bluuebunny/crossref_metadata_2025_split huggingface dataset:
DNA-Protein Cross-links and Replication-Dependent Histone H2AX Phosphorylation Induced by Aminoflavone (NSC 686288), a Novel Anticancer Agent Active against Human Breast Cancer Cells
Authors: Meng Ling-hua , Kohlhagen Glenda , Liao Zhi-yong , Antony Smitha , Sausville Edward , Pommier Yves 
Published: September 2005

AbstractAminoflavone (5-amino-2,3-fluorophenyl)-6,8-difluoro-7-methyl-4H-1-benzopyran-4-one) (NSC 686288) is a candidate for possible advancement to phase I clinical trial. Aminoflavone has a unique activity profile in the NCI 60 cell lines (COMPARE analysis; http://www.dtp.nci.nih.gov/docs/dtp_search.html), and exhibits potent cellular and animal antitumor activity. To elucidate the mechanism of action of aminoflavone, we studied DNA damage in MCF-7 cells. Aminoflavone induced DNA-protein cross-links (DPC) and DNA single-strand breaks (SSB). Aminoflavone induced high levels of DPC and much lower level of SSB than camptothecin, which induces equal levels of DPC and SSB due to the trapping topoisomerase I-DNA complexes. Accordingly, neither topoisomerase I nor topoisomerase II were detectable in the aminoflavone-induced DPC. Aminoflavone also induced dose- and time-dependent histone H2AX phosphorylation (γ-H2AX). γ-H2AX foci occurred with DPC formation, and like DPC, persisted after aminoflavone removal. Aphidicolin prevented γ-H2AX formation, suggesting that γ-H2AX foci correspond to replication-associated DNA double-strand breaks. Accordingly, no γ-H2AX foci were found in proliferating cell nuclear antigen–negative or in mitotic cells. Bromodeoxyuridine incorporation and fluorescence-activated cell sorting analyses showed DNA synthesis inhibition uniformly throughout the S phase after exposure to aminoflavone. Aminoflavone also induced RPA2 and p53 phosphorylation, and induced p21Waf1/Cip1 and MDM2, demonstrating S-phase checkpoint activation. These studies suggest that aminoflavone produces replication-dependent DNA lesions and S-phase checkpoint activation following DPC formation. γ-H2AX may be a useful clinical marker for monitoring the efficacy of aminoflavone in tumor therapies.
p53 Regulation and Function in Renal Cell Carcinoma
Authors: Warburton Hazel E. , Brady Mark , Vlatković Nikolina , Linehan W. Marston , Parsons Keith , Boyd Mark T. 
Published: September 2005

Abstract
Loss of p53 function is a critical event in tumor evolution. This occurs through a range of molecular events, typically a missense p53 mutation followed by loss of heterozygosity. In many cancers, there is compelling evidence that cells that can compromise p53 function have a selective advantage. The situation in renal cell carcinoma is unclear. It has recently been suggested that p53 function is unusually compromised in renal carcinoma cells by a novel dominant, MDM2/p14ARF-independent mechanism. This is hard to reconcile with other recent studies that have identified p53 as an important prognostic indicator. Indeed, one of these latter studies found that the best predictor of poor outcome was the presence of high levels of both p53 (usually indicative of p53 mutation) and MDM2. Thus, it is important that we gain a clearer understanding of the regulation of p53 and the role of MDM2 in renal cell cancer. To address this, we have investigated the transcriptional activity of p53 in a panel of renal cell carcinoma cell lines and the contribution of MDM2 and p14ARF to p53 regulation. We have found that p53 is functional in p53 wild-type renal cell carcinoma cells and that this activity is significantly regulated by MDM2 and to a much lesser extent by p14ARF. Moreover, following induction of DNA damage with UV, the p53 response in these cells is intact. Thus, future studies of renal cell carcinoma that focus on p53 and MDM2 and their role in determining disease outcome will be required to create a better understanding of this notoriously difficult to manage disease.
Human CTL Epitopes Prostatic Acid Phosphatase-3 and Six-Transmembrane Epithelial Antigen of Prostate-3 as Candidates for Prostate Cancer Immunotherapy
Authors: Machlenkin Arthur , Paz Adrian , Bar Haim Erez , Goldberger Ofir , Finkel Eran , Tirosh Boaz , Volovitz Ilan , Vadai Ezra , Lugassy Gilles , Cytron Shmuel , Lemonnier Francois , Tzehoval Esther , Eisenbach Lea 
Published: September 2005

Abstract
Specific immunotherapy of prostate cancer may be an alternative or be complementary to other approaches for treatment of recurrent or metastasized disease. This study aims at identifying and characterizing prostate cancer–associated peptides capable of eliciting specific CTL responses in vivo. Evaluation of peptide-induced CTL activity in vitro was done following immunization of HLA-A2 transgenic (HHD) mice. An in vivo tumor rejection was tested by adoptive transfer of HHD immune lymphocytes to nude mice bearing human tumors. To confirm the existence of peptide-specific CTL precursors in human, lymphocytes from healthy and prostate cancer individuals were stimulated in vitro in the presence of these peptides and CTL activities were assayed. Two novel immunogenic peptides derived from overexpressed prostate antigens, prostatic acid phosphatase (PAP) and six-transmembrane epithelial antigen of prostate (STEAP), were identified; these peptides were designated PAP-3 and STEAP-3. Peptide-specific CTLs lysed HLA-A2.1+ LNCaP cells and inhibited tumor growth on adoptive immunotherapy. Furthermore, peptide-primed human lymphocytes derived from healthy and prostate cancer individuals lysed peptide-pulsed T2 cells and HLA-A2.1+ LNCaP cells. Based on the results presented herein, PAP-3 and STEAP-3 are naturally processed CTL epitopes possessing anti–prostate cancer reactivity in vivo and therefore may constitute vaccine candidates to be investigated in clinical trials.
Mutations in Two Short Noncoding Mononucleotide Repeats in Most Microsatellite-Unstable Colorectal Cancers
Authors: Hienonen Tuija , Sammalkorpi Heli , Enholm Susa , Alhopuro Pia , Barber Thomas D. , Lehtonen Rainer , Nupponen Nina N. , Lehtonen Heli , Salovaara Reijo , Mecklin Jukka-Pekka , Järvinen Heikki , Koistinen Riitta , Arango Diego , Launonen Virpi , Vogelstein Bert , Karhu Auli , Aaltonen Lauri A. 
Published: September 2005

Abstract
DNA mismatch repair (MMR)–deficient cells typically accumulate mutations in short repetitive DNA tracts. This microsatellite instability (MSI) facilitates malignant transformation when affecting genes with growth-related and caretaker functions. To date, several putative MSI target genes have been proposed mainly based on high mutation frequency within their coding regions. However, some intronic repeat mutations have also been suggested to associate with MSI tumorigenesis, indicating the need for additional analyses on noncoding repeats. Here we have analyzed an intronic T9 repeat of semenogelin I (SEMG1) and report mutation frequencies of 51% (75 of 146) and 62% (8 of 13) in MMR-deficient primary colorectal cancers and cell lines, respectively. The putative effect of the SEMG1 mutations was assessed by RNA and protein level analyses, but no differences were detected between colorectal cancer cell lines with different SEMG1 status. Subsequently, the general background mutation frequency of MSI colorectal cancers was assessed by screening for intergenic T9 repeat alterations. One of 10 examined repeats was mutated in 70% (102 of 145) of the colorectal cancers evaluated. The frequencies observed here are notably higher than previously published in noncoding repeats shorter than 10 bp in MMR-deficient primary tumors. Our results indicate that high mutation frequencies, similar or higher than those observed in proposed and approved target genes, can be detected in repeat tracts of MSI tumors without any apparent selection pressure. These data call for urgent and thorough large-scale evaluation of mutation frequencies in neutral short repetitive sequences in MMR-deficient tumors.
Expression of Membrane Type 1 Matrix Metalloproteinase Is Associated with Cervical Carcinoma Progression and Invasion
Authors: Zhai Yali , Hotary Kevin B. , Nan Bin , Bosch F. Xavier , Muñoz Nubia , Weiss Stephen J. , Cho Kathleen R. 
Published: September 2005

Abstract
Membrane type 1 matrix metalloproteinase (MT1-MMP) is frequently expressed by cancer cells and is believed to play an important role in cancer cell invasion and metastasis. However, little is known about the role of MT1-MMP in mediating invasiveness of cervical cancer cells. In this study, we examined MT1-MMP expression in 58 primary human cervical tissue specimens, including normal cervix, low-grade squamous intraepithelial lesions (LSIL), high-grade SILs (HSIL), and invasive carcinomas. We also evaluated MT1-MMP, MMP-2, and tissue inhibitor of metalloproteinase-2 expression in several cervical cancer–derived cell lines, human papillomavirus (HPV)–immortalized keratinocytes, and keratinocytes derived from a LSIL. Using in situ hybridization techniques to study the cervical tissue specimens, we found that MT1-MMP expression increases with cervical tumor progression (Spearman correlation coefficient = 0.66; P &lt; 0.0001, exact test). Specifically, MT1-MMP expression is very low or absent in normal cervix and LSILs, is readily detectable in HSILs, and is very strongly expressed in nearly all invasive carcinomas. Most but not all cervical cancer–derived cell lines also expressed significant levels of MT1-MMP and MMP-2. Constitutive expression of exogenous MT1-MMP in cervical carcinoma–derived cells and HPV-immortalized keratinocytes with low endogenous levels of MT1-MMP induced invasiveness in collagen I, but this effect was not observed in LSIL-derived keratinocytes. Our results show that MT1-MMP is a key enzyme mediating cervical cancer progression. However, MT1-MMP alone is not always sufficient for inducing keratinocyte invasiveness at least in the collagen I invasion assay used in this study. Further studies of gene expression in preinvasive and invasive cervical cancers should assist with identification of additional critical factors mediating cervical cancer progression.
Seliciclib (CYC202, R-Roscovitine) Induces Cell Death in Multiple Myeloma Cells by Inhibition of RNA Polymerase II–Dependent Transcription and Down-regulation of Mcl-1
Authors: MacCallum David E. , Melville Jean , Frame Sheelagh , Watt Kathryn , Anderson Sian , Gianella-Borradori Athos , Lane David P. , Green Simon R. 
Published: September 2005

AbstractSeliciclib (CYC202, R-roscovitine) is a cyclin-dependent kinase (CDK) inhibitor that competes for the ATP binding site on the kinase. It has greatest activity against CDK2/cyclin E, CDK7/cyclin H, and CDK9/cyclin T. Seliciclib induces apoptosis from all phases of the cell cycle in tumor cell lines, reduces tumor growth in xenografts in nude mice and is currently in phase II clinical trials. This study investigated the mechanism of cell death in multiple myeloma cells treated with seliciclib. In myeloma cells treated in vitro, seliciclib induced rapid dephosphorylation of the carboxyl-terminal domain of the large subunit of RNA polymerase II. Phosphorylation at these sites is crucial for RNA polymerase II–dependent transcription. Inhibition of transcription would be predicted to exert its greatest effect on gene products where both mRNA and protein have short half-lives, resulting in rapid decline of the protein levels. One such gene product is the antiapoptotic factor Mcl-1, crucial for the survival of a range of cell types including multiple myeloma. As hypothesized, following the inhibition of RNA polymerase II phosphorylation, seliciclib caused rapid Mcl-1 down-regulation, which preceded the induction of apoptosis. The importance of Mcl-1 was confirmed by short interfering RNA, demonstrating that reducing Mcl-1 levels alone was sufficient to induce apoptosis. These results suggest that seliciclib causes myeloma cell death by disrupting the balance between cell survival and apoptosis through the inhibition of transcription and down-regulation of Mcl-1. This study provides the scientific rationale for the clinical development of seliciclib for the treatment of multiple myeloma.
Tomographic Fluorescence Mapping of Tumor Targets
Authors: Montet Xavier , Ntziachristos Vasilis , Grimm Jan , Weissleder Ralph 
Published: September 2005

Abstract
Methods that allow robust imaging of specific molecular targets and biological processes in vivo should have widespread applications in biology and clinical medicine. Here we use a quantitative, three-dimensional fluorescence-mediated tomographic technique (FMT) that enables rapid measurements of fluorochrome-based affinity tags in live xenograft models. We validate the method by showing its sensitivity in quantitating tumor angiogenesis and therapeutic modulation using an anti–vascular endothelial growth factor antibody. Furthermore, we show the feasibility of simultaneous multichannel measurements of distinct biological phenomena such as receptor tyrosine kinase expression and angiogenesis. FMT measurements can be done serially, with short imaging times and within the same live animal. The described method should be valuable for rapidly profiling biological phenomena in vivo.
Proteasome Inhibitors Trigger NOXA-Mediated Apoptosis in Melanoma and Myeloma Cells
Authors: Qin Jian-Zhong , Ziffra Jeffrey , Stennett Lawrence , Bodner Barbara , Bonish Brian K. , Chaturvedi Vijaya , Bennett Frank , Pollock Pamela M. , Trent Jeffrey M. , Hendrix Mary J.C. , Rizzo Paola , Miele Lucio , Nickoloff Brian J. 
Published: September 2005

Abstract
Patients with metastatic melanoma or multiple myeloma have a dismal prognosis because these aggressive malignancies resist conventional treatment. A promising new oncologic approach uses molecularly targeted therapeutics that overcomes apoptotic resistance and, at the same time, achieves tumor selectivity. The unexpected selectivity of proteasome inhibition for inducing apoptosis in cancer cells, but not in normal cells, prompted us to define the mechanism of action for this class of drugs, including Food and Drug Administration–approved bortezomib. In this report, five melanoma cell lines and a myeloma cell line are treated with three different proteasome inhibitors (MG-132, lactacystin, and bortezomib), and the mechanism underlying the apoptotic pathway is defined. Following exposure to proteasome inhibitors, effective killing of human melanoma and myeloma cells, but not of normal proliferating melanocytes, was shown to involve p53-independent induction of the BH3-only protein NOXA. Induction of NOXA at the protein level was preceded by enhanced transcription of NOXA mRNA. Engagement of mitochondrial-based apoptotic pathway involved release of cytochrome c, second mitochondria-derived activator of caspases, and apoptosis-inducing factor, accompanied by a proteolytic cascade with processing of caspases 9, 3, and 8 and poly(ADP)-ribose polymerase. Blocking NOXA induction using an antisense (but not control) oligonucleotide reduced the apoptotic response by 30% to 50%, indicating a NOXA-dependent component in the overall killing of melanoma cells. These results provide a novel mechanism for overcoming the apoptotic resistance of tumor cells, and validate agents triggering NOXA induction as potential selective cancer therapeutics for life-threatening malignancies such as melanoma and multiple myeloma.
Dual Induction of Apoptosis and Senescence in Cancer Cells by Chk2 Activation: Checkpoint Activation as a Strategy against Cancer
Authors: Chen Chang-Rung , Wang Wenxian , Rogoff Harry A. , Li Xiaotong , Mang William , Li Chiang J. 
Published: September 2005

Abstract
The human checkpoint kinase 2 (Chk2) plays a central role in regulation of the cellular response to DNA damage, resulting in cell cycle arrest, DNA repair, or apoptosis depending on severity of DNA damage and the cellular context. Chk2 inhibitors are being developed as sensitizers for chemotherapeutic agents. In contrast, here we report that direct activation of Chk2 alone (without chemotherapeutic agents) led to potent inhibition of cancer cell proliferation. In the absence of de novo DNA damage, checkpoint activation was achieved by increased Chk2 expression, as evidenced by its phosphorylation at Thr68, resulting in senescence and apoptosis of cancer cells (DLD1 and HeLa). The Chk2-induced apoptosis was p53 independent and was mediated by caspase activation triggered by loss of mitochondrial potential. The Chk2-induced senescence was also p53 independent and was associated with induction of p21. These results suggest that direct activation of checkpoint kinases may be a novel approach for cancer therapy.
Differential Regulation of Noxa in Normal Melanocytes and Melanoma Cells by Proteasome Inhibition: Therapeutic Implications
Authors: Fernández Yolanda , Verhaegen Monique , Miller Thomas P. , Rush Jenny L. , Steiner Philipp , Opipari Anthony W. , Lowe Scott W. , Soengas María S. 
Published: September 2005

Abstract
Melanoma is the most aggressive form of skin cancer and advanced stages are invariably resistant to conventional therapeutic agents. Using bortezomib as a prototypic proteasome inhibitor, we have identified a novel and critical role of the proteasome in the maintenance of the malignant phenotype of melanoma cells that could have direct translational implications. Thus, melanoma cells from early, intermediate, and late stages of the disease could not sustain proteasome inhibition and underwent an effective activation of caspase-dependent and -independent death programs. This effect was tumor cell selective, because under similar conditions, normal melanocytes remained viable. Intriguingly, and despite of interfering with a cellular machinery in charge of controlling the half-life of the vast majority of cellular proteins, bortezomib did not promote a generalized disruption of melanoma-associated survival factors (including NF-κB, Bcl-2, Bcl-xL, XIAP, TRAF-2, or FLIP). Instead, we identified a dramatic induction in vitro and in vivo of the BH3-only protein Noxa in melanoma cells (but not in normal melanocytes) in response to proteasome inhibition. RNA interference validated a critical role of Noxa for the cytotoxic effect of bortezomib. Notably, the proteasome-dependent regulation of Noxa was found to extend to other tumor types, and it could not be recapitulated by standard chemotherapeutic drugs. In summary, our results revealed Noxa as a new biomarker to gauge the efficacy of bortezomib specifically in tumor cells, and provide a new strategy to overcome tumor chemoresistance.
A Single Nucleotide Polymorphism in the MDM2 Gene: From a Molecular and Cellular Explanation to Clinical Effect
Authors: Bond Gareth L. , Hu Wenwei , Levine Arnold 
Published: September 2005

Abstract
In a recent article, a candidate pathway approach was taken to try to identify single nucleotide polymorphisms (SNP) that make up the genetic variation, which underlies the phenotypic variation seen between individuals in their susceptibility to cancer and the progression of their disease. The p53 stress response pathway was chosen given its well-documented importance in tumor suppression. A SNP was found which associates with the attenuation of the p53 pathway and the acceleration of tumor formation in humans and data was presented which describe a molecular mechanism for these phenotypes.
It's About Time: Scheduling Alters Effect of Histone Deacetylase Inhibitors on Camptothecin-Treated Cells
Authors: Bevins Robert L. , Zimmer Stephen G. 
Published: September 2005

Abstract
Chemotherapeutic treatment with combinations of drugs is front-line therapy for many types of cancer. Combining drugs which target different signaling pathways often lessens adverse side effects while increasing the efficacy of treatment and reducing patient morbidity. A defined scheduling protocol is described by which histone deacetylase inhibitors (HDIs) facilitate the cytotoxic effectiveness of the topoisomerase I inhibitor camptothecin in the killing of tumor cells. Breast and lung cancer cell lines were treated with camptothecin and sodium butyrate (NaB) or suberoylanilide hydroxamic acid on the day of, the day before, or the day after camptothecin addition. Depending on the time of addition, NaB-treated cells displayed a spectrum of responses from protection to sensitization, indicating the critical nature of timing in the use of HDIs. The IC80 (72-hour assay) dose of 100 nmol/L camptothecin could be lowered to 15 nmol/L camptothecin while maintaining or surpassing cell killing of the single agent if combined with an HDI added 24 to 48 hours after camptothecin. Experiments determined that cells arrested in G2-M by camptothecin were most sensitive to subsequent HDI addition. Western blot analysis indicated that in camptothecin-arrested cells, NaB decreases cyclin B levels, as well as the levels of the antiapoptotic proteins XIAP and survivin. These findings suggest that reducing the levels of these critical antiapoptotic factors may increase the efficacy of topoisomerase I inhibitors in the clinical setting if given in a sequence that does not prevent or inhibit tumor cell progression through the S phase.
RLIP76 Is a Major Determinant of Radiation Sensitivity
Authors: Awasthi Sanjay , Singhal Sharad S. , Yadav Sushma , Singhal Jyotsana , Drake Kenneth , Nadkar Aalok , Zajac Ewa , Wickramarachchi Dilki , Rowe Nancy , Yacoub Adly , Boor Paul , Dwivedi Seema , Dent Paul , Jarman Wendy E. , John Berchmans , Awasthi Yogesh C. 
Published: September 2005

Abstract
RLIP76 (RALBP1) is a glutathione-conjugate transporter that is a critical component of clathrin-coated pit–mediated endocytosis, as well as in stress responses. In cultured cells, it provides protection from stressors including heat, oxidant chemicals, chemotherapeutic agents, UV irradiation, and X-irradiation. Here, we show marked reduction in glutathione conjugate transport capacity and stepwise increase in radiation sensitivity associated with heterozygous or homozygous loss of the RLIP76 gene in mice. Survival after radiation in homozygous knockout animals was significantly shorter than either the heterozygous knockouts or the wild type. Delivery of recombinant RLIP76 to mice lacking RLIP76 via a liposomal delivery system rescued radiation sensitivity. Furthermore, treatment of wild-type mice with RLIP76-containing liposomes conferred resistance to radiation. These findings suggest that inhibiting RLIP76 could be used for sensitization to radiation during cancer therapy and that RLIP76 liposomes could be radioprotective agents useful for treatment of iatrogenic or catastrophic radiation poisoning.