bluuebunny/crossref_metadata_2025 huggingface dataset:
Human Papillomavirus Type 16 and
TP53
Mutation in Oral Cancer
Authors: Dai Min , Clifford Gary M. , le Calvez Florence , Castellsagué Xavier , Snijders Peter J. F. , Pawlita Michael , Herrero Rolando , Hainaut Pierre , Franceschi Silvia ,   for the IARC Multicenter Oral Cancer Study Group
Published: September 2005

TP53 mutations were analyzed in 35 human papillomavirus (HPV) type 16 DNA-positive cancers of the oral cavity and oropharynx and in 35 HPV DNA-negative cancers matched by subsite, country, sex, age, and tobacco and alcohol consumption. Wild-type TP53 was found more frequently in cancer specimens that contained HPV16 DNA than in those that did not. All 14 HPV16 DNA-positive cancers in HPV16 E6 antibody-positive patients contained wild-type TP53, compared with 50% of corresponding HPV DNA-negative cancers (matched odds ratio, ∞; 95% confidence interval, 1.4–∞). In contrast, for HPV16 DNA-positive cancers in E6-negative patients, wild-type TP53 frequency was similar to that in corresponding HPV DNA-negative cancers (matched odds ratio, 1.0; 95% confidence interval, 0.2–5.4). TP53 inactivation is a major mechanism of HPV-related carcinogenesis in the oral cavity and oropharynx. The role of HPV in cancers also containing TP53 mutations remains to be clarified.
Tbx2 Directly Represses the Expression of the p21WAF1 Cyclin-Dependent Kinase Inhibitor
Authors: Prince Sharon , Carreira Suzanne , Vance Keith W. , Abrahams Amaal , Goding Colin R.
Published: September 2005

T-box factors play a crucial role in the development of many tissues, and mutations in T-box factor genes have been implicated in multiple human disorders. Some T-box factors have been implicated in cancer; for example, Tbx2 and Tbx3 can suppress replicative senescence, whereas Tbx3 can cooperate with Myc and Ras in cellular transformation. The p21WAF1 cyclin-dependent kinase inhibitor plays a key role in senescence and in cell cycle arrest after DNA damage. Here, using a combination of in vitro DNA-binding, transfection, and chromatin immunoprecipitation assays, we show that Tbx2 can bind and repress the p21 promoter in vitro and in vivo. Moreover, small interfering RNA-mediated down-regulation of Tbx2 expression results in a robust activation of p21 expression. Taken together, these results implicate Tbx2 as a novel direct regulator of p21 expression and have implications for our understanding of the role of T-box factors in the regulation of senescence and oncogenesis, as well as in development.
An Integrated View of Copy Number and Allelic Alterations in the Cancer Genome Using Single Nucleotide Polymorphism Arrays
Authors: Zhao Xiaojun , Li Cheng , Paez J. Guillermo , Chin Koei , Jänne Pasi A. , Chen Tzu-Hsiu , Girard Luc , Minna John , Christiani David , Leo Chris , Gray Joe W. , Sellers William R. , Meyerson Matthew
Published: September 2005

Changes in DNA copy number contribute to cancer pathogenesis. We now show that high-density single nucleotide polymorphism (SNP) arrays can detect copy number alterations. By hybridizing genomic representations of breast and lung carcinoma cell line and lung tumor DNA to SNP arrays, and measuring locus-specific hybridization intensity, we detected both known and novel genomic amplifications and homozygous deletions in these cancer samples. Moreover, by combining genotyping with SNP quantitation, we could distinguish loss of heterozygosity events caused by hemizygous deletion from those that occur by copy-neutral events. The simultaneous measurement of DNA copy number changes and loss of heterozygosity events by SNP arrays should strengthen our ability to discover cancer-causing genes and to refine cancer diagnosis.
Identification of Aryl Hydrocarbon Receptor as a Putative Wnt/β-Catenin Pathway Target Gene in Prostate Cancer Cells
Authors: Chesire Dennis R. , Dunn Thomas A. , Ewing Charles M. , Luo Jun , Isaacs William B.
Published: September 2005

Recent genetic and functional analyses have implicated the wnt/β-catenin signaling pathway in prostate cancer (CaP) pathogenesis. Thus, there is much interest in understanding the consequences of wnt signaling in CaP; target gene expression is one important area of inquiry and is the focus of this report. Adenoviral-mediated overexpression of a mutant, hyperactive form of β-catenin in CWR22-Rv1 CaP cells led to increased aryl hydrocarbon receptor (AhR, or dioxin receptor) and transmembrane protein 2 RNA transcript expression, as detected by cDNA-microarray analyses. Validating these results, reverse transcription-PCR assays demonstrated that in CWR22-Rv1 cells as well as in LAPC-4 CaP cells, increased putative target gene RNA expression occurs with transient overexpression of mutant β-catenin, treatment of cells with lithium chloride, or with wnt3a-conditioned medium, three distinct modes of experimental wnt/β-catenin pathway activation. This β-catenin-associated expression of AhR and transmembrane protein 2 does not require de novo protein synthesis and may only involve a certain subset of CaP cell lines. Western and immunofluorescence analyses were undertaken to assess the relationship between the wnt/β-catenin-stimulated increase in AhR transcripts and AhR protein expression; we provide evidence that an association exists whereby up-regulation of AhR RNA by wnt or β-catenin is coupled with augmented AhR protein levels. Intriguingly, these studies also demonstrated that nuclear β-catenin staining may not be a sole deciding factor when predicting the status of wnt/β-catenin signaling in CaP cells. Finally, the extent to which wnt signaling may synergize with an environmental agonist of AhR (2,3,7,8-tetrachlorodibenzo-p-dioxin) to potentiate AhR transcriptional activity was examined. Considering previous work linking AhR to processes of development and carcinogenesis, our data may highlight one particular role for wnt/β-catenin signaling in prostate tumor biology.
Selective Estrogen Receptor Modulators
Authors: Frasor Jonna , Stossi Fabio , Danes Jeanne M. , Komm Barry , Lyttle C. Richard , Katzenellenbogen Benita S.
Published: September 2005

Selective estrogen receptor modulators (SERMs) such as tamoxifen are effective in the treatment of many estrogen receptor-positive breast cancers and have also proven to be effective in the prevention of breast cancer in women at high risk for the disease. The comparative abilities of tamoxifen versus raloxifene in breast cancer prevention are currently being compared in the Study of Tamoxifen and Raloxifene trial. To better understand the actions of these compounds in breast cancer, we have examined their effects on the expression of ∼12,000 genes, using Affymetrix GeneChip microarrays, with quantitative PCR verification in many cases, categorizing their actions as agonist, antagonist, or partial agonist/antagonist. Analysis of gene stimulation and inhibition by the SERMs trans-hydroxytamoxifen (TOT) and raloxifene (Ral) or ICI 182,780 (ICI) and by estradiol (E2) in estrogen receptor-containing MCF-7 human breast cancer cells revealed that (a) TOT was the most E2-like of the three compounds, (b) all three compounds either partially or fully antagonized the action of E2 on most genes, with the order of antagonist activity being ICI > Ral > TOT, (c) TOT and Ral, but not ICI, displayed partial agonist/partial antagonist activity on a number of E2-regulated genes, (d) several stimulatory cell cycle-related genes were down-regulated exclusively by ICI, (e) the estrogen-like activity of Ral nearly always overlapped with that of TOT, indicating that Ral has little unique agonist activity different from that of TOT, and (f) some genes were specifically up-regulated by TOT but not Ral, ICI, or E2. Hence, gene expression profiling can discern fundamental differences among SERMs and provides insight into the distinct biologies of TOT, Ral, and ICI in breast cancer.
Menin Inactivation Leads to Loss of Transforming Growth Factor β Inhibition of Parathyroid Cell Proliferation and Parathyroid Hormone Secretion
Authors: Sowa Hideaki , Kaji Hiroshi , Kitazawa Riko , Kitazawa Sohei , Tsukamoto Tatsuo , Yano Shozo , Tsukada Toshihiko , Canaff Lucie , Hendy Geoffrey N. , Sugimoto Toshitsugu , Chihara Kazuo
Published: September 2005

Primary hyperparathyroidism is a common endocrine disorder caused by parathyroid gland enlargement and excessive parathyroid hormone (PTH) secretion. However, the precise mechanisms of tumorigenesis of the parathyroids are unknown. Here we have investigated the roles of transforming growth factor (TGF)-β and menin, the product of the multiple endocrine neoplasia type 1 (Men1) gene, in the proliferation and PTH production of parathyroid cells from either patients with secondary hyperparathyroidism or Men1. TGF-β was expressed in the parathyroid endocrine cells. Addition of TGF-β to parathyroid cells from patients with secondary hyperparathyroidism inhibited their proliferation and PTH secretion. These responses to TGF-β were lost when menin was specifically inactivated by antisense oligonucleotides. Moreover, TGF-β did not affect the proliferation and PTH production of parathyroid cells from a Men1 patient. These results indicate that menin is required for TGF-β action in the parathyroid. We conclude that TGF-β is an important autocrine/paracrine negative regulator of parathyroid cell proliferation and PTH secretion and that loss of TGF-β signaling due to menin inactivation contributes to parathyroid tumorigenesis.
Survival Efficacy of Adjuvant Cytosine-Analogue CS-682 in a Fluorescent Orthotopic Model of Human Pancreatic Cancer
Authors: Katz Matthew H. , Bouvet Michael , Takimoto Shinako , Spivack Daniel , Moossa Abdool R. , Hoffman Robert M.
Published: September 2005

Adjuvant treatment with the cytosine analogue 1-(2-C-cyano-2-deoxy-β-d-arabino-pentofuranosyl)-N4-palmitoylcytosine (CS-682) results in a highly significant increase in survival in the aggressive orthotopic MIA-PaCa-2 human pancreatic cancer mouse model. Seven days after implantation, mice were randomized into eight groups, depending on whether they were to be treated by tumor resection, 5 weeks of CS-682 chemotherapy at 40–60 mg/kg once daily, or both. Throughout the course of treatment, noninvasive optical whole-body imaging based on brilliant red fluorescent protein expression of the tumor permitted visualization and quantification of primary, metastatic, and recurrent disease. Total tumor burden negatively correlated with survival. Untreated mice died of disseminated disease with a median survival of 26 days. Surgical resection alone conferred a small but significant survival advantage (median survival, 28 days, P = 0.03). Primary CS-682 treatment at all doses also significantly prolonged survival compared with untreated animals (P < 0.05) and was more effective than surgery alone at doses of 50 and 60 mg/kg (median survival, 34 days, P = 0.045, and 38.5 days, P = 0.03, respectively). Maximal survival (median, 48 days, with 30% of animals surviving longer than 60 days) was achieved by adjuvant CS-682 (50 mg/kg), given after surgical resection of the primary pancreatic tumor (P = 0.004 compared with surgery alone). The results demonstrate that adjuvant oral administration of CS-682 for pancreatic cancer is highly effective with acceptable toxicity, suggesting its potential for cure of this disease in appropriate combinations.
Impact of Types of Lymphocyte Chromosomal Aberrations on Human Cancer Risk
Authors: Hagmar Lars , Strömberg Ulf , Bonassi Stefano , Hansteen Inger-Lise , Knudsen Lisbeth Ehlert , Lindholm Carita , Norppa Hannu
Published: September 2005

The frequency of cells with structural chromosomal aberrations (CAs) in peripheral blood lymphocytes is the first genotoxicity biomarker that has shown an association with cancer risk. CAs are usually divided into chromosome-type (CSAs) and chromatid-type aberrations (CTAs), with different mechanisms of formation. From a mechanistic point of view, it is of interest to clarify whether the cancer predictivity of CAs is different with respect to CSAs and CTAs. We report here cancer risk for cytogenetically tested, healthy subjects with respect to frequency of CAs, CSAs, and CTAs in peripheral blood lymphocytes, using Nordic (1981 subjects with CA data, 1871 subjects with CSA/CTA data) and Italian (1573 subjects with CA data, 877 subjects with CTA/CSA data) cohorts, with a median follow-up of 17 years. High levels of CAs at test were clearly associated with increased total cancer incidence in the Nordic cohorts and increased total cancer mortality in the Italian cohort. In the Nordic cohorts, significantly elevated cancer risks were observed for subjects with both high CSAs and high CTAs at test, and these variables showed equally strong cancer predictivity. The results of the Italian cohort did not indicate any clear-cut difference in cancer predictivity between the CSA and CTA biomarkers. There was no significant effect modification by age at test, gender, country, or time since test. The results suggest that both DNA double-strand breaks and other initial DNA lesions responsible for CSAs and CTAs are associated with cancer risk.
An Increase in the Expression of Ribonucleotide Reductase Large Subunit 1 Is Associated with Gemcitabine Resistance in Non-Small Cell Lung Cancer Cell Lines
Authors: Davidson Jennifer D. , Ma Liandong , Flagella Michael , Geeganage Sandaruwan , Gelbert Lawrence M. , Slapak Christopher A.
Published: September 2005

The mechanisms of resistance to the antimetabolite gemcitabine in non-small cell lung cancer have not been extensively evaluated. In this study, we report the generation of two gemcitabine-selected non-small cell lung cancer cell lines, H358-G200 and H460-G400. Expression profiling results indicated that there was evidence for changes in the expression of 134 genes in H358-G200 cells compared with its parental line, whereas H460-G400 cells exhibited 233 genes that appeared to be under- or overexpressed compared with H460 cells. However, only the increased expression of ribonucleotide reductase subunit 1 (RRM1), which appeared in both resistant cell lines, met predefined analysis criteria for genes to investigate further. Quantitative PCR analysis demonstrated H358-G200 cells had a greater than 125-fold increase in RRM1 RNA expression. Western blot analysis confirmed high levels of RRM1 protein in this line compared with the gemcitabine-sensitive parent. No significant change in the expression of RRM2 was observed in either cell line, although both gemcitabine-resistant cell lines had an approximate 3-fold increase in p53R2 protein. A partial revertant of H358-G200 cells had reduced levels of RRM1 protein (compared with G200 cells), without observed changes in RRM2 or p53R2. In vitro analyses of ribonucleotide reductase activity demonstrated that despite high levels of RRM1 protein, ribonucleotide reductase activity was not increased in H358-G200 cells when compared with parental cells. The cDNA encoding RRM1 from H358-G200 cells was cloned and sequenced but did not reveal the presence of any mutations. The results from this study indicate that the level of RRM1 may affect gemcitabine response. Furthermore, RRM1 may serve as a biomarker for gemcitabine response.
Differential Activation of the Phosphatidylinositol 3′-Kinase/Akt Survival Pathway by Ionizing Radiation in Tumor and Primary Endothelial Cells
Authors: Zingg Daniel , Riesterer Oliver , Fabbro Doriano , Glanzmann Christoph , Bodis Stephan , Pruschy Martin
Published: September 2005

Ionizing radiation induces an intracellular stress response via activation of the phosphatidylinositol 3′-kinase (PI3K)/Akt survival pathway. In tumor cells, the PI3K/Akt pathway is induced through activation of members of ErbB receptor tyrosine kinases. Here, we investigated the receptor dependence of radiation-induced PI3K/Akt activation in tumor cells and in endothelial cells. The integrity of both the ErbB and the vascular endothelial growth factor (VEGF) ligand-activated PI3K/Akt pathway in endothelial cells was demonstrated using specific ErbB and VEGF receptor tyrosine kinase inhibitors. Irradiation of endothelial cells resulted in protein kinase B (PKB)/Akt activation in a similar time course as observed in response to VEGF. More importantly, radiation-induced PKB/Akt phosphorylation in endothelial cells was strongly down-regulated by the VEGF receptor tyrosine kinase inhibitor, whereas the ErbB receptor tyrosine kinase inhibitor did not affect PKB/Akt stimulation in response to irradiation. An opposite receptor dependence for radiation-induced PKB/Akt phosphorylation was observed in ErbB receptor-overexpressing A431 tumor cells. Furthermore, direct VEGF receptor phosphorylation was detected after irradiation in endothelial cells in absence of VEGF, which was almost completely inhibited after irradiation in presence of the VEGF receptor tyrosine kinase inhibitor. These data demonstrate that ionizing radiation induces VEGF ligand-independent but VEGF receptor-dependent PKB/Akt activation in endothelial cells and that PI3K/Akt pathway activation by radiation occurs in a differential cell type and receptor-dependent pattern.
A Genetically Defined Model for Human Ovarian Cancer
Authors: Liu Jinsong , Yang Gong , Thompson-Lanza Jennifer A. , Glassman Armand , Hayes Kimberly , Patterson Andrea , Marquez Rebecca T. , Auersperg Nelly , Yu Yinhua , Hahn William C. , Mills Gordon B. , Bast Robert C.
Published: September 2005

Disruptions of the p53, retinoblastoma (Rb), and RAS signaling pathways and activation of human telomerase reverse transcriptase (hTERT) are common in human ovarian cancer; however, their precise role in ovarian cancer development is not clear. We thus introduced the catalytic subunit of hTERT, the SV40 early genomic region, and the oncogenic alleles of human HRAS or KRAS into human ovarian surface epithelial cells and examined the phenotype and gene expression profile of those cells. Disruption of p53 and Rb pathway by SV40 early genomic region and hTERT immortalized but did not transform the cells. Introduction of HRASV12 or KRASV12 into the immortalized cells, however, allowed them to form s.c. tumors after injection into immunocompromised mice. Peritoneal injection of the transformed cells produced undifferentiated carcinoma or malignant mixed Mullerian tumor and developed ascites; the tumor cells are focally positive for CA125 and mesothelin. Gene expression profile analysis of transformed cells revealed elevated expression of several cytokines, including interleukin (IL)-1β, IL-6, and IL-8, that are up-regulated by the nuclear factor-κB pathway, which is known to contribute to the tumor growth of naturally ovarian cancer cells. Incubation with antibodies to IL-1β or IL-8 led to apoptosis in the ras-transformed cells and ovarian cancer cells but not in immortalized cells that had not been transformed. Thus, the transformed human ovarian surface epithelial cells recapitulated many features of natural ovarian cancer including a subtype of ovarian cancer histology, formation of ascites, CA125 expression, and nuclear factor-κB-mediated cytokine activation. These cells provide a novel model system to study human ovarian cancer.
T-bet Regulates Metastasis Rate in a Murine Model of Primary Prostate Cancer
Authors: Peng Stanford L. , Townsend Michael J. , Hecht Jonathan L. , White Ian A. , Glimcher Laurie H.
Published: September 2005

The local progression of primary tumors is extrinsically controlled by type 1 immune responses, particularly via the cytokine IFN-γ, whose secretion is highly dependent on helper T cells. The T-box transcription factor T-bet (Tbx21) plays a critical role in the development of type 1 helper T cells and is essential for the production of IFN-γ. Here, the T-bet pathway in the autochthonous transgenic adenocarcinoma mouse prostate model is demonstrated to have only a modest effect on the characteristics of primary prostate cancers but rather exerts a significant suppressor function in the development of metastatic disease.
Distinct Responses of Xenografted Gliomas to Different Alkylating Agents Are Related to Histology and Genetic Alterations
Authors: Leuraud Pascal , Taillandier Luc , Medioni Jacques , Aguirre-Cruz Lucinda , Crinière Emmanuelle , Marie Yannick , Kujas Michèle , Golmard Jean-Louis , Duprez Adrien , Delattre Jean-Yves , Sanson Marc , Poupon Marie-France
Published: September 2005

A series of 12 human gliomas was established as xenografts in nude mice and used to evaluate the relationship between histology, genetic parameters, and response to alkylating agents. Eight were high-grade oligodendroglial tumors, and four were glioblastoma. They were characterized for their genetic alterations, including those considered as “early” alterations, namely loss of chromosome 1 ± loss of chromosome 19q, TP53 mutation, and those considered as “late” alterations, namely loss of chromosome 10, loss of chromosome 9p, EGFR genomic amplification, PTEN mutation, CDKN2A homozygous deletion, and telomerase reactivation. Chemosensitivity of xenografts to four alkylating agents, temozolomide (42 mg/kg, days 1–5, p.o.), 1,3-bis(2-chloroethyl)-1-nitrosourea (5 mg/kg, day 1, i.p.), Ifosfamide (90 mg/kg, days 1–3, i.p.), and carboplatin (66 mg/kg, day 1, i.p.) was tested by administration of drugs to tumor-bearing mice. Although each tumor presented an individual response pattern, glioblastoma had a lower chemosensitivity than oligodendrogliomas, and temozolomide was the most effective drug. Deletion of 1p ± 19q was associated with higher chemosensitivity, whereas late molecular alterations, particularly EGFR amplification, were associated with chemoresistance. These results suggest that the combined use of histology and molecular markers should eventually be helpful selecting the most appropriate agents for treatment of malignant oligodendrogliomas and astrocytomas.
Induction of Melanoma Phenotypes in Human Skin by Growth Factors and Ultraviolet B
Authors: Berking Carola , Takemoto Richelle , Satyamoorthy Kapaettu , Shirakawa Takahashi , Eskandarpour Malihe , Hansson Johan , VanBelle Patricia A. , Elder David E. , Herlyn Meenhard
Published: September 2005

Exposure to UV radiation likely plays a key role in melanoma development, whereas other etiologic agents remain unknown. Here we show that in normal human skin an increased expression of a combination of three growth factors, basic fibroblast growth factor, stem cell factor, and endothelin-3, along with exposure to UVB can transform normal melanocytes into a melanoma phenotype within 4 weeks. Invasion of melanoma lesions was found in skin from newborn donors, whereas melanomas in adult skin were of a noninvasive in situ type only. This suggests that susceptibility of skin to exogenous tumor promoters is dependent on age. This is the first report on human cancer initiation in vivo in which an imbalance of physiological factors combined with an environmental carcinogen can lead to transformation of normal tissue.
Vaccination by Genetically Modified Dendritic Cells Expressing a TruncatedneuOncogene Prevents Development of Breast Cancer in Transgenic Mice
Authors: Sakai Yoshio , Morrison Brian J. , Burke J. Douglas , Park Jong-Myun , Terabe Masaki , Janik John E. , Forni Guido , Berzofsky Jay A. , Morris John C.
Published: September 2005

Dendritic cells (DCs) are powerful antigen-presenting cells that process antigens and present peptide epitopes in the context of the major histocompatibility complex molecules to generate immune responses. DCs are being studied as potential anticancer vaccines because of their ability to present antigens to naïve T cells and to stimulate the expansion of antigen-specific T-cell populations. We investigated an antitumor vaccination using DCs modified by transfer of a nonsignaling neu oncogene, a homologue of human HER-2/neu, in a transgenic model of breast cancer. BALB-neuT mice develop breast cancers as a consequence of mammary gland-specific expression of an activated neu oncogene. We vaccinated BALB-neuT mice with bone marrow-derived DCs transduced with Ad.Neu, a recombinant adenovirus expressing a truncated neu oncoprotein. The vaccine stimulated the production of specific anti-neu antibodies, enhanced interferon-γ expression by T cells, and prevented or delayed the onset of mammary carcinomas in the mice. Over 65% of vaccinated mice remained tumor free at 28 weeks of age, whereas all of the mice in the control groups developed tumors. When challenged with a neu-expressing breast cancer cell line, vaccinated tumor-free animals had delayed tumor growth compared with controls. The antitumor effect of the vaccine was specific for expression of neu. Studies showed that CD4+ T cells were required in order to generate antitumor immunity. Importantly, the effectiveness of the vaccine was not diminished by preexisting immunity to adenovirus, whereas the protection afforded by vaccination that used direct injection of Ad.Neu was markedly reduced in mice with anti-adenovirus antibody titers. DCs modified by recombinant adenoviruses expressing tumor-associated antigens may provide an effective antitumor vaccination strategy.
Activation of Akt-1 (PKB-α) Can Accelerate ErbB-2-Mediated Mammary Tumorigenesis but Suppresses Tumor Invasion
Authors: Hutchinson John N. , Jin Jing , Cardiff Robert D. , Woodgett Jim R. , Muller William J.
Published: September 2005

Elevated expression of Akt-1 (PKBα) has been noted in a significant percentage of primary human breast cancers. Another frequent event in the genesis of human breast cancers is amplification and overexpression of the ErbB-2 receptor tyrosine kinase, an event which is associated with activation of Akt-1. To directly assess the importance of Akt-1 activation in ErbB-2 mammary tumor progression, we interbred separate strains of transgenic mice carrying mouse mammary tumor virus/activated Akt-1 and mouse mammary tumor virus/activated ErbB-2 to derive progeny that coexpress the transgenes in the mammary epithelium. Female transgenic mice coexpressing activated Akt-1 and ErbB-2 develop multifocal mammary tumors with a significantly shorter latency period than mice expressing activated ErbB-2 alone. This dramatic acceleration of mammary tumor progression correlates with enhanced cellular proliferation, elevated Cyclin D1 protein levels, and phosphorylation of retinoblastoma protein. These bitransgenic mammary tumors also exhibit lower levels of invasion into the surrounding tissue and more differentiated phenotypes. Consistent with these observations, female mice coexpressing activated Akt-1 and ErbB-2 developed significantly fewer metastatic lesions than the activated ErbB-2 strain alone. Taken together, these observations suggest that activation of Akt-1 during ErbB-2-induced mammary tumorigenesis may have opposing effects on tumor growth and metastatic progression.
Ultraviolet Irradiation Represses
PATCHED
Gene Transcription in Human Epidermal Keratinocytes through an Activator Protein-1-Dependent Process
Authors: Brellier Florence , Marionnet Claire , Chevallier-Lagente Odile , Toftgard Rune , Mauviel Alain , Sarasin Alain , Magnaldo Thierry
Published: September 2005

Basal cell carcinoma (BCC) is one of the major types of skin cancer arising from keratinocytes. The SONIC HEDGEHOG pathway is deregulated in 100% of sporadic BCCs, as indicated by the overexpression of PATCHED, whose product encodes the receptor of SONIC HEDGEHOG, in 100% of analyzed BCCs. Reverse transcription-PCR analysis revealed that exposure to UVB irradiation, which is a risk factor known to contribute to BCC development, induces a strong and sharp decrease of PATCHED mRNA level both in vitro and ex vivo. Transcription of a reporter gene driven by the 4.4-kb 5′-regulatory region of the human PATCHED gene was shown to be down-regulated after UVB irradiation. Furthermore, overexpression of c-JUN, a member of the activator protein (AP)-1 family, induced repression of the PATCHED promoter. The role of AP-1 in UVB-induced PATCHED repression was confirmed in mouse embryonic fibroblasts knocked out for c-JUN NH2-terminal protein kinase. This study thus provides the first evidence of UV-induced down-regulation at the transcriptional level of the BCC-associated tumor suppressor PATCHED relying on activation of the AP-1 oncogenic pathway.
Androgen Receptor Signaling
Authors: Jia Li , Choong Catherine S-Y. , Ricciardelli Carmela , Kim Joshua , Tilley Wayne D. , Coetzee Gerhard A
Published: September 2005

Nonsteroidal signaling via the androgen receptor (AR) plays an im-portant role in hormone-refractory prostate cancer. Previously, we have reported that the pleiotropic cytokine, interleukin (IL)-6, inhibited dihydrotestosterone-mediated expression of prostate-specific antigen in LNCaP cells (Jia et al., Mol Can Res 2003;1:385–92). In the present study, we explored the mechanisms involved in this inhibition and considered possible effects on AR nuclear translocation, recruitment of transcription cofactors, and the signaling pathways that may mediate this inhibitory effect. IL-6 neither induced nuclear localization of the AR nor inhibited dihydrotestosterone-induced nuclear translocation of the receptor. IL-6 did not affect AR or p160 coactivator recruitment to the transcription initiation complex on the prostate-specific antigen enhancer and promoter. Moreover, it did not lead to the recruitment of the corepressor silencing mediator of retinoic acid and thyroid hormone receptor (SMRT) or histone deacetylase 1 (HDAC1) at the same sites. IL-6 did, however, prevent the recruitment of the secondary coactivator, p300, to the complex and partially inhibited histone H3 acetylation at the same loci. Furthermore, inhibition by IL-6 was not mediated by the mitogen-activated protein kinase or the Akt pathways and was partially abrogated by signal transducers and activators of transcription-3 knock-down using small interfering RNA. Our results show that IL-6 modulates androgen action through the differential recruitment of cofactors to target genes. These findings may account for the pleiotropic actions of IL-6 in malignant prostate cells.
Extensive Chromosomal Breaks Are Induced by Tamoxifen and Estrogen in DNA Repair-Deficient Cells
Authors: Mizutani Aki , Okada Takashi , Shibutani Shinya , Sonoda Eiichiro , Hochegger Helfrid , Nishigori Chikako , Miyachi Yoshiki , Takeda Shunichi , Yamazoe Mitsuyoshi
Published: September 2005

Tamoxifen (TAM) possesses antiestrogen activity and is widely used for the treatment or prevention of breast cancer. However, it is also carcinogenic in human uterus and rat liver, highlighting the profound complexity of its actions. To explore the molecular mechanisms of TAM-induced mutagenesis, we analyzed the effects of this drug on gene-disrupted chicken B lymphocyte (DT40) clones deficient in various DNA repair pathways. Rad18, Rev3, and Polκ are involved in translesion DNA synthesis (TLS), which facilitates recovery from replication blocks on damaged template strands. DT40 cells deficient in TLS were found to be hypersensitive to TAM, exhibiting an increase in chromosomal breaks. Furthermore, these mutants were also hypersensitive to 4-hydroxyestradiol, a physiological metabolite of estrogen. These data suggest a contribution of TLS to the prevention of chromosomal breaks by TAM and estrogen, and they therefore indicate that such error-prone DNA synthesis underlies mutagenesis induced by these agents.
Genetic Polymorphisms in the
TGF-
β
1
Gene and Breast Cancer Survival
Authors: Shu Xiao-Ou , Gao Yu-Tang , Cai Qiuyin , Pierce Larry , Cai Hui , Ruan Zhi-Xian , Yang Gong , Jin Fan , Zheng Wei
Published: September 2005

The effect of genetic polymorphisms in the TGF-β1 gene at codon 10 (T+29C), codon 25 (G+74C), and the promoter region [C → T at −509 from the transcription site, (C-509T)] on breast cancer survival was evaluated among a cohort of 1111 patients. The median follow-up time for the cohort was 5.17 years after cancer diagnosis. No DNA sequence variation at codon 25 of the TGF-β1 gene was found, whereas polymorphisms in C-509T and T+29C were in strong linkage disequilibrium. Patients who carried the C allele of T+29C polymorphism had a reduced 5-year disease-free survival rate (75.6% for T/C, and 78.2% for C/C) compared with the T/T genotype (85.1%; P, 0.04); the age-adjusted hazard ratio was 1.5 (95% confidence interval, 1.1–2.2). Adjustment for clinical prognostic factors slightly attenuated the association (hazard ratio, 1.4, 95% confidence interval, 1.0–1.9). Our study suggests that genetic polymorphisms in the TGF-β1 gene may play a role in breast cancer progression.
Activation of Signal Transducer and Activator of Transcription 5 in Human Prostate Cancer Is Associated with High Histological Grade
Authors: Li Hongzhen , Ahonen Tommi J. , Alanen Kalle , Xie Jianwu , LeBaron Matthew J. , Pretlow Thomas G. , Ealley Erica L. , Zhang Ying , Nurmi Martti , Singh Baljit , Martikainen Paula M. , Nevalainen Marja T.
Published: September 2005

We have recently identified signal transducer and activator of transcription 5 (Stat5) as a critical survival factor for prostate cancer cells. We now report that activation of Stat5 is associated with high histological grade of human prostate cancer. Specifically, immunohistochemical analysis demonstrated a strong positive correlation with activation of Stat5 and high Gleason score in 114 human prostate cancers. To investigate the mechanisms underlying constitutive activation of Stat5 in prostate cancer, a dominant-negative mutant of Janus kinase 2 (Jak2) was delivered by adenovirus to CWR22Rv cells. Dominant-negative-Jak2 effectively blocked the activation of Stat5 whereas wild-type Jak2 enhanced activation, indicating that Jak2 is the main kinase that phosphorylates Stat5 in human prostate cancer cells. A ligand-induced mechanism for activation of Stat5 in prostate cancer was suggested by the ability of prolactin (Prl) to stimulate activation of both Jak2 and Stat5 in CWR22Rv human prostate cancer cells and in CWR22Rv xenograft tumors. In addition, Prl restored constitutive activation of Stat5 in five of six human prostate cancer specimens in ex vivo long-term organ cultures. Finally, Prl protein was locally expressed in the epithelium of 54% of 80 human prostate cancer specimens with positive correlation with high Gleason scores and activation of Stat5. In conclusion, our data indicate that increased activation of Stat5 was associated with more biologically aggressive behavior of prostate cancer. The results further suggest that Jak2 is the principal Stat5 tyrosine kinase in human prostate cancer, possibly activated by autocrine/paracrine Prl.
Inhibition of the Raf–MEK1/2–ERK1/2 Signaling Pathway, Bcl-xL Down-Regulation, and Chemosensitization of Non-Hodgkin’s Lymphoma B Cells by Rituximab
Authors: Jazirehi Ali R. , Vega Mario I. , Chatterjee Devasis , Goodglick Lee , Bonavida Benjamin
Published: September 2005

Rituximab (Rituxan, IDEC-C2B8) has been shown to sensitize non-Hodgkin’s lymphoma (NHL) cell lines to chemotherapeutic drug-induced apoptosis. Rituximab treatment of Bcl-2–deficient Ramos cells and Bcl-2–expressing Daudi cells selectively decreases Bcl-xL expression and sensitizes the cells to paclitaxel-induced apoptosis. This study delineates the signaling pathway involved in rituximab-mediated Bcl-xL down-regulation in Ramos and Daudi NHL B cells. We hypothesized that rituximab may interfere with the extracellular signal-regulated kinase (ERK) 1/2 pathway, leading to decreased Bcl-xL expression. Rituximab (20 μg/mL) inhibited the kinase activity of mitogen-activated protein kinase kinase (MEK) 1/2 and reduced the phosphorylation of the components of the ERK1/2 pathway (Raf-1, MEK1/2, and ERK1/2) and decreased activator protein-1 DNA binding activity and Bcl-xL gene expression. These events occurred with similar kinetics and were observed 3 to 6 hours after rituximab treatment. Rituximab-mediated effects were corroborated by using specific inhibitors of the ERK1/2 pathway, which also reduced Bcl-xL levels and sensitized the NHL B cells to paclitaxel-induced apoptosis. Previous findings implicated a negative regulatory role of the Raf-1 kinase inhibitor protein (RKIP) on the ERK1/2 pathway. Rituximab treatment of NHL B cells significantly up-regulated RKIP expression, thus interrupting the ERK1/2 signaling pathway through the physical association between Raf-1 and RKIP, which was concomitant with Bcl-xL down-regulation. These novel findings reveal a signaling pathway triggered by rituximab, whereby rituximab-mediated up-regulation of RKIP adversely regulates the activity of the ERK1/2 pathway, Bcl-xL expression, and subsequent chemosensitization of drug-refractory NHL B cells. The significance of these findings is discussed.
Identification of Genes Uniquely Involved in Frequent Microsatellite Instability Colon Carcinogenesis by Expression Profiling Combined with Epigenetic Scanning
Authors: Mori Yuriko , Yin Jing , Sato Fumiaki , Sterian Anca , Simms Lisa A. , Selaru Florin M. , Schulmann Karsten , Xu Yan , Olaru Andreea , Wang Suna , Deacu Elena , Abraham John M. , Young Joanne , Leggett Barbara A. , Meltzer Stephen J.
Published: September 2005

Gene silencing through CpG island hypermethylation has been associated with genesis or progression of frequent microsatellite instability (MSI-H) cancers. To identify novel methylation sites unique to MSI-H colon cancers in an unbiased fashion, we conducted a global expression profiling-based methylation target search. We identified 81 genes selectively down-regulated in MSI-H cancers using cDNA microarray analysis of 41 primary colon cancers. Forty six of these 81 genes contained CpG islands overlapping their 5′untranslated regions. Initial screening of six genes in 57 primary colon cancers detected the following gene with MSI-H cancer-specific hypermethylation: RAB32, a ras family member and A-kinase-anchoring protein, was methylated in 14 of 25 (56%) MSI-H cancers but in none of 32 non-MSI-H cancers or 23 normal colonic specimens. RAB32 hypermethylation correlated with RAB32 mRNA down-regulation and with hMLH1 hypermethylation. In addition, the protein-tyrosine phosphatase receptor type Ogene, PTPRO, was frequently methylated in right-sided tumors. This methylation screening strategy should identify additional genes inactivated by epigenetic silencing in colorectal and other cancers.
Inducible Release of TRAIL Fusion Proteins from a Proapoptotic Form for Tumor Therapy
Authors: Shah Khalid , Tung Ching-Hsuan , Yang Katherine , Weissleder Ralph , Breakefield Xandra O.
Published: September 2005

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can selectively kill neoplastic cells and control of its activity could enhance tumor therapy. We have developed means to control the secretion of a novel recombinant (r) TRAIL fusion protein using a viral protease. This system uses the endoplasmic reticulum (ER) as a storage depot for rTRAIL, because TRAIL acts by binding to its cognate receptors on the cell surface. We have engineered two TRAIL variants: (a) a secretable form that enhances apoptosis via a bystander effect; and (b) an ER-targeted TRAIL that is retained in the ER until selectively released by the viral protease. Gene delivery can be monitored in vivo by systemic administration of a near infrared fluorescent (NIRF) probe activated by the protease. This study serves as a template for design of recombinant proteins to enhance and control apoptosis of tumor cells via specific viral proteases and for use of viral proteases as in vivo reporters for cancer therapy.
Ubiquitination and Proteasomal Degradation of Nucleophosmin-Anaplastic Lymphoma Kinase Induced by 17-Allylamino-Demethoxygeldanamycin
Authors: Bonvini Paolo , Rosa Henry Dalla , Vignes Nadia , Rosolen Angelo
Published: September 2005

Nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) is a constitutively active fusion tyrosine kinase involved in lymphomagenesis of human anaplastic large cell lymphomas (ALCL), the maturation and activity of which depend on the association with the heat shock protein (hsp) 90 protein chaperone. Targeting hsp90 by the ansamycins geldanamycin and 17-allyl-amino-demethoxygeldanamycin (17-AAG) promotes degradation of several proteins through the ubiquitin-proteasome pathway, including oncogenic Raf, v-Src, erbB2, and BCR-ABL. We have previously shown that 17-AAG prevents hsp90/NPM-ALK complex formation and fosters NPM-ALK turnover, perhaps through its association with the hsp70 chaperone. Here, we show that inhibition of the proteasome activity by the potent and specific compound pyrazylcarbonyl-Phe-Leu-boronate (PS-341) blocks 17-AAG-induced down-regulation of NPM-ALK, which becomes detergent-insoluble and relocates into ubiquitin-rich perinuclear vesicles that represent aggregated polyubiquitinated forms of the protein. Kinase activity was not mandatory for proteasomal degradation of NPM-ALK, because kinase-defective NPM-ALK was even more rapidly degraded upon 17-AAG treatment. Prolonged exposure to the proteasome inhibitor was shown to trigger caspase-3-mediated apoptosis in proliferating ALCL cells at nanomolar concentrations. However, we verified that the accumulation of detergent-insoluble NPM-ALK in ALCL cells was not a spurious consequence of PS341-committed apoptosis, because caspase inhibitors prevented poly(ADP-ribose) polymerase cleavage whereas they did not affect par-titioning of aggregated NPM-ALK. In line with these observations, the carboxyl hsp70-interacting ubiquitin ligase (CHIP), was shown to increase basal ubiquitination and turnover of NPM-ALK kinase, supporting a mechanism whereby NPM-ALK proceeds rapidly toward hsp70-assisted ubiquitin-dependent proteasomal degradation, when chaperoning activity of hsp90 is prohibited by 17-AAG.
Survivin As a Therapeutic Target for Radiation Sensitization in Lung Cancer
Authors: Lu Bo , Mu Yi , Cao Carolyn , Zeng Fenghua , Schneider Sylke , Tan Jiahui , Price Jim , Chen Jun , Freeman Michael , Hallahan Dennis E.
Published: September 2005

Expression of survivin is elevated in most malignancies, especially in radiation-resistant cell lines. In this study, we investigated how radiation affects survivin expression in primary endothelial cells as well as in malignant cell lines. We found that 3 Gy significantly reduced survivin protein level in human umbilical vein endothelial cells (HUVECs) but not in tumor cell lines. Flow cytometry studies suggest that the down-regulation of survivin is independent of cell cycle. In addition, survivin mRNA level was also down-regulatable by irradiation. However, it was abrogated by actinomycin D-mediated inhibition of gene transcription. Luciferase reporter gene assays suggest that irradiation suppressed the survivin promoter. p53 overexpression reduced survivin expression, but overexpression of a p53 mutant failed to abolish the radiation-induced down-regulation in HUVECs. Alteration of p53 status in Val138 lung cancer cell line also failed to restore the radiation-inducible down-regulation. Overexpression of survivin in 293 cells prevented apoptosis induced by irradiation and increased cell viability after irradiation. The inhibition of survivin using antisense oligonucleotides caused a significant decrease in cell viability of irradiated H460 lung cancer cells. These data suggest that radiation transcriptionally down-regulates survivin in HUVECs. This regulatory mechanism is defective in malignancies and is not mediated by p53. Survivin overexpression may lead to resistance to radiotherapy by inhibiting apoptosis and enhancing cell viability. The inhibition of survivin results in sensitization of H460 lung cancer cells to radiation. These studies suggest that survivin may be a target for cancer therapy.
Lack of Correlation between Expression of HIF-1α Protein and Oxygenation Status in Identical Tissue Areas of Squamous Cell Carcinomas of the Uterine Cervix
Authors: Mayer Arnulf , Wree Alexander , Höckel Michael , Leo Cornelia , Pilch Henryk , Vaupel Peter
Published: September 2005

Hypoxia inducible factor-1α (HIF-1α) has been proposed as a candidate endogenous marker of tumor hypoxia and as a molecular mediator of hypoxia-driven malignant progression and acquired treatment resistance. In this study, HIF-1α expression in 68 biopsies of oxygenation measurement tracks from squamous cell carcinomas of the uterine cervix of 38 patients was assessed. Expression of HIF-1α was commonly found to increase as a function of distance from microvessels, at the center of tumor cell aggregations, and in the vicinity of necrotic areas. However, there was no correlation of HIF-1α expression with median oxygen tension (oxygen partial pressure; pO2) and hypoxic fractions (hypoxic fraction < 2.5 mm Hg, hypoxic fraction < 5 mm Hg). The results indicate that HIF-1α should not be used as an endogenous marker of tumor hypoxia in locally advanced squamous cell carcinomas of the uterine cervix. Additionally, no significant prognostic impact of HIF-1α expression was found in this group of patients.
Identification of a Novel Estrogen Response Element in the
Breast Cancer Resistance Protein
(
ABCG2
) Gene
Authors: Ee Pui Lai Rachel , Kamalakaran Sitharthan , Tonetti Debra , He Xiaolong , Ross Douglas D. , Beck William T.
Published: September 2005

The breast cancer resistance protein (BCRP) is an ATP-binding cassette half transporter that confers resistance to anticancer drugs such as mitoxantrone, anthracyclines, topotecan, and SN-38. Initial characterization of the BCRP promoter revealed that it is TATA-less with 5 putative Sp1 sites downstream from a putative CpG island and several AP1 sites (K. J. Bailey-Dell et al., Biochim. Biophys. Acta, 1520: 234–241, 2001). Here, we examined the sequence of the 5′-flanking region of the BCRP gene and found a putative estrogen response element (ERE). We showed that estrogen enhanced the expression of BCRP mRNA in the estrogen receptor (ER)-positive T47D:A18 cells and PA-1 cells stably expressing ERα. In BCRP promoter-luciferase assays, sequential deletions of the BCRP promoter showed that the region between −243 and −115 is essential for the ER effect. Mutation of the ERE found within this region attenuated the estrogen response, whereas deletion of the site completely abrogated the estrogen effect. Furthermore, electrophoretic mobility shift assays revealed specific binding of ERα to the BCRP promoter through the identified ERE. Taken together, we provide evidence herein for a novel ERE in the BCRP promoter.
Host Stromal Bradykinin B2 Receptor Signaling Facilitates Tumor-Associated Angiogenesis and Tumor Growth
Authors: Ikeda Yasuhiro , Hayashi Izumi , Kamoshita Emi , Yamazaki Akira , Endo Hirahito , Ishihara Keiko , Yamashina Shohei , Tsutsumi Yoshiaki , Matsubara Hiroaki , Majima Masataka
Published: September 2005

We evaluated the significance of the host kallikrein-kinin system in tumor angiogenesis and tumor growth using two rodent models genetically deficient in a kallikrein-kinin system. Inoculation of Walker 256 carcinoma cells into the s.c. tissues of the back of normal Brown Norway Kitasato rats (BN-Ki rats) resulted in the rapid development of solid tumors with marked angiogenesis. By contrast, in kininogen-deficient Brown Norway Katholiek rats (BN-Ka rats), which cannot generate intrinsic bradykinin (BK), the weights of the tumors and the extent of angiogenesis were significantly less than those in BN-Ki rats. Daily administration of B2 receptor antagonists significantly reduced angiogenesis and tumor weights in BN-Ki rats to levels similar to those in BN-Ka rats but did not do so in BN-Ka rats. Angiogenesis and tumor growth were significantly suppressed in B2 receptor knockout mice bearing sarcoma 180 compared with their wild-type counterparts. Immunoreactive vascular endothelial growth factor (VEGF) was localized in Walker tumor stroma more extensively in BN-Ki rats than in BN-Ka rats, although immunoreactive B2 receptor also was detected in the stroma to the same extent in both types of rats. Cultured stromal fibroblasts isolated from BN-Ki rats and BN-Ka rats produced VEGF in response to BK (10−8-10−6 m), and this stimulatory effect of BK was abolished with a B2 receptor antagonist, Hoe140 (10−5 m). These results suggest that BK generated from kininogens supplied from the host may facilitate tumor-associated angiogenesis and tumor growth by stimulating stromal B2 signaling to up-regulate VEGF production mainly in fibroblasts.