bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Human Kallikrein 8 Protease Confers a Favorable Clinical Outcome in Non–Small Cell Lung Cancer by Suppressing Tumor Cell Invasiveness
Authors: Sher Yuh-Pyng , Chou Cheng-Chung , Chou Ruey-Hwang , Wu Han-Ming , Wayne Chang Wun-Shaing , Chen Chun-Houh , Yang Pan-Chyr , Wu Cheng-Wen , Yu Chia-Li , Peck Konan
Published: March 2023

Abstract
The human kallikrein 8 (KLK8) gene, a member of the human tissue kallikrein gene family, encodes a serine protease. The KLK8 protein (hK8) is known to be a favorable prognostic marker in ovarian cancer, but the biological basis of this is not understood. We found that overexpressing the KLK8 gene in highly invasive lung cancer cell lines suppresses their invasiveness. This role in invasiveness was further confirmed by the fact that inhibition of endogenous KLK8 expression with a specific short hairpin RNA reduced cancer cell invasiveness. In situ degradation and cell adhesion assays showed that proteins produced from KLK8 splice variants modify the extracellular microenvironment by cleaving fibronectin. DNA microarray experiments and staining of cells for actin filaments revealed that the degradation of fibronectin by hK8 suppresses integrin signaling and retards cancer cell motility by inhibiting actin polymerization. In addition, studies in a mouse model coupled with the detection of circulating tumor cells by quantitative PCR for the human Alu sequence showed that KLK8 suppresses tumor growth and invasion in vivo. Finally, studies of clinical specimens from patients with non–small cell lung cancer showed that the time to postoperative recurrence was longer for early-stage patients (stages I and II) with high KLK8 expression (mean, 49.9 months) than for patients with low KLK8 expression (mean, 22.9 months). Collectively, these findings show that KLK8 expression confers a favorable clinical outcome in non–small cell lung cancer by suppressing tumor cell invasiveness. (Cancer Res 2006; 66(24): 11763-70)
Data from Cyclooxygenase-1 Is Overexpressed in Multiple Genetically Engineered Mouse Models of Epithelial Ovarian Cancer
Authors: Daikoku Takiko , Tranguch Susanne , Trofimova Irina N. , Dinulescu Daniela M. , Jacks Tyler , Nikitin Alexander Yu. , Connolly Denise C. , Dey Sudhansu K.
Published: March 2023

Abstract
Cyclooxygenases-1 and -2 (Cox-1 and Cox-2) are two distinct isoforms that catalyze the conversion of arachidonic acid to prostaglandins. The role of Cox-2 in a variety of cancers is well recognized, but the contribution of Cox-1 remains much less explored. We have previously shown that human epithelial ovarian tumors have increased levels of Cox-1, but not Cox-2. We also observed that Cox-1 is highly expressed in a mouse model of epithelial ovarian cancer (EOC), which lacks p53 but overexpresses c-myc and K-ras or c-myc and Akt. More importantly, a Cox-1-selective inhibitor, SC-560, attenuates EOC growth. In the present investigation, we used various genetically engineered mouse models of EOC to determine whether Cox-1 overexpression is unique to specific genetic and oncogenic alterations or is widespread. These models include: (a) deletion of both p53 and Rb, (b) induction of the transforming region of SV40 under the control of Mullerian inhibitory substance type II receptor, or (c) activation of K-Ras in the absence of Pten locally in the ovarian surface epithelium. We found that these three models, which produce spontaneous EOC, also show up-regulated expression of Cox-1, but not Cox-2. The results provide further evidence that Cox-1 overexpression is common in various models of EOC. Thus, Cox-1 serves as a potential marker of EOC and is a possible target for the prevention and/or treatment of this deadly disease. (Cancer Res 2006; 66(5): 2527-31)
Data from Human Lymphoblastoid Proteome Analysis Reveals a Role for the Inhibitor of Acetyltransferases Complex in DNA Double-Strand Break Response
Authors: Dirksen Eef H.C. , Cloos Jacqueline , Braakhuis Boudewijn J.M. , Brakenhoff Ruud H. , Heck Albert J.R. , Slijper Monique
Published: March 2023

Abstract
A DNA double-strand break (DSB) is highly cytotoxic; it emerges as the type of DNA damage that most severely affects the genomic integrity of the cell. It is essential that DNA DSBs are recognized and repaired efficiently, in particular, prior to mitosis, to prevent genomic instability and eventually, the development of cancer. To assess the pathways that are induced on DNA DSBs, 14 human lymphoblastoid cell lines were challenged with bleomycin for 30 and 240 minutes to establish the fast and more prolonged response, respectively. The proteomes of 14 lymphoblastoid cell lines were investigated to account for the variation among individuals. The primary DNA DSB response was expected to occur within the nucleus; therefore, the nuclear extracts were considered. Differential analysis was done using two-dimensional difference in gel electrophoresis; paired ANOVA statistics were used to recognize significant changes in time. Many proteins whose nuclear levels changed statistically significantly showed a fast response, i.e., within 30 minutes after bleomycin challenge. A significant number of these proteins could be assigned to known DNA DSB response processes, such as sensing DSBs (Ku70), DNA repair through effectors (high-mobility group protein 1), or cell cycle arrest at the G2-M phase checkpoint (14-3-3 ζ). Interestingly, the nuclear levels of all three proteins in the INHAT complex were reduced after 30 minutes of bleomycin challenge, suggesting that this complex may have a role in changing the chromatin structure, allowing the DNA repair enzymes to gain access to the DNA lesions. (Cancer Res 2006; 66(3): 1473-80)
Data from Molecular Mechanisms of RET Receptor–Mediated Oncogenesis in Multiple Endocrine Neoplasia 2B
Authors: Gujral Taranjit S. , Singh Vinay K. , Jia Zongchao , Mulligan Lois M.
Published: March 2023

Abstract
Multiple endocrine neoplasia 2B (MEN 2B) is an inherited syndrome of early onset endocrine tumors and developmental anomalies. The disease is caused primarily by a methionine to threonine substitution of residue 918 in the kinase domain of the RET receptor (2B-RET); however, the molecular mechanisms that lead to the disease phenotype are unclear. In this study, we show that the M918T mutation causes a 10-fold increase in ATP binding affinity and leads to a more stable receptor-ATP complex, relative to the wild-type receptor. Further, the M918T mutation alters local protein conformation, correlating with a partial loss of RET kinase autoinhibition. Finally, we show that 2B-RET can dimerize and become autophosphorylated in the absence of ligand stimulation. Our data suggest that multiple distinct but complementary molecular mechanisms underlie the MEN 2B phenotype and provide potential targets for effective therapeutics for this disease. (Cancer Res 2006; 66(22): 10741-9)
Data from Metformin Is an AMP Kinase–Dependent Growth Inhibitor for Breast Cancer Cells
Authors: Zakikhani Mahvash , Dowling Ryan , Fantus I. George , Sonenberg Nahum , Pollak Michael
Published: March 2023

Abstract
Recent population studies provide clues that the use of metformin may be associated with reduced incidence and improved prognosis of certain cancers. This drug is widely used in the treatment of type 2 diabetes, where it is often referred to as an “insulin sensitizer” because it not only lowers blood glucose but also reduces the hyperinsulinemia associated with insulin resistance. As insulin and insulin-like growth factors stimulate proliferation of many normal and transformed cell types, agents that facilitate signaling through these receptors would be expected to enhance proliferation. We show here that metformin acts as a growth inhibitor rather than an insulin sensitizer for epithelial cells. Breast cancer cells can be protected against metformin-induced growth inhibition by small interfering RNA against AMP kinase. This shows that AMP kinase pathway activation by metformin, recently shown to be necessary for metformin inhibition of gluconeogenesis in hepatocytes, is also involved in metformin-induced growth inhibition of epithelial cells. The growth inhibition was associated with decreased mammalian target of rapamycin and S6 kinase activation and a general decrease in mRNA translation. These results provide evidence for a mechanism that may contribute to the antineoplastic effects of metformin suggested by recent population studies and justify further work to explore potential roles for activators of AMP kinase in cancer prevention and treatment. (Cancer Res 2006; 66(21): 10269-73)
Data from Gene Expression Analysis of Preinvasive and Invasive Cervical Squamous Cell Carcinomas Identifies HOXC10 as a Key Mediator of Invasion
Authors: Zhai Yali , Kuick Rork , Nan Bin , Ota Ichiro , Weiss Stephen J. , Trimble Cornelia L. , Fearon Eric R. , Cho Kathleen R.
Published: March 2023

Abstract
If left untreated, a subset of high-grade squamous intraepithelial lesions (HSIL) of the cervix will progress to invasive squamous cell carcinomas (SCC). To identify genes whose differential expression is linked to cervical cancer progression, we compared gene expression in microdissected squamous epithelial samples from 10 normal cervices, 7 HSILs, and 21 SCCs using high-density oligonucleotide microarrays. We identified 171 distinct genes at least 1.5-fold up-regulated (and P < 0.001) in the SCCs relative to HSILs and normal cervix samples. Differential expression of a subset of these genes was confirmed by quantitative reverse transcription-PCR and immunohistochemical staining of cervical tissue samples. One of the genes up-regulated during progression, HOXC10, was selected for functional studies aimed at assessing its role in mediating invasive behavior of neoplastic squamous epithelial cells. Elevated HOXC10 expression was associated with increased invasiveness of human papillomavirus–immortalized keratinocytes and cervical cancer–derived cell lines in both in vitro and in vivo assays. Cervical cancer cells with high endogenous levels of HOXC10 were less invasive after short hairpin RNA–mediated knockdown of HOXC10 expression. Our findings support a key role for the HOXC10 homeobox protein in cervical cancer progression. Other genes with differential expression in invasive SCC versus HSIL may contribute to tumor progression or may be useful as markers for cancer diagnosis or progression risk. [Cancer Res 2007;67(21):10163–72]
Data from Patterns of EGFR, HER2, TP53, and KRAS Mutations of p14arf Expression in Non–Small Cell Lung Cancers in Relation to Smoking History
Authors: Mounawar Mounia , Mukeria Anush , Le Calvez Florence , Hung Rayjean J. , Renard Helene , Cortot Alexis , Bollart Claire , Zaridze David , Brennan Paul , Boffetta Paolo , Brambilla Elisabeth , Hainaut Pierre
Published: March 2023

Abstract
Mutations in the tyrosine kinase domain of the epidermal growth factor receptor EGFR are common in non–small cell lung cancer (NSCLC) of never smokers, whereas HER2 mutations are rare. We have analyzed EGFR and HER2 mutations and the expression of the two products of the CDKN2A gene (p14arf and p16INK4a) in 116 NSCLC that have been previously analyzed for TP53 and KRAS mutations in relation to smoking history of patients. EGFR mutations were detected in 20 of 116 (17%) tumors, whereas five (4.3%) tumors contained HER2 mutations. No tumor contained both mutations. Of tumors with EGFR or HER2 mutation, 72% were adenocarcinomas, 68% were from never smokers, and 32% were from former smokers. EGFR but not HER2 mutations were mutually exclusive with KRAS mutation. Among never smokers, 11 of 16 tumors with EGFR mutation also had TP53 mutation, in contrast with two of 17 tumors without EGFR mutation (P = 0.0008). Expression of p14arf, but not p16ink4a, was more frequently down-regulated in never smokers (62.5%) than ever smokers (35%; P = 0.008). All tumors with EGFR or HER2 mutations and wild-type TP53 showed down-regulation of p14arf expression. These observations suggest that functional inactivation of the p14arf/p53 connection is required in tumors with EGFR or HER2 mutations, consistent with the notion that these proteins are part of a fail-safe mechanism protecting cells against untimely or excessive mitotic signals. [Cancer Res 2007;67(12):5667–72]
Data from Knock-in of Mutant K-ras in Nontumorigenic Human Epithelial Cells as a New Model for Studying K-ras–Mediated Transformation
Authors: Konishi Hiroyuki , Karakas Bedri , Abukhdeir Abde M. , Lauring Josh , Gustin John P. , Garay Joseph P. , Konishi Yuko , Gallmeier Eike , Bachman Kurtis E. , Park Ben Ho
Published: March 2023

Abstract
The oncogenic function of mutant ras in mammalian cells has been extensively investigated using multiple human and animal models. These systems include overexpression of exogenous mutant ras transgenes, conditionally expressed knock-in mouse models, and somatic cell knockout of mutant and wild-type ras genes in human cancer cell lines. However, phenotypic discrepancies between knock-in mice and transgenic mutant ras overexpression prompted us to evaluate the consequences of targeted knock-in of an oncogenic K-ras mutation in the nontumorigenic human breast epithelial cell line MCF-10A and hTERT-immortalized human mammary epithelial cells. Our results show several significant differences between mutant K-ras knock-in cells versus their transgene counterparts, including limited phosphorylation of the downstream molecules extracellular signal-regulated kinase and AKT, minor proliferative capacity in the absence of an exogenous growth factor, and the inability to form colonies in semisolid medium. Analysis of 16 cancer cell lines carrying mutant K-ras genes indicated that 50% of cancer cells harbor nonoverexpressed heterozygous K-ras mutations similar to the expression seen in our knock-in cell lines. Thus, this system serves as a new model for elucidating the oncogenic contribution of mutant K-ras as expressed in a large fraction of human cancer cells. [Cancer Res 2007;67(18):8460–7]
Data from Dormant Tumor Cells Develop Cross-Resistance to Apoptosis Induced by CTLs or Imatinib Mesylate via Methylation of Suppressor of Cytokine Signaling 1
Authors: Saudemont Aurore , Hamrouni Abdelbasset , Marchetti Philippe , Liu Jizhong , Jouy Nathalie , Hetuin Dominique , Colucci Francesco , Quesnel Bruno
Published: March 2023

Abstract
In the BCR/ABL DA1-3b mouse model of acute myelogenous leukemia, dormant tumor cells may persist in the host in a state of equilibrium with the CD8+ CTL-mediated immune response by actively inhibiting T cells. Dormant tumor cells also show a progressive decrease of suppressor of cytokine signaling 1 (SOCS1) gene expression and a deregulation of the Janus-activated kinase/signal transducers and activators of transcription (JAK/STAT) pathway due to methylation of the SOCS1 gene. Dormant tumor cells were more resistant to apoptosis induced by specific CTLs, but resistance decreased when SOCS1 expression was restored via demethylation or gene transfer. AG490 JAK2 inhibitor decreased the resistance of dormant tumor cells to CTLs, but MG132 proteasome inhibitor was effective only in SOCS1-transfected cells. Thus, SOCS1 regulation of the JAK/STAT pathways contributes to the resistance of tumor cells to CTL-mediated killing. Resistance of dormant tumor cells to apoptosis was also observed when induced by irradiation, cytarabine, or imatinib mesylate, but was reduced by SOCS1 gene transfer. This cross-resistance to apoptosis was induced by interleukin 3 (IL-3) overproduction by dormant tumor cells and was reversed with an anti–IL-3 antibody. Thus, tumor cells that remain dormant for long periods in the host in spite of a specific CTL immune response may deregulate their JAK/STAT pathways and develop cross-resistance to various treatments through an IL-3 autocrine loop. These data suggest possible new therapeutic targets to eradicate dormant tumor cells. [Cancer Res 2007;67(9):4491–8]
Data from Association of Wwox with ErbB4 in Breast Cancer
Authors: Aqeilan Rami I. , Donati Valentina , Gaudio Eugenio , Nicoloso Milena S. , Sundvall Maria , Korhonen Anna , Lundin Johan , Isola Jorma , Sudol Marius , Joensuu Heikki , Croce Carlo M. , Elenius Klaus
Published: March 2023

Abstract
WWOX, WW domain-containing oxidoreductase, is a tumor suppressor that is altered in many human cancers, including breast cancer. Wwox interacts with the ErbB4 receptor, reduces nuclear translocation of the cleaved intracellular domain of ErbB4, and inhibits its transactivation function mediated through Yes-associated protein. Here, we assessed the clinical significance of the Wwox-ErbB4 association. We determined Wwox protein expression by immunohistochemistry in a series of 556 breast cancers. Wwox expression was absent in 36% of the cancers, and loss of Wwox expression was associated with unfavorable outcome (P = 0.02). Membranous location of ErbB4 was associated with favorable survival compared with women whose cancer lacked such ErbB4 expression (P = 0.02). Wwox expression was strongly associated with membranous ErbB4 localization (P = 0.0003) and with overall ErbB4 expression (P = 0.0002). Coexpression of membranous ErbB4 and Wwox was associated with favorable outcome compared with cases with membranous ErbB4 and no Wwox immunoreactivity (P = 0.002). In vitro, Wwox associated with the two ErbB4 isoforms, JM-a CYT-1 and JM-a CYT-2, expressed in breast cancer. Moreover, expression of Wwox both in vitro and in vivo led to accumulation of total full-length membrane-associated ErbB4. These results suggest that expression of Wwox is associated with ErbB4 expression and that their coexpression has prognostic significance in breast cancer. [Cancer Res 2007;67(19):9330–6]
Data from Superoxide Signaling Mediates N-acetyl-l-cysteine–Induced G1 Arrest: Regulatory Role of Cyclin D1 and Manganese Superoxide Dismutase
Authors: Menon Sarita G. , Sarsour Ehab H. , Kalen Amanda L. , Venkataraman Sujatha , Hitchler Michael J. , Domann Frederick E. , Oberley Larry W. , Goswami Prabhat C.
Published: March 2023

Abstract
Thiol antioxidants, including N-acetyl-l-cysteine (NAC), are widely used as modulators of the intracellular redox state. We investigated the hypothesis that NAC-induced reactive oxygen species (ROS) signaling perturbs cellular proliferation by regulating the cell cycle regulatory protein cyclin D1 and the ROS scavenging enzyme Mn–superoxide dismutase (MnSOD). When cultured in media containing NAC, mouse fibroblasts showed G1 arrest with decreased cyclin D1 protein levels. The absence of a NAC-induced G1 arrest in fibroblasts overexpressing cyclin D1 (or a nondegradable mutant of cyclin D1-T286A) indicates that cyclin D1 regulates this G1 arrest. A delayed response to NAC exposure was an increase in both MnSOD protein and activity. NAC-induced G1 arrest is exacerbated in MnSOD heterozygous fibroblasts. Results from electron spin resonance spectroscopy and flow cytometry measurements of dihydroethidine fluorescence showed an approximately 2-fold to 3-fold increase in the steady-state levels of superoxide (O2•−) in NAC-treated cells compared with control. Scavenging of O2•− with Tiron reversed the NAC-induced G1 arrest. These results show that an O2•− signaling pathway regulates NAC-induced G1 arrest by decreasing cyclin D1 protein levels and increasing MnSOD activity. [Cancer Res 2007;67(13):6392–9]
Data from Dual Role of Mitochondrial Reactive Oxygen Species in Hypoxia Signaling: Activation of Nuclear Factor-κB via c-SRC– and Oxidant-Dependent Cell Death
Authors: Lluis Josep M. , Buricchi Francesca , Chiarugi Paola , Morales Albert , Fernandez-Checa José C.
Published: March 2023

Abstract
Hypoxia is a prominent feature of solid tumor development and is known to stimulate mitochondrial ROS (mROS), which, in turn, can activate hypoxia-inducible transcription factor-1α and nuclear factor-κB (NF-κB). Because NF-κB plays a central role in carcinogenesis, we examined the mechanism of mROS-mediated NF-κB activation and the fate of cancer cells during hypoxia after mitochondrial reduced glutathione (mGSH) depletion. Hypoxia generated mROS in hepatoma (HepG2, H35), neuroblastoma (SH-SY5Y), and colon carcinoma (DLD-1) cells, leading to hypoxia-inducible transcription factor-1α–dependent gene expression and c-Src activation that was prevented in cells expressing a redox-insensitive c-Src mutant (C487A). c-Src stimulation activated NF-κB without IκB-α degradation due to IκB-α tyrosine phosphorylation that was inhibited by rotenone/TTFA or c-Src antagonism. The c-Src–NF-κB signaling contributed to the survival of cells during hypoxia as c-Src inhibition or p65 down-regulation by small interfering RNA–sensitized HepG2 cells to hypoxia-induced cell death. Moreover, selective mGSH depletion resulted in an accelerated and enhanced mROS generation by hypoxia that killed SH-SY5Y and DLD-1 cells without disabling the c-Src–NF-κB pathway. Thus, although mROS promote cell survival by NF-κB activation via c-Src, mROS overgeneration may be exploited to sensitize cancer cells to hypoxia. [Cancer Res 2007;67(15):7368–77]
Data from Eukaryotic Translation Initiation Factor 4E–Induced Progression of Primary Human Mammary Epithelial Cells along the Cancer Pathway Is Associated with Targeted Translational Deregulation of Oncogenic Drivers and Inhibitors
Authors: Larsson Ola , Li Shunan , Issaenko Olga A. , Avdulov Svetlana , Peterson Mark , Smith Karen , Bitterman Peter B. , Polunovsky Vitaly A.
Published: March 2023

Abstract
Pathologic redirection of translational control by constitutive activation of eukaryotic translation initiation factor 4F (eIF4F), the cap-dependent translation initiation apparatus, is an obligatory step in oncogenesis; however, its mechanism remains undefined. Here, we simulate this pro-oncogenic state by overexpressing eIF4E, the rate-limiting component of eIF4F, in primary human mammary epithelial cells (HMECs) and examine the resultant changes in cell biology and gene expression profiles of total and polyribosome-bound mRNA genome wide. Overexpressed eIF4E rescues primary HMECs from telomere-independent growth arrest and disables checkpoints governing S-phase entry as well as apoptosis in HMECs immortalized by telomerase, imparting cells with proliferative and survival autonomy. Although the transcriptional response to increased eIF4E was modest, the translational response was large, selective, and bidirectional. In addition to translational activation of known and novel eIF4E-responsive oncogenic drivers regulating cell growth and survival, our data unveil previously unrecognized cellular defenses including translational activation of tumor suppressors, translational repression of transcripts enriched with miRNA target sites, and translational modulation of genes governing translation itself. These findings provide insight into the proneoplastic and compensatory mechanisms embedded in the oncogenic translational program. They support a model whereby deregulated eIF4E moves human epithelial cells along the cancer pathway by profoundly altering ribosomal recruitment to cancer-related transcripts, and eIF4E-modified cells counter these potentially oncogenic alterations with a compensatory translational mechanism that mitigates acquisition of malignancy. [Cancer Res 2007;67(14):6814–24]
Data from Reactive Oxygen Species, DNA Damage, and Error-Prone Repair: A Model for Genomic Instability with Progression in Myeloid Leukemia?
Authors: Rassool Feyruz V. , Gaymes Terry J. , Omidvar Nader , Brady Nicola , Beurlet Stephanie , Pla Marika , Reboul Murielle , Lea Nicholas , Chomienne Christine , Thomas Nicholas S.B. , Mufti Ghulam J. , Padua Rose Ann
Published: March 2023

Abstract
Myelodysplastic syndromes (MDS) comprise a heterogeneous group of disorders characterized by ineffective hematopoiesis, with an increased propensity to develop acute myelogenous leukemia (AML). The molecular basis for MDS progression is unknown, but a key element in MDS disease progression is loss of chromosomal material (genomic instability). Using our two-step mouse model for myeloid leukemic disease progression involving overexpression of human mutant NRAS and BCL2 genes, we show that there is a stepwise increase in the frequency of DNA damage leading to an increased frequency of error-prone repair of double-strand breaks (DSB) by nonhomologous end-joining. There is a concomitant increase in reactive oxygen species (ROS) in these transgenic mice with disease progression. Importantly, RAC1, an essential component of the ROS-producing NADPH oxidase, is downstream of RAS, and we show that ROS production in NRAS/BCL2 mice is in part dependent on RAC1 activity. DNA damage and error-prone repair can be decreased or reversed in vivo by N-acetyl cysteine antioxidant treatment. Our data link gene abnormalities to constitutive DNA damage and increased DSB repair errors in vivo and provide a mechanism for an increase in the error rate of DNA repair with MDS disease progression. These data suggest treatment strategies that target RAS/RAC pathways and ROS production in human MDS/AML. [Cancer Res 2007;67(18):8762–71]
Data from Breast Cancer Expressing the Activated HER2/neu Is Sensitive to Gefitinib In vitro and In vivo and Acquires Resistance through a Novel Point Mutation in the HER2/neu
Authors: Piechocki Marie P. , Yoo George H. , Dibbley Susan K. , Lonardo Fulvio
Published: March 2023

Abstract
The HER2/neu oncogene is an important diagnostic and prognostic factor and therapeutic target in breast and other cancers. We developed and characterized a breast cancer cell line (Bam1a) that overexpresses the activated HER2/neu and ErbB-3 and has a gene expression profile consistent with the ErbB-2 genetic signature. We evaluated the effects of the epidermal growth factor receptor (EGFR)/HER2 inhibitor, gefitinib, on this breast tumor line in vitro and in vivo. We characterized the effects of gefitinib on EGFR, HER2, and ErbB-3 phosphorylation by Western blot and determined the effects on downstream signaling through growth, survival, and stress pathways and the effect on proliferation, cell cycle, and apoptosis. Gefitinib treatment diminished phosphorylation of the ErbB-3 > EGFR > HER2/neu and signal transducers and activators of transcriptions in a dose-dependent fashion. Downstream mitogenic signaling through mitogen-activated protein (MAP)/extracellular signal regulated kinase kinase, p44/42 MAP kinase (MAPK) and stress signaling through c-Jun-NH2-kinase (JNK) 1 and c-Jun was impaired (1 μmol/L, 4–24 h), leading to cytostasis and cell cycle arrest within 24 h by decreased cyclin D1, cyclin B1, and pSer795Rb and increased p27. Proliferation and colony formation were inhibited at 0.5 and 1 μmol/L, respectively, and correlated with altered gene expression profiles. Diminished survival signaling through Akt, induction of bim, loss of connexin43, and decreased production of vascular endothelial growth factor-D preceded caspase-3 and poly(ADP)ribose polymerase (PARP) cleavage and apoptosis (>50% 2 μmol/L, 48 h). Oral administration of gefitinib was able to prevent the outgrowth of Bam1a tumor cells from palpable lesions, shrink established tumors, eliminate HER2 and HER3 phosphorylation, and decrease MAPK and Akt signaling in vivo. A variant of the Bam1a cell line, IR-5, with acquired ability to grow in 5 μmol/L gefitinib was developed and characterized. IR-5 bears a novel point mutation in the HER2/neu that corresponds to a L726I in the ATP-binding pocket and correlates with a log decrease in sensitivity to gefitinib, increased heterodimerization with EGFR and HER3, and impaired down-regulation. Gene expression profiling of IR-5 showed increased expression of EMP-1, NOTCH-1, FLT-1, PDGFB, and several other genes that may contribute to the resistant phenotype and sustain signaling through MAPK and Akt. This model will be useful in understanding the differences between intrinsic drug sensitivity and acquired resistance in the context of therapeutic strategies that target oncogene addicted diseases. [Cancer Res 2007;67(14):6825–43]
Data from Farnesol-Induced Apoptosis in Human Lung Carcinoma Cells Is Coupled to the Endoplasmic Reticulum Stress Response
Authors: Joo Joung Hyuck , Liao Grace , Collins Jennifer B. , Grissom Sherry F. , Jetten Anton M.
Published: March 2023

Abstract
Farnesol (FOH) and other isoprenoid alcohols induce apoptosis in various carcinoma cells and inhibit tumorigenesis in several in vivo models. However, the mechanisms by which they mediate their effects are not yet fully understood. In this study, we show that FOH is an effective inducer of apoptosis in several lung carcinoma cells, including H460. This induction is associated with activation of several caspases and cleavage of poly(ADP-ribose) polymerase (PARP). To obtain insight into the mechanism involved in FOH-induced apoptosis, we compared the gene expression profiles of FOH-treated and control H460 cells by microarray analysis. This analysis revealed that many genes implicated in endoplasmic reticulum (ER) stress signaling, including ATF3, DDIT3, HERPUD1, HSPA5, XBP1, PDIA4, and PHLDA1, were highly up-regulated within 4 h of FOH treatment, suggesting that FOH-induced apoptosis involves an ER stress response. This was supported by observations showing that treatment with FOH induces splicing of XBP1 mRNA and phosphorylation of eIF2α. FOH induces activation of several mitogen-activated protein kinase (MAPK) pathways, including p38, MAPK/extracellular signal–regulated kinase (ERK) kinase (MEK)-ERK, and c-jun NH2-terminal kinase (JNK). Inhibition of MEK1/2 by U0126 inhibited the induction of ER stress response genes. In addition, knockdown of the MEK1/2 and JNK1/2 expression by short interfering RNA (siRNA) effectively inhibited the cleavage of caspase-3 and PARP and apoptosis induced by FOH. However, only MEK1/2 siRNAs inhibited the induction of ER stress–related genes, XBP1 mRNA splicing, and eIF2α phosphorylation. Our results show that FOH-induced apoptosis is coupled to ER stress and that activation of MEK1/2 is an early upstream event in the FOH-induced ER stress signaling cascade. [Cancer Res 2007;67(16):7929–36]
Data from Requirement for Rac1 in a K-ras–Induced Lung Cancer in the Mouse
Authors: Kissil Joseph L. , Walmsley Marita J. , Hanlon Linda , Haigis Kevin M. , Bender Kim Carla F. , Sweet-Cordero Alejandro , Eckman Matthew S. , Tuveson David A. , Capobianco Anthony J. , Tybulewicz Victor L.J. , Jacks Tyler
Published: March 2023

Abstract
Given the prevalence of Ras mutations in human cancer, it is critical to understand the effector pathways downstream of oncogenic Ras leading to transformation. To directly assess the requirement for Rac1 in K-ras–induced tumorigenesis, we employed a model of lung cancer in which an oncogenic allele of K-ras could be activated by Cre-mediated recombination in the presence or absence of conditional deletion of Rac1. We show that Rac1 function is required for tumorigenesis in this model. Furthermore, although Rac1 deletion alone was compatible with cell viability and proliferation, when combined with K-ras activation in primary epithelial cells, loss of Rac1 caused a profound reduction in proliferation. These data show a specific requirement for Rac1 function in cells expressing oncogenic K-ras. [Cancer Res 2007;67(17):8089–94]
Data from Transforming Growth Factor-β Can Suppress Tumorigenesis through Effects on the Putative Cancer Stem or Early Progenitor Cell and Committed Progeny in a Breast Cancer Xenograft Model
Authors: Tang Binwu , Yoo Naomi , Vu Mary , Mamura Mizuko , Nam Jeong-Seok , Ooshima Akira , Du Zhijun , Desprez Pierre-Yves , Anver Miriam R. , Michalowska Aleksandra M. , Shih Joanna , Parks W. Tony , Wakefield Lalage M.
Published: March 2023

Abstract
The transforming growth factor-β (TGF-β) pathway has tumor-suppressor activity in many epithelial tissues. Because TGF-β is a potent inhibitor of epithelial cell proliferation, it has been widely assumed that this property underlies the tumor-suppressor effect. Here, we have used a xenograft model of breast cancer to show that endogenous TGF-β has the potential to suppress tumorigenesis through a novel mechanism, involving effects at two distinct levels in the hierarchy of cellular progeny that make up the epithelial component of the tumor. First, TGF-β reduces the size of the putative cancer stem or early progenitor cell population, and second it promotes differentiation of a more committed, but highly proliferative, progenitor cell population to an intrinsically less proliferative state. We further show that reduced expression of the type II TGF-β receptor correlates with loss of luminal differentiation in a clinical breast cancer cohort, suggesting that this mechanism may be clinically relevant. At a molecular level, the induction of differentiation by TGF-β involves down-regulation of Id1, and forced overexpression of Id1 can promote tumorigenesis despite persistence of the antiproliferative effect of TGF-β. These data suggest new roles for the TGF-β pathway in regulating tumor cell dynamics that are independent of direct effects on proliferation. [Cancer Res 2007;67(18):8643–52]
Data from Positive Cross-Regulatory Loop Ties GATA-3 to Estrogen Receptor α Expression in Breast Cancer
Authors: Eeckhoute Jérôme , Keeton Erika Krasnickas , Lupien Mathieu , Krum Susan A. , Carroll Jason S. , Brown Myles
Published: March 2023

Abstract
The transcription factor GATA-3 is required for normal mammary gland development, and its expression is highly correlated with estrogen receptor α (ERα) in human breast tumors. However, the functional role of GATA-3 in ERα-positive breast cancers is yet to be established. Here, we show that GATA-3 is required for estradiol stimulation of cell cycle progression in breast cancer cells. The role of GATA-3 in estradiol signaling requires the direct positive regulation of the expression of the ERα gene itself by GATA-3. GATA-3 binds to two cis-regulatory elements located within the ERα gene, and this is required for RNA polymerase II recruitment to ERα promoters. Reciprocally, ERα directly stimulates the transcription of the GATA-3 gene, indicating that these two factors are involved in a positive cross-regulatory loop. Moreover, GATA-3 and ERα regulate their own expression in breast cancer cells. Hence, this transcriptional coregulatory mechanism accounts for the robust coexpression of GATA-3 and ERα in human breast cancers. In addition, these results highlight the crucial role of GATA-3 for the response of ERα-positive breast cancers to estradiol. Moreover, they identify GATA-3 as a critical component of the master cell-type–specific transcriptional network including ERα and FoxA1 that dictates the phenotype of hormone-dependent breast cancer. [Cancer Res 2007;67(13):6477–83]
Data from Activation of Holliday Junction–Recognizing Protein Involved in the Chromosomal Stability and Immortality of Cancer Cells
Authors: Kato Tatsuya , Sato Nagato , Hayama Satoshi , Yamabuki Takumi , Ito Tomoo , Miyamoto Masaki , Kondo Satoshi , Nakamura Yusuke , Daigo Yataro
Published: March 2023

Abstract
We identified a novel gene HJURP (Holliday junction–recognizing protein) whose activation seemed to play a pivotal role in the immortality of cancer cells. HJURP was considered a possible downstream target for ataxia telangiectasia mutated signaling, and its expression was increased by DNA double-strand breaks (DSB). HJURP was involved in the homologous recombination pathway in the DSB repair process through interaction with hMSH5 and NBS1, which is a part of the MRN protein complex. HJURP formed nuclear foci in cells at S phase and those subjected to DNA damage. In vitro assays implied that HJURP bound directly to the Holliday junction and rDNA arrays. Treatment of cancer cells with small interfering RNA (siRNA) against HJURP caused abnormal chromosomal fusions and led to genomic instability and senescence. In addition, HJURP overexpression was observed in a majority of lung cancers and was associated with poor prognosis as well. We suggest that HJURP is an indispensable factor for chromosomal stability in immortalized cancer cells and is a potential novel therapeutic target for the development of anticancer drugs. [Cancer Res 2007;67(18):8544–53]
Data from Cisplatin-Induced Apoptosis Involves Membrane Fluidification via Inhibition of NHE1 in Human Colon Cancer Cells
Authors: Rebillard Amélie , Tekpli Xavier , Meurette Olivier , Sergent Odile , LeMoigne-Muller Gwenaëlle , Vernhet Laurent , Gorria Morgane , Chevanne Martine , Christmann Markus , Kaina Bernd , Counillon Laurent , Gulbins Erich , Lagadic-Gossmann Dominique , Dimanche-Boitrel Marie-Thérèse
Published: March 2023

Abstract
We have previously shown that cisplatin triggers an early acid sphingomyelinase (aSMase)-dependent ceramide generation concomitantly with an increase in membrane fluidity and induces apoptosis in HT29 cells. The present study further explores the role and origin of membrane fluidification in cisplatin-induced apoptosis. The rapid increase in membrane fluidity following cisplatin treatment was inhibited by membrane-stabilizing agents such as cholesterol or monosialoganglioside-1. In HT29 cells, these compounds prevented the early aggregation of Fas death receptor and of membrane lipid rafts on cell surface and significantly inhibited cisplatin-induced apoptosis without altering drug intracellular uptake or cisplatin DNA adducts formation. Early after cisplatin treatment, Na+/H+ membrane exchanger-1 (NHE1) was inhibited leading to intracellular acidification, aSMase was activated, and ceramide was detected at the cell membrane. Treatment of HT29 cells with Staphylococcus aureus sphingomyelinase increased membrane fluidity. Moreover, pretreatment with cariporide, a specific inhibitor of NHE1, inhibited cisplatin-induced intracellular acidification, aSMase activation, ceramide membrane generation, membrane fluidification, and apoptosis. Finally, NHE1-expressing PS120 cells were more sensitive to cisplatin than NHE1-deficient PS120 cells. Altogether, these findings suggest that the apoptotic pathway triggered by cisplatin involves a very early NHE1-dependent intracellular acidification leading to aSMase activation and increase in membrane fluidity. These events are independent of cisplatin-induced DNA adducts formation. The membrane exchanger NHE1 may be another potential target of cisplatin, increasing cell sensitivity to this compound. [Cancer Res 2007;67(16):7865–74]
Data from Pharmacologic Characterization of a Potent Inhibitor of Class I Phosphatidylinositide 3-Kinases
Authors: Raynaud Florence I. , Eccles Suzanne , Clarke Paul A. , Hayes Angela , Nutley Bernard , Alix Sonia , Henley Alan , Di-Stefano Francesca , Ahmad Zahida , Guillard Sandrine , Bjerke Lynn M. , Kelland Lloyd , Valenti Melanie , Patterson Lisa , Gowan Sharon , de Haven Brandon Alexis , Hayakawa Masahiko , Kaizawa Hiroyuki , Koizumi Tomonubu , Ohishi Takahide , Patel Sonal , Saghir Nahid , Parker Peter , Waterfield Mike , Workman Paul
Published: March 2023

Abstract
Extensive evidence implicates activation of the lipid phosphatidylinositide 3-kinase (PI3K) pathway in the genesis and progression of various human cancers. PI3K inhibitors thus have considerable potential as molecular cancer therapeutics. Here, we detail the pharmacologic properties of a prototype of a new series of inhibitors of class I PI3K. PI103 is a potent inhibitor with low IC50 values against recombinant PI3K isoforms p110α (2 nmol/L), p110β (3 nmol/L), p110δ (3 nmol/L), and p110γ (15 nmol/L). PI103 also inhibited TORC1 by 83.9% at 0.5 μmol/L and exhibited an IC50 of 14 nmol/L against DNA-PK. A high degree of selectivity for the PI3K family was shown by the lack of activity of PI103 in a panel of 70 protein kinases. PI103 potently inhibited proliferation and invasion of a wide variety of human cancer cells in vitro and showed biomarker modulation consistent with inhibition of PI3K signaling. PI103 was extensively metabolized, but distributed rapidly to tissues and tumors. This resulted in tumor growth delay in eight different human cancer xenograft models with various PI3K pathway abnormalities. Decreased phosphorylation of AKT was observed in U87MG gliomas, consistent with drug levels achieved. We also showed inhibition of invasion in orthotopic breast and ovarian cancer xenograft models and obtained evidence that PI103 has antiangiogenic potential. Despite its rapid in vivo metabolism, PI103 is a valuable tool compound for exploring the biological function of class I PI3K and importantly represents a lead for further optimization of this novel class of targeted molecular cancer therapeutic. [Cancer Res 2007;67(12):5840–50]
Data from Proteasome Function Is Required for DNA Damage Response and Fanconi Anemia Pathway Activation
Authors: Jacquemont Céline , Taniguchi Toshiyasu
Published: March 2023

Abstract
Proteasome inhibitors sensitize tumor cells to DNA-damaging agents, including ionizing radiation (IR), and DNA cross-linking agents (melphalan and cisplatin) through unknown mechanisms. The Fanconi anemia pathway is a DNA damage–activated signaling pathway, which regulates cellular resistance to DNA cross-linking agents. Monoubiquitination and nuclear foci formation of FANCD2 are critical steps of the Fanconi anemia pathway. Here, we show that proteasome function is required for the activation of the Fanconi anemia pathway and for DNA damage signaling. Proteasome inhibitors (bortezomib and MG132) and depletion of 19S and 20S proteasome subunits (PSMD4, PSMD14, and PSMB3) inhibited monoubiquitination and/or nuclear foci formation of FANCD2, whereas depletion of DSS1/SHFM1, a subunit of the 19S proteasome that also directly binds to BRCA2, did not inhibit FANCD2 monoubiquitination or foci formation. On the other hand, DNA damage–signaling processes, such as IR-induced foci formation of phosphorylated ATM (phospho-ATM), 53BP1, NBS1, BRCA1, FANCD2, and RAD51, were delayed in the presence of proteasome inhibitors, whereas ATM autophosphorylation and nuclear foci formation of γH2AX, MDC1, and RPA were not inhibited. Furthermore, persistence of DNA damage and abrogation of the IR-induced G1-S checkpoint resulted from proteasome inhibition. In summary, we showed that the proteasome function is required for monoubiquitination of FANCD2, foci formation of 53BP1, phospho-ATM, NBS1, BRCA1, FANCD2, and RAD51. The dependence of specific DNA damage–signaling steps on the proteasome may explain the sensitization of tumor cells to DNA-damaging chemotherapeutic agents by proteasome inhibitors. [Cancer Res 2007;67(15):7395–405]
Data from MFG-E8/Lactadherin Promotes Tumor Growth in an Angiogenesis-Dependent Transgenic Mouse Model of Multistage Carcinogenesis
Authors: Neutzner Melanie , Lopez Theresa , Feng Xu , Bergmann-Leitner Elke S. , Leitner Wolfgang W. , Udey Mark C.
Published: March 2023

Abstract
The relevance of angiogenesis in tumor biology and as a therapeutic target is well established. MFG-E8 (also termed lactadherin) and developmental endothelial locus 1 (Del1) constitute a two-gene family of αvβ3/β5 ligands that regulate angiogenesis. After detecting MFG-E8 mRNA in murine tumor cell lines, we sought to determine if MFG-E8 influenced tumorigenesis in Rip1-Tag2 transgenic mice, a cancer model in which angiogenesis is critical. MFG-E8 mRNA and protein were increased in angiogenic islets and tumors in Rip1-Tag2 mice compared with normal pancreas. Frequencies of angiogenic islets and tumor burdens were decreased in MFG-E8–deficient Rip1-Tag2 mice compared with those in control Rip1-Tag2 mice. Invasive carcinomas were modestly underrepresented in MFG-E8–deficient mice, but tumor frequencies and survivals were comparable in these two strains. Absence of MFG-E8 also led to decreases in tumor vascular permeability without obvious changes in vascular morphology. Decreased proliferation was noted in angiogenic islets and increases in apoptotic cells were detected in islets and tumors. Compensatory increases in mRNA encoding proangiogenic proteins, including FGF2, in angiogenic islets, and Del1, in angiogenic islets and tumors, were also detected in MFG-E8–deficient mice. MFG-E8 and its homologue Del1 may represent relevant targets in cancer and other diseases in which angiogenesis is prominent. [Cancer Res 2007;67(14):6777–84]
Data from Clinical Validity of the Lung Cancer Biomarkers Identified by Bioinformatics Analysis of Public Expression Data
Authors: Kim Bumjin , Lee Hyun Joo , Choi Hye Young , Shin Youngah , Nam Seungyoon , Seo Gilju , Son Dae-Soon , Jo Jisuk , Kim Jaesang , Lee Jinseon , Kim Jhingook , Kim Kwhanmien , Lee Sanghyuk
Published: March 2023

Abstract
Identification of molecular markers often leads to important clinical applications such as early diagnosis, prognosis, and drug targeting. Lung cancer, the leading cause of cancer-related deaths, still lacks reliable molecular markers. We have combined the bioinformatics analysis of the public gene expression data and clinical validation to identify biomarker genes for non–small-cell lung cancer. The serial analysis of gene expression and the expressed sequence tag data were meta-analyzed to produce a list of the differentially expressed genes in lung cancer. Through careful inspection of the predicted genes, we selected 20 genes for experimental validation using semiquantitative reverse transcriptase-PCR. The microdissected clinical specimens used in the study consisted of three groups: lung tissues from benign diseases and the paired (cancer and pathologic normal) tissues from non–small-cell lung cancer patients. After extensive statistical analyses, seven genes (CBLC, CYP24A1, ALDH3A1, AKR1B10, S100P, PLUNC, and LOC147166) were identified as potential diagnostic markers. Quantitative real-time PCR was carried out to additionally assess the value of the seven identified genes leading to the confirmation of at least two genes (CBLC and CYP24A1) as highly probable novel biomarkers. The gene properties of the identified markers, especially their relationship to lung cancer and cell signaling pathway regulation, further suggest their potential value as drug targets as well. [Cancer Res 2007;67(15):7431–8]
Data from Mutations of C-RAF Are Rare in Human Cancer because C-RAF Has a Low Basal Kinase Activity Compared with B-RAF
Authors: Emuss Victoria , Garnett Mathew , Mason Clive , Marais Richard
Published: March 2023

Abstract
The protein kinase B-RAF is mutated in ∼8% of human cancers. Here we show that presumptive mutants of the closely related kinase, C-RAF, were detected in only 4 of 545 (0.7%) cancer cell lines. The activity of two of the mutated proteins is not significantly different from that of wild-type C-RAF and these variants may represent rare human polymorphisms. The basal and B-RAF–stimulated kinase activities of a third variant are unaltered but its activation by RAS is significantly reduced, suggesting that it may act in a dominant-negative manner to modulate pathway signaling. The fourth variant has elevated basal kinase activity and is hypersensitive to activation by RAS but does not transform mammalian cells. Furthermore, when we introduce the equivalent of the most common cancer mutation in B-RAF (V600E) into C-RAF, it only has a weak effect on kinase activity and does not convert C-RAF into an oncogene. This lack of activation occurs because C-RAF lacks a constitutive charge within a motif in the kinase domain called the N-region. This fundamental difference in RAF isoform regulation explains why B-RAF is frequently mutated in cancer whereas C-RAF mutations are rare.