bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitric Oxide and Ionizing Radiation Synergistically Promote Apoptosis and Growth Inhibition of Cancer by Activating p53
Authors: Cook Tracy , Wang Zifa , Alber Sean , Liu Kaihong , Watkins Simon C. , Vodovotz Yoram , Billiar Timothy R. , Blumberg David
Published: September 2005

Nitric oxide (NO) is a potent tumor radiosensitizer; however, its clinical use is limited by systemic side effects. We have demonstrated previously that gene transfer of the human inducible NO synthase (iNOS) gene into tumor cells and tumors induces high-output NO production that significantly enhances tumor radioresponsiveness, with no observed side effects. Notably, iNOS gene transfer enhances tumor radioresponsiveness via apoptotic cell death. Because NO and ionizing radiation are both known to promote p53-dependent apoptosis, we hypothesized that p53 activation might be a primary mechanism for the synergy of these two genotoxic stresses. We report that NO and ionizing radiation synergistically activate p53 in colorectal cancers grown in athymic mice by augmenting phosphorylation of p53 at serine 15. The effect of NO and ionizing radiation on tumor cell apoptosis and tumor radioresponsiveness is significantly reduced in p53 knockout isogenic cancer cell lines. Furthermore, the transfer of both p53 and iNOS genes into tumor cells lacking functional p53 enhanced their radioresponsiveness more than transfer of either gene alone.
Functional Analysis of the Contribution of RhoA and RhoC GTPases to Invasive Breast Carcinoma
Authors: Simpson Kaylene J. , Dugan Aisling S. , Mercurio Arthur M.
Published: September 2005

Although the RhoA and RhoC proteins comprise an important subset of the Rho GTPase family that have been implicated in invasive breast carcinomas, attributing specific functions to these individual members has been difficult. We have used a stable retroviral RNA interference approach to generate invasive breast carcinoma cells (SUM-159 cells) that lack either RhoA or RhoC expression. Analysis of these cells enabled us to deduce that RhoA impedes and RhoC stimulates invasion. Unexpectedly, this analysis also revealed a compensatory relationship between RhoA and RhoC at the level of both their expression and activation, and a reciprocal relationship between RhoA and Rac1 activation.
Bone Morphogenetic Protein (BMP)-6 Signaling and BMP Antagonist Noggin in Prostate Cancer
Authors: Haudenschild Dominik R. , Palmer Sabrina M. , Moseley Timothy A. , You Zongbing , Reddi A. Hari
Published: September 2005

It has been proposed that the osteoblastic nature of prostate cancer skeletal metastases is due in part to elevated activity of bone morphogenetic proteins (BMPs). BMPs are osteoinductive morphogens, and elevated expression of BMP-6 correlates with skeletal metastases of prostate cancer. In this study, we investigated the expression levels of BMPs and their modulators in prostate, using microarray analysis of cell cultures and gene expression. Addition of exogenous BMP-6 to DU-145 prostate cancer cell cultures inhibited their growth by up-regulation of several cyclin-dependent kinase inhibitors such as p21/CIP, p18, and p19. Expression of noggin, a BMP antagonist, was significantly up-regulated by BMP-6 by microarray analysis and was confirmed by quantitative reverse transcription-polymerase chain reaction and at the protein level. Noggin protein was present in prostate biopsies and localized to the epithelial components of prostate by immunohistochemistry. Recombinant noggin inhibited the function of BMP-6, suggesting a negative feedback regulation of BMP activity and indicating a strategy for the development of a novel therapeutic target in the treatment of painful osteosclerotic bone metastases of prostate cancer.
Immunological Prevention of a Multigene Cancer Syndrome
Authors: Croci Stefania , Nicoletti Giordano , Landuzzi Lorena , De Giovanni Carla , Astolfi Annalisa , Marini Chiara , Di Carlo Emma , Musiani Piero , Forni Guido , Nanni Patrizia , Lollini Pier-Luigi
Published: September 2005

Vaccines effectively prevent the onset of tumors in transgenic mice carrying activated oncogenes; however, human tumors are caused by combined alterations in oncogenes and oncosuppressor genes. We evaluated the impact of prophylactic vaccines in HER-2/neu transgenic, p53 wild-type/null mice that succumb to an aggressive cancer syndrome comprising mammary and salivary gland carcinomas and rhabdomyosarcoma. A vaccine made of allogeneic mammary carcinoma cells expressing HER-2/neu and interleukin 12 afforded long-term protection from tumor onset. Tumor prevention was mediated by T cell–derived cytokines, in particular γ-interferon, and by anti–HER-2/neu antibodies. HER-2/neu expression was inhibited in target tissues of vaccinated mice, and somatic loss of the wild-type p53 allele did not occur. A highly effective vaccine against a single oncoprotein induced a powerful immune response that arrested multistep carcinogenesis in distinct target tissues.
Head and Neck Cancer
Authors: Grandis Jennifer R. , Pietenpol Jennifer A. , Greenberger Joel S. , Pelroy Richard A. , Mohla Suresh
Published: September 2005

Head and neck squamous cell carcinoma (HNSCC) is the most common malignant neoplasm arising in the mucosa of the upper aerodigestive tract. Nearly two thirds of patients present with advanced (stage III and IV) disease. Fifty percent of HNSCC patients die of their disease, and 5% of HNSCC patients per year will develop additional second primary tumors. Currently used therapeutic modalities (surgery, radiation, and/or chemotherapy) have been associated with rather modest improvements in patient survival. The Head and Neck Cancer: Research and Therapeutic Opportunities Workshop (held in Washington, DC, May 24–26, 2004) was organized by the Division of Cancer Biology at the National Cancer Institute to identify research areas and directions that will advance understanding of HNSCC biology and accelerate clinical translation. The primary goal of the workshop was to identify the barriers that impede basic science discovery and the translation of these developments to the clinical setting. Over a 2.5-day period, experts in both HNSCC and other cancer-related fields met to identify and prioritize the key areas for future research. The overall consensus was that HNSCC is a relatively understudied malignancy and that investigations that focus on the biology of this tumor have the potential to impact significantly on the prevention and treatment of epithelial malignancies. The chief objective is to communicate these research goals to the cancer biology community and encourage more interest in HNSCC as a tumor model to test translational research hypotheses.
Increased Insulin-Like Growth Factor I Receptor Expression and Signaling Are Components of Androgen-Independent Progression in a Lineage-Derived Prostate Cancer Progression Model
Authors: Krueckl Sandra L. , Sikes Robert A. , Edlund N. Magnus , Bell Robert H. , Hurtado-Coll Antonio , Fazli Ladan , Gleave Martin E. , Cox Michael E.
Published: September 2005

Apoptosis and inhibition of mitosis are primary mechanisms mediating androgen ablation therapy-induced regression of prostate cancer (PCa). However, PCa readily becomes androgen independent, leading to fatal disease. Up-regulated growth and survival signaling is implicated in development of resistance to androgen ablation therapy. We are testing the hypothesis that insulin-like growth factor (IGF) responsiveness is required for androgen-independent (AI) progression. Using the LNCaP human PCa progression model, we have determined that IGF-I–mediated protection from apoptotic stress and enhanced mitotic activity is androgen dependent in LNCaP cells but is androgen independent in lineage-derived C4-2 cells. Both cell lines exhibit androgen-responsive patterns of IGF-I receptor (IGF-IR) expression, activation, and signaling to insulin receptor substrate-2 and AKT. However, C4-2 cells express higher levels of IGF-IR mRNA and protein and exhibit enhanced IGF-I–mediated phosphorylation and downstream signaling under androgen-deprived conditions. In comparisons of naïve and AI metastatic human PCa specimens, we have confirmed that IGF-IR levels are elevated in advanced disease. Together with our LNCaP/C4-2 AI progression model data, these results indicate that increased IGF-IR expression is associated with AI antiapoptotic and promitotic IGF signaling in PCa disease progression.
Spontaneous Regression of Grade 3 Vulvar Intraepithelial Neoplasia Associated with Human Papillomavirus-16–Specific CD4+ and CD8+ T-Cell Responses
Authors: Villada Isabelle Bourgault , Barracco Micheline Moyal , Ziol Marianne , Chaboissier Aude , Barget Nathalie , Berville Sophie , Paniel Bernard , Jullian Eric , Clerici Thierry , Maillère Bernard , Guillet Jean Gérard
Published: September 2005

Cell-mediated immunity directed against human papillomavirus 16 (HPV-16) antigens was studied in six patients affected with grade 3 vulvar intraepithelial neoplasia (VIN3, also known as bowenoid papulosis). Five of the patients presented with a chronic and persistent disease that relapsed after destructive treatments. They showed no detectable anti-HPV blood T-cell responses and no T-cell intraepidermal vulvar infiltrate containing both CD4+ and CD8+ lymphocytes. The last patient had a complete clearance of viral lesions, 8 months after disease onset and 2 months after electrocoagulation of <50% of the VIN3 lesions. She showed high frequency anti-E6 and anti-E7 effector blood T cells by ex vivo ELISpot-IFNγ assay before clinical regression. Immunohistochemical study of her vulvar biopsy revealed a marked dermal infiltrate containing a majority of CD4+ T lymphocytes and an epidermal infiltrate made up of both CD4+ and CD8+ T cells. This seems to be the first evidence of an association between spontaneous regression of VIN3 lesions and HPV-specific T-cell responses detectable in the blood. Hence, an increase of HPV-specific effector T lymphocyte responses by vaccine-based therapeutic strategies might be useful to clear the lesions in bowenoid papulosis disease.
Survivin Deregulation in β-Tubulin Mutant Ovarian Cancer Cells Underlies Their Compromised Mitotic Response to Taxol
Authors: Zhou Jun , O’Brate Aurora , Zelnak Amelia , Giannakakou Paraskevi
Published: September 2005

Taxol is one of the most successful drugs for the treatment of cancer because of its ability to target tubulin, block cell cycle progression at mitosis, and induce apoptosis. Despite the success of Taxol, the development of drug resistance hampers its clinical applicability. Herein we report that β-tubulin mutant, Taxol-resistant ovarian cancer cells exhibit defective mitotic response to Taxol, even at high concentrations that are sufficient to trigger apoptosis. This mitotic response-defective phenotype is independent of p53 status. We have found that survivin, the mitosis regulator and inhibitor of apoptosis protein, is deregulated in these Taxol-resistant cancer cells; Taxol fails to induce survivin levels and survivin phosphorylation in these cells, in contrast to their parental drug-sensitive counterparts. Exogenous expression of wild-type survivin is able to restore the mitotic response of the resistant cells to Taxol treatment. On the other hand, exogenous expression of dominant-negative survivin abrogates the Taxol-induced mitotic response in drug-sensitive cancer cells. We have also found that overexpression of the mitotic kinase Cdk1, which phosphorylates survivin, is unable to restore the Taxol-induced mitotic response in the resistant cells. Our results show the importance of survivin for the mitotic response in the context of Taxol resistance and provide novel insights into the mechanisms of mitotic arrest and apoptosis induced by microtubule-targeting agents.
Nanoparticle-Aptamer Bioconjugates
Authors: Farokhzad Omid C. , Jon Sangyong , Khademhosseini Ali , Tran Thanh-Nga T. , LaVan David A. , Langer Robert
Published: September 2005

Nucleic acid ligands (aptamers) are potentially well suited for the therapeutic targeting of drug encapsulated controlled release polymer particles in a cell- or tissue-specific manner. We synthesized a bioconjugate composed of controlled release polymer nanoparticles and aptamers and examined its efficacy for targeted delivery to prostate cancer cells. Specifically, we synthesized poly(lactic acid)-block-polyethylene glycol (PEG) copolymer with a terminal carboxylic acid functional group (PLA-PEG-COOH), and encapsulated rhodamine-labeled dextran (as a model drug) within PLA-PEG-COOH nanoparticles. These nanoparticles have the following desirable characteristics: (a) negative surface charge (−50 ± 3 mV, mean ± SD, n = 3), which may minimize nonspecific interaction with the negatively charged nucleic acid aptamers; (b) carboxylic acid groups on the particle surface for potential modification and covalent conjugation to amine-modified aptamers; and (c) presence of PEG on particle surface, which enhances circulating half-life while contributing to decreased uptake in nontargeted cells. Next, we generated nanoparticle-aptamer bioconjugates with RNA aptamers that bind to the prostate-specific membrane antigen, a well-known prostate cancer tumor marker that is overexpressed on prostate acinar epithelial cells. We demonstrated that these bioconjugates can efficiently target and get taken up by the prostate LNCaP epithelial cells, which express the prostate-specific membrane antigen protein (77-fold increase in binding versus control, n = 150 cells per group). In contrast to LNCaP cells, the uptake of these particles is not enhanced in cells that do not express the prostate-specific membrane antigen protein. To our knowledge, this represents the first report of targeted drug delivery with nanoparticle-aptamer bioconjugates.
Loss of Heterozygosity of Chromosome 3p21 Is Associated with Mutant
TP53
and Better Patient Survival in Non–Small-Cell Lung Cancer
Authors: Marsit Carmen J. , Hasegawa Masayuki , Hirao Tomoko , Kim Duk-Hwan , Aldape Kenneth , Hinds Philip W. , Wiencke John K. , Nelson Heather H. , Kelsey Karl T.
Published: September 2005

Allelic loss of chromosome region 3p21.3 occurs early and frequently in non–small-cell lung cancer, and numerous tumor suppressor genes at this locus may be targets of inactivation. Using an incident case series study of non–small-cell lung cancer, we sought to determine the prevalence of loss of heterozygosity (LOH) in the 3p21.3 region and to examine the associations between this alteration and patient outcome, exposure to tobacco smoke, occupational asbestos exposure, and additional molecular alterations in these tumors. We examined LOH at 7 microsatellite markers in the chromosome 3p21.3 region, and LOH was present in at least one of the loci examined in 60% (156 of 258) of the tumors, with the prevalence of LOH at individual loci ranging from 15 to 56%. Occupational asbestos exposure and TP53 mutation were significantly associated with more extensive 3p21 LOH. In squamous cell carcinomas, measures of cumulative smoking dose were significantly lower in patients with LOH at 3p21, particularly in TP53 mutant tumors. Examining patient outcome, we found that in squamous cell carcinomas, having any LOH in this region was associated with a better overall survival (log-rank test, P < 0.04). Together, these results indicate that allelic loss at 3p21 can affect patient outcome, and that this loss may initially be related to carcinogen exposure, but that extension of this loss is related to TP53 mutation status and occupational asbestos exposure.
The Prosurvival Activity of p53 Protects Cells from UV-Induced Apoptosis by Inhibiting c-Jun NH2-terminal Kinase Activity and Mitochondrial Death Signaling
Authors: Lo Pang-Kuo , Huang Sheng-Zhu , Chen Hsiang-Chin , Wang Fung-Fang
Published: September 2005

The cytoprotective function of p53 recently has been exploited as a therapeutic advantage for cancer prevention; agents activating the prosurvival activity of p53 are shown to prevent UV-induced damages. To explore the mechanisms of p53-mediated protection from UV-induced apoptosis, we have established stable clones of H1299 lung carcinoma cells expressing a temperature-sensitive p53 mutant, tsp53V143A. At the permissive temperature of 32°C, the tsp53V143A-expressing cells were arrested in G1 phase without the occurrence of apoptosis; consistent with this is the preferential induction of genes related to growth arrest and DNA damage repair. Previous expression of functional tsp53V143A for ≥18 hours inhibited the release of proapoptotic molecules from mitochondria and protected the cells from UV-induced apoptosis; moreover, it suppressed the activation of c-Jun NH2-terminal kinase (JNK) signaling and relieved the effect of UV on p53 target gene activation. p53 associated with JNK and inhibited its kinase activity. Using the p53-null H1299 cells, we showed that inhibition of JNK blocked the UV-elicited mitochondrial death signaling and caspase activation. Our results suggest that the ability of p53 to bind and inactivate JNK, together with the activation of the p53 target genes related to cell cycle arrest and DNA damage repair, is responsible for its protection of cells against UV-induced apoptosis.
COP1, the Negative Regulator of p53, Is Overexpressed in Breast and Ovarian Adenocarcinomas
Authors: Dornan David , Bheddah Sheila , Newton Kim , Ince William , Frantz Gretchen D. , Dowd Patrick , Koeppen Hartmut , Dixit Vishva M. , French Dorothy M.
Published: September 2005

The tumor suppressor protein p53 plays a central role in protecting normal cells from undergoing transformation. Thus, it is fitting that cancer cells selectively dampen the p53 response to gain a selective growth advantage. In fact, the p53 gene is the most commonly mutated tumor suppressor gene in human cancers, and if the gene is not mutated, then other components of the p53 pathways are skewed to dampen the p53 response to stress. We recently identified COP1 as a novel and critical negative regulator of p53. COP1 is a RING finger-containing protein that targets p53 for degradation to the proteasome and is necessary for p53 turnover in normal and cancer cells. However, the association between COP1 and cancer remains to be determined. We performed expression analysis of COP1 in ovarian and breast cancer tissue microarrays. COP1 is significantly overexpressed in 81% (25 of 32) of breast and 44% (76 of 171) of ovarian adenocarcinoma as assessed by in situ hybridization and immunohistochemistry. Overexpression of COP1 correlated with a striking decrease in steady state p53 protein levels and attenuation of the downstream target gene, p21, in cancers that retain a wild-type p53 gene status. Overall, these results suggest that overexpression of COP1 contributes to the accelerated degradation of p53 protein in cancers and attenuates the tumor suppressor function of p53.
Conditional Expression of K-
ras
in an Epithelial Compartment that Includes the Stem Cells Is Sufficient to Promote Squamous Cell Carcinogenesis
Authors: Vitale-Cross Lynn , Amornphimoltham Panomwat , Fisher Galen , Molinolo Alfredo A. , Gutkind J. Silvio
Published: September 2005

Ras genes are the most frequently mutated oncogenes in human cancer. However, the contribution of ras to tumor initiation still is unclear because ras expression in primary cells can cause cell cycle arrest and even cell death by apoptosis. Furthermore, when expressed in the epidermis of mice, mutant ras promotes the formation of benign papillomas, only few of which will progress into carcinomas. However, in these cases, ras-transgene expression often is restricted to suprabasal or follicular epithelial cells that may lack self-renewal capacity. Thus, it still is conceivable that expression of active ras in other epithelial compartments may exert a distinct ability to promote malignant progression. To address this possibility, transgenic mice carrying the tetracycline-inducible system (tet-on receptor) targeted to the basal layer of stratified epithelium, which includes the epithelial stem cells, were engineered and crossed with mice expressing the K-rasG12D oncogene under the control of tet-regulated responsive elements. On doxycycline administration, proliferative lesions ranging from hyperplasias, papillomas, and dysplasias to metastatic carcinomas developed in squamous epithelia of the skin, oral mucosa, salivary glands, tongue, esophagus, forestomach, and uterine cervix within just 10 to 20 days. The most noticeable lesions were invasive squamous carcinomas of the skin and oral mucosa. These findings suggest that the expression of oncogenes in an epithelial compartment that includes the stem cells may be sufficient to promote squamous carcinogenesis. They also provide a molecularly defined conditional animal model system in which the mechanisms responsible for cancer initiation, maintenance, and metastatic spread can be readily investigated.
Sixteenth Annual Pezcoller Symposium
Authors: Mihich Enrico , Jaenisch Rudolf
Published: September 2005

In the postgenomic era of cancer biology, it is becoming increasingly evident that epigenetic controls of gene expression play an important role in determining the phenotype of cancer cells, also indicating the possibility of restoring epigenetically a normal phenotype in cancer cells. Related to these mechanisms of control and their dynamic changes during carcinogenesis and tumor progression are the phenomena determining the relationships between stem cells and cancer cells. This symposium focused on epigenetic mechanisms affecting cancer development and possibly providing a basis for intervention. The basic biology of stem cells and the relationships between stem cells and cancer were discussed. Epigenetic control mechanisms affecting gene expression with emphasis on DNA methylation and histone function were considered. Therapeutic strategies stemming from the knowledge acquired in the basic topics discussed also were outlined.
2-(8-Hydroxy-6-methoxy-1-oxo-1Η-2-benzopyran-3-yl)propionic Acid, a Small Molecule Isocoumarin, Potentiates Dexamethasone-Induced Apoptosis of Human Multiple Myeloma Cells
Authors: Agata Naoki , Nogi Hiroko , Milhollen Michael , Kharbanda Surender , Kufe Donald
Published: September 2005

2-(8-Hydroxy-6-methoxy-1-oxo-1Η-2-benzopyran-3-yl)propionic acid (NM-3) is a small molecule isocoumarin derivative that has recently entered clinical trials as an orally bioavailable anticancer agent. NM-3 induces lethality of human carcinoma cells by both apoptotic and nonapoptotic mechanisms and potentiates the effects of cytotoxic chemotherapeutic agents. The present studies have evaluated the effects of NM-3 on human multiple myeloma (MM) cells. The results demonstrate that NM-3 potentiates dexamethasone-induced killing of both dexamethasone-sensitive MM1.S and dexamethasone-resistant RPMI8226 and U266 MM cells. We show that NM-3 enhances dexamethasone-induced release of the mitochondrial apoptogenic factors cytochrome c and Smac/DIABLO. The results also demonstrate that NM-3 enhances dexamethasone-induced activation of the intrinsic caspase-9->caspase-3 apoptotic pathway. In concert with these results, NM-3 potentiates dexamethasone-induced apoptosis of MM1.S cells. Moreover, NM-3 acts synergistically with dexamethasone in inducing apoptosis of the dexamethasone-resistant RPMI8226 and U266 MM cells. These findings indicate that NM-3 may be effective in combination with dexamethasone in the treatment of MM.
Phosphorylation of the Eukaryotic Translation Initiation Factor eIF4E Contributes to Its Transformation and mRNA Transport Activities
Authors: Topisirovic Ivan , Ruiz-Gutierrez Melisa , Borden Katherine L. B.
Published: September 2005

The eukaryotic translation initiation factor eIF4E is dysregulated in a wide variety of human cancers. In the cytoplasm, eIF4E acts in the rate-limiting step of translation initiation whereas in the nucleus, eIF4E forms nuclear bodies and promotes the nucleo-cytoplasmic export of a subset of growth-promoting mRNAs including cyclin D1. The only known post-translational modification of eIF4E is its phosphorylation at S209. Many studies have examined the role of phosphorylation on cap-dependent translation. However, no studies to date have explored the role of phosphorylation on the ability of eIF4E to transform cells. Using mutagenesis and separately a small molecular inhibitor of eIF4E phosphorylation, we show that eIF4E phosphorylation enhances both its mRNA transport function and its transformation activity in cell culture. Thus, phosphorylation of nuclear eIF4E seems to be an important step in control of the mRNA transport and thus the transforming properties of eIF4E.
Gene Expression Profiling for Molecular Characterization of Inflammatory Breast Cancer and Prediction of Response to Chemotherapy
Authors: Bertucci François , Finetti Pascal , Rougemont Jacques , Charafe-Jauffret Emmanuelle , Nasser Valéry , Loriod Béatrice , Camerlo Jacques , Tagett Rebecca , Tarpin Carole , Houvenaeghel Gilles , Nguyen Catherine , Maraninchi Dominique , Jacquemier Jocelyne , Houlgatte Rémi , Birnbaum Daniel , Viens Patrice
Published: September 2005

Inflammatory breast cancer (IBC) is a rare but aggressive form of breast cancer with a 5-year survival limited to ∼40%. Diagnosis, based on clinical and/or pathological criteria, may be difficult. Optimal systemic neoadjuvant therapy and accurate predictors of pathological response have yet to be defined for increasing response rate and survival. Using DNA microarrrays containing ∼8,000 genes, we profiled breast cancer samples from 81 patients, including 37 with IBC and 44 with noninflammatory breast cancer (NIBC). Global unsupervised hierarchical clustering was able to some extent to distinguish IBC and NIBC cases and revealed subclasses of IBC. Supervised analysis identified a 109-gene set the expression of which discriminated IBC from NIBC samples. This molecular signature was validated in an independent series of 26 samples, with an overall performance accuracy of 85%. Discriminator genes were associated with various cellular processes possibly related to the aggressiveness of IBC, including signal transduction, cell motility, adhesion, and angiogenesis. A similar approach, with leave-one-out cross-validation, identified an 85-gene set that divided IBC patients with significantly different pathological complete response rate (70% in one group and 0% in the other group). These results show the potential of gene expression profiling to contribute to a better understanding of IBC, and to provide new diagnostic and predictive factors for IBC, as well as for potential therapeutic targets.
Identification of a Binding Partner for the Endothelial Cell Surface Proteins TEM7 and TEM7R
Authors: Nanda Akash , Buckhaults Phillip , Seaman Steven , Agrawal Nishant , Boutin Paula , Shankara Srinivas , Nacht Mariana , Teicher Beverly , Stampfl Jason , Singh Sujay , Vogelstein Bert , Kinzler Kenneth W. , St. Croix Brad
Published: September 2005

Tumor endothelial marker 7 (TEM7) was recently identified as an mRNA transcript overexpressed in the blood vessels of human solid tumors. Here, we identify several new variants of TEM7, derived by alternative splicing, that are predicted to be intracellular (TEM7-I), secreted (TEM7-S), or on the cell surface membrane (TEM7-M) of tumor endothelium. Using new antibodies against the TEM7 protein, we confirmed the predicted expression of TEM7 on the cell surface and demonstrated that TEM7-M protein, like its mRNA, is overexpressed on the endothelium of various tumor types. We then used an affinity purification strategy to search for TEM7-binding proteins and identified cortactin as a protein capable of binding to the extracellular region of both TEM7 and its closest homologue, TEM7-related (TEM7R), which is also expressed in tumor endothelium. The binding domain of cortactin was mapped to a unique nine-amino acid region in its plexin-like domain. These studies establish the overexpression of TEM7 protein in tumor endothelium and provide new opportunities for the delivery of therapeutic and imaging agents to the vessels of solid tumors.
Synergistic Interaction between Sphingomyelin and Gemcitabine Potentiates Ceramide-Mediated Apoptosis in Pancreatic Cancer
Authors: Modrak David E. , Cardillo Thomas M. , Newsome Guy A. , Goldenberg David M. , Gold David V.
Published: September 2005

We have examined the mechanism by which sphingomyelin (SM) enhances chemotherapy in human pancreatic cancer cells, focusing on the correlation between ceramide metabolism and apoptosis. Dose response curves for gemcitabine in the absence or presence of 0.2 mg/mL SM provided IC50 values of 78.3 ± 13.7 and 13.0 ± 3.0 nmol/L, respectively. The cytotoxic effect of the combined treatment was synergistic (combination index = 0.36). Using annexin-V staining, the percentage of apoptotic cells was 3.6 ± 2.6% for the untreated cells, 6.5 ± 3.8% for the 0.2 mg/mL SM-treated cells, and 19.9 ± 12.9% for the 100 nmol/L gemcitabine-treated cells, but increased significantly to 42.1 ± 12.7% with the combined treatment (P < 0.001, compared with gemcitabine-treated group). The percentage of cells losing mitochondrial membrane potential followed a similar trend. The ceramide content of untreated and gemcitabine-treated cells was not significantly different (0.46 ± 0.29 and 0.59 ± 0.34 pmol ceramide/nmole PO4). However, when 0.2 mg/mL SM was added, ceramide levels were 1.09 ± 0.42 and 1.58 ± 0.55 pmol ceramide/nmol PO4, for the SM alone and SM with gemcitabine-treated cells, respectively (P = 0.038). Acidic SMase was activated by exposure to gemcitabine but not SM, whereas the activities of neutral SMase and glycosylceramide synthase did not change with either gemcitabine or SM. The data are consistent with gemcitabine-induced activation of acidic SMase and indicate that the addition of SM can yield increased production of ceramide, mitochondrial depolarization, apoptosis, and cell death. Because SM by itself is relatively nontoxic, addition of this lipid to agents that induce apoptosis may prove useful to enhance apoptosis and increase cytotoxicity in cancer cells.
Transgenic Nude Mouse with Ubiquitous Green Fluorescent Protein Expression as a Host for Human Tumors
Authors: Yang Meng , Reynoso Jose , Jiang Ping , Li Lingna , Moossa Abdool R. , Hoffman Robert M.
Published: September 2005

We report here the development of the transgenic green fluorescent protein (GFP) nude mouse with ubiquitous GFP expression. The GFP nude mouse was obtained by crossing nontransgenic nude mice with the transgenic C57/B6 mouse in which the β-actin promoter drives GFP expression in essentially all tissues. In crosses between nu/nu GFP male mice and nu/+ GFP female mice, the embryos fluoresced green. Approximately 50% of the offspring of these mice were GFP nude mice. Newborn mice and adult mice fluoresced very bright green and could be detected with a simple blue–light-emitting diode flashlight with a central peak of 470 nm and a bypass emission filter. In the adult mice, the organs all brightly expressed GFP, including the heart, lungs, spleen, pancreas, esophagus, stomach, and duodenum. The following systems were dissected out and shown to have brilliant GFP fluorescence: the entire digestive system from tongue to anus; the male and female reproductive systems; brain and spinal cord; and the circulatory system, including the heart and major arteries and veins. The skinned skeleton highly expressed GFP. Pancreatic islets showed GFP fluorescence. The spleen cells were also GFP positive. Red fluorescent protein (RFP)–expressing human cancer cell lines, including PC-3-RFP prostate cancer, HCT-116-RFP colon cancer, MDA-MB-435-RFP breast cancer, and HT1080-RFP fibrosarcoma were transplanted to the transgenic GFP nude mice. All of these human tumors grew extensively in the transgenic GFP nude mouse. Dual-color fluorescence imaging enabled visualization of human tumor–host interaction by whole-body imaging and at the cellular level in fresh and frozen tissues. The GFP mouse model should greatly expand our knowledge of human tumor–host interaction.
2-Arachidonoylglycerol
Authors: Nithipatikom Kasem , Endsley Michael P. , Isbell Marilyn A. , Falck John R. , Iwamoto Yoshiki , Hillard Cecilia J. , Campbell William B.
Published: September 2005

Endocannabinoids have been implicated in cancer. Increasing endogenous 2-arachidonoylglycerol (2-AG) by blocking its metabolism inhibits invasion of androgen-independent prostate cancer (PC-3 and DU-145) cells. Noladin ether (a stable 2-AG analog) and exogenous CB1 receptor agonists possess similar effects. Conversely, reducing endogenous 2-AG by inhibiting its synthesis or blocking its binding to CB1 receptors with antagonists increases the cell invasion. 2-AG and noladin ether decrease protein kinase A activity in these cells, indicating coupling of the CB1 receptor to downstream effectors. The results suggest that cellular 2-AG, acting through the CB1 receptor, is an endogenous inhibitor of invasive prostate cancer cells.
S179D Prolactin Increases Vitamin D Receptor and p21 through Up-regulation of Short 1b Prolactin Receptor in Human Prostate Cancer Cells
Authors: Wu Wei , Ginsburg Erika , Vonderhaar Barbara K. , Walker Ameae M.
Published: September 2005

In this study, we further investigated the mechanisms by which pseudophosphorylated prolactin (S179D PRL) inhibits the growth of human prostate cancer cells. When treated with S179D PRL for 3 days, LnCAP cells responded by increasing expression of the vitamin D receptor (VDR) and the cell cycle regulatory molecule, p21, whereas PC3 and DU145 cells did not. After 5 days of treatment, both PC3 and DU145 cells responded. Untreated LnCAP cells express the short 1b form (SF1b) of the human prolactin receptor, but DU145 and PC3 cells express only low amounts of this receptor until elevated by treatment with S179D PRL. DU145 and PC3 cells become sensitive to the negative effects of S179D PRL on cell number after induction of the SF1b. Transfection of either SF1b or SF1a into PC3 or DU145 cells made them sensitive to S179D PRL in the 3-day time frame, a finding that was not duplicated by transfection with the long form of the receptor. Treatment of LnCAP cells with S179D PRL increased long-term activation of extracellular signal-regulated kinase 1/2 (ERK1/2). This did not occur in PC3 and DU145 cells until transfection with SF1a/SF1b. Blockade of ERK signaling eliminated S179D PRL-stimulated expression of the VDR and p21 in LnCAP cells and transfected PC3 and DU145 cells. We conclude that initiation of alternative splicing to produce SF1b, and subsequent altered signaling, contribute to the growth inhibitory mechanisms of S179D PRL. This is the first indication of a role for short prolactin receptors in the regulation of cell proliferation.
Combined Immunostimulation and Conditional Cytotoxic Gene Therapy Provide Long-term Survival in a Large Glioma Model
Authors: Ali Sumia , King Gwendalyn D. , Curtin James F. , Candolfi Marianela , Xiong Weidong , Liu Chunyan , Puntel Mariana , Cheng Queng , Prieto Jesus , Ribas Antoni , Kupiec-Weglinski Jerzy , van Rooijen Nico , Lassmann Hans , Lowenstein Pedro R. , Castro Maria G.
Published: September 2005

In spite of preclinical efficacy and recent randomized, controlled studies with adenoviral vectors expressing herpes simplex virus-1 thymidine kinase (HSV1-TK) showing statistically significant increases in survival, most clinical trials using single therapies have failed to provide major therapeutic breakthroughs. Because glioma is a disease with dismal prognosis and rapid progression, it is an attractive target for gene therapy. Preclinical models using microscopic brain tumor models (e.g., ≤0.3 mm3) may not reflect the pathophysiology and progression of large human tumors. To overcome some of these limitations, we developed a syngeneic large brain tumor model. In this model, administration of single therapeutic modalities, either conditional cytotoxicity or immunostimulation, fail. However, when various immunostimulatory therapies were delivered in combination with conditional cytotoxicity (HSV1-TK), only the combined delivery of fms-like tyrosine kinase ligand (Flt3L) and HSV1-TK significantly prolonged the survival of large tumor-bearing animals (≥80%; P ≤ 0.005). When either macrophages or CD4+ cells were depleted before administration of viral therapy, TK + Flt3L therapy failed to prolong survival. Meanwhile, depletion of CD8+ cells or natural killer cells did not affect TK + Flt3L efficacy. Spinal cord of animals surviving 6 months after TK + Flt3L were evaluated for the presence of autoimmune lesions. Whereas macrophages were present within the corticospinal tract and low levels of T-cell infiltration were detected, these effects are not indicative of an overt autoimmune disorder. We propose that combined Flt3L and HSV1-TK adenoviral-mediated gene therapy may provide an effective antiglioma treatment with increased efficacy in clinical trials of glioma.
Down-Regulation of Regulatory Subunit Type 1A of Protein Kinase A Leads to Endocrine and Other Tumors
Authors: Griffin Kurt J. , Kirschner Lawrence S. , Matyakhina Ludmila , Stergiopoulos Sotirios , Robinson-White Audrey , Lenherr Sara , Weinberg Frank D. , Claflin Edward , Meoli Elise , Cho-Chung Yoon S. , Stratakis Constantine A.
Published: September 2005

Mutations of the human type Iα regulatory subunit (RIα) of cyclic AMP-dependent protein kinase (PKA; PRKAR1A) lead to altered kinase activity, primary pigmented nodular adrenocortical disease, and tumors of the thyroid and other tissues. To bypass the early embryonic lethality of Prkar1a−/− mice, we established transgenic mice carrying an antisense transgene for Prkar1a exon 2 (X2AS) under the control of a tetracycline-responsive promoter. Down-regulation of Prkar1a by up to 70% was achieved in transgenic mouse tissues and embryonic fibroblasts, with concomitant changes in kinase activity and increased cell proliferation, respectively. Mice developed thyroid follicular hyperplasia and adenomas, adrenocortical hyperplasia, and other features reminiscent of primary pigmented nodular adrenocortical disease, histiocytic and epithelial hyperplasias, lymphomas, and other mesenchymal tumors. These were associated with allelic losses of the mouse chromosome 11 Prkar1a locus, an increase in total type II PKA activity, and higher RIIβ protein levels. This mouse provides a novel, useful tool for the investigation of cyclic AMP, RIα, and PKA functions and confirms the critical role of Prkar1a in tumorigenesis in endocrine and other tissues.
Telomerase-Dependent Virotherapy Overcomes Resistance of Hepatocellular Carcinomas against Chemotherapy and Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand by Elimination of Mcl-1
Authors: Wirth Thomas , Kühnel Florian , Fleischmann-Mundt Bettina , Woller Norman , Djojosubroto Meta , Rudolph Karl Lenhard , Manns Michael , Zender Lars , Kubicka Stefan
Published: September 2005

Hepatocellular carcinomas (HCC) are drug-resistant tumors that frequently possess high telomerase activity. It was therefore the aim of our study to investigate the potential of telomerase-dependent virotherapy in multimodal treatment of HCC. In contrast to normal liver, HCC xenografts showed high telomerase activity, resulting in tumor-restricted expression of E1A by a telomerase-dependent replicating adenovirus (hTERT-Ad). Neither tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) or chemotherapy alone nor the combined treatment with both agents resulted in significant destruction of HCC cells. Application of hTERT-Ad at low titers was also not capable to destroy HCC cells, but telomerase-dependent virotherapy overcame the resistance of HCC against TRAIL and chemotherapy. The synergistic effects are explained by a strong down-regulation of Mcl-1 expression through hTERT-Ad that sensitizes HCC for TRAIL- and chemotherapy-mediated apoptosis. To investigate whether down-regulation of Mcl-1 alone is sufficient to explain synergistic effects observed with virotherapy, Mcl-1 expression was inhibited by RNA interference. Treatment with Mcl-1-siRNA significantly enhanced caspase-3 activity after chemotherapy and TRAIL application, confirming that elimination of Mcl-1 is responsible for the drug sensitization by hTERT-Ad. Consistent with these results, heterologous overexpression of Mcl-1 significantly reduced the sensitization of hTERT-Ad transduced cells against apoptosis-inducing agents. Chemotherapy did not interfere with quantitative hTERT-Ad production in HCC cells. Whereas hTERT-Ad virotherapy alone was only capable to inhibit the growth of Hep3B xenografts, virochemotherapy resulted in vast destruction of the drug-resistant HCC. In conclusion our data indicate that telomerase-dependent virotherapy is an attractive strategy to overcome the natural resistance of HCC against anticancer drugs by elimination of Mcl-1.
Immortalization of Human Bronchial Epithelial Cells in the Absence of Viral Oncoproteins
Authors: Ramirez Ruben D. , Sheridan Shelley , Girard Luc , Sato Mitsuo , Kim Young , Pollack Jon , Peyton Michael , Zou Ying , Kurie Jonathan M. , DiMaio J. Michael , Milchgrub Sara , Smith Alice L. , Souza Rhonda F. , Gilbey Laura , Zhang Xi , Gandia Kenia , Vaughan Melville B. , Wright Woodring E. , Gazdar Adi F. , Shay Jerry W. , Minna John D.
Published: September 2005

By expressing two genes (hTERT and Cdk4), we have developed a method to reproducibly generate continuously replicating human bronchial epithelial cell (HBEC) lines that provide a novel resource to study the molecular pathogenesis of lung cancer and the differentiation of bronchial epithelial cells. Twelve human bronchial epithelial biopsy specimens obtained from persons with and without lung cancer were placed into short-term culture and serially transfected with retroviral constructs containing cyclin-dependent kinase (Cdk) 4 and human telomerase reverse transcriptase (hTERT), resulting in continuously growing cultures. The order of introduction of Cdk4 and hTERT did not appear to be important; however, transfection of either gene alone did not result in immortalization. Although they could be cloned, the immortalized bronchial cells did not form colonies in soft agar or tumors in nude mice. The immortalized HBECs have epithelial morphology; express epithelial markers cytokeratins 7, 14, 17, and 19, the stem cell marker p63, and high levels of p16INK4a; and have an intact p53 checkpoint pathway. Cytogenetic analysis and array comparative genomic hybridization profiling show immortalized HBECs to have duplication of parts of chromosomes 5 and 20. Microarray gene expression profiling demonstrates that the Cdk4/hTERT-immortalized bronchial cell lines clustered together and with nonimmortalized bronchial cells, distinct from lung cancer cell lines. We also immortalized several parental cultures with viral oncoproteins human papilloma virus type 16 E6/E7 with and without hTERT, and these cells exhibited loss of the p53 checkpoint and significantly different gene expression profiles compared with Cdk4/hTERT-immortalized HBECs. These HBEC lines are a valuable new tool for studying of the pathogenesis of lung cancer.
Cyclophosphamide Inhibition of Anti-CD40 Monoclonal Antibody–Based Therapy of B Cell Lymphoma Is Dependent on CD11b+ Cells
Authors: Honeychurch Jamie , Glennie Martin J. , Illidge Timothy M.
Published: September 2005

Monoclonal antibody (mAb)–based immunotherapy is now established as an important option for treating some cancers. The antitumor effects may be further enhanced by combining mAb with conventional chemotherapy. Certain novel immunomodulatory mAbs such as anti-CD40 have shown significant activity in preclinical models. We therefore assessed the efficacy of combining anti-CD40 mAb, known to elicit CTL responses against murine lymphoma models with the commonly used cytotoxic drug, cyclophosphamide. Using the syngeneic tumor model, BCL1, we have shown that timing of cyclophosphamide relative to mAb is critical to therapeutic outcome. Pretreatment with cyclophosphamide 7 to 10 days prior to mAb results in markedly reduced survival levels, similar to that achieved with cyclophosphamide alone. Conversely, when anti-CD40 is given before cyclophosphamide, the level of tumor protection was moderately increased. In vivo tracking experiments reveal that pretreatment with cyclophosphamide leads to diminished CTL expansion, as well as an increased number of CD11b+ cells that display an activated phenotype. These latter cells are able to inhibit T-cell proliferation, at least in part via production of nitric oxide, but do not induce T-cell apoptosis. Furthermore, adoptive transfer of the induced CD11b+ cells is sufficient to inhibit anti-CD40 therapy in tumor-bearing recipients. We have shown that the timing of cyclophosphamide relative to mAb administration is critical to the therapeutic outcome, and although the combination can improve survival, cyclophosphamide given prior to immunotherapy may generate a population of myeloid cells that can interfere with CTL responses and compromise the therapeutic outcome.
Tumor-Associated Antigen Preferentially Expressed Antigen of Melanoma (PRAME) Induces Caspase-Independent Cell Death In vitro and Reduces Tumorigenicity In vivo
Authors: Tajeddine Nicolas , Gala Jean-Luc , Louis Magali , Van Schoor Monique , Tombal Bertrand , Gailly Philippe
Published: September 2005

Preferentially expressed antigen of melanoma (PRAME) is expressed in a wide variety of tumors, but in contrast with most other tumor associated antigens, it is also expressed in leukemias. The physiologic role of PRAME remains elusive. Interestingly, PRAME expression is correlated with a favorable prognosis in childhood acute leukemias. Moreover, a high expression of PRAME seems to be predominantly found in acute leukemias carrying a favorable prognosis. On these clinical observations, we assumed that PRAME could be involved in the regulation of cell death or cell cycle. In this study, we show that transient overexpression of PRAME induces a caspase-independent cell death in cultured cell lines (CHO-K1 and HeLa). Cells stably transfected with PRAME also exhibit a decreased proliferation rate due, at least partially, to an elevated basal rate of cell death. Immunocytochemistry of a FLAG-tagged PRAME, in vivo imaging of an enhanced green fluorescent protein–tagged PRAME, and Western blotting after cell fractionation reveal a nuclear localization of the protein. Using a microarray-based approach, we show that KG-1 leukemic cells stably transfected with PRAME present a significant decrease of expression of the heat-shock protein Hsp27, the cyclin-dependent kinase inhibitor p21, and the calcium-binding protein S100A4. The expression of these three proteins is known to inhibit apoptosis and has been associated with an unfavorable prognosis in a series of cancers. Finally, repression of PRAME expression by a short interfering RNA strategy increases tumorigenicity of K562 leukemic cells in nude mice. We suggest that all these observations might explain the favorable prognosis of the leukemias expressing high levels of PRAME.