bluuebunny/crossref_metadata_2025 huggingface dataset:
Transcriptional Regulation of Cyclin A2 by RASSF1A through the Enhanced Binding of p120E4F to the Cyclin A2 Promoter
Authors: Ahmed-Choudhury Jalal , Agathanggelou Angelo , Fenton Sarah L. , Ricketts Christopher , Clark Geoffrey J. , Maher Eamonn R. , Latif Farida
Published: September 2005

Recent advances in the study of RASSF1A, the candidate tumor suppressor gene, indicate a possible role of RASSF1A in cell cycle regulation; however, very little is known regarding molecular mechanisms underlying this control. Using small interfering RNA to knockdown endogenous RASSF1A in the breast tumor cell line HB2 and in the cervical cancer cell line HeLa, we identify that a key player in cell cycle progression, cyclin A2, is concomitantly increased at both protein and mRNA levels. In A549 clones stably expressing RASSF1A, cyclin A2 levels were diminished compared with vector control. A known transcriptional regulator of cyclin A2, p120E4F (a repressor of cyclin A2), has been shown previously by our group to interact with RASSF1A. We show that levels of p120E4F are not affected by RASSF1A small interfering RNA in HB2 and HeLa cells. However, electrophoretic mobility shift assays indicate that knockdown of endogenous RASSF1A in HB2 and HeLa cells leads to a reduction in the binding capacity of p120E4F to the cyclin A2 promoter, whereas in the A549 clone stably expressing RASSF1A the binding capacity is increased. These data are further corroborated in vitro by the luciferase assay and in vivo by chromatin immunoprecipitation experiments. Together, these data identify the cyclin A2 gene as a cellular target for RASSF1A through p120E4F and for the first time suggest a transcriptional mechanism for RASSF1A-dependent cell cycle regulation.
Stimulation of Mitochondrial Activity by p43 Overexpression Induces Human Dermal Fibroblast Transformation
Authors: Grandemange Stéphanie , Seyer Pascal , Carazo Angel , Bécuwe Philippe , Pessemesse Laurence , Busson Muriel , Marsac Cécile , Roger Pascal , Casas François , Cabello Gérard , Wrutniak-Cabello Chantal
Published: September 2005

Mitochondrial dysfunctions are frequently reported in cancer cells, but their direct involvement in tumorigenesis remains unclear. To understand this relation, we stimulated mitochondrial activity by overexpression of the mitochondrial triiodothyronine receptor (p43) in human dermal fibroblasts. In all clones, this stimulation induced morphologic changes and cell fusion in myotube-like structures associated with the expression of several muscle-specific genes (Myf5, desmin, connectin, myosin, AchRα). In addition, these clones displayed all the in vivo and in vitro features of cell transformation. This phenotype was related to an increase in c-Jun and c-Fos expression and extinction of tumor suppressor gene expression (p53, p21WAF1, Rb3). Lastly, reactive oxygen species (ROS) production was increased in positive correlation to the stimulation of mitochondrial activity. The direct involvement of mitochondrial activity in this cell behavior was studied by adding chloramphenicol, an inhibitor of mitochondrial protein synthesis, to the culture medium. This inhibition resulted in partial restoration of the normal phenotype, with the loss of the ability to fuse, a strong decrease in muscle-specific gene expression, and potent inhibition of the transformed phenotype. However, expression of tumor suppressor genes was not restored. Similar results were obtained by using N-acetylcysteine, an inhibitor of ROS production. These data indicate that stimulation of mitochondrial activity in human dermal fibroblasts induces cell transformation through events involving ROS production.
Synergistic Induction of DOC-2/DAB2 Gene Expression in Transitional Cell Carcinoma in the Presence of GATA6 and Histone Deacetylase Inhibitor
Authors: Zhou Jian , Hernandez Gina , Tu Szu-wei , Scholes Jessica , Chen Hong , Tseng Ching-Ping , Hsieh Jer-Tsong
Published: September 2005

The down-regulation of DOC-2/DAB2 gene, which encodes a unique phosphoprotein modulating signal pathways elicited by exogenous stimuli, is often associated with several cancer types; however, the underlying mechanism is still unknown. Dramatically different expression levels of DOC-2/DAB2 mRNA and protein are observed among several human transitional cell carcinoma (TCC) cell lines, suggesting that transcriptional regulation may play a role in these cells. In this study, we have shown that the histone acetylation status associated with the 5′ upstream regulatory sequence of DOC-2/DAB2 gene is one of the key determinants for its gene expression. In addition, GATA6 but not other GATA family members, such as GATA2 and GATA4, can specifically induce DOC-2/DAB2 promoter activity, although GATA transcription factors share a very similar DNA-binding sequence. We also show that increased histone acetylation and the presence of GATA6 have a synergistic effect on DOC-2/DAB2 promoter activity, which results in the elevation of DOC-2/DAB2 protein expression. Thus, we conclude that transcriptional regulation of DOC-2/DAB2 gene in human TCC is determined by histone acetylation and a specific transcription factor (i.e., GATA6), which underlie the reduced DOC-2/DAB2 protein expression in TCC cells.
p53 Mutations in Benzo(a)Pyrene-Exposed Human p53 Knock-in Murine Fibroblasts Correlate with p53 Mutations in Human Lung Tumors
Authors: Liu Zhipei , Muehlbauer Karl-Rudolf , Schmeiser Heinz H. , Hergenhahn Manfred , Belharazem Djeda , Hollstein Monica C.
Published: September 2005

Human p53 mutation spectra differ significantly from one cancer type to another. One possible reason is that carcinogenic risk factors differ, and these factors elicit distinct mutation patterns. There has been no mammalian assay, however, with which to generate mutation patterns in human p53 sequences experimentally, hampering interpretation of the human tumor spectra. We have designed a new mammalian cell assay using gene targeting technology that selects and scores human p53 gene sequence mutations in human-p53 knock-in (Hupki) murine embryonic fibroblasts (HUF) that have undergone immortalization. With the Hupki assay we examined here whether benzo(a)pyrene (BaP), a major tobacco smoke carcinogen could elicit p53 mutation patterns characterizing the human lung tumor p53 mutation spectrum. We found that, in contrast to unexposed HUFs or HUFs exposed to other carcinogenic agents, HUFs exposed to BaP acquire mutations that display major features of the human lung tumor p53 mutation spectrum: (a) predominance of G-to-T mutations, (b) unequivocal strand bias of the transversions, and (c) a mutation hotspot at codons 157 to 158. These data are consistent with the hypothesis that BaP has a direct role in causing smokers' lung tumor p53 mutations. The assay can be used to examine various hypotheses on the endogenous or exogenous factors responsible for the p53 mutations in human tumors arising in other tissues.
Characterizing Extravascular Fluid Transport of Macromolecules in the Tumor Interstitium by Magnetic Resonance Imaging
Authors: Pathak Arvind P. , Artemov Dmitri , Ward B. Douglas , Jackson David G. , Neeman Michal , Bhujwalla Zaver M.
Published: September 2005

Noninvasive imaging techniques to image and characterize delivery and transport of macromolecules through the extracellular matrix (ECM) and supporting stroma of a tumor are necessary to develop treatments that alter the porosity and integrity of the ECM for improved delivery of therapeutic agents and to understand factors which influence and control delivery, movement, and clearance of macromolecules. In this study, a noninvasive imaging technique was developed to characterize the delivery as well as interstitial transport of a macromolecular agent, albumin-GdDTPA, in the MCF-7 human breast cancer model in vivo, using magnetic resonance imaging. The transport parameters derived included vascular volume, permeability surface area product, macromolecular fluid exudate volume, and drainage and pooling rates. Immunohistochemical staining for the lymphatic endothelial marker LYVE-1 was done to determine the contribution of lymphatics to the macromolecular drainage. Distinct pooling and draining regions were detected in the tumors using magnetic resonance imaging. A few lymphatic vessels positively stained for LYVE-1 were also detected although these were primarily collapsed and tenuous suggesting that lymphatic drainage played a minimal role, and that the bulk of drainage was due to convective transport through the ECM in this tumor model.
Dual Inhibition of Epidermal Growth Factor Receptor and Vascular Endothelial Growth Factor Receptor Phosphorylation by AEE788 Reduces Growth and Metastasis of Human Colon Carcinoma in an Orthotopic Nude Mouse Model
Authors: Yokoi Kenji , Thaker Premal H. , Yazici Sertac , Rebhun Robert R. , Nam Do-Hyun , He Junqin , Kim Sun-Jin , Abbruzzese James L. , Hamilton Stanley R. , Fidler Isaiah J.
Published: September 2005

We studied growth factors and their receptors in tumor cells and tumor-associated endothelial cells as the therapeutic targets in colon cancer. Immunohistochemical analysis of 13 surgical specimens of human colon adenocarcinoma revealed that both tumor cells and tumor-associated endothelial cells in 11 of the 13 specimens expressed the epidermal growth factor (EGF), transforming growth factor α (TGF-α), EGF receptor (EGFR), phosphorylated EGFR (pEGFR), vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR), and phosphorylated VEGFR (pVEGFR). HT29 human colon cancer cells growing orthotopically in the cecum of nude mice expressed a high level of EGF, EGFR, pEGFR, VEGF, VEGFR, and pVEGFR. Double-immunofluorescence staining found that tumor-associated mouse endothelial cells also expressed pEGFR and pVEGFR. Tumors in mice treated for 5 weeks with oral AEE788 (an inhibitor of EGFR and VEGFR tyrosine kinase) as a single agent or with CPT-11 alone were smaller (>50%) than those in control mice. Mice treated with the combination of AEE788 and CPT-11 had significantly smaller tumors (P < 0.01) and complete inhibition of lymph node metastasis. AEE788 alone or in combination with CPT-11 inhibited pEGFR, pVEGFR, and phosphorylated Akt expression on tumor-associated endothelial cells as well as on tumor cells. The combination therapy also significantly decreased microvessel density and tumor cell proliferation and increased the level of apoptosis in both tumor cells and tumor-associated endothelial cells. Collectively, these data suggest that the dual inhibition of EGFR and VEGFR signaling pathways in tumor cells and tumor-associated endothelial cells in combination with chemotherapy can provide a new approach to the treatment of colon cancer.
Bortezomib Abolishes Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand Resistance via a p21-Dependent Mechanism in Human Bladder and Prostate Cancer Cells
Authors: Lashinger Laura M. , Zhu Keyi , Williams Simon A. , Shrader Marissa , Dinney Colin P.N. , McConkey David J.
Published: September 2005

Tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor family of cytokines that induces apoptosis in some tumor cells but not in normal cells. Unfortunately, many human cancer cell lines are refractory to TRAIL-induced cell death, and the molecular mechanisms underlying resistance are unclear. Here we report that TRAIL resistance was reversed in human bladder and prostate cancer cell lines by the proteasome inhibitor bortezomib (PS-341, Velcade). Synergistic induction of apoptosis occurred within 4 to 6 hours in cells treated with TRAIL plus bortezomib and was associated with accumulation of p21WAF-1/Cip-1 (p21) and inhibition of cyclin-dependent kinase (cdk) activity. Roscovitine, a specific cdk1/2 inhibitor, also sensitized cells to TRAIL. Silencing p21 expression reduced levels of DNA fragmentation by 50% in cells treated with bortezomib and TRAIL, confirming that p21 was required for the response. Analysis of the TRAIL pathway revealed that caspase-8 processing was enhanced in a p21-dependent fashion in cells exposed to TRAIL and bortezomib as compared with cells treated with TRAIL alone. Thus, all downstream components of the pathway (Bid cleavage, cytochrome c release, and caspase-3 activation) were amplified. These data strongly suggest that p21-mediated cdk inhibition promotes TRAIL sensitivity via caspase-8 activation and that TRAIL and bortezomib should be combined in appropriate in vivo models as a possible approach to solid tumor therapy.
Two Functional Epitopes of Pigment Epithelial–Derived Factor Block Angiogenesis and Induce Differentiation in Prostate Cancer
Authors: Filleur Stephanie , Volz Karl , Nelius Thomas , Mirochnik Yelena , Huang Hanhua , Zaichuk Tetiana A. , Aymerich Maria S. , Becerra Sofia P. , Yap Ronald , Veliceasa Dorina , Shroff Emelyn H. , Volpert Olga V.
Published: September 2005

Pigment epithelial-derived factor (PEDF), an angiogenesis inhibitor with neurotrophic properties, balances angiogenesis in the eye and blocks tumor progression. Its neurotrophic function and the ability to block vascular leakage is replicated by the PEDF 44-mer peptide (residues 58-101). We analyzed PEDFs' three-dimensional structure and identified a potential receptor-binding surface. Seeking PEDF-based antiangiogenic agents we generated and tested peptides representing the middle and lower regions of this surface. We identified previously unknown antiangiogenic epitopes consisting of the 34-mer (residues 24-57) and a shorter proximal peptide (TGA, residues 16-26) with the critical stretch L19VEEED24 and a fragment within the 44-mer (ERT, residues 78-94), which retained neurotrophic activity. The 34-mer and TGA, but not the 44-mer reproduced PEDF angioinhibitory signals hinged on c-jun-NH2-kinase–dependent nuclear factor of activated T cell deactivation and caused apoptosis. Conversely, the ERT, but not the 34-mer/TGA induced neuronal differentiation. For the 44-mer/ERT, we showed a novel ability to cause neuroendocrine differentiation in prostate cancer cells. PEDF and the peptides bound endothelial and PC-3 prostate cancer cells. Bound peptides were displaced by PEDF, but not by each other, suggesting multiple receptors. PEDF and its active fragments blocked tumor formation when conditionally expressed by PC-3 cells. The 34- and 44-mer used distinct mechanisms: the 34-mer acted on endothelial cells, blocked angiogenesis, and induced apoptosis whereas 44-mer prompted neuroendocrine differentiation in cancer cells. Our results map active regions for the two PEDF functions, signaling via distinct receptors, identify candidate peptides, and provide their mechanism of action for future development of PEDF-based tumor therapies.
A Novel Ring-Substituted Diindolylmethane,1,1-Bis[3′-(5-Methoxyindolyl)]-1-(p-t-Butylphenyl) Methane, Inhibits Extracellular Signal-Regulated Kinase Activation and Induces Apoptosis in Acute Myelogenous Leukemia
Authors: Contractor Rooha , Samudio Ismael J. , Estrov Zeev , Harris David , McCubrey James A. , Safe Stephen H. , Andreeff Michael , Konopleva Marina
Published: September 2005

We investigated the antileukemic activity and molecular mechanisms of action of a newly synthesized ring-substituted diindolylmethane derivative, 1,1-bis[3′-(5-methoxyindolyl)]-1-(p-t-butylphenyl) methane (DIM #34), in acute myelogenous leukemia (AML) cells. DIM #34 inhibited AML cell growth via the induction of apoptosis and abrogated clonogenic growth of primary AML samples. Exposure to DIM #34 induced loss of mitochondrial inner transmembrane potential, release of cytochrome c into the cytosol, and caspase activation. Bcl-2–overexpressing, Bax knockout, and caspase-9–deficient cells were partially resistant to cell death, suggesting the involvement of the intrinsic apoptotic pathway. Furthermore, DIM #34 transiently inhibited the phosphorylation and activity of the extracellular signal-regulated kinase and abrogated Bcl-2 phosphorylation. Because other methylene-substituted diindolylmethane analogues have been shown to transactivate the nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ), we studied the role of PPARγ in apoptosis induction. Cotreatment of cells with a selective PPARγ antagonist or with retinoid X receptor and retinoic acid receptor ligands partially modulated apoptosis when combined with DIM #34, suggesting PPARγ receptor-dependent and receptor-independent cell death. Together, these findings suggest that diindolylmethanes are a new class of compounds that selectively induce apoptosis in AML cells through the modulation of the extracellular signal-regulated kinase and PPARγ signaling pathways.
Haplotype Loss of HLA Class I Antigen as an Escape Mechanism from Immune Attack in Lung Cancer
Authors: So Tetsuya , Takenoyama Mitsuhiro , Mizukami Makiko , Ichiki Yoshinobu , Sugaya Masakazu , Hanagiri Takeshi , Sugio Kenji , Yasumoto Kosei
Published: September 2005

One of tumor escape mechanisms from the host's immunosurveillance system (i.e., a haplotype loss of HLA class I antigens) has been detected in various tumor cells. We hypothesize that the majority of tumor cells with normal HLA class I expression were attacked and eradicated by CTLs, and only a minority with an abnormal expression of HLA class I antigens could escape the host's immunosurveillance system. Using HLA class I–transfected tumor variants as stimulators in A904L lung cancer cell line, which has a haplotype loss of HLA class I antigens, both the transfected HLA-A26 and HLA-B39–restricted CTL lines were induced from autologous lymphocytes. However, only one HLA-B39–restricted CTL clone (CTL G3b) was established, and it was then used to identify the antigen. SGT1B [suppressor of G2 allele of SKP1 (SGT1), suppressor of kinetochore protein (SKP1)] was identified as the antigen recognized by CTL G3b. Further experiments using 13 subclones from a primary culture of A904L were found to confirm our above-mentioned hypothesis. Tumor cells with a normal HLA class I expression may thus be killed by CTL at an early stage of carcinogenesis, and only tumor cells with a haplotype loss of HLA class I antigens can escape an immune attack and develop into clinical cancer.
Recovery of CD8+ T-Cell Function During Systemic Chemotherapy in Advanced Ovarian Cancer
Authors: Coleman Sharon , Clayton Aled , Mason Malcolm D. , Jasani Bharat , Adams Malcolm , Tabi Zsuzsanna
Published: September 2005

Immunologic approaches are emerging as new treatment options in several types of cancer. However, whereas the ability of patients to develop potent CD8+ T-cell responses is crucial for efficient antitumor responses, immunocompetence and T-cell function are not tested routinely in patients entering immunotherapy. The objective of our study was to monitor T-cell function in advanced cancer and during chemotherapy. CD8+ T-cell function of 21 patients with advanced ovarian cancer (stages III-IV) was assessed by cytokine flow cytometry following stimulation of 42 PBMC samples with a panel of synthetic viral peptides in vitro, consisting of pan-Caucasian epitopes. CD8+ T-cell responses were significantly lower in patients with high levels (>200 units/mL) of Ca125 (marker of tumor load and progression) than in those with low Ca125 levels (P = 0.0013). In longitudinal studies of nine patients, chemotherapy was associated with decreasing Ca125 levels in seven cases and also with improvement or maintenance of CD8+ T-cell function in seven cases. After the full course of chemotherapy, five of nine patients in remission displayed potent CD8+ T-cell responses, whereas four of nine patients in progression displayed low or decreasing T-cell responses, pointing toward a correlation between T-cell function and clinical response. Our results show for the first time that CD8+ T-cell function is not permanently suppressed in advanced cancer and successful chemotherapy is associated with improved antigen-specific T-cell reactivity. We suggest that functional assays determining T-cell immunocompetence can be valuable tools for optimizing cancer immunotherapy for improved clinical success.
Genetic Polymorphism in Cytochrome P450 7A1 and Risk of Colorectal Cancer: The Fukuoka Colorectal Cancer Study
Authors: Hagiwara Tomoko , Kono Suminori , Yin Guang , Toyomura Kengo , Nagano Jun , Mizoue Tetsuya , Mibu Ryuichi , Tanaka Masao , Kakeji Yoshihiro , Maehara Yoshihiko , Okamura Takeshi , Ikejiri Kouji , Futami Kitaroh , Yasunami Youichi , Maekawa Takafumi , Takenaka Kenji , Ichimiya Hitoshi , Imaizumi Nobutoshi
Published: September 2005

Bile acids have long been implicated in the etiology of colorectal cancer, but epidemiologic evidence remains elusive. Cholesterol 7α-hydroxylase (CYP7A1) is the rate-limiting enzyme in the synthesis of bile acids from cholesterol in the liver, and thus may be an important determinant of bile acid production. We examined the association between the CYP7A1 A-203C polymorphism and colorectal cancer. The CYP7A1 A-203C polymorphism was determined by the PCR-RFLP method in 685 incident cases of colorectal cancer and 778 controls randomly selected from a community in the Fukuoka area, Japan. The CC genotype was slightly less frequent in the case group, and the adjusted odds ratio for the CC versus AA genotype was 0.88 (95% confidence interval, 0.65-1.20). In the analysis by subsite of the colorectum, a decreased risk associated with the CYP7A1 CC genotype was observed for proximal colon cancer, but not for either distal colon or rectal cancer. The adjusted odds ratios (95% confidence intervals) of proximal colon cancer for the CC genotype were 0.63 (0.36-1.10) compared with the AA genotype, and 0.59 (0.37-0.96) compared with the AA and AC genotypes combined. A decreased risk of proximal colon cancer in relation to the CC genotype of CYP7A1 A-203C, which probably renders less activity of the enzyme converting cholesterol to bile acids, is new evidence for the role of bile acids in colorectal carcinogenesis.
The Proinflammatory Cytokine Interleukin 1β and Hypoxia Cooperatively Induce the Expression of Adrenomedullin in Ovarian Carcinoma Cells through Hypoxia Inducible Factor 1 Activation
Authors: Frede Stilla , Freitag Patricia , Otto Teresa , Heilmaier Christina , Fandrey Joachim
Published: September 2005

Adrenomedullin (ADM) is a potent hypotensive peptide produced by macrophages and endothelial cells during ischemia and sepsis. The molecular mechanisms that control ADM gene expression in tumor cells are still poorly defined. It is known, however, that hypoxia potently increases ADM expression by activation of the transcription factor complex hypoxia inducible factor 1 (HIF-1). Proinflammatory cytokines produced by tumor invading macrophages likewise activate expression of ADM. Herein, we show that apart from hypoxia, the proinflammatory cytokine interleukin 1β (IL-1β) induced the expression of ADM mRNA through activation of HIF-1 under normoxic conditions and enhanced the hypoxia-induced expression in the human ovarian carcinoma cell line OVCAR-3. IL-1β significantly increased accumulation and nuclear translocation of HIF-1α under normoxic conditions and amplified hypoxic HIF-1 activation. IL-1β treatment affected neither HIF-1α mRNA levels nor the hydroxylation status of HIF-1α and, thus, stability of the protein. Instead cycloheximide effectively prevented the increase in HIF-1α protein, indicating a stimulatory effect of IL-1β on HIF-1α translation. Finally, treatment of HIF-1α with short interfering RNA revealed a significant role for HIF-1 in the IL-1β–dependent stimulation of ADM expression.
Androgen Receptor Cytosine, Adenine, Guanine Repeats, and Haplotypes in Relation to Ovarian Cancer Risk
Authors: Terry Kathryn L. , De Vivo Immaculata , Titus-Ernstoff Linda , Shih Mei-Chiung , Cramer Daniel W.
Published: September 2005

Biological and epidemiologic evidence suggest that androgen or its receptor may play a role in ovarian cancer pathogenesis. The most notable genetic factor influencing androgen receptor (AR) activity is the functional cytosine, adenine, guanine (CAG) repeat in which length is inversely proportional to its transactivational activity. Additional genetic variation due to single nucleotide polymorphisms in the AR gene may be captured through haplotypes. We genotyped the CAG microsatellite and six haplotype-tagging single nucleotide polymorphisms (rs962458, rs6152, rs1204038, rs2361634, rs1337080, rs1337082) of the androgen receptor gene in 987 ovarian cancer cases and 1,034 controls from a study conducted in New Hampshire and eastern Massachusetts between May 1992 and July 2003. We estimated haplotype frequencies and calculated odds ratios with 95% confidence intervals to evaluate the association between the haplotypes and the AR CAG microsatellite with ovarian cancer risk. We observed that carriage of two alleles with ≥22 CAG repeats was associated with an increased risk of ovarian cancer compared with carriage of two alleles with <22 CAG repeats (covariate-adjusted odds ratios, 1.31; 95% confidence intervals, 1.01-1.69). Five common haplotypes in the AR gene were identified, but no association between these and ovarian cancer risk was observed. Our results suggest that possession of two long AR alleles (≥22 CAG repeats) may be associated with increased risk of ovarian cancer compared with women with two short AR alleles (<22 CAG repeats).
Hsp70-Like Protein 1 Fusion Protein Enhances Induction of Carcinoembryonic Antigen–Specific CD8+ CTL Response by Dendritic Cell Vaccine
Authors: Wu Yanfeng , Wan Tao , Zhou Xiangyang , Wang Baomei , Yang Feng , Li Nan , Chen Guoyou , Dai Shengming , Liu Shuxun , Zhang Minghui , Cao Xuetao
Published: September 2005

Heat shock proteins (HSP) have been revealed to interact with antigen-presenting cells and have potent adjuvant capability to induce antigen-specific CD8+ CTL and Th1 responses. Our previous work shows how Hsp70-like protein 1 (Hsp70L1), as a new member of the Hsp70 subfamily, acts as potent Th1 adjuvant. Here, we report the efficient induction of tumor antigen-specific immune response by dendritic cells pulsed with recombinant fusion protein of Hsp70L1 and CEA576-669 fragment of the carcinoembryonic antigen (CEA) containing CAP-1 (a HLA-A2–restricted CTL epitope). Fusion protein CEA576-669-Hsp70L1 can promote dendritic cell maturation and activate dendritic cells to produce cytokines, such as interleukin-12, interleukin-1β, and tumor necrosis factor-α, and chemokines, such as macrophage inflammatory protein-1α, macrophage inflammatory protein-1β, and regulated on activation, normal T expressed and secreted, indicating the adjuvant ability of Hsp70L1 in the fusion protein. CEA-specific HLA-A2.1–restricted CD8+ CTLs either from patients with CEA+/HLA-A2.1+ colon carcinoma or from splenocytes of immunized HLA-A2.1/Kb transgenic mice can be generated more efficiently after stimulations or immunizations with dendritic cells pulsed by CEA576-669-Hsp70L1 than with dendritic cells pulsed by CEA576-669 alone, resulting in secreting more Th1 cytokine IFN-γ and killing target cells more potently in an antigen-specific and HLA-A2.1–restricted manner. Adoptive transfer of splenocytes from transgenic mice immunized with CEA576-669-Hsp70L1–pulsed dendritic cells can inhibit tumor growth and prolong survival in nude mice bearing CEA+/HLA-A2.1+ human colon carcinoma more markedly. Therefore, Hsp70L1 has potent adjuvant effect in form of fusion protein, indicating that Hsp70L1 may be widely used as Th1 adjuvant to prepare antigenic fusion protein for the therapeutics of cancer or infectious diseases.
Nanoparticle Targeting of Anticancer Drug Improves Therapeutic Response in Animal Model of Human Epithelial Cancer
Authors: Kukowska-Latallo Jolanta F. , Candido Kimberly A. , Cao Zhengyi , Nigavekar Shraddha S. , Majoros Istvan J. , Thomas Thommey P. , Balogh Lajos P. , Khan Mohamed K. , Baker James R.
Published: September 2005

Prior studies suggested that nanoparticle drug delivery might improve the therapeutic response to anticancer drugs and allow the simultaneous monitoring of drug uptake by tumors. We employed modified PAMAM dendritic polymers <5 nm in diameter as carriers. Acetylated dendrimers were conjugated to folic acid as a targeting agent and then coupled to either methotrexate or tritium and either fluorescein or 6-carboxytetramethylrhodamine. These conjugates were injected i.v. into immunodeficient mice bearing human KB tumors that overexpress the folic acid receptor. In contrast to nontargeted polymer, folate-conjugated nanoparticles concentrated in the tumor and liver tissue over 4 days after administration. The tumor tissue localization of the folate-targeted polymer could be attenuated by prior i.v. injection of free folic acid. Confocal microscopy confirmed the internalization of the drug conjugates into the tumor cells. Targeting methotrexate increased its antitumor activity and markedly decreased its toxicity, allowing therapeutic responses not possible with a free drug.
CK2 Inhibits Apoptosis and Changes Its Cellular Localization Following Ionizing Radiation
Authors: Yamane Kazuhiko , Kinsella Timothy J.
Published: September 2005

In this study, we show that CK2 (casein kinase II, CKII) participates in apoptotic responses following ionizing radiation (IR). Using HeLa human cervical carcinoma cells, we find that transfection of small interfering RNA against the CK2 α and/or α′ catalytic subunits results in enhanced apoptosis following IR damage as measured by flow cytometry techniques, compared with a control small interfering RNA. Within 2 to 6 hours of IR, CK2 α partially localizes to perinuclear structures, whereas a marked nuclear localization of α′ occurs. Treatment with a pan-caspase inhibitor or transfection of ARC (apoptosis repressor with caspase recruitment domain) suppresses the apoptotic response to IR in the CK2-reduced cells, indicating involvement of caspases. Additionally, we find that CK2 α and/or α′ reduction affects cell cycle progression independent of IR damage in this human cell line. However, the G2-M checkpoint following IR is not affected in CK2 α- and/or α′-reduced cells. Thus, our data suggest that CK2 participates in inhibition of apoptosis and negatively regulates caspase activity following IR damage.
A Cell Proliferation Signature Is a Marker of Extremely Poor Outcome in a Subpopulation of Breast Cancer Patients
Authors: Dai Hongyue , van't Veer Laura , Lamb John , He Yudong D. , Mao Mao , Fine Bernard M. , Bernards Rene , van de Vijver Marc , Deutsch Paul , Sachs Alan , Stoughton Roland , Friend Stephen
Published: September 2005

Breast cancer comprises a group of distinct subtypes that despite having similar histologic appearances, have very different metastatic potentials. Being able to identify the biological driving force, even for a subset of patients, is crucially important given the large population of women diagnosed with breast cancer. Here, we show that within a subset of patients characterized by relatively high estrogen receptor expression for their age, the occurrence of metastases is strongly predicted by a homogeneous gene expression pattern almost entirely consisting of cell cycle genes (5-year odds ratio of metastasis, 24.0; 95% confidence interval, 6.0-95.5). Overexpression of this set of genes is clearly associated with an extremely poor outcome, with the 10-year metastasis-free probability being only 24% for the poor group, compared with 85% for the good group. In contrast, this gene expression pattern is much less correlated with the outcome in other patient subpopulations. The methods described here also illustrate the value of combining clinical variables, biological insight, and machine-learning to dissect biological complexity. Our work presented here may contribute a crucial step towards rational design of personalized treatment.
Androgen Causes Growth Suppression and Reversion of Androgen-Independent Prostate Cancer Xenografts to an Androgen-Stimulated Phenotype in Athymic Mice
Authors: Chuu Chih-pin , Hiipakka Richard A. , Fukuchi Junichi , Kokontis John M. , Liao Shutsung
Published: September 2005

Most prostate cancer patients develop androgen-independent recurrent prostate tumors a few years after androgen ablation therapy. No therapy, however, has been shown to substantially extend survival in these patients. Previously, we reported that androgen suppresses the growth of androgen-independent LNCaP prostate tumor cells both in vitro and in vivo. In cell culture, androgen receptor (AR)–rich androgen-independent LNCaP 104-R1 cells adapt to growth suppression by androgen and then their growth is androgen stimulated. Because maintaining androgen dependency of prostate tumor cells should prolong the usefulness of androgen ablation therapy, we determined if androgen-independent prostate tumors would revert to an androgen-stimulated phenotype in vivo upon androgen treatment. Growth of the LNCaP 104-R1 tumors was suppressed by androgen, but tumors then adapted to suppression by androgen and growth became androgen stimulated. Tumor AR and prostate-specific antigen mRNA and protein were initially high in 104-R1 tumors but decreased during adaptation. Subsequent removal of androgen decreased the serum prostate-specific antigen level further and stopped the growth of the adapted tumors. Because androgen caused growth suppression and then reversion of androgen-independent tumors to an androgen-stimulated phenotype and because the growth of androgen-stimulated tumors could be restrained by androgen ablation, these results suggest a novel therapy for AR-positive androgen-independent prostate cancer.
Lost in Transcription: p21 Repression, Mechanisms, and Consequences
Authors: Gartel Andrei L. , Radhakrishnan Senthil K.
Published: September 2005

The cyclin-dependent kinase inhibitor p21WAF1/CIP1 is a major player in cell cycle control and it is mainly regulated at the transcriptional level. Whereas induction of p21 predominantly leads to cell cycle arrest, repression of p21 may have a variety of outcomes depending on the context. In this review, we concentrate on transcriptional repression of p21 by cellular and viral factors, and delve in detail into its possible biological implications and its role in cancer. It seems that the major mode of p21 transcriptional repression by negative regulators is the interference with positive transcription factors without direct binding to the p21 promoter. Specifically, the negative factors may either inhibit binding of positive regulators to the promoter or hinder their transcriptional activity. The ability of p21 to inhibit proliferation may contribute to its tumor suppressor function. Because of this, it is not surprising that a number of oncogenes repress p21 to promote cell growth and tumorigenesis. However, p21 is also an inhibitor of apoptosis and p21 repression may also have an anticancer effect. For example, c-Myc and chemical p21 inhibitors, which repress p21, sensitize tumor cells to apoptosis by anticancer drugs. Further identification of factors that repress p21 is likely to contribute to the better understanding of its role in cancer.
E2F-Dependent Repression of Topoisomerase II Regulates Heterochromatin Formation and Apoptosis in Cells with Melanoma-Prone Mutation
Authors: Jiao Wan , Lin Huei-Min , Timmons Jamie , Nagaich Akhilesh K. , Ng Shu-Wing , Misteli Tom , Rane Sushil G.
Published: September 2005

RB pathway mutations, especially at the CDK4 and INK4A loci, are hallmarks of melanomagenesis. It is presently unclear what advantages these alterations confer during melanoma progression and how they influence melanoma therapy. Topoisomerase II inhibitors are widely used to treat human malignancies, including melanoma, although their variable success is attributable to a poor understanding of their mechanism of action. Using mouse and human cells harboring the melanoma-prone p16Ink4a-insensitive CDK4R24C mutation, we show here that topoisomerase II proteins are direct targets of E2F-mediated repression. Drug-treated cells fail to load repressor E2Fs on topoisomerase II promoters leading to elevated topoisomerase II levels and an enhanced sensitivity of cells to apoptosis. This is associated with the increased formation of heterochromatin domains enriched in structural heterochromatin proteins, methylated histones H3/H4, and topoisomerase II. We refer to these preapoptotic heterochromatin domains as apoptosis-associated heterochromatic foci. We suggest that cellular apoptosis is preceded by an intermediary chromatin remodeling state that involves alterations of DNA topology by topoisomerase II enzymes and gene silencing via formation of heterochromatin. These observations provide novel insight into the mechanism of drug action that influence treatment outcome: drug sensitivity or drug resistance.
Antibody against Junctional Adhesion Molecule-C Inhibits Angiogenesis and Tumor Growth
Authors: Lamagna Chrystelle , Hodivala-Dilke Kairbaan M. , Imhof Beat A. , Aurrand-Lions Michel
Published: September 2005

The junctional adhesion molecule-C (JAM-C) was recently described as an adhesion molecule localized at interendothelial contacts and involved in leukocyte transendothelial migration. The protein JAM-C interacts with polarity complex molecules and regulates the activity of the small GTPase Cdc42. The angiogenesis process involves rearrangement of endothelial junctions and implicates modulation of cell polarity. We tested whether JAM-C plays a role in angiogenesis using tumor grafts and hypoxia-induced retinal neovascularization. Treatment with a monoclonal antibody directed against JAM-C reduces tumor growth and infiltration of macrophages into tumors. The antibody decreases angiogenesis in the model of hypoxia-induced retinal neovascularization in vivo and vessel outgrowth from aortic rings in vitro. Importantly, the antibody does not induce pathologic side effects in vivo. These findings show for the first time a role for JAM-C in angiogenesis and define JAM-C as a valuable target for antitumor therapies.
The Novel Gene EG-1 Stimulates Cellular Proliferation
Authors: Lu Ming , Zhang Liping , Maul Raymond Scott , Sartippour Maryam R. , Norris Andrew , Whitelegge Julian , Rao Jian Yu , Brooks Mai N.
Published: September 2005

We recently discovered a novel gene and named it endothelial-derived gene 1 (EG-1). Previously, we have shown that the expression of EG-1 is significantly elevated in the epithelial cells of breast cancer, colorectal cancer, and prostate cancer. Here, we report that EG-1 can stimulate cellular proliferation. Transfection experiments which overexpressed the full-length EG-1 gene in human embryonic kidney HEK-293 cells or human breast cancer cell lines resulted in significantly increased in vitro proliferation, in comparison with transfection with empty vectors. On the other hand, small interfering RNA cotransfection resulted in inhibition of proliferation. S.c. xenograft assays were carried out in a severe combined immunodeficient mouse model. We found that injection of high EG-1 expressing HEK-293 clones resulted in significantly larger tumors, in comparison with clones carrying the empty vectors. To further clarify the function of this gene, we investigated its interaction with Src and members of the mitogen-activated protein kinase (MAPK) family. Immunoprecipitation with anti-Src antibody, followed by immunoblotting with anti–EG-1 antibody, showed an association between these two molecules. Overexpression of EG-1 was correlated with activation of the following kinases: extracellular signal-regulated kinases 1 and 2, c-jun-NH2-kinase, and p38. These observations collectively support the hypothesis that the novel gene EG-1 is a positive stimulator of cellular proliferation, and may possibly be involved in signaling pathways involving Src and MAPK activation.
Salivary Gland Tumors in Transgenic Mice with Targeted PLAG1 Proto-Oncogene Overexpression
Authors: Declercq Jeroen , Van Dyck Frederik , Braem Caroline V. , Van Valckenborgh Isabelle C. , Voz Marianne , Wassef Michel , Schoonjans Luc , Van Damme Boudewijn , Fiette Laurence , Van de Ven Wim J.M.
Published: September 2005

Pleomorphic adenoma gene 1 (PLAG1) proto-oncogene overexpression is implicated in various human neoplasias, including salivary gland pleomorphic adenomas. To further assess the oncogenic capacity of PLAG1, two independent PLAG1 transgenic mouse strains were established, PTMS1 and PTMS2, in which activation of PLAG1 overexpression is Cre mediated. Crossbreeding of PTMS1 or PTMS2 mice with MMTV-Cre transgenic mice was done to target PLAG1 overexpression to salivary and mammary glands, in the P1-Mcre/P2-Mcre offspring. With a prevalence of 100% and 6%, respectively, P1-Mcre and P2-Mcre mice developed salivary gland tumors displaying various pleomorphic adenoma features. Moreover, histopathologic analysis of salivary glands of 1-week-old P1-Mcre mice pointed at early tumoral stages in epithelial structures. Malignant characteristics in the salivary gland tumors and frequent lung metastases were found in older tumor-bearing mice. PLAG1 overexpression was shown in all tumors, including early tumoral stages. The tumors revealed an up-regulation of the expression of two distinct, imprinted gene clusters (i.e., Igf2/H19 and Dlk1/Gtl2). With a latency period of about 1 year, 8% of the P2-Mcre mice developed mammary gland tumors displaying similar histopathologic features as the salivary gland tumors. In conclusion, our results establish the strong and apparently direct in vivo tumorigenic capacity of PLAG1 and indicate that the transgenic mice constitute a valuable model for pleomorphic salivary gland tumorigenesis and potentially for other glands as well.
Plasmacytoid Dendritic Cells Induce CD8+ Regulatory T Cells In Human Ovarian Carcinoma
Authors: Wei Shuang , Kryczek Ilona , Zou Linhua , Daniel Ben , Cheng Pui , Mottram Peter , Curiel Tyler , Lange Andrzej , Zou Weiping
Published: September 2005

To directly dissect the role of each immune component in human tumor immunopathogenesis, we have studied the interaction between dendritic cells and T cells in the tumor environment of patients with ovarian carcinoma. We previously reported that functional plasmacytoid dendritic cells, but not functionally mature myeloid dendritic cells, accumulated in tumor microenvironments. We now show that tumor ascites macrophage-derived dendritic cells induced tumor-associated antigen–specific CD8+ T cells with effector functions. Strikingly, tumor ascites plasmacytoid dendritic cells induced interleukin-10+CCR7+CD45RO+CD8+ regulatory T cells. Four characteristics have been identified in tumor plasmacytoid dendritic cell–induced CD8+ regulatory T cells: (a) induction of CD8+ regulatory T cells is independent of CD4+CD25+ T cells; (b) CD8+ regulatory T cells significantly suppress myeloid dendritic cell–mediated tumor-associated antigen–specific T cell effector functions through interleukin-10; (c) repetitive myeloid dendritic cell stimulation can recover CD8+ regulatory T cell–mediated poor T cell proliferation, but not T cell effector function; (d) CD8+ regulatory T cells express functional CCR7, and efficiently migrate with lymphoid homing chemokine MIP-3β. Primary suppressive CCR7+CD45RO+CD8+ T cells are found in the tumor environment of patients with ovarian cancers. Thus, tumor-associated plasmacytoid dendritic cells contribute to the tumor environmental immunosuppressive network. Collectively, tumors manipulate tumor microenvironmental dendritic cell subset distribution and function to subvert tumor immunity. The data are relevant to understanding tumor immunopathology as well as reevaluating tumor immunotherapeutic strategies.
Proteomic Analysis Reveals Hyperactivation of the Mammalian Target of Rapamycin Pathway in Neurofibromatosis 1–Associated Human and Mouse Brain Tumors
Authors: Dasgupta Biplab , Yi Yijun , Chen David Y. , Weber Jason D. , Gutmann David H.
Published: September 2005

Individuals with the tumor predisposition syndrome, neurofibromatosis 1 (NF1), are prone to development of nervous system tumors, including neurofibromas and pilocytic astrocytomas. Based on the ability of the NF1 gene product (neurofibromin) to function as a GTPase activating protein for RAS, initial biologically based therapies for NF1-associated tumors focused on the use of RAS inhibitors, but with limited clinical success. In an effort to identify additional targets for therapeutic drug design in NF1, we used an unbiased proteomic approach to uncover unanticipated intracellular signaling pathways dysregulated in Nf1-deficient astrocytes. We found that the expression of proteins involved in promoting ribosome biogenesis was increased in the absence of neurofibromin. In addition, Nf1-deficient astrocytes exhibit high levels of mammalian target of rapamycin (mTOR) pathway activation, which was inhibited by blocking K-RAS or phosphatidylinositol 3-kinase activation. This mTOR pathway hyperactivation was reflected by high levels of ribosomal S6 activation in both Nf1 mutant mouse optic nerve gliomas and in human NF1-associated pilocytic astrocytoma tumors. Moreover, inhibition of mTOR signaling in Nf1−/− astrocytes abrogated their growth advantage in culture, restoring normal proliferative rates. These results suggest that mTOR pathway inhibition may represent a logical and tractable biologically based therapy for brain tumors in NF1.
Role of the Ras-Association Domain Family 1 Tumor Suppressor Gene in Human Cancers
Authors: Agathanggelou Angelo , Cooper Wendy N. , Latif Farida
Published: September 2005

In recent years, the list of tumor suppressor genes (or candidate TSG) that are inactivated frequently by epigenetic events rather than classic mutation/deletion events has been growing. Unlike mutational inactivation, methylation is reversible and demethylating agents and inhibitors of histone deacetylases are being used in clinical trails. Highly sensitive and quantitative assays have been developed to assess methylation in tumor samples, early lesions, and bodily fluids. Hence, gene silencing by promoter hypermethylation has potential clinical benefits in early cancer diagnosis, prognosis, treatment, and prevention. The hunt for a TSG located at 3p21.3 resulted in the identification of the RAS-association domain family 1, isoform A gene (RASSF1A). RASSF1A falls into the category of genes frequently inactivated by methylation rather than mutational events. This gene is silenced and frequently inactivated by promoter region hypermethylation in many adult and childhood cancers, including lung, breast, kidney, gastric, bladder, neuroblastoma, medulloblastoma, gliomas and it has homology to a mammalian Ras effector (i.e., Nore1). RASSF1A inhibits tumor growth in both in vitro and in vivo systems, further supporting its role as a TSG. We and others identified the gene in 2000, but already there are over a 150 publications demonstrating RASSF1A methylation in a large number of human cancers. Many laboratories including ours are actively investigating the biology of this novel protein family. Thus far, it has been shown to play important roles in cell cycle regulation, apoptosis, and microtubule stability. This review summarizes our current knowledge on genetic, epigenetic, and functional analysis of RASSF1A tumor suppressor gene and its homologues.