bluuebunny/crossref_metadata_2025 huggingface dataset:
Vascular Normalization by Vascular Endothelial Growth Factor Receptor 2 Blockade Induces a Pressure Gradient Across the Vasculature and Improves Drug Penetration in Tumors
Authors: Tong Ricky T. , Boucher Yves , Kozin Sergey V. , Winkler Frank , Hicklin Daniel J. , Jain Rakesh K.
Published: September 2005

Elevated interstitial fluid pressure, a hallmark of solid tumors, can compromise the delivery of therapeutics to tumors. Here we show that blocking vascular endothelial growth factor (VEGF) signaling by DC101 (a VEGF-receptor-2 antibody) decreases interstitial fluid pressure, not by restoring lymphatic function, but by producing a morphologically and functionally “normalized” vascular network. We demonstrate that the normalization process prunes immature vessels and improves the integrity and function of the remaining vasculature by enhancing the perivascular cell and basement membrane coverage. We also show that DC101 induces a hydrostatic pressure gradient across the vascular wall, which leads to a deeper penetration of molecules into tumors. Thus, vascular normalization may contribute to the improved survival rates in tumor-bearing animals and in colorectal carcinoma patients treated with an anti-VEGF antibody in combination with cytotoxic therapies.
CpG Hypermethylation of
MDR1
Gene Contributes to the Pathogenesis and Progression of Human Prostate Cancer
Authors: Enokida Hideki , Shiina Hiroaki , Igawa Mikio , Ogishima Tatsuya , Kawakami Toshifumi , Bassett William W. , Anast Jason W. , Li Long-Cheng , Urakami Shinji , Terashima Masaharu , Verma Mukesh , Kawahara Motoshi , Nakagawa Masayuki , Kane Christopher J. , Carroll Peter R. , Dahiya Rajvir
Published: September 2005

Multidrug resistance 1 (MDR1) gene encodes for P-glycoprotein (P-gp), a Mr 170,000 transmembrane calcium-dependent efflux pump that is inactivated in prostate cancer. We hypothesize that inactivation of the MDR1 gene through CpG methylation contributes to the pathogenesis and progression of prostate cancer. To test this hypothesis, CpG methylation status of the MDR1 promoter and its correlation with clinicopathological findings were evaluated in 177 prostate cancer samples and 69 benign prostate hypertrophy (BPH) samples. Cellular proliferation index and apoptotic index were determined by proliferating cell nuclear antigen (PCNA) and single-strand DNA immunostaining, respectively. After 5-aza-2′-deoxycytidine treatment, increased expression of MDR1 mRNA transcript was found in prostate cancer cell lines (DU145, DuPro, and ND1). MDR1 methylation frequency was significantly higher in prostate cancer samples compared with BPH samples (54.8 versus 11.6%, respectively, P < 0.001). Logistic regression analysis revealed that PC patients are 11.5 times more likely to have MDR1 methylation than BPH patients (95% confidence interval 4.87–27.0) and that MDR1 methylation is independent of the age. Significant correlation of MDR1 methylation was observed with high pT category (P < 0.001), high Gleason sum (P = 0.008), high preoperative prostate-specific antigen (P = 0.01), and advancing pathological features. In addition, PCNA-labeling index were significantly higher in methylation-specific PCR (MSP)-positive than in MSP-negative prostate cancer samples (P = 0.048). In contrast, no significant difference in apoptotic index was found between MSP-positive and -negative prostate cancer samples. These findings suggest that CpG hypermethylation of MDR1 promoter is a frequent event in prostate cancer and is related to disease progression via increased cell proliferation in prostate cancer cells.
Silencing of the Hypoxia-Inducible Cell Death Protein BNIP3 in Pancreatic Cancer
Authors: Okami Jiro , Simeone Diane M. , Logsdon Craig D.
Published: September 2005

Hypoxic conditions exist within pancreatic adenocarcinoma, yet pancreatic cancer cells survive and replicate within this environment. To understand the mechanisms involved in pancreatic cancer adaptation to hypoxia, we analyzed expression of a regulator of hypoxia-induced cell death, Bcl-2/adenovirus E1B 19 kDa interacting protein 3 (BNIP3). We found that BNIP3 was down-regulated in nine of nine pancreatic adenocarcinomas compared with normal pancreas despite the up-regulation of other hypoxia-inducible genes, including glucose transporter-1 and insulin-like growth factor-binding protein 3. Also, BNIP3 expression was undetectable even after hypoxia treatment in six of seven pancreatic cancer cell lines. The BNIP3 promoter, which was remarkably activated by hypoxia, is located within a CpG island. The methylation status of CpG dinucleotides within the BNIP3 promoter was analyzed after bisulfite treatment by sequencing and methylation-specific PCR. Hypermethylation of the BNIP3 promoter was observed in all BNIP3-negative pancreatic cancer cell lines and eight of 10 pancreatic adenocarcinoma samples. Treatment of BNIP3-negative pancreatic cancer cell lines with a DNA methylation inhibitor, 5-aza-2′ deoxycytidine, restored hypoxia-induced BNIP3 expression. BNIP3 expression was also restored by introduction of a construct consisting of a full-length BNIP3 cDNA regulated by a cloned BNIP3 promoter. Restoration of BNIP3 expression rendered the pancreatic cancer cells notably more sensitive to hypoxia-induced cell death. In conclusion, down-regulation of BNIP3 by CpG methylation likely contributes to resistance to hypoxia-induced cell death in pancreatic cancer.
Proadrenomedullin NH2-Terminal 20 Peptide Is a Potent Angiogenic Factor, and Its Inhibition Results in Reduction of Tumor Growth
Authors: Martínez Alfredo , Zudaire Enrique , Portal-Núñez Sergio , Guédez Liliana , Libutti Steven K. , Stetler-Stevenson William G. , Cuttitta Frank
Published: September 2005

We have found through ex vivo and in vivo angiogenesis models that the adrenomedullin gene-related peptide, proadrenomedullin NH2-terminal 20 peptide (PAMP), exhibits a potent angiogenic potential at femtomolar concentrations, whereas classic angiogenic factors such as vascular endothelial growth factor and adrenomedullin mediate a comparable effect at nanomolar concentrations. We found that human microvascular endothelial cells express PAMP receptors and respond to exogenous addition of PAMP by increasing migration and cord formation. Exposure of endothelial cells to PAMP increases gene expression of other angiogenic factors such as adrenomedullin, vascular endothelial growth factor, basic fibroblast growth factor, and platelet-derived growth factor C. In addition, the peptide fragment PAMP(12-20) inhibits tumor cell–induced angiogenesis in vivo and reduces tumor growth in xenograft models. Together, our data demonstrate PAMP to be an extremely potent angiogenic factor and implicate this peptide as an attractive molecular target for angiogenesis-based antitumor therapy.
Cell-Type-Specific Responses to Chemotherapeutics in Breast Cancer
Authors: Troester Melissa A. , Hoadley Katherine A. , Sørlie Therese , Herbert Brittney-Shea , Børresen-Dale Anne-Lise , Lønning Per Eystein , Shay Jerry W. , Kaufmann William K. , Perou Charles M.
Published: September 2005

Recent microarray studies have identified distinct subtypes of breast tumors that arise from different cell types and that show statistically significant differences in patient outcome. To gain insight into these differences, we identified in vitro and in vivo changes in gene expression induced by chemotherapeutics. We treated two cell lines derived from basal epithelium (immortalized human mammary epithelial cells) and two lines derived from luminal epithelium (MCF-7 and ZR-75–1) with chemotherapeutics used in the treatment of breast cancer and assayed for changes in gene expression using DNA microarrays. Treatment doses for doxorubicin and 5-fluorouracil were selected to cause comparable cytotoxicity across all four cell lines. The dominant expression response in each of the cell lines was a general stress response; however, distinct expression patterns were observed. Both cell types induced DNA damage-response genes such as p21waf1, but the response in the luminal cells showed higher fold changes and included more p53-regulated genes. Luminal cell lines repressed a large number of cell cycle-regulated genes and other genes involved in cellular proliferation, whereas the basal cell lines did not. Instead, the basal cell lines repressed genes that were involved in differentiation. These in vitro responses were compared with expression responses in breast tumors sampled before and after treatment with doxorubicin or 5-fluorouracil/mitomycin C. The in vivo data corroborated the cell-type-specific responses to chemotherapeutics observed in vitro, including the induction of p21waf1. Similarities between in vivo and in vitro responses help to identify important response mechanisms to chemotherapeutics.
Cytoplasmic Mislocalization of p27Kip1 Protein Is Associated with Constitutive Phosphorylation of Akt or Protein Kinase B and Poor Prognosis in Acute Myelogenous Leukemia
Authors: Min Yoo Hong , Cheong June-Won , Kim Ji Yeon , Eom Ju In , Lee Seung Tae , Hahn Jee Sook , Ko Yun Woong , Lee Mark Hong
Published: September 2005

Cyclin-dependent kinase inhibitor p27Kip1 functions at the nuclear level by binding to cyclin E/cyclin-dependent kinase-2. It was shown that Akt or protein kinase B (Akt/PKB)-dependent phosphorylation of p27Kip1 led to the cytoplasmic mislocalization of p27Kip1, suggesting the potential abrogation of its activity. Here, we evaluated the localization of p27Kip1 protein in leukemic blasts in relation to Akt/PKB phosphorylation and clinical outcomes in acute myelogenous leukemia (AML). Western blot analysis of the nuclear and cytoplasmic fractions revealed a heterogenous localization pattern of p27Kip1 in AML. Cytoplasmic mislocalization of p27Kip1 was significantly associated with the constitutive serine473 Akt/PKB phosphorylation in AML cells (P < 0.05). Transfection of U937 cells with an expression construct encoding the constitutively active form of Akt/PKB resulted in a remarkable increase in the levels of cytoplasmic p27Kip1. Whereas the transfection of U937 cells with a construct encoding dominant-negative Akt/PKB resulted in a recovery of nuclear localization of p27Kip1. Both the disease-free survival and overall survival are significantly shorter in AML cases with high cytoplasmic to nuclear ratio of p27Kip1 localization compared with the cases with low cytoplasmic to nuclear ratio (P = 0.0353, P = 0.0023, respectively). Multivariate analysis indicated that the cytoplasmic to nuclear ratio of p27Kip1 localization was an independent prognostic variable for both disease-free survival and overall survival (P = 0.043, P = 0.008, respectively). These findings additionally extend our understanding of the role of p27Kip1 in AML, and buttress the case of p27Kip1 mislocalization as a prognostic indicator and Akt/PKB/p27Kip1 pathway as a ready target for antileukemia therapy.
Evaluation of Human Thymidine Kinase 1 Substrates as New Candidates for Boron Neutron Capture Therapy
Authors: Al-Madhoun Ashraf S. , Johnsamuel Jayaseharan , Barth Rolf F. , Tjarks Werner , Eriksson Staffan
Published: September 2005

Thymidine analogs containing o-carboranylalkyl groups at the 3-position were screened as potential substrates for human thymidine kinase 1 (TK1), an enzyme that is selectively expressed in a variety of rapidly proliferating cells, including tumor cells. On the basis of previous studies, 12 of these were identified as potential delivery agents for boron neutron capture therapy, a therapeutic method used for the treatment of high-grade brain tumors. Compound 4 with a pentylene spacer between the o-carborane cage and the thymidine scaffold and compound 10, which has an additional dihydroxypropyl substituent at the o-carborane cage, were the best substrates for TK1 with kcat/Km values of 27% and 36% relative to that of thymidine, respectively. These compounds showed partial competitive inhibition for thymidine phosphorylation by TK1. Neither compound was a substrate of recombinant human thymidine phosphorylase nor were their respective 5′-monophosphates substrates of 5′-deoxynucleotidase 1, thereby indicating potential in vivo stability. The octanol/water partition coefficient for compound 10 was 2.09, suggesting that it has excellent physiochemical properties for crossing the blood brain barrier and penetrating brain tissue. The in vitro cytotoxic effect of the 12 analogs was moderate to low in mammalian cell cultures with IC50 values between 10 and 160 μmol/L. Compounds 4 and 10 were taken up selectively and retained by the murine fibroblast L929 cell line, in contrast to its TK1-deficient variant. These findings suggest that compound 10 is a promising candidate for selective delivery of boron-10 to malignant cells, and additional in vivo studies are planned to evaluate it for boron neutron capture therapy of brain tumors.
Melanoma Differentiation Associated Gene-7/Interleukin-24 Promotes Tumor Cell-Specific Apoptosis through Both Secretory and Nonsecretory Pathways
Authors: Sauane Moira , Lebedeva Irina V. , Su Zao-zhong , Choo Heng-tong , Randolph Aaron , Valerie Kristoffer , Dent Paul , Gopalkrishnan Rahul V. , Fisher Paul B.
Published: September 2005

Melanoma differentiation associated gene-7/interleukin-24 (Mda-7/IL-24), a novel member of the IL-10 family of cytokines, uniquely displays cancer-specific apoptosis-inducing activity. Positive results in ongoing phase I/II clinical trials have strengthened the possibility of its utilization as a cancer gene therapeutic. Previous studies document that signaling events leading to Ad.mda-7-induced transformed cell apoptosis are tyrosine kinase-independent. These results suggest that mda-7/IL-24 cancer cell-specific activity could occur through mechanisms independent of binding to its currently recognized cognate receptors and might even occur independent of receptor function. An adenovirus vector expressing a nonsecreted version of MDA-7/IL-24 protein was generated via deletion of its signal peptide. This nonsecreted protein was as effective as wild-type secreted MDA-7/IL-24 in inducing apoptosis in prostate carcinoma cell lines and displayed transformed cell specificity and localization of MDA-7/IL-24 in the Golgi/endoplasmic reticulum compartments. Our results indicate that mda-7/IL-24-mediated apoptosis can be triggered through a combination of intracellular as well as secretory mechanisms and can occur efficiently in the absence of protein secretion.
Flavopiridol Induces p53 via Initial Inhibition of Mdm2 and p21 and, Independently of p53, Sensitizes Apoptosis-Reluctant Cells to Tumor Necrosis Factor
Authors: Demidenko Zoya N. , Blagosklonny Mikhail V.
Published: September 2005

Flavopiridol (FP) inhibits gene expression and causes apoptosis, and these effects cannot be explained by inhibition of cyclin-dependent kinases that govern cell cycle. The simple and established notion that FP is an inhibitor of transcription predicts its effects. Because Mdm-2 targets p53 for degradation, FP, as predicted, dramatically induced p53 by inhibiting Mdm-2. Once p53 was induced, restoration of transcription (by removal of FP) resulted in superinduction of p21 and Mdm-2. Similarly, low concentrations of FP (50 nm) induced p21 and Mdm-2 because of their initial down-regulation. A sustained decrease of Mdm-2/p21 expression and accumulation of p53 coincided with near-maximal cytotoxicity of FP at concentrations >100 nm. Induction of p53 was a marker, not a cause, of cytotoxicity. FP caused rapid apoptosis (caspase-dependent cell death) in p53-null leukemia cells. In these cells, FP-induced apoptosis was converted to growth arrest by inhibitors of caspases. In apoptosis-reluctant A549 and PC3M cancer cells, FP inhibited cell proliferation but did not cause apoptosis. Like typical inhibitors of transcription, FP sensitized cells to apoptotic stimuli, allowing tumor necrosis factor to cause rapid and massive apoptosis in otherwise apoptosis-reluctant cells. We discuss that, as a reversible inhibitor of transcription, FP can be used clinically in novel rational drug combinations.
Complex Regulation of Signal Transducers and Activators of Transcription 3 Activation in Normal and Malignant Keratinocytes
Authors: Quadros Marlene R. D. , Peruzzi Francesca , Kari Csaba , Rodeck Ulrich
Published: September 2005

Previous work implicated activation of the signal transducer and activator of transcription (STAT)3 downstream of the epidermal growth factor receptor (EGFR) in the malignant phenotype of squamous carcinoma cells (SCC). Here, we show that EGFR-dependent STAT3 activation is restricted to malignant keratinocytes. Specifically, constitutive and epidermal growth factor-induced phosphorylation of STAT3 on Y705 was observed only in SCC but not in either immortalized (HaCaT) or normal keratinocyte strains. Furthermore, STAT3 activation as determined by DNA binding assays was restricted to SCC and dependent on EGFR activation. Forced expression of EGFR in immortalized keratinocytes (HaCaT cells) was associated with enhanced EGFR activation but not STAT3-Y705 phosphorylation. EGFR-dependent activation of mitogen-activated protein kinase (MAPK) kinase 1 negatively regulated STAT3-Y705 phosphorylation in normal and malignant keratinocytes. Together, these results underscore that EGFR activation is required but not sufficient for STAT3 activation to occur in malignant keratinocytes. They also highlight complex regulation of STAT3 phosphorylation through EGFR activation including negative regulation via the MAPK kinase/MAPK signaling pathway.
Position in Cell Cycle Controls the Sensitivity of Colon Cancer Cells to Nitric Oxide-Dependent Programmed Cell Death
Authors: Jarry Anne , Charrier Laetitia , Bou-Hanna Chantal , Devilder Marie-Claire , Crussaire Véronique , Denis Marc G. , Vallette Geneviève , Laboisse Christian L.
Published: September 2005

Mounting evidence suggests that the position in the cell cycle of cells exposed to an oxidative stress could determine their survival or apoptotic cell death. This study aimed at determining whether nitric oxide (NO)-induced cell death in colon cancer cells might depend on their position in the cell cycle, based on a clone of the cancer cell line HT29 exposed to an NO donor, in combination with the manipulation of the cell entry into the cell cycle. We show that PAPA NONOate (pNO), from 10−4 m to 10−3 m, exerted early and reversible cytostatic effects through ribonucleotide reductase inhibition, followed by late resumption of cell growth at 5 × 10−4 m pNO. In contrast, 10−3 m pNO led to late programmed cell death that was accounted for by the progression of cells into the cell cycle as shown by (a) the accumulation of apoptotic cells in the G2-M phase at 10−3 m pNO treatment; and (b) the prevention of cell death by inhibiting the entry of cells into the cell cycle. The entry of pNO-treated cells into the G2-M phase was associated with actin depolymerization and its S-glutathionylation in the same way as in control cells. However, the pNO treatment interfered with the build-up of a high reducing power, associated in control cells with a dramatic increase in reduced glutathione biosynthesis in the G2-M phase. This oxidative stress prevented the exit from the G2-M phase, which requires a high reducing power for actin deglutathionylation and its repolymerization. Finally, our demonstration that programmed cell death occurred through a caspase-independent pathway is in line with the context of a nitrosative/oxidative stress. In conclusion, this work, which deciphers the connection between the position of colonic cancer cells in the cell cycle and their sensitivity to NO-induced stress and their programmed cell death, could help optimize anticancer protocols based on NO-donating compounds.
Quantifying Transient Hypoxia in Human Tumor Xenografts by Flow Cytometry
Authors: Bennewith Kevin L. , Durand Ralph E.
Published: September 2005

Transient hypoxia is a poorly understood and potentially important factor that may limit tumor response to various forms of therapy. We assessed transient hypoxia on a global scale in two different human tumor xenografts by sequentially administering two hypoxia markers followed by quantification of hypoxic cells using flow cytometry. High levels of the first hypoxia marker (pimonidazole) were maintained in the circulation over an 8-hour period by multiple hourly injections, providing a “time-integrated” hypoxia measure showing an asymptotic increase in the total number of hypoxic cells. Subsequent administration of a second hypoxia marker (CCI-103F) showed that substantial numbers of the previously pimonidazole-labeled cells were no longer hypoxic during the circulation lifetime of the second marker. The overall fraction of tumor cells that demonstrated changes in hypoxic status with time increased with different kinetics and by different magnitudes in the two xenograft systems. Specifically, up to 20% of the cells in SiHa (human cervical squamous cell carcinoma) tumors and up to 8% of the cells in WiDr (human colon adenocarcinoma) tumors were intermittently hypoxic over an 8-hour period. Also, the tumor cells that demonstrated transient hypoxia were typically not adjacent to functional tumor blood vessels. Similar approaches could be used in the clinic to provide information on the duration of intermittent hypoxia episodes and the fraction of transiently hypoxic tumor cells, which would, in turn, have important implications for the strategic improvement of cancer therapy.
Molecular Profiling of Human Hepatocellular Carcinoma Defines Mutually Exclusive Interferon Regulation and Insulin-Like Growth Factor II Overexpression
Authors: Breuhahn Kai , Vreden Sebastian , Haddad Ramsi , Beckebaum Susanne , Stippel Dirk , Flemming Peer , Nussbaum Tanja , Caselmann Wolfgang H. , Haab Brian B. , Schirmacher Peter
Published: September 2005

Molecular subtyping of human hepatocellular carcinoma (HCC) with potential mechanistic and therapeutic impact has not been achieved thus far. We have analyzed the mRNA expression patterns of 43 different human HCC samples and 3 HCC cell lines in comparison with normal adult liver using high-density cDNA microarrays. Two main groups of HCC, designated group A (65%) and group B (35%), were distinguished based on clustering of the most highly varying genes. Group A HCCs were characterized by induction of a number of interferon (IFN)-regulated genes, whereas group B was characterized mainly by down-regulation of several apoptosis-relevant and IFN-regulated genes. The number of apoptotic tumor cells and tumor-infiltrating lymphocytes was significantly higher in tumors of group A as compared with those of group B. Based on the expression pattern, group B was further subdivided into two subgroups, designated subgroup B1 (6 of 43 tumors, 14%) and subgroup B2 (9 of 43 tumors, 21%). A prominent characteristic of subgroup B1 was high overexpression of insulin-like growth factor (IGF)-II. All tested HCC cell lines expressed equally high concentrations of IGF-II transcripts and co-segregated with group B1 in clustering. IGF-II overexpression and induction of IFN-related genes were mutually exclusive, even when analysis was extended to other cancer expression profile studies. Moreover, IFN-γ treatment substantially reduced IGF-II expression in HCC cells. In conclusion, cDNA microarray analyses provided subtyping of HCCs that is related to intratumor inflammation and tumor cell apoptosis. This profiling may be of mechanistic and therapeutic impact because IGF-II overexpression has been linked to reduced apoptosis and increased proliferation and may be accessible to therapeutic intervention.
Transduction of Soluble
Flt-1
Gene to Peritoneal Mesothelial Cells Can Effectively Suppress Peritoneal Metastasis of Gastric Cancer
Authors: Sako Akihiro , Kitayama Joji , Koyama Hiroyuki , Ueno Hikaru , Uchida Hiroaki , Hamada Hirofumi , Nagawa Hirokazu
Published: September 2005

The prognosis of gastric cancer with peritoneal metastasis has not improved. Despite many promising studies, gene therapy has limited clinical application because of the lack of suitable vector systems to enable selective gene transduction to tumor cells. The aim of this study was to clarify whether gene therapy targeted to peritoneal mesothelial cells (PMCs) can inhibit peritoneal dissemination of gastric cancer. In vitro experiments showed that adenovirus expressing LacZ infected human omental tissue-derived PMCs more efficiently than human gastric cancer cell lines MKN1 and MKN45. When adenovirus expressing LacZ was injected into the peritoneal cavity of nude mice, the expression was detected in the peritoneum for at least 4 weeks. Furthermore, when adenovirus expressing soluble Flt-1 (Ad-sFLT-1) was i.p. administered in vivo, a high level of sFlt-1 protein could be detected in peritoneal lavage for 8 weeks. When MKN45 cells were i.p. inoculated 3 days after adenoviral vector injection, Ad-sFLT-1 markedly reduced the number of metastatic nodules larger than 1 mm in diameter on the peritoneal surface, and significantly prolonged the survival of nude mice without any significant side effects. Thus, peritoneal dissemination was significantly suppressed by a single i.p. injection of Ad-sFlt-1. Anti-angiogenic gene therapy targeted to PMCs could be a novel and practical strategy against peritoneal dissemination of gastric cancer, because it does not require tumor-specific gene transfer.
Tetrandrine Induces Early G1 Arrest in Human Colon Carcinoma Cells by Down-Regulating the Activity and Inducing the Degradation of G1-S–Specific Cyclin-Dependent Kinases and by Inducing p53 and p21Cip1
Authors: Meng Ling-hua , Zhang Hongliang , Hayward Larry , Takemura Haruyuki , Shao Rong-Guang , Pommier Yves
Published: September 2005

Tetrandrine is an antitumor alkaloid isolated from the root of Stephania tetrandra. We find that micromolar concentrations of tetrandrine irreversibly inhibit the proliferation of human colon carcinoma cells in MTT and clonogenic assays by arresting cells in G1. Tetrandrine induces G1 arrest before the restriction point in nocodazole- and serum-starved synchronized HT29 cells, without affecting the G1-S transition in aphidicolin-synchronized cells. Tetrandrine-induced G1 arrest is followed by apoptosis as shown by fluorescence-activated cell sorting, terminal deoxynucleotidyl transferase–mediated nick end labeling, and annexin V staining assays. Tetrandrine-induced early G1 arrest is mediated by at least three different mechanisms. First, tetrandrine inhibits purified cyclin-dependent kinase 2 (CDK2)/cyclin E and CDK4 without affecting significantly CDK2/cyclin A, CDK1/cyclin B, and CDK6. Second, tetrandrine induces the proteasome-dependent degradation of CDK4, CDK6, cyclin D1, and E2F1. Third, tetrandrine increases the expression of p53 and p21Cip1 in wild-type p53 HCT116 cells. Collectively, these results show that tetrandrine arrests cells in G1 by convergent mechanisms, including down-regulation of E2F1 and up-regulation of p53/p21Cip1.
The
ADPRT V762A
Genetic Variant Contributes to Prostate Cancer Susceptibility and Deficient Enzyme Function
Authors: Lockett Kristin L. , Hall M. Craig , Xu Jianfeng , Zheng S. Lilly , Berwick Marianne , Chuang Shu-Chun , Clark Peter E. , Cramer Scott D. , Lohman Kurt , Hu Jennifer J.
Published: September 2005

The ADP-ribosyltransferase (ADPRT) gene encodes a zinc-finger DNA-binding protein, poly(ADP-ribose) polymerase-1 (PARP-1), that modifies various nuclear proteins by poly(ADP-ribosyl)ation and functions as a key enzyme in the base excision repair pathway. We have conducted two studies to test whether an amino acid substitution variant, ADPRT V762A (T2444C), is associated with prostate cancer (CaP) risk and decreased enzyme function. The first study used genomic DNA samples from an ongoing, clinic-based case-control study (488 cases and 524 controls) to show that a higher percentage of the CaP cases carried the ADPRT 762 AA genotype than controls (4% versus 2%). In Caucasians, the AA genotype was significantly associated with increased CaP risk [odds ratio (OR), 2.65; 95% confidence interval (CI), 1.08–6.49], and the VA genotype was associated with a slight but not significantly increased CaP risk (OR, 1.18; 95% CI, 0.85–1.64) using VV as the referent group after adjustment for age, benign prostatic hyperplasia, and family history. Furthermore, this association was stronger in younger (<65) men (OR, 4.77; 95% CI, 1.01–22.44) than older (≥65) men (OR, 1.78; 95% CI, 0.55–5.82). The second study used freshly isolated peripheral lymphocytes from 354 cancer-free subjects to demonstrate that the ADPRT 762 A allele contributed to significantly lower adenosine diphosphate ribosyl transferase (ADPRT)/PARP-1 activities in response to H2O2 in a gene dosage-dependent manner (P < 0.0001, test for linear trend). The PARP-1 activities (mean ± SD dpm/106 cells) were 18,554 ± 9,070 (n = 257), 14,847 ± 7,082 (n = 86), and 12,155 ± 6,334 (n = 11) for VV, VA, and AA genotypes, respectively. This study is the first to provide evidence that the ADPRT V762A-genetic variant contributes to CaP susceptibility and altered ADPRT/PARP-1 enzyme function in response to oxidative damage.
Hypoxia-Induced Vascular Endothelial Growth Factor Transcription and Protection from Apoptosis Are Dependent on α6β1 Integrin in Breast Carcinoma Cells
Authors: Chung Jun , Yoon Sangoh , Datta Kaustubh , Bachelder Robin E. , Mercurio Arthur M.
Published: September 2005

The α6β1 integrin has been implicated in breast carcinoma progression, but the mechanisms involved remain elusive. MDA-MB-435 cells engineered to be deficient in α6β1 expression form primary tumors that are highly apoptotic and unable to metastasize, although they exhibit no increased apoptosis in vitro under standard culture conditions. Based on the hypothesis that α6β1 is necessary for the survival of these cells in the tumor microenvironment, we report here that hypoxia protects these cells from apoptosis induced by serum deprivation and that hypoxia-mediated protection requires α6β1 expression. We investigated the influence of α6β1 on vascular endothelial growth factor (VEGF) expression because autocrine VEGF is necessary for the survival of serum-deprived cells in hypoxia. The results obtained indicate that α6β1 is necessary for VEGF expression because the ability of hypoxia to activate HIF-1 and to stimulate VEGF transcription in MDA-MB-435 cells is dependent on α6β1 expression by a mechanism that involves protein kinase C-α.
Identification of Genetic Variants in Base Excision Repair Pathway and Their Associations with Risk of Esophageal Squamous Cell Carcinoma
Authors: Hao Bingtao , Wang Haijian , Zhou Kaixin , Li Yi , Chen Xiaoping , Zhou Gangqiao , Zhu Yunping , Miao Xiaoping , Tan Wen , Wei Qingyi , Lin Dongxin , He Fuchu
Published: September 2005

The etiology of esophageal squamous cell carcinoma (ESCC) has been shown to be associated with genetic and certain environmental factors that produce DNA damage. Base excision repair (BER) genes are responsible for repair of DNA damage caused by reactive oxygen species and other electrophiles and therefore are good candidate susceptibility genes for ESCC. We first screened eight BER genes for new and potential functional polymorphisms by resequencing 27 DNA samples. We then identified and genotyped for important tagging single nucleotide polymorphisms (SNPs) in a case-control study of 419 patients with newly diagnosed esophageal cancer and 480 healthy controls by frequency matching on age and sex. The association between genotypes and ESCC risk was estimated by unconditional multivariate logistic regression analysis, and stepwise regression procedure was used for constructing the final logistic regression model. We identified 129 SNPs in the eight BER genes, including 18 SNPs that cause amino acid changes. In the final model, 4 SNPs, including 2 in the coding regions (ADPRT Val762Ala and MBD4 Glu346Lys) and others in noncoding regions (LIG3 A3704G and XRCC1 T-77C), remained as significant predictors for the risk of ESCC. The adjusted odd ratios were 1.25 [95% confidence interval (CI) 1.02–1.53] for the ADPRT 762Ala allele, 1.25 (95% CI 1.02–1.53) for the MBD4 346 Lys allele, 0.78 (95% CI 0.63–0.97) for the LIG3 3704G allele, and 1.38 (95% CI 1.01–1.89) for the XRCC1–77C allele. In addition, we observed a significant gene-gene interaction between XRCC1 Gln399Arg and ADPRT Val762Ala. The results suggest that the polymorphisms in five BER genes may be associated with the susceptibility to ESCC in a Chinese population.
Frontiers of Mutagenesis and DNA Repair
Authors: Kelley Mark R. , Tompkinson Alan E. , Williams Kandace J. , Drinkwater Norman R. , Fung Victor A.
Published: September 2005

The Chemical Pathology Study Section, Center for Scientific Review, NIH hosted a 1-day workshop in Ventura, California, in the winter of 2003. There were 32 invited participants including invited speakers. The workshop consisted of three sessions and focused on recent developments in our understanding of the molecular mechanisms of mutagenesis and DNA repair, namely, error-prone DNA polymerases, DNA repair models and DNA repair networks.
Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand
Authors: Ludwig Aaron T. , Moore Jill M. , Luo Yi , Chen Xiaohong , Saltsgaver Nicole A. , O’Donnell Michael A. , Griffith Thomas S.
Published: September 2005

Mycobacterium bovis Bacillus Calmette-Guérin (BCG) use in the treatment of bladder cancer was first reported in 1976, but the mechanism of the induced antitumor activity has still not been fully explained. BCG is a potent immunostimulant, normally producing a Th1 cytokine response, including IFN. Recent studies have shown CpG oligodeoxynucleotide induce tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) expression via IFN production. Given that Mycobacterial DNA contains high amounts of CpG motifs, we hypothesized that BCG’s antitumor properties are akin to CpG oligodeoxynucleotide, where the cytokine response to BCG induces TRAIL up-regulation. Using ELISA, urine IFN-γ, and TRAIL levels were initially undetectable in BCG therapy patients but were high after later induction treatments. More importantly, patients that responded to BCG therapy had significantly higher urine TRAIL levels, which killed bladder tumor cells in vitro versus nonresponders. Flow cytometry of fresh urine revealed TRAIL-expressing neutrophils. Given these data, we propose TRAIL plays a role in BCG-induced antitumor effects.
Increased Plasma Vascular Endothelial Growth Factor (VEGF) as a Surrogate Marker for Optimal Therapeutic Dosing of VEGF Receptor-2 Monoclonal Antibodies
Authors: Bocci Guido , Man Shan , Green Shane K. , Francia Giulio , Ebos John M. L. , du Manoir Jeanne M. , Weinerman Adina , Emmenegger Urban , Ma Li , Thorpe Philip , Davidoff Andrew , Huber James , Hicklin Daniel J. , Kerbel Robert S.
Published: September 2005

A major obstacle compromising the successful application of many of the new targeted anticancer drugs, including angiogenesis inhibitors, is the empiricism associated with determining an effective biological/therapeutic dose because many of these drugs express optimum therapeutic activity below the maximum tolerated dose, if such a dose can be defined. Hence, surrogate markers are needed to help determine optimal dosing. Here we describe such a molecular marker, increased plasma levels of vascular endothelial growth factor (VEGF), in normal or tumor-bearing mice that received injections of an anti-VEGF receptor (VEGFR)-2 monoclonal antibody, such as DC101. Rapid increases of mouse VEGF (e.g., within 24 hours) up to 1 order of magnitude were observed after single injections of DC101 in non–tumor-bearing severe combined immunodeficient or nude mice; similar increases in human plasma VEGF were detected in human tumor-bearing mice. RAFL-1, another anti-VEGFR-2 antibody, also caused a significant increase in plasma VEGF. In contrast, increases in mouse VEGF levels were not seen when small molecule VEGFR-2 inhibitors were tested in normal mice. Most importantly, the increases in plasma VEGF were induced in a dose-dependent manner, with the maximum values peaking when doses previously determined to be optimally therapeutic were used. Plasma VEGF should be considered as a possible surrogate pharmacodynamic marker for determining the optimal biological dose of antibody drugs that block VEGFR-2 (KDR) activity in a clinical setting.
Hedgehog Signaling Pathway is a New Therapeutic Target for Patients with Breast Cancer
Authors: Kubo Makoto , Nakamura Masafumi , Tasaki Akira , Yamanaka Naoki , Nakashima Hiroshi , Nomura Masatoshi , Kuroki Syoji , Katano Mitsuo
Published: September 2005

The Hedgehog (Hh) signaling pathway functions as an organizer in embryonic development. Genetic analysis has demonstrated a critical role for the Hh pathway in mammary gland morphogenesis. Disruption of Patched1, a component of the Hh pathway, results in abnormal growth of mammary duct. Recent studies have shown constitutive activation of the Hh pathway in various types of malignancies. However, it remains unclear whether this pathway is activated in human breast cancer. Here, we determined the expression of the components, including Sonic Hh, Patched1, and Gli1, of the Hh pathway by immunohistochemical staining in a series of 52 human breast carcinomas. All of 52 tumors display staining of high intensity for Gli1 when compared with adjacent normal tissue. The nuclear staining ratio of Gli1 correlates with expression of estrogen receptor and histologic type. Exposure to cyclopamine, a steroidal alkaloid that blocks the Hh pathway, suppresses expression of Gli1 and the growth of the Hh pathway-activated breast carcinoma cells. These data indicate that the Hh pathway is a new candidate for therapeutic target of breast cancer.
PT-100, a Small Molecule Dipeptidyl Peptidase Inhibitor, Has Potent Antitumor Effects and Augments Antibody-Mediated Cytotoxicity via a Novel Immune Mechanism
Authors: Adams Sharlene , Miller Glenn T. , Jesson Michael I. , Watanabe Takeshi , Jones Barry , Wallner Barbara P.
Published: September 2005

The amino boronic dipeptide, PT-100 (Val-boro-Pro), a dipeptidyl peptidase (DPP) inhibitor, has been shown to up-regulate gene expression of certain cytokines in hematopoietic tissue via a high-affinity interaction, which appears to involve fibroblast activation protein. Because fibroblast activation protein is also expressed in stroma of lymphoid tissue and tumors, the effect of PT-100 on tumor growth was studied in mice in vivo. PT-100 has no direct cytotoxic effect on tumors in vitro. Oral administration of PT-100 to mice slowed growth of syngeneic tumors derived from fibrosarcoma, lymphoma, melanoma, and mastocytoma cell lines. In WEHI 164 fibrosarcoma and EL4 and A20/2J lymphoma models, PT-100 caused regression and rejection of tumors. The antitumor effect appeared to involve tumor-specific CTL and protective immunological memory. PT-100 treatment of WEHI 164-inoculated mice increased mRNA expression of cytokines and chemokines known to promote T-cell priming and chemoattraction of T cells and innate effector cells. The role of innate activity was further implicated by observation of significant, although reduced, inhibition of WEHI 164 and A20/2J tumors in immunodeficient mice. PT-100 also demonstrated ability to augment antitumor activity of rituximab and trastuzumab in xenograft models of human CD20+ B-cell lymphoma and HER-2+ colon carcinoma where antibody-dependent cytotoxicity can be mediated by innate effector cells responsive to the cytokines and chemokines up-regulated by PT-100. Although CD26/DPP-IV is a potential target for PT-100 in the immune system, it appeared not to be involved because antitumor activity and stimulation of cytokine and chemokine production was undiminished in CD26−/− mice.
Disappearance of the Telomere Dysfunction-Induced Stress Response in Fully Senescent Cells
Authors: Bakkenist Christopher J. , Drissi Rachid , Wu Jing , Kastan Michael B. , Dome Jeffrey S.
Published: September 2005

Replicative senescence is a natural barrier to cellular proliferation that is triggered by telomere erosion and dysfunction. Here, we demonstrate that ATM activation and H2AX-γ nuclear focus formation are sensitive markers of telomere dysfunction in primary human fibroblasts. Whereas the activated form of ATM and H2AX-γ foci were rarely observed in early-passage cells, they were readily detected in late-passage cells. The ectopic expression of telomerase in late-passage cells abrogated ATM activation and H2AX-γ focus formation, suggesting that these stress responses were the consequence of telomere dysfunction. ATM activation was induced in quiescent fibroblasts by inhibition of TRF2 binding to telomeres, indicating that telomere uncapping is sufficient to initiate the telomere signaling response; breakage of chromosomes with telomeric associations is not required for this activation. Although ATM activation and H2AX-γ foci were readily observed in late-passage cells, they disappeared once cells became fully senescent, indicating that constitutive signaling from dysfunctional telomeres is not required for the maintenance of senescence.
Specific Recognition and Killing of Glioblastoma Multiforme by Interleukin 13-Zetakine Redirected Cytolytic T Cells
Authors: Kahlon Kanwarpal S. , Brown Christine , Cooper Laurence J. N. , Raubitschek Andrew , Forman Stephen J. , Jensen Michael C.
Published: September 2005

The interleukin (IL) 13 receptor α2 (IL13Rα2) is a glioma-restricted cell-surface epitope not otherwise detected within the central nervous system. Here, we describe a novel approach for targeting glioblastoma multiforme (GBM) with IL13Rα2-specific cytolytic T cells (CTLs) by their genetic modification to express a membrane-tethered IL13 cytokine chimeric T-cell antigen receptor, or zetakine. Our prototype zetakine incorporates an IL13 E13Y mutein for selective binding to IL13Rα2. Human IL13-zetakine+CD8+ CTL transfectants display IL13Rα2-specific antitumor effector function including tumor cell cytolysis, TC1 cytokine production, and zetakine-regulated autocrine proliferation. The E13Y amino acid substitution of the IL13 mutein of the zetakine endows CTL transfectants with the capacity to discriminate between IL13Rα2+ GBM targets from targets expressing IL13Rα1. In vivo, the adoptive transfer of IL13-zetakine+CD8+ CTL clones results in the regression of established human glioblastoma orthotopic xenografts. Pilot clinical trials have been initiated to evaluate the feasibility and safety of local-regional delivery of autologous IL13-zetakine redirected CTL clones in patients with recurrent GBM. Our IL13-zetakine is a prototype of a new class of chimeric immunoreceptors that signal through an engineered immune synapse composed of membrane-tethered cytokine muteins bound to cell-surface cytokine receptors on tumors.
Chromosome Transfer Induced Aneuploidy Results in Complex Dysregulation of the Cellular Transcriptome in Immortalized and Cancer Cells
Authors: Upender Madhvi B. , Habermann Jens K. , McShane Lisa M. , Korn Edward L. , Barrett J. Carl , Difilippantonio Michael J. , Ried Thomas
Published: September 2005

Chromosomal aneuploidies are observed in essentially all sporadic carcinomas. These aneuploidies result in tumor-specific patterns of genomic imbalances that are acquired early during tumorigenesis, continuously selected for and faithfully maintained in cancer cells. Although the paradigm of translocation induced oncogene activation in hematologic malignancies is firmly established, it is not known how genomic imbalances affect chromosome-specific gene expression patterns in particular and how chromosomal aneuploidy dysregulates the genetic equilibrium of cells in general. To model specific chromosomal aneuploidies in cancer cells and dissect the immediate consequences of genomic imbalances on the transcriptome, we generated artificial trisomies in a karyotypically stable diploid yet mismatch repair-deficient, colorectal cancer cell line and in telomerase immortalized, cytogenetically normal human breast epithelial cells using microcell-mediated chromosome transfer. The global consequences on gene expression levels were analyzed using cDNA arrays. Our results show that regardless of chromosome or cell type, chromosomal trisomies result in a significant increase in the average transcriptional activity of the trisomic chromosome. This increase affects the expression of numerous genes on other chromosomes as well. We therefore postulate that the genomic imbalances observed in cancer cells exert their effect through a complex pattern of transcriptional dysregulation.
Choline Kinase Activation Is a Critical Requirement for the Proliferation of Primary Human Mammary Epithelial Cells and Breast Tumor Progression
Authors: de Molina Ana Ramírez , Báñez-Coronel Mónica , Gutiérrez Ruth , Rodríguez-González Agustín , Olmeda David , Megías Diego , Lacal Juan Carlos
Published: September 2005

Breast cancer is still one of the most important tumors among women in industrialized countries. Improvement in both understanding the molecular events associated with the disease and the development of new additional treatments is still an important goal to be achieved. Choline kinase (ChoK) is increased in human mammary tumors with high incidence, and this activation is associated with clinical variable indicators of greater malignancy. Here, we have investigated the role of ChoK in the development of breast cancer and found that ChoK is both necessary and sufficient for growth factor-induced proliferation in primary human mammary epithelial cells and an absolute requirement for the specific mitogenic response to heregulin in breast tumor-derived cells. These results demonstrate that ChoK plays an essential role in both normal human mammary epithelial cell proliferation and breast tumor progression. Furthermore, inhibition of ChoK shows a strong in vivo antitumor activity against human breast cancer xenografts. Thus, ChoK constitutes a novel bona fide molecular target for the treatment of breast cancer patients.
Oncolytic Activity of p53-Expressing Conditionally Replicative Adenovirus AdΔ24-p53 against Human Malignant Glioma
Authors: Geoerger Birgit , Vassal Gilles , Opolon Paule , Dirven Clemens M. F. , Morizet Jackie , Laudani Lysiane , Grill Jacques , Giaccone Giuseppe , Vandertop W. Peter , Gerritsen Winald R. , van Beusechem Victor W.
Published: September 2005

Prognosis of malignant glioma is poor, and results of treatment remain mediocre. Conditionally replicative adenoviruses hold promise as alternative anticancer agents for the treatment of malignant glioma. Here, we evaluated the conditionally replicative adenovirus AdΔ24 and its recently developed derivative AdΔ24-p53, which expresses functional p53 tumor suppressor protein while replicating in cancer cells, for treatment of malignant glioma. In comparison to its parent AdΔ24, AdΔ24-p53 killed most malignant glioma cell lines and primary glioblastoma multiforme short-term cultures more effectively, irrespective of their p53 status. Moreover, AdΔ24-p53 caused more frequent regression and more delayed growth of IGRG121 xenografts derived from a glioblastoma multiforme in vivo. Five intratumoral injections of 107 pfu AdΔ24 gave 24 days median tumor growth delay (P < 0.01), 30% tumor regressions, and 30% animals surviving >120 days tumor-free or with a minimal tumor residual. The same dose of AdΔ24-p53 caused >113 days of median tumor growth delay (P < 0.001), 70% tumor regressions, and 60% animals surviving >120 days tumor-free or with a minimal tumor residual. Antitumor effects in vivo were associated with extensive conditionally replicative adenovirus replication, apoptosis induction, and tumor morphology changes, including dissociation, inflammatory cell infiltration, and necrosis. We conclude that conditionally replicative adenoviruses expressing p53 are promising new agents for treatment of malignant glioma.