bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Growth and Metastasis of Human Hepatocellular Carcinoma Xenografts Are Inhibited by Small Interfering RNA Targeting to the Subunit ATP6L of Proton Pump
Authors: Lu Xiaodong , Qin Wenxin , Li Jinjun , Tan Ning , Pan Dongning , Zhang Haitao , Xie Li , Yao Genfu , Shu Huiqun , Yao Ming , Wan Dafang , Gu Jianren , Yang Shengli 
Published: September 2005

Abstract
Extracellular pH is usually low in solid tumors, in contrast to the approximately neutral intracellular pH. V-ATPase, which overly functions in some cancers with metastatic potential, plays an important role in maintaining neutral cytosolic pH, very acidic luminal pH, and acidic extracellular pH. ATP6L, the 16 kDa subunit of proton pump V-ATPase, can provide proton hydrophilic transmembrane path. In this study, ATP6L in a human hepatocellular carcinoma cell line with highly metastatic potential (HCCLM3) was knocked down using DNA vector–based small interfering RNA (siRNA) to suppress the metastasis. The expression of ATP6L in stable siRNA transfectants, designated as si-HCCLM3 cells, was inhibited by ∼60%. The proton secretion and the intracellular pH recovery from NH4Cl-prepulsed acidification were inhibited in si-HCCLM3 cells. The invasion of the si-HCCLM3 cells was suppressed in vitro; simultaneously, the expressions of matrix metalloproteinase-2 and gelatinase activity were reduced. In vivo, at 35th day after implantation of the si-HCCLM3 xenografts into the livers in BalB/c (nu+/nu+) mice, the size of liver tumor tissues was dramatically smaller in siRNA group than in the controlled group. The most impressing effect of ATP6L siRNA is its striking reduction of the metastatic potential of HCCLM3 cells. In control, all eight mice had the intrahepatic metastasis and six of eight the pulmonary metastasis, whereas in ATP6L siRNA-treated group, three of eight had the intrahepatic metastasis and only one of eight the pulmonary metastasis. The results suggest that the inhibition of V-ATPase function via knockdown of ATP6L expression using RNA interfering technology can effectively retard the cancer growth and suppress the cancer metastasis by the decrease of proton extrusion and the down-regulation of gelatinase activity.
Mesalazine Improves Replication Fidelity in Cultured Colorectal Cells
Authors: Gasche Christoph , Goel Ajay , Natarajan Loki , Boland C. Richard 
Published: September 2005

Abstract
Epidemiologic studies indicate that mesalazine has chemopreventive effects in inflammatory bowel disease–associated colorectal cancer. Most of our general understanding of chemoprevention in colorectal cancer is, however, derived from aspirin, which is structurally similar to mesalazine. Herein we determined the influence of aspirin and mesalazine on replication fidelity in cultured colorectal cells. Flow cytometry was used for quantitation of mutation rates at a (CA)13 microsatellite in HCT116 cells (mismatch repair deficient) and HCT116+chr3 cells (mismatch repair proficient) that had been stably transfected with pIREShyg2-EGFP/CA13, an enhanced green fluorescence protein–based plasmid, and cultured in the absence or presence of various concentrations of aspirin or mesalazine. Aspirin at doses above 1.25 mmol/L markedly reduced cell growth. Mesalazine doses up to 5.0 mmol/L had no such effect. The mutation rate in mismatch repair–deficient HCT116 cells was 6.8 × 10−4 ± 9.0 × 10−5. In aspirin-treated cultures the mutation rate was 8.2 × 10−4 ± 1.3 × 10−4 (121% of control). Instead, mesalazine lowered the mutation rate in a dose-dependent fashion (5.5 × 10−4 ± 1.1 × 10−4; 81% of control). The effects of mesalazine were most significant in the M1 fraction (P &lt; 0.0001), which represents a mutant population immediate after the polymerase error and were confirmed in mismatch repair–proficient HCT116+chr3 cells. Our data indicate that mesalazine reduces frameshift mutations at a (CA)13 microsatellite in cultured colorectal cells independent of mismatch repair proficiency. This finding suggests that mesalazine improves replication fidelity, an effect that may be active in reducing mutations independent of its anti-inflammatory properties.
p53 Translocation to Mitochondria Precedes Its Nuclear Translocation and Targets Mitochondrial Oxidative Defense Protein-Manganese Superoxide Dismutase
Authors: Zhao Yunfeng , Chaiswing Luksana , Velez Joyce M. , Batinic-Haberle Ines , Colburn Nancy H. , Oberley Terry D. , St. Clair Daret K. 
Published: September 2005

Abstract
The tumor suppressor gene p53 is activated by reactive oxygen species–generating agents. After activation, p53 migrates to mitochondria and nucleus, a response that eventually leads to apoptosis, but how the two events are related is unknown. Herein, we show that p53 translocation to mitochondria precedes its translocation to nucleus in JB6 skin epidermal cells treated with the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). Translocation of p53 to mitochondria occurs within 10 minutes after TPA application. In the mitochondria, p53 interacts with the primary antioxidant enzyme, manganese superoxide dismutase (MnSOD), consistent with the reduction of its superoxide scavenging activity, and a subsequent decrease of mitochondrial membrane potential. In contrast to the immediate action on mitochondria, p53 transcriptional activity in the nucleus increases at 1 hour following TPA application, accompanied by an increase in the levels of its target gene bax at 15 hours following TPA treatment. Activation of p53 transcriptional activity is preventable by application of a SOD mimetic (MnTE-2-PyP5+). Thus, p53 translocation to mitochondria and subsequent inactivation of MnSOD explains the observed mitochondrial dysfunction, which leads to transcription-dependent mechanisms of p53-induced apoptosis.
Distinct Structural Domains within C19ORF5 Support Association with Stabilized Microtubules and Mitochondrial Aggregation and Genome Destruction
Authors: Liu Leyuan , Vo Amy , Liu Guoqin , McKeehan Wallace L. 
Published: September 2005

Abstract
C19ORF5 is a sequence homologue of microtubule-associated proteins MAP1A/MAP1B of unknown function, except for its association with mitochondria-associated proteins and the paclitaxel-like microtubule stabilizer and candidate tumor suppressor RASSF1A. Here, we show that when overexpressed in mammalian cells the recombinant 393–amino acid residue COOH terminus of C19ORF5 (C19ORF5C) exhibited four types of distribution patterns proportional to expression level. Although normally distributed throughout the cytosol without microtubular association, C19ORF5C specifically accumulated on stabilized microtubules in paclitaxel-treated cells and interacted directly with paclitaxel-stabilized microtubules in vitro. The native 113-kDa full-length C19ORF5 and a shorter 56-kDa form similarly associated with stabilized microtubules in liver cells and stabilized microtubules from their lysates. As C19ORF5 accumulated, it appeared on mitochondria and progressively induced distinct perinuclear aggregates of mitochondria. C19ORF5 overlapped with cytochrome c–deficient mitochondria with reduced membrane potential. Mitochondrial aggregation resulted in gross degradation of DNA, a cell death–related process we refer to as mitochondrial aggregation and genome destruction (MAGD). Deletion mutagenesis revealed that the C19ORF5 hyperstabilized microtubule-binding domain resides in a highly basic sequence of &lt;100 residues, whereas the MAGD activity resides further downstream in a distinct 25-residue sequence (F967-A991). Our results suggest that C19ORF5 mediates communication between the microtubular cytoskeleton and mitochondria in control of cell death and defective genome destruction through distinct bifunctional structural domains. The accumulation of C19ORF5 and resultant MAGD signaled by hyperstabilized microtubules may be involved in the tumor suppression activity of RASSF1A, a natural microtubule stabilizer and interaction partner with C19ORF5, and the taxoid drug family.
Transcriptional Programs following Genetic Alterations inp53,INK4A, andH-RasGenes along Defined Stages of Malignant Transformation
Authors: Milyavsky Michael , Tabach Yuval , Shats Igor , Erez Neta , Cohen Yehudit , Tang Xiaohu , Kalis Marina , Kogan Ira , Buganim Yosef , Goldfinger Naomi , Ginsberg Doron , Harris Curtis C. , Domany Eytan , Rotter Varda 
Published: September 2005

AbstractThe difficulty to dissect a complex phenotype of established malignant cells to several critical transcriptional programs greatly impends our understanding of the malignant transformation. The genetic elements required to transform some primary human cells to a tumorigenic state were described in several recent studies. We took the advantage of the global genomic profiling approach and tried to go one step further in the dissection of the transformation network. We sought to identify the genetic signatures and key target genes, which underlie the genetic alterations in p53, Ras, INK4A locus, and telomerase, introduced in a stepwise manner into primary human fibroblasts. Here, we show that these are the minimally required genetic alterations for sarcomagenesis in vivo. A genome-wide expression profiling identified distinct genetic signatures corresponding to the genetic alterations listed above. Most importantly, unique transformation hallmarks, such as differentiation block, aberrant mitotic progression, increased angiogenesis, and invasiveness, were identified and coupled with genetic signatures assigned for the genetic alterations in the p53, INK4A locus, and H-Ras, respectively. Furthermore, a transcriptional program that defines the cellular response to p53 inactivation was an excellent predictor of metastasis development and bad prognosis in breast cancer patients. Deciphering these transformation fingerprints, which are affected by the most common oncogenic mutations, provides considerable insight into regulatory circuits controlling malignant transformation and will hopefully open new avenues for rational therapeutic decisions.
Somatic Induction of Pten Loss in a Preclinical Astrocytoma Model Reveals Major Roles in Disease Progression and Avenues for Target Discovery and Validation
Authors: Xiao Andrew , Yin Chaoying , Yang Chunyu , Di Cristofano Antonio , Pandolfi Pier Paolo , Van Dyke Terry 
Published: September 2005

Abstract
High-grade astrocytomas are invariably deadly and minimally responsive to therapy. Pten is frequently mutated in aggressive astrocytoma but not in low-grade astrocytoma. However, the Pten astrocytoma suppression mechanisms are unknown. Here we introduced conditional null alleles of Pten (Ptenloxp/loxp) into a genetically engineered mouse astrocytoma model [TgG(ΔZ)T121] in which the pRb family proteins are inactivated specifically in astrocytes. Pten inactivation was induced by localized somatic retroviral (MSCV)-Cre delivery. Depletion of Pten function in adult astrocytoma cells alleviated the apoptosis evoked by pRb family protein inactivation and also induced tumor cell invasion. In primary astrocytes derived from TgG(ΔZ)T121; Ptenloxp/loxp mice, Pten deficiency resulted in a marked increase in cell invasiveness that was suppressed by inhibitors of protein kinase C (PKC) or of PKC-ζ, specifically. Finally, focal induction of Pten deficiency in vivo promoted angiogenesis in affected brains. Thus, we show that Pten deficiency in pRb-deficient astrocytoma cells contributes to tumor progression via multiple mechanisms, including suppression of apoptosis, increased cell invasion, and angiogenesis, all of which are hallmarks of high-grade astrocytoma. These studies not only provide mechanistic insight into the role of Pten in astrocytoma suppression but also describe a valuable animal model for preclinical testing that is coupled with a primary cell-based system for target discovery and drug screening.
The p53 Protein Is a Novel Substrate of Ribosomal S6 Kinase 2 and a Critical Intermediary for Ribosomal S6 Kinase 2 and Histone H3 Interaction
Authors: Cho Yong-Yeon , He Zhiwei , Zhang Yiguo , Choi Hong Seok , Zhu Feng , Choi Bu Young , Kang Bong Seok , Ma Wei-Ya , Bode Ann M. , Dong Zigang 
Published: September 2005

Abstract
The tumor suppressor p53 protein is one of the most highly connected nodes in cellular signal transduction pathways and acts as a central regulatory switch in networks controlling cell proliferation and apoptosis. It is involved in the activation of genes that maintain control over cellular responses to DNA errors such as DNA repair, chromosomal recombination, and chromosome segregation. Here we show that ribosomal S6 kinase 2 (RSK2) activates and phosphorylates p53 (Ser15) in vitro and in vivo and colocalizes with p53 in the nucleus. Deficiency of p53 diminishes RSK2-mediated phosphorylation of histone H3 (Ser10) and adding back p53 to p53−/− embryonic fibroblasts restored phosphorylation of histone H3 at Ser10. These results show that the p53 protein is an important substrate of RSK2 and a critical intermediary in the RSK2 and histone H3 interaction. The RSK2-p53-histone H3 complex may likely contribute to chromatin remodeling and cell cycle regulation.
Glyceraldehyde-3-Phosphate Dehydrogenase Binds to the AU-Rich 3′ Untranslated Region of Colony-Stimulating Factor–1 (CSF-1) Messenger RNA in Human Ovarian Cancer Cells: Possible Role in CSF-1 Posttranscriptional Regulation and Tumor Phenotype
Authors: Bonafé Nathalie , Gilmore-Hebert Maureen , Folk Nancy L. , Azodi Masoud , Zhou Yi , Chambers Setsuko K. 
Published: September 2005

Abstract
The overexpression of the colony-stimulating factor–1(CSF-1) by epithelial ovarian cancer cells enhances invasiveness and metastatic properties, contributing to the poor prognosis of the patients. It has been suggested that CSF-1 3′ untranslated region containing AU-rich elements (ARE) could regulate CSF-1 posttranscriptional expression and be responsible for its aberrant abundance in such cancer cells. In this study, normal (NOSE.1) and malignant (Hey) ovarian epithelial cells were used to examine CSF-1 expression and regulation. CSF-1 overexpression in Hey cells was found to associate with increased invasiveness, motility, urokinase activity, and virulence of tumorigenicity, compared with NOSE.1 cells, which expressed little CSF-1. CSF-1 ARE was further found to serve as an mRNA decay element that correlates with down-regulation of protein translation. Moreover, such down-regulation was found more prominent in NOSE.1 than in Hey cells, suggesting differences in posttranscriptional regulation. As a variety of trans-acting factors [AU-binding protein (AUBP)] are known to modulate messenger stability through binding to such elements, we examined the protein content of both cell lines for their ability to bind the CSF-1 ARE. Our results strongly suggested the abundance of such AUBP activity in Hey cells. We isolated a 37-kDa AUBP, which was identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH).
To summarize, our study identified GAPDH as an AUBP abundant in Hey cells, where it binds to CSF-1 ARE that imparts mRNA decay. These data suggest that GAPDH binding to CSF-1 ARE sequence prevents CSF-1 mRNA decay and subsequent down-regulation of CSF-1 protein translation, leading to CSF-1 overexpression and increased metastatic properties seen in ovarian cancer.
PED Mediates AKT-Dependent Chemoresistance in Human Breast Cancer Cells
Authors: Stassi Giorgio , Garofalo Michela , Zerilli Monica , Ricci-Vitiani Lucia , Zanca Ciro , Todaro Matilde , Aragona Federico , Limite Gennaro , Petrella Giuseppe , Condorelli Gerolama 
Published: September 2005

Abstract
Killing of tumor cells by cytotoxic therapies, such as chemotherapy or gamma-irradiation, is predominantly mediated by the activation of apoptotic pathways. Refractoriness to anticancer therapy is often due to a failure in the apoptotic pathway. The mechanisms that control the balance between survival and cell death in cancer cells are still largely unknown. Tumor cells have been shown to evade death signals through an increase in the expression of antiapoptotic molecules or loss of proapoptotic factors. We aimed to study the involvement of PED, a molecule with a broad antiapoptotic action, in human breast cancer cell resistance to chemotherapeutic drugs–induced cell death. We show that human breast cancer cells express high levels of PED and that AKT activity regulates PED protein levels. Interestingly, exogenous expression of a dominant-negative AKT cDNA or of PED antisense in human breast cancer cells induced a significant down-regulation of PED and sensitized cells to chemotherapy-induced cell death. Thus, AKT-dependent increase of PED expression levels represents a key molecular mechanism for chemoresistance in breast cancer.
Poly(ADP-Ribose) Polymerase-1 Could Facilitate the Religation of Topoisomerase I-linked DNA Inhibited by Camptothecin
Authors: Park Shin-Young , Cheng Yung-Chi 
Published: September 2005

Abstract
Poly(ADP-ribose) polymerase-1 (PARP-1) is known to have an important role in camptothecin sensitivity and interacts with topoisomerase I. In the present study, the impact of PARP-1 on the topoisomerase I-DNA complex stabilized by camptothecin was assessed. It was shown that NH2 terminus–truncated topoisomerase I (amino acids 201-765) showed at least 4-fold less sensitivity to camptothecin than full-length topoisomerase I in the oligonucleotide religation assay. PARP-1 could prevent the action of camptothecin on the religation activity of full-length topoisomerase I, which is linked to DNA in a stoichiometrical manner. However, the religation activity of NH2 terminus–truncated topoisomerase I, which is linked to DNA, could not be enhanced by PARP-1 in the presence of camptothecin. Both full-length and NH2 terminus–truncated topoisomerase I interact with PARP-1. This data suggests that PARP-1 destabilizes the topoisomerase I-camptothecin-DNA complex with the participation of the NH2-terminal domain of topoisomerase I. Poly(ADP-ribosyl)ation of topoisomerase I by PARP-1 in the presence its substrate, NAD, could also promote the religation activity of full-length topoisomerase I as well as NH2 terminus–truncated topoisomerase I. PARP-1 inhibitors (3-aminobenzamide, PJ34) could inhibit this process. Therefore, PARP-1 could facilitate the religation activity of topoisomerase I by itself through topoisomerase I-PARP-1 interaction (PARP-1 action) or by the formation of poly(ADP-ribosyl)ation of topoisomerase I (PARP-1/NAD action). This study also implies that PARP-1 and PARP-1/NAD actions need to be highly regulated by cellular factors for camptothecin to exert its cytotoxicity inside the cells. We propose ATP to be one of the important regulatory factors.
Targeting Tomoregulin for Radioimmunotherapy of Prostate Cancer
Authors: Zhao Xiao-Yan , Schneider Doug , Biroc Sandra L. , Parry Renate , Alicke Bruno , Toy Pamela , Xuan Jian-Ai , Sakamoto Choitsu , Wada Ken , Schulze Michael , Müller-Tiemann Beate , Parry Gordon , Dinter Harald 
Published: September 2005

Abstract
Radiotherapy is an effective approach for the treatment of local prostate cancer. However, once prostate cancer metastasizes, radiotherapy cannot be used due to the distribution of multiple metastases to lymph nodes and bones. In contrast, radioimmunotherapy should still be efficacious in metastatic prostate cancer as radioisotopes are brought to tumor cells by targeting antibodies. Here we identify and validate a prostate-expressed molecule, tomoregulin, as a target for radioimmunotherapy of prostate cancer. Tomoregulin is a transmembrane protein selectively expressed in the brain, prostate, and prostate cancer, but not expressed in other normal tissues. Immunohistochemical studies of tomoregulin protein in clinical samples show its location in the luminal epithelium of normal prostate, benign prostatic hyperplasia, and prostatic intraepithelial neoplasia. More importantly, the tomoregulin protein is expressed in primary prostate tumors and in their lymph node and bone metastases. The nature of tomoregulin as a transmembrane protein and its tissue-specific expression make tomoregulin an attractive target for radioimmunotherapy, in which tomoregulin-specific antibodies will deliver a radioisotope to prostate tumor cells and metastases. Indeed, biodistribution studies using a prostate tumor xenograft model showed that the 111In-labeled anti-tomoregulin antibody 2H8 specifically recognizes tomoregulin protein in vivo, leading to a strong tumor-specific accumulation of the antibody. In efficacy studies, a single i.p. dose of 150 μCi (163 μg) 90Y-labeled 2H8 substantially inhibits the growth rate of established LNCaP human prostate tumor xenograft in nude mice but produces no overt toxicity despite cross-reactivity of 2H8 with mouse tomoregulin. Our data clearly validate tomoregulin as a target for radioimmunotherapy of prostate cancer.
Activation of ErbB2 by Overexpression or by Transmembrane Neuregulin Results in Differential Signaling and Sensitivity to Herceptin
Authors: Yuste Laura , Montero Juan C. , Esparís-Ogando Azucena , Pandiella Atanasio 
Published: September 2005

Abstract
The ligands of the epidermal growth factor family and their receptors, the ErbB proteins, have been linked to the development of different types of cancer. Particular attention has focused on ErbB2, whose activation may occur by receptor overexpression or by ligand-induced oligomerization with other ErbB receptors. Whether these two modes of ErbB2 activation cause the same biological responses is unknown. Here, we uncovered important differences in the signaling, proliferation rates, and the response to anti-ErbB2 antibodies when comparing MCF7 cells expressing the ligand neuregulin, to MCF7 cells overexpressing ErbB2. Expression of neuregulin caused higher proliferation than ErbB2 overexpression. Transmembrane neuregulin expression was accompanied by constitutive activation of ErbB2, ErbB3, and ErbB4 receptors. ErbB2 overexpression caused tyrosine phosphorylation of ErbB2, whereas ErbB3 and ErbB4 were only slightly tyrosine phosphorylated. Autocrine transmembrane neuregulin also caused constitutive activation of several signaling pathways, such as the Erk1/2, Erk5, and Akt routes, which have been linked to breast cancer cell proliferation. Interestingly, expression of neuregulin increased p21 levels and this was required for the proliferation of MCF7 cells. Treatment with the anti-ErbB2 receptor antibody Herceptin had an inhibitory effect on proliferation only in cells expressing neuregulin but not on cells overexpressing ErbB2, and its inhibitory activity was accompanied by a decrease in p21. These results suggest that Herceptin may also be of help in the treatment of tumors in which neuregulin feeds the tumoral tissue.