bluuebunny/crossref_metadata_2025 huggingface dataset:
Combinational FLt3 Ligand and Granulocyte Macrophage Colony-Stimulating Factor Treatment Promotes Enhanced Tumor Infiltration by Dendritic Cells and Antitumor CD8+ T-Cell Cross-priming but Is Ineffective as a Therapy
Authors: Berhanu Aklile , Huang Jian , Alber Sean M. , Watkins Simon C. , Storkus Walter J.
Published: May 2006

Dendritic cells play significant roles in the development and maintenance of antitumor immune responses. Therapeutic recruitment of dendritic cells into the tumor microenvironment has the potential to result in enhanced antitumor T-cell cross-priming against a broad array of naturally processed and presented tumor-associated antigens. We have observed that the treatment of BALB/c mice bearing syngeneic CMS4 sarcomas with the combination of recombinant Flt3 ligand and recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) for five sequential days is sufficient to optimize the number of tumor-infiltrating dendritic cells (TIDC). However, despite the significant increase in the number of TIDCs, the therapeutic benefit of Flt3 ligand and GM-CSF treatment is minimal. Therapy-associated TIDCs do not exhibit a “suppressed” or “suppressor” phenotype in vitro, and their enhanced numbers in cytokine-treated mice were associated with increased levels of peripheral antitumor CD8+ T effector cells and with an augmented population of CD8+ tumor-infiltrating lymphocytes (TIL). These data suggest that Flt3 ligand + GM-CSF therapy of murine tumors fails at a mechanistic point that is downstream of specific T-cell priming by therapy-induced TIDCs and the recruitment of these T cells into the tumor microenvironment. Based on the enhanced infiltration of tumors by CD4+CD25+ TIL in Flt3 ligand + GM-CSF–treated mice, this could reflect the dominant influence of regulatory T cells in situ. (Cancer Res 2006; 66(9): 4895-903)
Comparative Genome Analysis Identifies the Vitamin D Receptor Gene as a Direct Target of p53-Mediated Transcriptional Activation
Authors: Maruyama Reo , Aoki Fumio , Toyota Minoru , Sasaki Yasushi , Akashi Hirofumi , Mita Hiroaki , Suzuki Hiromu , Akino Kimishige , Ohe-Toyota Mutsumi , Maruyama Yumiko , Tatsumi Haruyuki , Imai Kohzoh , Shinomura Yasuhisa , Tokino Takashi
Published: May 2006

p53 is the most frequently mutated tumor suppressor gene in human neoplasia and encodes a transcriptional coactivator. Identification of p53 target genes is therefore key to understanding the role of p53 in tumorigenesis. To identify novel p53 target genes, we first used a comparative genomics approach to identify p53 binding sequences conserved in the human and mouse genome. We hypothesized that potential p53 binding sequences that are conserved are more likely to be functional. Using stringent filtering procedures, 32 genes were newly identified as putative p53 targets, and their responsiveness to p53 in human cancer cells was confirmed by reverse transcription-PCR and real-time PCR. Among them, we focused on the vitamin D receptor (VDR) gene because vitamin D3 has recently been used for chemoprevention of human tumors. VDR is induced by p53 as well as several other p53 family members, and analysis of chromatin immunoprecipitation showed that p53 protein binds to conserved intronic sequences of the VDR gene in vivo. Introduction of VDR into cells resulted in induction of several genes known to be p53 targets and suppression of colorectal cancer cell growth. In addition, p53 induced VDR target genes in a vitamin D3-dependent manner. Our in silico approach is a powerful method for identification of functional p53 binding sites and p53 target genes that are conserved among humans and other organisms and for further understanding the function of p53 in tumorigenesis. (Cancer Res 2006; 66(9): 4574-83)
Agonist Anti-GITR Antibody Enhances Vaccine-Induced CD8+ T-Cell Responses and Tumor Immunity
Authors: Cohen Adam D. , Diab Adi , Perales Miguel-Angel , Wolchok Jedd D. , Rizzuto Gabrielle , Merghoub Taha , Huggins Deonka , Liu Cailian , Turk Mary Jo , Restifo Nicholas P. , Sakaguchi Shimon , Houghton Alan N.
Published: May 2006

Immunization of mice with plasmids encoding xenogeneic orthologues of tumor differentiation antigens can break immune ignorance and tolerance to self and induce protective tumor immunity. We sought to improve on this strategy by combining xenogeneic DNA vaccination with an agonist anti–glucocorticoid-induced tumor necrosis factor receptor family–related gene (GITR) monoclonal antibody (mAb), DTA-1, which has been shown previously both to costimulate activated effector CD4+ and CD8+ T cells and to inhibit the suppressive activity of CD4+CD25+ regulatory T cells. We found that ligation of GITR with DTA-1 just before the second, but not the first, of 3 weekly DNA immunizations enhanced primary CD8+ T-cell responses against the melanoma differentiation antigens gp100 and tyrosinase-related protein 2/dopachrome tautomerase and increased protection from a lethal challenge with B16 melanoma. This improved tumor immunity was associated with a modest increase in focal autoimmunity, manifested as autoimmune hypopigmentation. DTA-1 administration on this schedule also led to prolonged persistence of the antigen-specific CD8+ T cells as well as to an enhanced recall CD8+ T-cell response to a booster vaccination given 4 weeks after the primary immunization series. Giving the anti-GITR mAb both during primary immunization and at the time of booster vaccination increased the recall response even further. Finally, this effect on vaccine-induced CD8+ T-cell responses was partially independent of CD4+ T cells (both helper and regulatory), consistent with a direct costimulatory effect on the effector CD8+ cells themselves. (Cancer Res 2006; 66(9); 4904-12)
p130Cas as a New Regulator of Mammary Epithelial Cell Proliferation, Survival, and HER2-Neu Oncogene–Dependent Breast Tumorigenesis
Authors: Cabodi Sara , Tinnirello Agata , Di Stefano Paola , Bisarò Brigitte , Ambrosino Elena , Castellano Isabella , Sapino Anna , Arisio Riccardo , Cavallo Federica , Forni Guido , Glukhova Marina , Silengo Lorenzo , Altruda Fiorella , Turco Emilia , Tarone Guido , Defilippi Paola
Published: May 2006

To investigate the mechanisms through which p130Cas adaptor protein is linked to tumorigenesis, we generated mouse mammary tumor virus (MMTV)-p130Cas mice overexpressing p130Cas in the mammary gland. MMTVp130Cas transgenic mice are characterized by extensive mammary epithelial hyperplasia during development and pregnancy and by delayed involution at the end of lactation. These phenotypes are associated with activation of Src kinase, extracellular signal-regulated kinase 1/2, mitogen-activated protein kinase, and Akt pathways, leading to an increased rate of proliferation and a decreased apoptosis. A double-transgenic line derived from crossing MMTV-p130Cas with MMTV-HER2-Neu mice expressing the activated form of the HER2-Neu oncogene develops multifocal mammary tumors with a significantly shorter latency than the HER2-Neu parental strain alone. Mammary epithelial cells isolated from tumors of double-transgenic mice display increased tyrosine phosphorylation, c-Src, and Akt activation compared with cells derived from HER2-Neu tumors. In addition, p130Cas down-regulation by RNA interference increases apoptosis in HER2-Neu-expressing cells, indicating that p130Cas regulates cell survival. Consistently with the double-transgenic mice model, p130Cas is overexpressed in a significant subset of human breast cancers and high levels of p130Cas in association with HER2 expression correlate with elevated proliferation. These findings provide evidences for a role of p130Cas as a positive regulator of both proliferation and survival in normal and transformed mammary epithelial cells. Its overexpression contributes to HER2-Neu-induced breast tumorigenesis, thus identifying this protein as a putative target for clinical therapy. (Cancer Res 2006; 66(9): 4672-80)
Dose-Response Relationship between Cooking Fumes Exposures and Lung Cancer among Chinese Nonsmoking Women
Authors: Yu Ignatius T.S. , Chiu Yuk-lan , Au Joseph S.K. , Wong Tze-wai , Tang Jin-ling
Published: May 2006

The high incidence of lung cancer among Chinese females, despite a low smoking prevalence, remains poorly explained. Cooking fume exposure during frying could be an important risk factor. We carried out a population-based case-control study in Hong Kong. Cases were Chinese female nonsmokers with newly diagnosed primary lung cancer. Controls were female nonsmokers randomly sampled from the community, frequency matched by age groups. Face-to-face interviews were conducted using a standardized questionnaire. The “total cooking dish-years,” categorized by increments of 50, was used as a surrogate of cooking fumes exposure. Multiple unconditional logistic regression was used to estimate the odds ratios (OR) for different levels of exposure after adjusting for various potential confounding factors. We interviewed 200 cases and 285 controls. The ORs of lung cancer across increasing levels of cooking dish-years were 1, 1.17, 1.92, 2.26, and 6.15. After adjusting for age and other potential confounding factors, the increasing trend of ORs with increasing exposure categories became clearer, being 1, 1.31, 4.12, 4.68, and 34. The OR of lung cancer was highest for deep-frying (2.56 per 10 dish-years) followed by that of frying (1.47), and stir-frying had the lowest OR (1.12) among the three methods. Cumulative exposure to cooking by means of any form of frying could increase the risk of lung cancer in Hong Kong nonsmoking women. Practical means to reduce exposures to cooking fumes should be given top priority in future research. (Cancer Res 2006; 66(9): 4961-7)
Trans-Repressive Effect of NUP98-PMX1 on PMX1-Regulated c-FOS Gene through Recruitment of Histone Deacetylase 1 by FG Repeats
Authors: Bai Xue-Tao , Gu Bai-Wei , Yin Tong , Niu Chao , Xi Xiao-Dong , Zhang Ji , Chen Zhu , Chen Sai-Juan
Published: May 2006

The formation of fusion genes between NUP98 and members of the HOX family represents a critical factor for the genesis of acute leukemia or acute transformation of chronic myeloid leukemia (CML). To gain insights into the molecular mechanisms underlying the leukemogenesis of NUP98-HOX fusion products, we cloned NUP98-PMX1 from a CML-blast crisis patient with t(1;11) as a secondary chromosomal translocation, and functionally studied the fusion products in detail through various molecular and protein biochemical assays. In addition to many interesting features, we have found that the NUP98-PMX1 fusion protein exerts a repressive effect on PMX1 or serum response factor–mediated c-FOS activation, probably through the recruitment of a common corepressor histone deacetylase 1 by FG domains of the NUP98-PMX1 fusion protein. Moreover, we have provided evidence that the FG domains of NUP98-PMX1 and two other NUP98-containing fusion proteins, i.e., NUP98-HOXA9 and NUP98-HOXC11, all exhibit dual binding ability to both CREB binding protein, a coactivator, and histone deacetylase 1, a corepressor. Accordingly, we have hypothesized that this dual binding activity is shared by most, if not all, NUP98-HOX-involved fusion proteins, enabling these fusion proteins to act as both trans-activators and trans-repressors, and contributing to the genesis of acute leukemia or acute transformation of CML. (Cancer Res 2006; 66(9): 4584-90)
Inhibition of the Phosphatidylinositol 3′-Kinase Pathway Promotes Autocrine Fas-Induced Death of Phosphatase and Tensin Homologue–Deficient Prostate Cancer Cells
Authors: Bertram Jerod , Peacock James W. , Tan Clara , Mui Alice L-F. , Chung Stephen W. , Gleave Martin E. , Dedhar Shoukat , Cox Michael E. , Ong Christopher J.
Published: May 2006

Rationally designed therapeutics that target the phosphatidylinositol 3′-kinase (PI3K) cell survival pathway are currently in preclinical and clinical development for cancer therapy. Drugs targeting the PI3K pathway aim to inhibit proliferation, promote apoptosis, and enhance chemosensitivity and radiosensitivity of cancer cells. The phosphatase and tensin homologue (PTEN) phosphatidylinositol 3′-phosphatase is a key negative regulator of the PI3K pathway. Inactivation of the PTEN tumor suppressor results in constitutive activation of the PI3K pathway and is found in ∼50% of advanced prostate cancers, which correlates with a high Gleason score and poor prognosis. Inhibition of the PI3K pathway leads to apoptosis of prostate cancer cells; however, the precise mechanism by which this occurs is unknown. Here we report that apoptotic cell death of PTEN-deficient LNCaP and PC3 prostate cancer cells induced by the PI3K inhibitor LY294002 can be abrogated by disrupting Fas/Fas ligand (FasL) interactions with recombinant Fas:Fc fusion protein or FasL neutralizing antibody (Nok-1), or by expressing dominant-negative Fas-associated death domain. Furthermore, we find that apoptosis induced by expression of wild-type PTEN, driven by a tetracycline-inducible expression system in LNCaP cells, can be inhibited by blocking Fas/FasL interaction using Fas:Fc or Nok-1. These data show that apoptosis induced by blockade of the PI3K pathway in prostate tumor cells is mediated by an autocrine Fas/FasL apoptotic mechanism and the Fas apoptotic pathway is both necessary and sufficient to mediate apoptosis by PI3K inhibition. (Cancer Res 2006; 66(9): 4781-8)
Platelet-Activating Factor Induces Up-regulation of Antiapoptotic Factors in a Melanoma Cell Line through Nuclear Factor-κB Activation
Authors: Heon Seo Kook , Ko Hyun-Mi , Kim Han-A , Choi Jung-Hwa , Jun Park Sung , Kim Kyoung-Jin , Lee Hern-Ku , Im Suhn-Young
Published: May 2006

In this study, we investigated the influence of platelet-activating factor (PAF) on the induction of apoptosis-regulating factors in B16F10 melanoma cells. PAF increased the expression of mRNA and the protein synthesis of antiapoptotic factors, such as Bcl-2 and Bcl-xL, but did not increase the expression of the proapoptotic factor, Bax. A selective nuclear factor-κB (NF-κB) inhibitor, parthenolide, inhibited the effects of PAF. Furthermore, PAF inhibited etoposide-induced increases in caspase-3, caspase-8, and caspase-9 activities, as well as cell death. p50/p65 heterodimer increased the mRNA expression of Bcl-2 and Bcl-xL and decreased etoposide-induced caspase activities and cell death. In an in vivo model in which Matrigel was injected s.c., PAF augmented the growth of B16F10 cells and attenuated etoposide-induced inhibition of B16F10 cells growth. These data indicate that PAF induces up-regulation of antiapoptotic factors in a NF-κB-dependent manner in a melanoma cell line, therefore suggesting that PAF may diminish the cytotoxic effect of chemotherapeutic agents. (Cancer Res 2006; 66(9): 4681-6)
Dynamic Imaging of Emerging Resistance during Cancer Therapy
Authors: Lee Kuei C. , Hall Daniel E. , Hoff Benjamin A. , Moffat Bradford A. , Sharma Surabhi , Chenevert Thomas L. , Meyer Charles R. , Leopold Wilbur R. , Johnson Timothy D. , Mazurchuk Richard V. , Rehemtulla Alnawaz , Ross Brian D.
Published: May 2006

One of the greatest challenges in developing therapeutic regimens is the inability to rapidly and objectively assess tumor response due to treatment. Moreover, tumor response to therapeutic intervention in many cases is transient, and progressive alterations within the tumor may mask the effectiveness of an initially successful therapy. The ability to detect these changes as they occur would allow timely initiation of alternative approaches, maximizing therapeutic outcome. We investigated the ability of diffusion magnetic resonance imaging (MRI) to provide a sensitive measure of tumor response throughout the course of treatment, possibly identifying changes in sensitivity to the therapy. Orthotopic 9L gliomas were subjected to two separate therapeutic regimens, with one group receiving a single 5-day cycle (1ω) of low-dose 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and a second group receiving two cycles at the same dose, bisected with 2 days of rest (2ω). Apparent diffusion coefficient maps were acquired before and throughout treatment to observe changes in water mobility, and these observations were correlated to standard measures of therapeutic response and outcome. Our results showed that diffusion MRI was indeed able to detect the emergence of a drug-resistant tumor subpopulation subsequent to an initially successful cycle of BCNU therapy, leading to minimal gains from a second cycle. These diffusion MRI findings were highly correlated with tumor growth delay, animal survival, and ex vivo growth inhibition assays showing emerging resistance in excised tumors. Overall, this study highlights the ability of diffusion MRI to provide sensitive dynamic assessment of therapy-induced response, allowing early opportunities for optimization of therapeutic protocols. (Cancer Res 2006; 66(9): 4687-92)
Melanoma Antigen A4 Is Expressed in Non–Small Cell Lung Cancers and Promotes Apoptosis
Authors: Peikert Tobias , Specks Ulrich , Farver Carol , Erzurum Serpil C. , Comhair Suzy A.A.
Published: May 2006

A variety of melanoma antigen A (MAGE-A) genes are commonly detected in non–small cell lung cancers. Their biological function is not well characterized but may involve the regulation of apoptosis and cell cycle progression. We hypothesized that MAGE-A4 is involved in the regulation of apoptosis. To investigate this, expression of MAGE-A was evaluated. MAGE-A4 was expressed in 48% of non–small cell lung carcinomas. Ninety percent of lung carcinomas expressing MAGE-A4 were classified as squamous cell carcinomas and 10% were adenocarcinomas. Tumor-free surrounding lung tissue was negative for MAGE-A4. A molecular clone of MAGE-A4 derived from human lung cancer was stably expressed in human embryonic kidney cells (293 cells) to evaluate effects on cell death. Overexpression of MAGE-A4 increased apoptosis as measured by the apoptotic index (P < 0.0001) and caspase-3 activity (P < 0.002). Exposure to 25 μmol/L etoposide, a chemotherapeutic agent, increased the apoptotic effect (P < 0.0001). Furthermore, we show that MAGE-A4 silencing using a small interfering RNA approach results in decreased caspase-3 activity in the squamous cell lung cancer cell line H1703 by 58% (P = 0.0027) and by 24% (P = 0.028) in 293/MAGE-A4 cells. These findings suggest that MAGE-A4 expression may promote tumor cell death, sensitize malignancies to apoptotic stimuli, such as chemotherapeutic agents, and therefore may represent a tumor suppressor protein. (Cancer Res 2006; 66(9): 4693-700)
Immunization of Stage IV Melanoma Patients with Melan-A/MART-1 and gp100 Peptides plus IFN-α Results in the Activation of Specific CD8+ T Cells and Monocyte/Dendritic Cell Precursors
Authors: Di Pucchio Tiziana , Pilla Lorenzo , Capone Imerio , Ferrantini Maria , Montefiore Enrica , Urbani Francesca , Patuzzo Roberto , Pennacchioli Elisabetta , Santinami Mario , Cova Agata , Sovena Gloria , Arienti Flavio , Lombardo Claudia , Lombardi Arianna , Caporaso Patrizia , D'Atri Stefania , Marchetti Paolo , Bonmassar Enzo , Parmiani Giorgio , Belardelli Filippo , Rivoltini Licia
Published: May 2006

The use of IFN-α in clinical oncology has generally been based on the rationale of exploiting its antiproliferative and antiangiogenic activities. However, IFN-α also exhibits enhancing effects on T-cell and dendritic cell functions, which may suggest a novel use as a vaccine adjuvant. We have carried out a pilot phase I-II trial to determine the effects of IFN-α, administered as an adjuvant of Melan-A/MART-1:26-35(27L) and gp100:209-217(210M) peptides, on immune responses in stage IV melanoma patients. In five of the seven evaluable patients, a consistent enhancement of CD8+ T cells recognizing modified and native MART-1 and gp100 peptides and MART-1+gp100+ melanoma cells was observed. Moreover, vaccination induced an increase in CD8+ T-cell binding to HLA tetramers containing the relevant peptides and an increased frequency of CD45RA+CCR7− (terminally differentiated effectors) and CD45RA−CCR7− (effector memory) cells. In all patients, treatment augmented significantly the percentage of CD14+ monocytes and particularly of the CD14+CD16+ cell fraction. An increased expression of CD40 and CD86 costimulatory molecules in monocytes was also observed. Notably, postvaccination monocytes from two of the three patients showing stable disease or long disease-free survival showed an enhanced antigen-presenting cell function and capability to secrete IP10/CXCL10 when tested in mixed leukocyte reaction assays, associated to a boost of antigen and melanoma-specific CD8+ T cells. Although further clinical studies are needed to show the adjuvant activity of IFN-α, the present data represent an important starting point for considering a new clinical use of IFN-α and new immunologic end points, potentially predictive of clinical response. (Cancer Res 2006; 66(9): 4943-51)
Doxorubicin-DNA Adducts Induce a Non-Topoisomerase II–Mediated Form of Cell Death
Authors: Swift Lonnie P. , Rephaeli Ada , Nudelman Abraham , Phillips Don R. , Cutts Suzanne M.
Published: May 2006

Doxorubicin (Adriamycin) is one of the most commonly used chemotherapeutic drugs and exhibits a wide spectrum of activity against solid tumors, lymphomas, and leukemias. Doxorubicin is classified as a topoisomerase II poison, although other mechanisms of action have been characterized. Here, we show that doxorubicin-DNA adducts (formed by the coadministration of doxorubicin with non-toxic doses of formaldehyde-releasing prodrugs) induce a more cytotoxic response in HL-60 cells than doxorubicin as a single agent. Doxorubicin-DNA adducts seem to be independent of classic topoisomerase II–mediated cellular responses (as observed by employing topoisomerase II catalytic inhibitors and HL-60/MX2 cells). Apoptosis induced by doxorubicin-DNA adducts initiates a caspase cascade that can be blocked by overexpressed Bcl-2, suggesting that adducts induce a classic mode of apoptosis. A reduction in the level of topoisomerase II–mediated double-strand-breaks was also observed with increasing levels of doxorubicin-DNA adducts and increased levels of apoptosis, further confirming that adducts exhibit a separate mechanism of action compared with the classic topoisomerase II poison mode of cell death by doxorubicin alone. Collectively, these results indicate that the presence of formaldehyde transfers doxorubicin from topoisomerase II–mediated cellular damage to the formation of doxorubicin-DNA adducts, and that these adducts are more cytotoxic than topoisomerase II–mediated lesions. These results also show that doxorubicin can induce apoptosis by a non-topoisomerase II–dependent mechanism, and this provides exciting new prospects for enhancing the clinical use of this agent and for the development of new derivatives and new tumor-targeted therapies. (Cancer Res 2006; 66(9): 4863-71)
DNA Damage–Induced BARD1 Phosphorylation Is Critical for the Inhibition of Messenger RNA Processing by BRCA1/BARD1 Complex
Authors: Kim Ho-Shik , Li Hongjie , Cevher Murat , Parmelee Alissa , Fonseca Danae , Kleiman Frida Esther , Lee Sean Bong
Published: May 2006

BRCA1-associated RING domain protein BARD1, along with its heterodimeric partner BRCA1, plays important roles in cellular response to DNA damage. Immediate cellular response to genotoxic stress is mediated by a family of phosphoinositide 3-kinase–related protein kinases, such as ataxia-telangiectasia mutated (ATM), ATM and Rad3-related, and DNA-dependent protein kinase. ATM-mediated phosphorylation of BRCA1 enhances the DNA damage checkpoint functions of BRCA1, but how BARD1 is regulated during DNA damage signaling has not been examined. Here, we report that BARD1 undergoes phosphorylation upon ionizing radiation or UV radiation and identify Thr714 as the in vivo BARD1 phosphorylation site. Importantly, DNA damage functions of BARD1 (i.e., inhibition of pre-mRNA polyadenylation and degradation of RNA polymerase II) are abrogated in T714A and T734A mutants. Our findings suggest that phosphorylation of BARD1 is critical for the DNA damage functions of the BRCA1/BARD1 complex. (Cancer Res 2006; 66(9): 4561-5)
Antitumor and Antimetastatic Activities of Docetaxel Are Enhanced by Genistein through Regulation of Osteoprotegerin/Receptor Activator of Nuclear Factor-κB (RANK)/RANK Ligand/MMP-9 Signaling in Prostate Cancer
Authors: Li Yiwei , Kucuk Omer , Hussain Maha , Abrams Judith , Cher Michael L. , Sarkar Fazlul H.
Published: May 2006

Bone metastasis is very common in advanced prostate cancer. Docetaxel has been shown to improve survival in patients with metastatic prostate cancer. However, treatment with docetaxel is associated with a certain degree of toxicity. Genistein, derived from soybeans, has been found to inhibit cancer cell growth without toxicity. We have recently reported that genistein could potentiate the antitumor activity of chemotherapeutic agents both in vitro and in vivo. However, the molecular mechanism of this novel effect of genistein has not been fully elucidated. In this study, we found that genistein significantly potentiated the antitumor, anti-invasive, and antimetastatic activities of docetaxel both in culture and in severe combined immunodeficient (SCID)-human model of experimental prostate cancer bone metastasis. We further conducted microarray analysis, real-time reverse transcription-PCR, Western blot analysis, small interfering RNA and cDNA transfection, matrix metalloproteinase-9 (MMP-9) activity assay, and invasion assay. We found that the expression of osteoprotegerin (OPG) was induced by genistein and inhibited by docetaxel, whereas genistein significantly down-regulated the expression and secretion of receptor activator of nuclear factor-κB (RANK) ligand (RANKL) and inhibited osteoclast formation. Moreover, genistein down-regulated the expression and activity of MMP-9, which was induced by docetaxel treatment, and inhibited invasion of PC-3 cells. These results suggest that the observed potentiation of antitumor activity of docetaxel by genistein in the SCID-human model of experimental bone metastasis could be mediated by regulation of OPG/RANK/RANKL/MMP-9 signaling, resulting in the inhibition of osteoclastic bone resorption and prostate cancer bone metastasis. From these results, we conclude that genistein could be a promising nontoxic agent to improve the treatment outcome of metastatic prostate cancer with docetaxel. (Cancer Res 2006; 66(9): 4816-25)
DNA Sequence Context Affects Repair of the Tobacco-Specific Adduct O6-[4-Oxo-4-(3-pyridyl)butyl]guanine by Human O6-Alkylguanine-DNA Alkyltransferases
Authors: Mijal Renée S. , Kanugula Sreenivas , Vu Choua C. , Fang Qingming , Pegg Anthony E. , Peterson Lisa A.
Published: May 2006

The repair protein O6-alkylguanine-DNA alkyltransferase (AGT) protects cells from the mutagenic and carcinogenic effects of alkylating agents by removing O6-alkylguanine adducts from DNA. Recently, we established that AGT protects against the mutagenic effects of pyridyloxobutylation resulting from the metabolic activation of the tobacco-specific nitrosamines (TSNA) 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and N-nitrosonornicotine by repairing O6-[4-oxo-4-(3-pyridyl)butyl]guanine (O6-pobG). There have been several epidemiologic studies examining the association between the I143V/K178R AGT genotype and lung cancer risk. Two studies have found positive associations, suggesting that AGT proteins differ in their repair of DNA damage caused by TSNA. However, it is not known how this genotype alters the biochemical activity of AGT. We proposed that AGT proteins may differ in their ability to remove large O6-alkylguanine adducts, such as O6-pobG, from DNA. Therefore, we examined the repair of O6-pobG by wild-type (WT) human, I143V/K178R, and L84F AGT proteins when contained in multiple sequence contexts, including the twelfth codon of H-ras, a mutational hotspot within this oncogene. The AGT-mediated repair of O6-pobG was more profoundly influenced by sequence context than that of O6-methylguanine. These differences are not the result of secondary structure (hairpin) formation in DNA. In addition, the I143V/K178R variant seems less sensitive to the effects of sequence context than the WT or L84F proteins. These studies indicate that the sequence dependence of O6-pobG repair by human AGT (hAGT) varies with subtle changes in protein structure. These data establish a novel functional difference between the I143V/K178R protein and other hAGTs in the repair of a toxicologically relevant substrate, O6-pobG. (Cancer Res 2006; 66(9): 4968-74)
Reversible Kinetic Analysis of Myc Targets In vivo Provides Novel Insights into Myc-Mediated Tumorigenesis
Authors: Lawlor Elizabeth R. , Soucek Laura , Brown-Swigart Lamorna , Shchors Ksenya , Bialucha C. Uli , Evan Gerard I.
Published: May 2006

Deregulated expression of the Myc transcription factor is a frequent causal mutation in human cancer. Thousands of putative Myc target genes have been identified in in vitro studies, indicating that Myc exerts highly pleiotropic effects within cells and tissues. However, the complexity and diversity of Myc gene targets has confounded attempts at identifying which of these genes are the critical targets mediating Myc-driven tumorigenesis in vivo. Acute activation of Myc in a reversibly switchable transgenic model of Myc-mediated β cell tumorigenesis induces rapid tumor onset, whereas subsequent Myc deactivation triggers equally rapid tumor regression. Thus, sustained Myc activity is required for tumor maintenance. We have used this reversibly switchable kinetic tumor model in combination with high-density oligonucleotide microarrays to develop an unbiased strategy for identifying candidate Myc-regulated genes responsible for maintenance of Myc-dependent tumors. Consistent with known Myc functions, some Myc-regulated genes are involved in cell growth, cycle, and proliferation. In addition, however, many Myc-regulated genes are specific to β cells, indicating that a significant component of Myc action is cell type specific. Finally, we identify a very restricted cadre of genes with expression that is inversely regulated upon Myc activation-induced tumor progression and deactivation-induced tumor regression. By definition, such genes are candidates for tumor maintenance functions. Combining reversibly switchable, transgenic models of tumor formation and regression with genomic profiling offers a novel strategy with which to deconvolute the complexities of oncogenic signaling pathways in vivo. (Cancer Res 2006; 66(9): 4591-601)
Survival Signaling by Notch1: Mammalian Target of Rapamycin (mTOR)–Dependent Inhibition of p53
Authors: Mungamuri Sathish Kumar , Yang XiaoHe , Thor Ann D. , Somasundaram Kumaravel
Published: May 2006

Notch signaling is believed to promote cell survival in general. However, the mechanism is not clearly understood. Here, we show that cells expressing intracellular domain of human Notch1 (NIC-1) are chemoresistant in a wild-type p53-dependent manner. NIC-1 inhibited p53 by inhibiting its activating phosphorylations at Ser15, Ser20, and Ser392 as well as nuclear localization. In addition, we found that inhibition of p53 by NIC-1 mainly occurs through mammalian target of rapamycin (mTOR) using phosphatidylinositol 3-kinase (PI3K)-Akt/protein kinase B (PKB) pathway as the mTOR inhibitor, rapamycin treatment abrogated NIC-1 inhibition of p53 and reversed the chemoresistance. Consistent with this, rapamycin failed to reverse NIC-1-induced chemoresistance in cells expressing rapamycin-resistant mTOR. Further, ectopic expression of eukaryotic initiation factor 4E (eIF4E), a translational regulator that acts downstream of mTOR, inhibited p53-induced apoptosis and conferred protection against p53-mediated cytotoxicity to similar extent as that of NIC-1 overexpression but was not reversed by rapamycin, which indicates that eIF4E is the major target of mTOR in Notch1-mediated survival signaling. Finally, we show that MCF7 (breast cancer) and MOLT4 (T-cell acute lymphoblastic leukemia) cells having aberrant Notch1 signaling are chemoresistant, which can be reversed by both PI3K and mTOR inhibitors. These results establish that Notch1 signaling confers chemoresistance by inhibiting p53 pathway through mTOR-dependent PI3K-Akt/PKB pathway and imply that p53 status perhaps is an important determinant in combination therapeutic strategies, which use mTOR inhibitors and chemotherapy. (Cancer Res 2006; 66(9): 4715-24)
Identification of a New Cancer/Germline Gene,KK-LC-1, Encoding an Antigen Recognized by Autologous CTL Induced on Human Lung Adenocarcinoma
Authors: Fukuyama Takashi , Hanagiri Takeshi , Takenoyama Mitsuhiro , Ichiki Yoshinobu , Mizukami Makiko , So Tetsuya , Sugaya Masakazu , So Tomoko , Sugio Kenji , Yasumoto Kosei
Published: May 2006

The purpose of our present study is to identify a tumor-specific antigen capable of inducing a specific cellular immune response in lung cancer patients. We established a lung adenocarcinoma cell line, designated as F1121L, and induced tumor-specific CTL clone H1 from regional lymph node lymphocytes of patient F1121. CTL clone H1 lysed autologous tumor cells in an HLA-B*1507-restricted manner, but not autologous EBV-B, phytohemagglutinin-blast cells, and K562. The CTL clone also recognized allogeneic HLA-B*1501- or 1507-positive lung cancer cell lines in the HLA-restricted manner. Using the CTL clone, we identified an antigen-coding gene by cDNA expression cloning technique. The gene consisted of 556 bp, including an open reading frame consisted of 113 amino acids, designated as Kita-kyushu lung cancer antigen 1 (KK-LC-1). A 9-mer peptide (KK-LC-176-84; RQKRILVNL) was identified as an epitope peptide. The genomic DNA of this antigen was located in chromosome Xq22. A reverse transcription-PCR analysis revealed that the mRNA of this gene was only expressed in the testis among normal tissues. It was expressed in 9 of 18 (50%) allogeneic non–small-cell lung cancer cell lines and in 40 of 100 (40%) non–small-cell lung cancer tissues. We thus identified a new tumor antigen–coding gene categorized as a cancer/germline gene by an autologous lung cancer and CTL system. The new cancer/germline gene was located in Xq22, which is apparently different from the locations of previously reported cancer/germline genes. (Cancer Res 2006; 66(9): 4922-8)
Exploring a New Twist on Tumor Metastasis
Authors: Yang Jing , Mani Sendurai A. , Weinberg Robert A.
Published: May 2006

Unraveling the genetic programs that drive -metastasis may offer insights into how to limit or prevent this deadly aspect of cancer progression. Our recent studies indicate that tumor cell metastasis involves the activity of the transcription factor, Twist, which regulates epithelial-mesenchymal transition and early embryonic morphogenesis. Here, we review the Twist signaling pathway during normal development and discuss how the transcription factor Twist and the epithelial-mesenchymal transition program impinge their biological functions during tumor metastasis. (Cancer Res 2006; 66(9): 4549-52)
Normal Stem Cells and Cancer Stem Cells: The Niche Matters
Authors: Li Linheng , Neaves William B.
Published: May 2006

Scientists have tried for decades to understand cancer development in the context of therapeutic strategies. The realization that cancers may rely on “cancer stem cells” that share the self-renewal feature of normal stem cells has changed the perspective with regard to new approaches for treating the disease. In this review, we propose that one of the differences between normal stem cells and cancer stem cells is their degree of dependence on the stem cell niche, a specialized microenvironment in which stem cells reside. The stem cell niche in adult somatic tissues plays an essential role in maintaining stem cells or preventing tumorigenesis by providing primarily inhibitory signals for both proliferation and differentiation. However, the niche also provides transient signals for stem cell division to support ongoing tissue regeneration. The balance between proliferation-inhibiting and proliferation-promoting signals is the key to homeostatic regulation of stem cell maintenance versus tissue regeneration. Loss of the niche can lead to loss of stem cells, indicating the reliance of stem cells on niche signals. Therefore, cancer stem cells may arise from an intrinsic mutation, leading to self-sufficient cell proliferation, and/or may also involve deregulation or alteration of the niche by dominant proliferation-promoting signals. Furthermore, the molecular machinery used by normal stem cells for homing to or mobilizing from the niche may be “hijacked” by cancer stem cells for invasion and metastasis. We hope this examination of the interaction between stem cells and their niche will enhance understanding of the process of cancer development, invasiveness, and metastasis and reveal possible targets for cancer treatment. (Cancer Res 2006; 66(9): 4553-7)
Luteolin Promotes Degradation in Signal Transducer and Activator of Transcription 3 in Human Hepatoma Cells: An Implication for the Antitumor Potential of Flavonoids
Authors: Selvendiran Karuppaiyah , Koga Hironori , Ueno Takato , Yoshida Takafumi , Maeyama Michiko , Torimura Takuji , Yano Hirohisa , Kojiro Masamichi , Sata Michio
Published: May 2006

In this study, we have investigated the underlying molecular mechanism for the potent proapoptotic effect of luteolin on human hepatoma cells both in vitro and in vivo, focusing on the signal transducer and activator of transcription 3 (STAT3)/Fas signaling. A clear apoptosis was found in the luteolin-treated HLF hepatoma cells in a time- and dosage-dependent manner. In concert with the caspase-8 activation by luteolin, an enhanced expression in functional Fas/CD95 was identified. Consistent with the increased Fas/CD95 expression, a drastic decrease in the Tyr705 phosphorylation of STAT3, a known negative regulator of Fas/CD95 transcription, was found within 20 minutes in the luteolin-treated cells, leading to down-regulation in the target gene products of STAT3, such as cyclin D1, survivin, Bcl-xL, and vascular endothelial growth factor. Of interest, the rapid down-regulation in STAT3 was consistent with an accelerated ubiquitin-dependent degradation in the Tyr705-phosphorylated STAT3, but not the Ser727-phosphorylated one, another regulator of STAT3 activity. The expression level of Ser727-phosphorylated STAT3 was gradually decreased by the luteolin treatment, followed by a fast and clear down-regulation in the active forms of CDK5, which can phosphorylate STAT3 at Ser727. An overexpression in STAT3 led to resistance to luteolin, suggesting that STAT3 was a critical target of luteolin. In nude mice with xenografted tumors using HAK-1B hepatoma cells, luteolin significantly inhibited the growth of the tumors in a dosage-dependent manner. These data suggested that luteolin targeted STAT3 through dual pathways—the ubiquitin-dependent degradation in Tyr705-phosphorylated STAT3 and the gradual down-regulation in Ser727-phosphorylated STAT3 through inactivation of CDK5, thereby triggering apoptosis via up-regulation in Fas/CD95. (Cancer Res 2006; 66(9): 4826-34)
Molecular Evidence for Independent Origin of Multifocal Neuroendocrine Tumors of the Enteropancreatic Axis
Authors: Katona Terrence M. , Jones Timothy D. , Wang Mingsheng , Abdul-Karim Fadi W. , Cummings Oscar W. , Cheng Liang
Published: May 2006

Neuroendocrine tumors of the enteropancreatic axis are often multifocal. We have investigated whether multifocal intestinal carcinoid tumors and multifocal pancreatic endocrine tumors arise independently or whether they originate from a single clone with subsequent intramural or intrapancreatic spread. Twenty-four cases, including 16 multifocal intestinal carcinoid tumors and eight multifocal pancreatic endocrine tumors, were studied. Genomic DNA samples were prepared from 72 distinct tumor nodules using laser capture microdissection. Loss of heterozygosity (LOH) assays were done using markers for putative tumor suppressor genes located on chromosomes 9p21 (p16), 11q13 (MEN1), 11q23 (SDHD), 16q21, 18q21, and 18q22-23. In addition, X chromosome inactivation analysis was done on the tumors from eight female patients. Twenty-two of 24 (92%) cases showed allelic loss in at least one tumor focus, including 15 of 16 (94%) cases of multifocal carcinoid tumors and 7 of 8 (88%) cases of multifocal pancreatic endocrine tumors. Eleven of 24 (46%) cases exhibited a different LOH pattern for each tumor. Additionally, 9 of 24 (38%) cases showed different LOH patterns among some of the coexisting tumors, whereas other coexisting tumors displayed the same allelic loss pattern. Two of 24 (8%) cases showed the same LOH pattern in every individual tumor. X chromosome inactivation analysis showed a discordant pattern of nonrandom X chromosome inactivation in two of six informative cases and concordant pattern of nonrandom X chromosome inactivation in the four remaining informative cases. Our data suggest that some multifocal neuroendocrine tumors of the enteropancreatic axis arise independently, whereas others originate as a single clone with subsequent local and discontinuous metastasis. (Cancer Res 2006; 66(9): 4936-42)
Functional Gene Expression Analysis Uncovers Phenotypic Switch in Aggressive Uveal Melanomas
Authors: Onken Michael D. , Ehlers Justis P. , Worley Lori A. , Makita Jun , Yokota Yoshifumi , Harbour J. William
Published: May 2006

Microarray gene expression profiling is a powerful tool for generating molecular cancer classifications. However, elucidating biological insights from these large data sets has been challenging. Previously, we identified a gene expression-based classification of primary uveal melanomas that accurately predicts metastatic death. Class 1 tumors have a low risk and class 2 tumors a high risk for metastatic death. Here, we used genes that discriminate these tumor classes to identify biological correlates of the aggressive class 2 signature. A search for Gene Ontology categories enriched in our class-discriminating gene list revealed a global down-regulation of neural crest and melanocyte-specific genes and an up-regulation of epithelial genes in class 2 tumors. Correspondingly, class 2 tumors exhibited epithelial features, such as polygonal cell morphology, up-regulation of the epithelial adhesion molecule E-cadherin, colocalization of E-cadherin and β-catenin to the plasma membrane, and formation of cell-cell adhesions and acinar structures. One of our top class-discriminating genes was the helix-loop-helix inhibitor ID2, which was strongly down-regulated in class 2 tumors. The class 2 phenotype could be recapitulated by eliminating Id2 in cultured class 1 human uveal melanoma cells and in a mouse ocular melanoma model. Id2 seemed to suppress the epithelial-like class 2 phenotype by inhibiting an activator of the E-cadherin promoter. Consequently, Id2 loss triggered up-regulation of E-cadherin, which in turn promoted anchorage-independent cell growth, a likely antecedent to metastasis. These findings reveal new roles for Id2 and E-cadherin in uveal melanoma progression, and they identify potential targets for therapeutic intervention. (Cancer Res 2006; 66(9): 4602-9)
The Role of Mitogen-Activated Protein Kinase Phosphatase-1 in Oxidative Damage–Induced Cell Death
Authors: Zhou Jun-Ying , Liu Yusen , Wu Gen Sheng
Published: May 2006

Mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1) is a member of the MAPK phosphatase family that functions as a negative regulator of MAPK signaling. MKP-1 is induced by oxidative stress, but the role of its induction in cell death is not fully understood. Here, we show that hydrogen peroxide (H2O2) induces MKP-1 and activates MAPKs. Induction of MKP-1 by H2O2 correlated with inactivation of p38 and c-Jun-NH2-kinase (JNK). Overexpression of MKP-1 increased cell resistance to H2O2-induced death. Furthermore, we show by small interfering RNA silencing that down-regulation of MKP-1 increases phosphorylated p38 and JNK and subsequent cell death induced by H2O2. More importantly, primary embryonic fibroblasts from mice lacking MKP-1 had a higher level of phosphorylated p38 and JNK and were more sensitive to H2O2-induced cell death compared with corresponding cells with MKP-1, indicating that p38 and JNK pathways may play important roles in H2O2-mediated cell death. Thus, these results suggest that activation of MKP-1 is a survival mechanism against oxidative damage. (Cancer Res 2006; 66(9): 4888-94)
Distinct Roles of Nonmuscle Myosin II Isoforms in the Regulation of MDA-MB-231 Breast Cancer Cell Spreading and Migration
Authors: Betapudi Venkaiah , Licate Lucila S. , Egelhoff Thomas T.
Published: May 2006

Initial stages of tumor cell metastasis involve an epithelial-mesenchyme transition that involves activation of amoeboid migration and loss of cell-cell adhesion. The actomyosin cytoskeleton has fundamental but poorly understood roles in these events. Myosin II, an abundant force-producing protein, has roles in cell body translocation and retraction of the posterior of the cell during migration. Recent studies have suggested that this protein may also have roles in leading edge protrusive events. The metastasis-promoting protein metastasin-1, a regulator of myosin II assembly, colocalizes with myosin IIA at the leading edge of cancer cells, suggesting direct roles for myosin II in metastatic behavior. We have assessed the roles of specific myosin II isoforms during lamellar spreading of MDA-MB-231 breast cancer cells on extracellular matrix. We find that the two major myosin II isoforms IIA and IIB are both expressed in these cells, and both are recruited dramatically to the lamellar margin during active spreading on fibronectin. There is also a transient increase in regulatory light chain phosphorylation that correlates the recruitment of myosin IIA and myosin IIB into this spreading margin. Pharmacologic inhibition of myosin II or myosin light chain kinase dramatically reduced spreading. Depletion of myosin IIA via small interfering RNA impaired migration but enhanced lamellar spreading, whereas depletion of myosin IIB impaired not only migration but also impaired initial rates of lamellar spreading. These results indicate that both isoforms are critical for the mechanics of cell migration, with myosin IIB seeming to have a preferential role in the mechanics of lamellar protrusion. (Cancer Res 2006; 66(9): 4725-33)
Chromatin Modification of the Trefoil Factor 1 Gene in Human Breast Cancer Cells by the Ras/Mitogen-Activated Protein Kinase Pathway
Authors: Espino Paula S. , Li Lin , He Shihua , Yu Jenny , Davie James R.
Published: May 2006

Histone H3 phosphorylation is a downstream response to activation of the Ras/mitogen-activated protein kinase (MAPK) pathway. This modification is thought to have a role in chromatin remodeling and in the initiation of gene transcription. In MCF-7 breast cancer cells, we observed that phosphorylated histone H3 (phospho-H3) at Ser10 but not Ser28 increased with phorbol ester (12-O-tetradecanoylphorbol-13-acetate, TPA) treatment. Although phosphorylated extracellular signal-regulated kinase 1/2 levels in these cells cultured under estradiol deplete and replete conditions displayed no change, a significant induction was observed after TPA treatment. Furthermore, whereas both estradiol and TPA increased trefoil factor 1 (TFF1) mRNA levels in these cells, only TPA-induced and not estradiol-induced TFF1 expression was inhibited by the H3 kinase mitogen and stress activated protein kinase (MSK) inhibitor H89 and MAPK kinase inhibitor UO126, showing the involvement of the Ras/MAPK following TPA induction. Mutation of the activator protein 1 (AP-1) binding site abrogated the TPA-induced transcriptional response of the luciferase reporter gene under the control of the TFF1 promoter, showing the requirement for the AP-1 site. In chromatin immunoprecipitation assays, estradiol treatment resulted in the association of the estrogen receptor-α (ERα) and acetylated H3 with the TFF1 promoter. The levels of phospho-H3 and MSK1 associated with the TFF1 promoter were moderately increased. In the presence of TPA, whereas ERα was not bound to the promoter, a strong association of acetylated and/or phospho-H3, MSK1, and c-Jun was observed. These results show that although both stimuli lead to TFF1 gene activation, estradiol and TPA exert their effects on TFF1 gene expression by different mechanisms. (Cancer Res 2006; 66(9): 4610-6)