was also much improved when compared with the control mice. The increased uptake of radioimmunotherapy into the tumor resulted in >400% increase in the tumor absorbed radiation doses in STI571 + radioimmunotherapy–treated mice compared with PBS + radioimmunotherapy–treated mice. The improved antibody uptake in response to the attenuation of tumor PIF was identified as the primary reason for the growth arrest of the STI571 + radioimmunotherapy–treated tumors. Two related causes were also identified: (a) the improved homogeneity of monoclonal antibody distribution in tumor and (b) the increased tumor radiosensitivity resulting from the improved tumor oxygenation.
Metabolic Characterization of Human Prostate Cancer with Tissue Magnetic Resonance Spectroscopy
Authors: Cheng Leo L. , Burns Melissa A. , Taylor Jennifer L. , He Wenlei , Halpern Elkan F. , McDougal W. Scott , Wu Chin-Lee
Published: July 2017

Diagnostic advancements for prostate cancer have so greatly increased early detections that hope abounds for improved patient outcomes. However, histopathology, which guides treatment, often subcategorizes aggressiveness insufficiently among moderately differentiated Gleason score (6 and 7) tumors (>70% of new cases). Here, we test the diagnostic capability of prostate metabolite profiles measured with intact tissue magnetic resonance spectroscopy and the sensitivity of local prostate metabolites in predicting prostate cancer status. Prostate tissue samples (n = 199) obtained from 82 prostate cancer patients after prostatectomy were analyzed with high-resolution magic angle spinning proton magnetic resonance spectroscopy, and afterwards with quantitative pathology. Metabolite profiles obtained from principal component analysis of magnetic resonance spectroscopy were correlated with pathologic quantitative findings by using linear regression analysis and evaluated against patient pathologic statuses by using ANOVA. Paired t tests show that tissue metabolite profiles can differentiate malignant from benign samples obtained from the same patient (P < 0.005) and correlate with patient serum prostate-specific antigen levels (P < 0.006). Furthermore, metabolite profiles obtained from histologically benign tissue samples of Gleason score 6 and 7 prostates can delineate a subset of less aggressive tumors (P < 0.008) and predict tumor perineural invasion within the subset (P < 0.03). These results indicate that magnetic resonance spectroscopy metabolite profiles of biopsy tissues may help direct treatment plans by assessing prostate cancer pathologic stage and aggressiveness, which at present can be histopathologically determined only after prostatectomy.
Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand–Mediated Proliferation of Tumor Cells with Receptor-Proximal Apoptosis Defects
Authors: Baader Eva , Toloczko Agnieszka , Fuchs Uta , Schmid Irene , Beltinger Christian , Ehrhardt Harald , Debatin Klaus-Michael , Jeremias Irmela
Published: July 2017

Tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) might represent a future cytotoxic drug to treat cancer as it induces apoptosis in tumor cells without toxicity in animal trials. We recently described that in contrast to apoptosis, TRAIL mediates tumor cell survival and proliferation in certain tumor cells. Here we studied the effect of TRAIL on 18 cell lines and 53 primary leukemia cells and classified these tumor cells into four groups: TRAIL, anti-DR4 or anti-DR5 induced apoptosis in group A cells, whereas they had no effect on group 0 cells and mediated proliferation in group P cells. To our surprise, TRAIL induced simultaneous apoptosis and proliferation in group AP cells. More than 20% of all cells tested belonged to group P and showed TRAIL-mediated proliferation even in the presence of certain cytotoxic drugs but not inhibitors of nuclear factor-κB. Transfection with B-cell leukemia/lymphoma protein 2 transformed group A cells into group 0 cells, whereas transfection with Fas-associated polypeptide with death domain (FADD)–like interleukin-1-converting enzyme–inhibitory protein (FLIP) transformed them into group AP cells. Loss of caspase-8 or transfection of dominant-negative FADD transformed group A cells into group P cells. Taken together, our data suggest that proliferation is a frequent effect of TRAIL on tumor cells, which is related to receptor-proximal apoptosis defects at the level of the death-inducing signaling complex and should be prevented during antitumor therapy with TRAIL.
Construction of a Minimal HIV-1 Variant that Selectively Replicates in Leukemic Derived T-Cell Lines: Towards a New Virotherapy Approach
Authors: Jeeninga Rienk E. , Jan Barbara , van der Linden Birgit , van den Berg Henk , Berkhout Ben
Published: July 2017

T-cell acute lymphoblastic leukemia is a high-risk type of blood-cell cancer. We analyzed the possibility of developing virotherapy for T-cell acute lymphoblastic leukemia. Virotherapy is based on the exclusive replication of a virus in leukemic cells, leading to the selective removal of these malignant cells. We constructed a minimized derivative of HIV-1, a complex lentivirus encoding multiple accessory functions that are essential for virus replication in untransformed cells, but dispensable in leukemic T cells. This mini-HIV virus has five deletions (vif, vpR, vpU, nef, and U3) and replicated in the SupT1 cell line, but did not replicate in normal peripheral blood mononuclear cells. The stripped down mini-HIV variant was also able to efficiently remove leukemic cells from a mixed culture with untransformed control cells. In contrast to wild-type HIV-1, we did not observe bystander killing in mixed culture experiments with the mini-HIV variant. Furthermore, viral escape was not detected in long-term cultures. The mini-HIV variant that uses CD4 and CXCR4 for cell entry could potentially be used against CXCR4-expressing malignancies such as T-lymphoblastic leukemia/lymphoma, natural killer leukemia, and some myeloid leukemias.
Inhibition of Mammalian Target of Rapamycin Reverses Alveolar Epithelial Neoplasia Induced by Oncogenic K-ras
Authors: Wislez Marie , Spencer M. Loreto , Izzo Julie G. , Juroske Denise M. , Balhara Kamna , Cody Dianna D. , Price Roger E. , Hittelman Walter N. , Wistuba Ignacio I. , Kurie Jonathan M.
Published: July 2017

The serine/threonine kinase AKT and its downstream mediator mammalian target of rapamycin (mTOR) are activated in lung adenocarcinoma, and clinical trials are under way to test whether inhibition of mTOR is useful in treating lung cancer. Here, we report that mTOR inhibition blocked malignant progression in K-rasLA1 mice, which undergo somatic activation of the K-ras oncogene and display morphologic changes in alveolar epithelial cells that recapitulate those of precursors of human lung adenocarcinoma. Levels of phospho-S6Ser236/235, a downstream mediator of mTOR, increased with malignant progression (normal alveolar epithelial cells to adenocarcinoma) in K-rasLA1 mice and in patients with lung adenocarcinoma. Atypical alveolar hyperplasia, an early neoplastic change, was prominently associated with macrophages and expressed high levels of phospho-S6Ser236/235. mTOR inhibition in K-rasLA1 mice by treatment with the rapamycin analogue CCI-779 reduced the size and number of early epithelial neoplastic lesions (atypical alveolar hyperplasia and adenomas) and induced apoptosis of intraepithelial macrophages. LKR-13, a lung adenocarcinoma cell line derived from K-rasLA1 mice, was resistant to treatment with CCI-779 in vitro. However, LKR-13 cells grown as syngeneic tumors recruited macrophages, and those tumors regressed in response to treatment with CCI-779. Lastly, conditioned medium from primary cultures of alveolar macrophages stimulated the proliferation of LKR-13 cells. These findings provide evidence that the expansion of lung adenocarcinoma precursors induced by oncogenic K-ras requires mTOR-dependent signaling and that host factors derived from macrophages play a critical role in adenocarcinoma progression.
Arginase-Producing Myeloid Suppressor Cells in Renal Cell Carcinoma Patients: A Mechanism of Tumor Evasion
Authors: Zea Arnold H. , Rodriguez Paulo C. , Atkins Michael B. , Hernandez Claudia , Signoretti Sabina , Zabaleta Jovanny , McDermott David , Quiceno David , Youmans Amanda , O'Neill Anne , Mier James , Ochoa Augusto C.
Published: July 2017

Myeloid suppressor cells with high arginase activity are found in tumors and spleen of mice with colon and lung cancer. These cells, described as macrophages or immature dendritic cells, deplete arginine and impair T cell proliferation and cytokine production. Although arginase activity has been described in cancer patients, it is thought to originate from tumor cells metabolizing arginine to ornithine needed to sustain rapid cell proliferation. The goal of this study was to determine whether myeloid suppressor cells producing high arginase existed in renal cell carcinoma patients. Peripheral blood mononuclear cells from 123 patients with metastatic renal cell carcinoma, prior to treatment, were found to have a significantly increased arginase activity. These patients had a markedly decreased cytokine production and expressed low levels of T cell receptor CD3ζ chain. Cell separation studies showed that the increased arginase activity was limited to a specific subset of CD11b+, CD14−, CD15+ cells with a polymorphonuclear granulocyte morphology and markers, instead of macrophages or dendritic cells described in mouse models. Furthermore, these patients had low levels of arginine and high levels of ornithine in plasma. Depletion of the CD11b+, CD14− myeloid suppressor cells reestablished T cell proliferation and CD3ζ chain expression. These results showed, for the first time, the existence of suppressor myeloid cells producing arginase in human cancer patients. In addition, it supports the concept that blocking arginase may be an important step in the success of immunotherapy.
IFN-β Down-Regulates the Expression of DNA Repair Gene MGMT and Sensitizes Resistant Glioma Cells to Temozolomide
Authors: Natsume Atsushi , Ishii Dai , Wakabayashi Toshihiko , Tsuno Takaya , Hatano Hisashi , Mizuno Masaaki , Yoshida Jun
Published: July 2017

Alkylating agents, such as temozolomide, are among the most effective cytotoxic agents used for malignant gliomas, but responses remain very poor. The DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) plays an important role in cellular resistance to alkylating agents. IFN-β can act as a drug sensitizer, enhancing toxicity against a variety of neoplasias, and is widely used in combination with other antitumor agents such as nitrosoureas. Here, we show that IFN-β sensitizes glioma cells that harbor the unmethylated MGMT promoter and are resistant to temozolomide. By means of oligonucleotide microarray and RNA interference, we reveal that the sensitizing effect of IFN-β was possibly due to attenuation of MGMT expression via induction of the protein p53. Our study suggests that clinical efficacy of temozolomide might be improved by combination with IFN-β using appropriate doses and schedules of administration.
Angiotensin II Type 2 Receptor Gene Deficiency Attenuates Susceptibility to Tobacco-Specific Nitrosamine-Induced Lung Tumorigenesis: Involvement of Transforming Growth Factor-β-Dependent Cell Growth Attenuation
Authors: Kanehira Tsutomu , Tani Tatsuo , Takagi Tetsuo , Nakano Yuichirou , Howard Eric F. , Tamura Masaaki
Published: July 2017

To clarify an involvement of angiotensin II signaling in lung neoplasia, we have examined the effect of angiotensin II receptor deficiency on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)–induced lung tumorigenesis. Male angiotensin II type 2 receptor (AT2)-null mice with an SWR/J genetic background and control wild-type mice were treated with NNK (100 mg/kg, i.p.) or saline vehicle. NNK treatment caused the development of lung tumors in all wild-type control mice (100 % tumor prevalence), but only 85% of AT2-null mice developed tumors. The tumor multiplicity in AT2-null mice (1.9 ± 0.3) was significantly smaller than that in wild-type mice (4.1 ± 0.9). Primary cultured lung fibroblasts prepared from both AT2-null and wild-type mice markedly increased the colony counts of A549 lung cancer cells in soft agar, but a consistently higher colony count was observed with the wild-type fibroblasts (fold increase in colony number, 5.6 ± 0.5) than with the AT2-null fibroblasts (3.5 ± 0.8). The underlying mechanism by which angiotensin II regulates cancer cell growth is due to the regulation of active transforming growth factor-β (TGF-β) production. Although the total level of TGF-β was significantly stimulated when A549 cells were cocultured with either type of fibroblasts, the level of active TGF-β in the conditioned medium was consistently higher with AT2-null fibroblasts than with wild-type fibroblasts. These results imply that the AT2 receptor negatively regulates the level of active TGF-β and thus increases NNK-induced lung tumorigenesis. The AT2 receptor function in lung stromal fibroblasts may be a potential modulator of tumor susceptibility in chemical carcinogen-induced lung tumorigenesis.
Partial, but not Complete, Tumor-Debulking Surgery Promotes Protective Antitumor Memory when Combined with Chemotherapy and Adjuvant Immunotherapy
Authors: Broomfield Steve , Currie Andrew , van der Most Robbert G. , Brown Matthew , van Bruggen Ivonne , Robinson Bruce W.S. , Lake Richard A.
Published: July 2017

Resection alone is rarely curative for advanced tumors, but the outcome generally improves with adjuvant therapy. We have previously shown that a combination of traditional chemotherapy (gemcitabine) and immunotherapy (anti-CD40/FGK-45) without surgery is synergistic and can lead to long-term cure when applied to small tumors. Such cured animals have immunologic memory and are protected from rechallenge. Here we investigate the effectiveness of combination chemotherapy and immunotherapy after partial or complete surgical debulking of large tumors. We found that complete resection followed by combination chemotherapy/immunotherapy led to a high rate of cure (>80%) but failed to induce a long-term, tumor-specific memory. Partial debulking followed by combination therapy elicited the same proportion of cured animals but in contrast to complete resection, a memory response was invoked. We postulate that chemotherapy induced apoptosis of the residual tumor cells following incomplete resection is absolutely required for the induction of long-term immunologic memory.
The Distal Zinc Finger Domain of AML1/MDS1/EVI1 Is an Oligomerization Domain Involved in Induction of Hematopoietic Differentiation Defects in Primary Cells In vitro
Authors: Senyuk Vitalyi , Li Donglan , Zakharov Alexander , Mikhail Fady M. , Nucifora Giuseppina
Published: July 2017

AML1/MDS1/EVI1 (AME) is a chimeric transcription factor produced by the (3;21)(q26;q22) translocation. This chromosomal translocation is associated with de novo and therapy-related acute myeloid leukemia and with the blast crisis of chronic myelogenous leukemia. AME is obtained by in-frame fusion of the AML1 and MDS1/EVI1 (ME) genes. The mechanisms by which AME induces a neoplastic transformation in bone marrow cells are unknown. AME interacts with the corepressors CtBP and HDAC1, and it was shown that AME is a repressor in contrast to the parent transcription factors AML1 and ME, which are transcription activators. Studies with murine bone marrow progenitors indicated that the introduction of a point mutation that destroys the CtBP-binding consensus impairs but does not abolish the disruption of cell differentiation and replication associated with AME expression, suggesting that additional events are required. Several chimeric proteins, such as AML1/ETO, BCR/ABL, and PML/RARa, are characterized by the presence of a self-interaction domain critical for transformation. We report that AME is also able to oligomerize and displays a complex pattern of self-interaction that involves at least three oligomerization regions, one of which is the distal zinc finger domain. Although the deletion of this short domain does not preclude the self-interaction of AME, it significantly reduces the differentiation defects caused in vitro by AME in primary murine bone marrow progenitors. The addition of a point mutation that inhibits CtBP binding completely abrogates the effects of AME on differentiation, suggesting that AME induces hematopoietic differentiation defects through at least two separate but cooperating pathways.