bluuebunny/crossref_metadata_2025 huggingface dataset:
Up-Regulation of c-Jun Inhibits Proliferation and Induces Apoptosis via Caspase-Triggered c-Abl Cleavage in Human Multiple Myeloma
Authors: Podar Klaus , Raab Marc S. , Tonon Giovanni , Sattler Martin , Barilà Daniela , Zhang Jing , Tai Yu-Tzu , Yasui Hiroshi , Raje Noopur , DePinho Ronald A. , Hideshima Teru , Chauhan Dharminder , Anderson Kenneth C.
Published: February 2007

Here we show the antimyeloma cytotoxicity of adaphostin and carried out expression profiling of adaphostin-treated multiple myeloma (MM) cells to identify its molecular targets. Surprisingly, c-Jun was the most up-regulated gene even at the earliest point of analysis (2 h). We also observed adaphostin-induced c-Abl cleavage in immunoblot analysis. Proteasome inhibitor bortezomib, but not melphalan or dexamethasone, induced similar effects, indicating unique agent-dependent mechanisms. Using caspase inhibitors, as well as caspase-resistant mutants of c-Abl (TM-c-Abl and D565A-Abl), we then showed that c-Abl cleavage in MM cells requires caspase activity. Importantly, both overexpression of the c-Abl fragment or c-Jun and knockdown of c-Abl and c-Jun expression by small interfering RNA confirmed that adaphostin-induced c-Jun up-regulation triggers downstream caspase-mediated c-Abl cleavage, inhibition of MM cell growth, and induction of apoptosis. Finally, our data suggest that this mechanism may not only be restricted to MM but may also be important in a broad range of malignancies including erythroleukemia and solid tumors. [Cancer Res 2007;67(4):1680–8]
A Src/Abl Kinase Inhibitor, SKI-606, Blocks Breast Cancer Invasion, Growth, and Metastasis In vitro and In vivo
Authors: Jallal Houda , Valentino Maria-Luisa , Chen Gaoping , Boschelli Frank , Ali Suhad , Rabbani Shafaat A.
Published: February 2007

The central role of Src in the development of several malignancies, including breast cancer, and the accumulating evidence of its interaction with receptor tyrosine kinases, integrins, and steroid receptors have identified it as an attractive therapeutic target. In the current study, we have evaluated the effect of a Src/Abl kinase inhibitor, SKI-606, on breast cancer growth, migration, invasion, and metastasis. Treatment of human breast cancer cells MDA-MB-231 with SKI-606 caused a marked inhibition of cell proliferation, invasion, and migration by inhibiting mitogen-activated protein kinase and Akt phosphorylation. For in vivo studies, MDA-MB-231 cells transfected with the plasmid encoding green fluorescent protein (GFP; MDA-MB-231-GFP) were inoculated into the mammary fat pads of female BALB/c nu/nu mice. Once tumor volume reached 30 to 50 mm3, animals were randomized and treated with vehicle alone or 150 mg/kg SKI-606 by daily oral gavage. Experimental animals receiving SKI-606 developed tumors of significantly smaller volume (45–54%) compared with control animals receiving vehicle alone. Analysis of lungs, liver, and spleen of these animals showed a significant decrease in GFP-positive tumor metastasis in animals receiving SKI-606 at a dose that was well tolerated. Western blot analysis and immunohistochemical analysis of primary tumors showed that these effects were due to the ability of SKI-606 to block tumor cell proliferation, angiogenesis, growth factor expression, and inhibition of Src-mediated signaling pathways in vivo. Together, the results from these studies provide compelling evidence for the role of Src inhibitors as therapeutic agents for blocking breast cancer growth and metastasis. [Cancer Res 2007;67(4):1580–8]
Aurora-A Regulation of Nuclear Factor-κB Signaling by Phosphorylation of IκBα
Authors: Briassouli Paraskevi , Chan Florence , Savage Kay , Reis-Filho Jorge S. , Linardopoulos Spiros
Published: February 2007

The Aurora-A/STK15 gene encodes a kinase that is frequently amplified in cancer. Overexpression of Aurora-A in mammalian cells leads to centrosome amplification, genetic instability, and transformation. In this study, we show that Aurora-A activates nuclear factor-κB (NF-κB) via IκBα phosphorylation. Inhibition of endogenous Aurora-A reduces tumor necrosis factor α (TNFα)–induced IκBα degradation. We analyzed primary human breast cancers, and 13.6% of samples showed Aurora-A gene amplification, all of which exhibited nuclear localization of NF-κB. We propose that this subgroup of patients with breast cancer might benefit from inhibiting Aurora-A. We also show that down-regulation of NF-κB via Aurora-A depletion can enhance cisplatin-dependent apoptosis. These data define a new role for Aurora-A in regulating IκBα that is critical for the activation of NF-κB–directed gene expression and may be partially responsible for the oncogenic effect of Aurora-A when the gene is amplified and overexpressed in human tumors. [Cancer Res 2007;67(4):1689–95]
c-Jun NH2-Terminal Kinase–Related Na+/H+ Exchanger Isoform 1 Activation Controls Hexokinase II Expression in Benzo(a)Pyrene-Induced Apoptosis
Authors: Huc Laurence , Tekpli Xavier , Holme Jørn A. , Rissel Mary , Solhaug Anita , Gardyn Claire , Le Moigne Gwénaelle , Gorria Morgane , Dimanche-Boitrel Marie-Thérèse , Lagadic-Gossmann Dominique
Published: February 2007

Regulation of the balance between survival, proliferation, and apoptosis on carcinogenic polycyclic aromatic hydrocarbon (PAH) exposure is still poorly understood and more particularly the role of physiologic variables, including intracellular pH (pHi). Although the involvement of the ubiquitous pHi regulator Na+/H+ exchanger isoform 1 (NHE1) in tumorigenesis is well documented, less is known about its role and regulation during apoptosis. Our previous works have shown the primordial role of NHE1 in carcinogenic PAH-induced apoptosis. This alkalinizing transporter was activated by an early CYP1-dependent H2O2 production, subsequently promoting mitochondrial dysfunction leading to apoptosis. The aim of this study was to further elucidate how NHE1 was activated by benzo(a)pyrene (BaP) and what the downstream events were in the context of apoptosis. Our results indicate that the mitogen-activated protein kinase kinase 4/c-Jun NH2-terminal kinase (MKK4/JNK) pathway was a link between BaP-induced H2O2 production and NHE1 activation. This activation, in combination with BaP-induced phosphorylated p53, promoted mitochondrial superoxide anion production, supporting the existence of a common target for NHE1 and p53. Furthermore, we showed that the mitochondrial expression of glycolytic enzyme hexokinase II (HKII) was decreased following a combined action of NHE1 and p53 pathways, thereby enhancing the BaP-induced apoptosis. Taken together, our findings suggest that, on BaP exposure, MKK4/JNK targets NHE1 with consequences on HKII protein, which might thus be a key protein during carcinogenic PAH apoptosis. [Cancer Res 2007;67(4):1696–705]
Sphingosine-1-Phosphate Protects Proliferating Endothelial Cells from Ceramide-Induced Apoptosis but not from DNA Damage–Induced Mitotic Death
Authors: Bonnaud Stéphanie , Niaudet Colin , Pottier Géraldine , Gaugler Marie-Hélène , Millour Julie , Barbet Jacques , Sabatier Laure , Paris François
Published: February 2007

Because of the central role of the endothelium in tissue homeostasis, protecting the vasculature from radiation-induced death is a major concern in tissue radioprotection. Premitotic apoptosis and mitotic death are two prevalent cell death pathways induced by ionizing radiation. Endothelial cells undergo apoptosis after radiation through generation of the sphingolipid ceramide. However, if mitotic death is known as the established radiation-induced death pathway for cycling eukaryotic cells, direct involvement of mitotic death in proliferating endothelial radiosensitivity has not been clearly shown. In this study, we proved that proliferating human microvascular endothelial cells (HMEC-1) undergo two waves of death after exposure to 15 Gy radiation: an early premitotic apoptosis dependent on ceramide generation and a delayed DNA damage–induced mitotic death. The fact that sphingosine-1-phosphate (S1P), a ceramide antagonist, protects HMEC-1 only from membrane-dependent apoptosis but not from DNA damage–induced mitotic death proves the independence of the two pathways. Furthermore, adding nocodazole, a mitotic inhibitor, to S1P affected both cell death mechanisms and fully prevented radiation-induced death. If our results fit with the standard model in which S1P signaling inhibits ceramide-mediated apoptosis induced by antitumor treatments, such as radiotherapy, they exclude, for the first time, a significant role of S1P-induced molecular survival pathway against mitotic death. Discrimination between ceramide-mediated apoptosis and DNA damage–induced mitotic death may give the opportunity to define a new class of radioprotectors for normal tissues in which quiescent endothelium represents the most sensitive target, while excluding malignant tumor containing proproliferating angiogenic endothelial cells that are sensitive to mitotic death. [Cancer Res 2007;67(4):1803–11]
Nuclear Translocation of the Tumor Marker Pyruvate Kinase M2 Induces Programmed Cell Death
Authors: Steták Attila , Veress Réka , Ovádi Judit , Csermely Péter , Kéri György , Ullrich Axel
Published: February 2007

Cancer cells often fail to respond to stimuli that normally activate their intrinsic apoptotic machinery. Moreover, they are able to adapt to hypoxia by changing their glycolytic rate. Pyruvate kinase (PK) is a rate-limiting enzyme in glycolysis that is converted to a less active dimer form of PKM2 isoenzyme during oncogenesis. Here, we show that both somatostatin and the structural analogue TT-232 interact with the PKM subtype. We further show that the PKM2 is translocated to the nucleus in response to TT-232 and different apoptotic agents. Nuclear translocation of PKM2 is sufficient to induce cell death that is caspase independent, isoform specific, and independent of its enzymatic activity. These results show that the tumor marker PKM2 plays a general role in caspase-independent cell death of tumor cells and thereby defines this glycolytic enzyme as a novel target for cancer therapy development. [Cancer Res 2007;67(4):1602–8]
G Protein–Coupled Receptor 30 (GPR30) Mediates Gene Expression Changes and Growth Response to 17β-Estradiol and Selective GPR30 Ligand G-1 in Ovarian Cancer Cells
Authors: Albanito Lidia , Madeo Antonio , Lappano Rosamaria , Vivacqua Adele , Rago Vittoria , Carpino Amalia , Oprea Tudor I. , Prossnitz Eric R. , Musti Anna Maria , Andò Sebastiano , Maggiolini Marcello
Published: February 2007

Estrogens play a crucial role in the development of ovarian tumors; however, the signal transduction pathways involved in hormone action are still poorly defined. The orphan G protein–coupled receptor 30 (GPR30) mediates the nongenomic signaling of 17β-estradiol (E2) in a variety of estrogen-sensitive cancer cells through activation of the epidermal growth factor receptor (EGFR) pathway. Whether estrogen receptor α (ERα) also contributes to GPR30/EGFR signaling is less understood. Here, we show that, in ERα-positive BG-1 ovarian cancer cells, both E2 and the GPR30-selective ligand G-1 induced c-fos expression and estrogen-responsive element (ERE)-independent activity of a c-fos reporter gene, whereas only E2 stimulated an ERE-responsive reporter gene, indicating that GPR30 signaling does not activate ERα-mediated transcription. Similarly, both ligands up-regulated cyclin D1, cyclin E, and cyclin A, whereas only E2 enhanced progesterone receptor expression. Moreover, both GPR30 and ERα expression are required for c-fos stimulation and extracellular signal-regulated kinase (ERK) activation in response to either E2 or G-1. Inhibition of the EGFR transduction pathway inhibited c-fos stimulation and ERK activation by either ligand, suggesting that in ovarian cancer cells GPR30/EGFR signaling relays on ERα expression. Interestingly, we show that both GPR30 and ERα expression along with active EGFR signaling are required for E2-stimulated and G-1–stimulated proliferation of ovarian cancer cells. Because G-1 was able to induce both c-fos expression and proliferation in the ERα-negative/GPR30-positive SKBR3 breast cancer cells, the requirement for ERα expression in GPR30/EGFR signaling may depend on the specific cellular context of different tumor types. [Cancer Res 2007;67(4):1859–66]
Human Mucin 1 Oncoprotein Represses Transcription of the p53 Tumor Suppressor Gene
Authors: Wei Xiaolong , Xu Hai , Kufe Donald
Published: February 2007

The mucin 1 (MUC1) heterodimeric protein is aberrantly overexpressed in human breast cancers and induces transformation. The MUC1 COOH-terminal subunit (MUC1-C) is targeted to the nucleus of transformed cells, where it interacts with p53 and regulates p53-mediated transcription. The present studies show that MUC1 represses activation of the p53 gene and that MUC1-C occupies the PE21 element in the p53 proximal promoter. Previous work has shown that the Kruppel-like factor 4 (KLF4) transcription factor represses p53 transcription by binding to the PE21 element. Our results show that MUC1-C binds constitutively to KLF4, occupies PE21 with KLF4, and enhances the KLF4 occupancy of PE21. The results also show that MUC1-C increases the recruitment of histone deacetylases 1/3, deacetylation of core histones, and repression of p53 transcription. These findings indicate that overexpression of MUC1, as found in human breast cancer cells, is of functional importance to repression of the p53 gene. [Cancer Res 2007;67(4):1853–8]
Human Epidermal Growth Factor Receptor 2 Regulates Angiopoietin-2 Expression in Breast Cancer via AKT and Mitogen-Activated Protein Kinase Pathways
Authors: Niu Guilian , Carter W. Bradford
Published: February 2007

Abnormal activation of human epidermal growth factor receptor 2 (HER2; ErbB-2) in breast tumors results in increased metastasis and angiogenesis, as well as reduced survival. Here, we show that angiopoietin-2 (Ang-2) expression correlates with HER2 activity in human breast cancer cell lines. Inhibiting HER2 activity with anti-HER2 monoclonal antibody trastuzumab (Herceptin) or HER2 short interfering RNA in tumor cells down-regulates Ang-2 expression. Consistent with the important roles of AKT and mitogen-activated protein kinase in the HER2 signaling pathway, AKT and ERK mitogen-activated protein kinase (MAPK) kinase activity is necessary for Ang-2 up-regulation by HER2. Moreover, overexpression of HER2 protein up-regulates Ang-2 expression. Heregulin-β1–induced Ang-2 up-regulation is abrogated when AKT and ERK kinase activity are blocked. Immunohistochemical analysis of HER2 and Ang-2 proteins in human breast carcinomas shows that Ang-2 expression in breast cancer correlates with HER2 expression. These studies provide evidence that the Ang-2 gene is regulated by HER2 activity in breast cancer, and propose an additional mechanism for HER2 contributing to tumor angiogenesis and metastasis. [Cancer Res 2007;67(4):1487–93]
Gonadotropin-Releasing Hormone Type II Antagonists Induce Apoptotic Cell Death in Human Endometrial and Ovarian Cancer Cells In vitro and In vivo
Authors: Fister Stefanie , Günthert Andreas R. , Emons Günter , Gründker Carsten
Published: February 2007

In human endometrial and ovarian cancers, gonadotropin-releasing hormone type I (GnRH-I), GnRH-II, and their receptors are parts of a negative autocrine regulatory system of cell proliferation. Based on a tumor-specific signal transduction, GnRH-I and GnRH-II agonists inhibit the mitogenic signal transduction of growth factor receptors and related oncogene products associated with tyrosine kinase activity via activation of a phosphotyrosine phosphatase resulting in down-regulation of cancer cell proliferation. Induction of apoptosis is not involved. In this study, we show that treatment of human endometrial and ovarian cancer cells with GnRH-II antagonists results in apoptotic cell death via dose-dependent activation of caspase-3. The antitumor effects of the GnRH-II antagonists could be confirmed in nude mice. GnRH-II antagonists inhibited the growth of xenotransplants of human endometrial and ovarian cancers in nude mice significantly, without any apparent side effects. Thus, GnRH-II antagonists seem to be suitable drugs for an efficacious and less toxic endocrine therapy for endometrial and ovarian cancers. [Cancer Res 2007;67(4):1750–6]
The Human Papillomavirus E6 Oncogene Dysregulates the Cell Cycle and Contributes to Cervical Carcinogenesis through Two Independent Activities
Authors: Shai Anny , Brake Tiffany , Somoza Chamorro , Lambert Paul F.
Published: February 2007

Cervical cancer is a leading cause of death due to cancer among women worldwide. Using transgenic mice to dissect the contributions of the human papillomavirus (HPV) 16 E6 and E7 oncogenes in cervical cancer, E7 was identified previously to be the dominant oncogene. Specifically, when treated with exogenous estrogen for 6 months, E7 transgenic mice developed cancer throughout the reproductive tract, but E6 transgenic mice did not. E6 contributed to carcinogenesis of the reproductive tract, as E6/E7 double transgenic mice treated for 6 months with estrogen developed larger cancers than E7 transgenic mice. In the current study, we investigated whether the E6 oncogene alone could cooperate with estrogen to induce cervical cancer after an extended estrogen treatment period of 9 months. We found that the E6 oncogene synergizes with estrogen to induce cervical cancer after 9 months, indicating that E6 has a weaker but detectable oncogenic potential in the reproductive tract compared with the E7 oncogene. Using transgenic mice that express mutant forms of HPV16 E6, we determined that the interactions of E6 with cellular α-helix and PDZ partners correlate with its ability to induce cervical carcinogenesis. In analyzing the tumors arising in E6 transgenic mice, we learned that E6 induces expression of the E2F-responsive genes, Mcm7 and cyclin E, in the absence of the E7 oncogene. E6 also prevented the expression of p16 in tumors of the reproductive tract through a mechanism mediated by the interaction of E6 with α-helix partners. [Cancer Res 2007;67(4):1626–35]
Younger Age of Cancer Initiation Is Associated with Shorter Telomere Length in Li-Fraumeni Syndrome
Authors: Tabori Uri , Nanda Sonia , Druker Harriet , Lees Jodi , Malkin David
Published: February 2007

Li-Fraumeni syndrome (LFS) is a cancer predisposition syndrome frequently associated with germ line TP53 mutations. Unpredictable and disparate age of cancer onset is a major challenge in the management of LFS. Genetic modifiers, including the MDM2-SNP309 polymorphism, and genetic anticipation have been suggested as plausible explanations for young age of tumor onset, but the molecular mechanisms for these observations are unknown. We speculated that telomere attrition will increase genomic instability and cause earlier tumor onset in successive generations. We analyzed mean telomere length and MDM2-SNP309 polymorphism status in individuals from multiple LFS families and controls. A total of 45 peripheral blood lymphocyte samples were analyzed from 9 LFS families and 15 controls. High rate of MDM2-SNP309 was found in TP53 carriers (P = 0.0003). In children, telomere length was shorter in carriers affected with cancer than in nonaffected carriers and wild-type controls (P < 0.0001). The same pattern was seen in adults (P = 0.002). Within each family, telomere length was shorter in children with cancer than in their nonaffected siblings and their noncarrier parents. Telomere attrition between children and adults was faster in carriers than in controls. Our results support the role of MDM2-SNP309 as a genetic modifier in LFS. The novel finding of accelerated telomere attrition in LFS suggests that telomere length could explain earlier age of onset in successive generations of the same family with identical TP53/MDM2-SNP309 genotypes. Furthermore, telomere shortening could predict genetic anticipation observed in LFS and may serve as the first rational biological marker for clinical monitoring of these patients. [Cancer Res 2007;67(4):1415–8
Insulin-like Growth Factor-1 (IGF-1) Induces WISP-2/CCN5 via Multiple Molecular Cross-talks and Is Essential for Mitogenic Switch by IGF-1 Axis in Estrogen Receptor–Positive Breast Tumor Cells
Authors: Dhar Kakali , Banerjee Snigdha , Dhar Gopal , Sengupta Krishanu , Banerjee Sushanta K.
Published: February 2007

Previously, we have shown that the expression of Wnt-1–induced signaling protein-2 (WISP-2), also known as CCN5, can be regulated by multiple stimulants in estrogen receptor (ER)–positive breast tumor cells to exert their mitogenic action in these cells. Here, we show that insulin-like growth factor-1 (IGF-1), a strong mitogen, enhanced the expression of the WISP-2/CCN5 gene parallel with the induction of proliferation of ER-positive breast tumor cells. An additive effect was also seen in combination with estrogen. Perturbation of IGF-1–induced WISP-2/CCN5 expression by WISP-2–specific RNA interference impaired the mitogenic action of IGF-1 on ER-positive breast tumor cells. Furthermore, the studies have shown that the multiple molecular cross-talks and side-talks among IGF-1R, ER-α, and phosphatidylinositol 3-kinase (PI3K)/Akt signaling molecules are required to induce WISP-2/CCN5 mRNA by IGF-1 in ER-positive, noninvasive breast tumor cells. Because a pure anti-ER ICI 182,780 is not only able to suppress the up-regulation of WISP-2/CCN5 mRNA expression by IGF-1, it also suppresses the PI3K/Akt activity induced by IGF-1 in MCF-7 cells; we anticipate that the membrane ER receptor may participate in this event. Collectively, these studies propose for the first time that WISP-2/CCN5 is an integral signaling molecule in mitogenic action of IGF-1 axis in ER-positive human breast tumor cells. [Cancer Res 2007;67(4):1520–6]
Antibody-Mediated p53 Protein Therapy Prevents Liver MetastasisIn vivo
Authors: Hansen James E. , Fischer Laurice K. , Chan Grace , Chang Sophia S. , Baldwin Scott W. , Aragon Robert J. , Carter Jacqueline J. , Lilly Michael , Nishimura Robert N. , Weisbart Richard H. , Reeves Mark E.
Published: February 2007

To evaluate the clinical efficacy of monoclonal antibody (mAb) 3E10 Fv antibody-mediated p53 protein therapy, an Fv-p53 fusion protein produced in Pichia pastoris was tested on CT26.CL25 colon cancer cells in vitro and in vivo in a mouse model of colon cancer metastasis to the liver. In vitro experiments showed killing of CT26.CL25 cells by Fv-p53 but not Fv or p53 alone, and immunohistochemical staining confirmed that Fv was required for transport of p53 into cells. Prevention of liver metastasis in vivo was tested by splenic injection of 100 nmol/L Fv-p53 10 min and 1 week after injection of CT26.CL25 cancer cells into the portal vein of BALB/c mice. Mice were sacrificed 1 week after the second injection of Fv-p53 and assigned a quantitative metastasis score. Control mice had an average metastasis score of 3.3 ± 1.3, whereas mice treated with Fv-p53 had an average metastasis score of 0.8 ± 0.4 (P = 0.004). These results indicate that Fv-p53 treatment had a profound effect on liver metastasis and represent the first demonstration of effective full-length p53 protein therapy in vivo. mAb 3E10 Fv has significant clinical potential as a mediator of intracellular and intranuclear delivery of p53 for prevention and treatment of cancer metastasis. [Cancer Res 2007;67(4):1769–74]
Interaction of Duffy Antigen Receptor for Chemokines and KAI1: A Critical Step in Metastasis Suppression
Authors: Iiizumi Megumi , Bandyopadhyay Sucharita , Watabe Kounosuke
Published: February 2007

Tumor metastases suppressor protein KAI1/CD82 is capable of blocking the tumor metastases without affecting the primary tumor formation, and its expression is significantly down-regulated in many types of human cancers. However, the exact molecular mechanism of the suppressor function of KAI1 remains elusive. Evidence from our laboratory supports a model in which tumor cells dislodge from the primary tumor and intravasate into the blood or lymphatic vessels followed by attachment to the endothelial cell surface whereby KAI1 interacts with the Duffy antigen receptor for chemokines (DARC) protein. This interaction transmits a senescent signal to cancer cells expressing KAI1, whereas cells that lost KAI1 expression can proliferate, potentially giving rise to metastases. Our model of the mechanism of action of KAI1 shows that metastasis suppressor activity can be dependent on interaction with host tissue and explains how KAI1 suppresses metastasis without affecting primary tumor formation. Taken together, in vitro and in vivo studies identify the KAI1-DARC interaction as a potential target for cancer therapy. [Cancer Res 2007;67(4):1411–4]
Genetic Unmasking of an Epigenetically Silenced microRNA in Human Cancer Cells
Authors: Lujambio Amaia , Ropero Santiago , Ballestar Esteban , Fraga Mario F. , Cerrato Celia , Setién Fernando , Casado Sara , Suarez-Gauthier Ana , Sanchez-Cespedes Montserrat , Gitt Anna , Spiteri Inmaculada , Das Partha P. , Caldas Carlos , Miska Eric , Esteller Manel
Published: February 2007

The mechanisms underlying microRNA (miRNA) disruption in human disease are poorly understood. In cancer cells, the transcriptional silencing of tumor suppressor genes by CpG island promoter hypermethylation has emerged as a common hallmark. We wondered if the same epigenetic disruption can “hit” miRNAs in transformed cells. To address this issue, we have used cancer cells genetically deficient for the DNA methyltransferase enzymes in combination with a miRNA expression profiling. We have observed that DNA hypomethylation induces a release of miRNA silencing in cancer cells. One of the main targets is miRNA-124a, which undergoes transcriptional inactivation by CpG island hypermethylation in human tumors from different cell types. Interestingly, we functionally link the epigenetic loss of miRNA-124a with the activation of cyclin D kinase 6, a bona fide oncogenic factor, and the phosphorylation of the retinoblastoma, a tumor suppressor gene. [Cancer Res 2007;67(4):1424–9]
A Role for the HOXB7 Homeodomain Protein in DNA Repair
Authors: Rubin Ethel , Wu Xinyan , Zhu Tao , Cheung Joyce C.Y. , Chen Hexin , Lorincz Annaka , Pandita Raj K. , Sharma Girdhar G. , Ha Hyo Chol , Gasson Judith , Hanakahi Les A. , Pandita Tej K. , Sukumar Saraswati
Published: February 2007

Homeobox genes encode transcription factors which function in body axis patterning in the developing embryo. Recent evidence suggests that the maintenance of specific HOX expression patterns is necessary for regulating the homeostasis of adult tissues as well. In this study, HOXB7 transformed human mammary epithelial cells, MCF10A, to grow in minimally supplemented medium, to form colonies in Matrigel, and display resistance to ionizing radiation. Searching for protein partners of HOXB7 that might contribute to resistance to ionizing radiation, we identified four HOXB7-binding proteins by GST pull-down/affinity chromatography and confirmed their interactions by coimmunoprecipitation in vivo. Interestingly, all four HOXB7-binding proteins shared functions as genomic caretakers and included members of the DNA-dependent protein kinase holoenzyme (Ku70, Ku80, DNA-PKcs) responsible for DNA double-strand break repair by nonhomologous end joining pathway and poly(ADP) ribose polymerase. Exogenous and endogenous expression of HOXB7 enhanced nonhomologous end joining and DNA repair functions in vitro and in vivo, which were reversed by silencing HOXB7. This is the first mechanistic study providing definitive evidence for the involvement of any HOX protein in DNA double-strand break repair. [Cancer Res 2007;67(4):1527–35]
The application of cassette dosing for pharmacokinetic screening in small-molecule cancer drug discovery
Authors: Smith Nicola F. , Raynaud Florence I. , Workman Paul
Published: February 2007

Pharmacokinetic evaluation is an essential component of drug discovery and should be conducted early in the process so that those compounds with the best chance of success are prioritized and progressed. However, pharmacokinetic analysis has become a serious bottleneck during the ‘hit-to-lead’ and lead optimization phases due to the availability of new targets and the large numbers of compounds resulting from advances in synthesis and screening technologies. Cassette dosing, which involves the simultaneous administration of several compounds to a single animal followed by rapid sample analysis by liquid chromatography/tandem mass spectrometry, was developed to increase the throughput of in vivo pharmacokinetic screening. Although cassette dosing is advantageous in terms of resources and throughput, there are possible complications associated with this approach, such as the potential for compound interactions. Following an overview of the cassette dosing literature, this article focuses on the application of the technique in anticancer drug discovery. Specific examples are discussed, including the evaluation of cassette dosing to assess pharmacokinetic properties in the development of cyclin-dependent kinase and heat shock protein 90 inhibitors. Subject to critical analysis and validation in each case, the use of cassette dosing is recommended in appropriate chemical series to enhance the efficiency of drug discovery and reduce animal usage. [Mol Cancer Ther 2007;6(2):428–40]
Inhibitory effect of snake venom toxin from Vipera lebetina turanica on hormone-refractory human prostate cancer cell growth: induction of apoptosis through inactivation of nuclear factor κB
Authors: Son Dong Ju , Park Mi Hee , Chae Sang Jin , Moon Soon Ok , Lee Jae Woong , Song Ho Sueb , Moon Dong Cheul , Kang Sang Sun , Kwon Young Ee , Hong Jin Tae
Published: February 2007

We investigated whether the snake venom toxin (SVT) from Vipera lebetina turanica inhibits cell growth of human prostate cancer cells by inducing apoptosis and also studied possible signaling pathways involved in this cell death. SVT inhibited growth of PC-3 and DU145 cells, androgen-independent prostate cancer cells, but not LNCaP cells, a human androgen-dependent prostate cancer cell. Cells were arrested in the G2-M phase by SVT with a concomitant decrease in the expression of the G2-M phase regulatory protein cyclin B1 and were also arrested in the G1-S phase with decreasing expression of cyclin-dependent kinase 4, cyclin D1 and cyclin E. In addition to the growth-inhibitory effect, SVT increased the induction of apoptotic cell death. Untreated PC-3 cells show high DNA binding activity of nuclear factor κB (NF-κB), an antiapoptotic transcriptional factor, but this was inhibited by SVT and accompanied by a significant inhibition of p50 translocation into the nucleus, as well as phosphorylation of inhibitory κB. Consistent with the induction of apoptosis and inhibition of NF-κB, this toxin increased the expression of proapoptotic proteins such as p53, Bax, caspase-3, and caspase-9, but down-regulated antiapoptotic protein Bcl-2. However, SVT did not show an inhibitory effect on cell growth and caspase-3 activity in cells carrying mutant p50 and inhibitory κB kinase plasmids. Confocal microscopy analysis showed that SVT is taken up into the nucleus of the cells. These findings suggest that a nanogram concentration range of SVT from V. lebetina turanica could inhibit hormone-refractory human prostate cancer cell growth, and the effect may be related to NF-κB signal–mediated induction of apoptosis. [Mol Cancer Ther 2007;6(2):675–83]
Pemetrexed: biochemical and cellular pharmacology, mechanisms, and clinical applications
Authors: Chattopadhyay Shrikanta , Moran Richard G. , Goldman I. David
Published: February 2007

Pemetrexed is a new-generation antifolate, approved for the treatment of mesothelioma and non–small cell lung cancer, currently being evaluated for the treatment of a variety of other solid tumors. This review traces the history of antifolates that led to the development of pemetrexed and describes the unique properties of this agent that distinguish it from other antifolates. These include (a) its very rapid conversion to active polyglutamate derivatives in cells that build to high levels and are retained for long intervals to achieve prolonged and potent inhibition of its major target enzyme thymidylate synthase, (b) its high affinity for three folate transporters, and (c) its marked sensitivity to the level of physiologic folates in cells. The latter results in the unique and paradoxical finding that when transport mediated by the major folate transporter (the reduced folate carrier) is impaired, pemetrexed activity is preserved. This is due to concurrent contraction of competing cellular physiologic folates and utilization of a novel second transport carrier for which pemetrexed has high affinity, recently identified as the proton-coupled folate transporter (PCFT). Laboratory studies are reviewed that raise the possibility of new approaches to the use of folic acid supplementation in clinical regimens with pemetrexed. [Mol Cancer Ther 2007;6(2):404–17]
Effect of frequently used chemotherapeutic drugs on the cytotoxic activity of human natural killer cells
Authors: Markasz Laszlo , Stuber Gyorgy , Vanherberghen Bruno , Flaberg Emilie , Olah Eva , Carbone Ennio , Eksborg Staffan , Klein Eva , Skribek Henriette , Szekely Laszlo
Published: February 2007

Tumors are considered to be possible targets of immunotherapy using stimulated and expanded autologous or allogeneic natural killer (NK) cells mismatched for MHC class I molecules and inhibitory NK receptors. NK cell–based immunoadjuvant therapies are carried out in combination with standard chemotherapeutic protocols. In the presented study, we characterized the effect of 28 frequently used chemotherapeutic agents on the capacity of NK cells to kill target cells. We found that treatment of NK cells with the drugs vinblastine, paclitaxel, docetaxel, cladribine, chlorambucil, bortezomib, and MG-132 effectively inhibited NK cell–mediated killing without affecting the viability of NK cells. On the other hand, the following drugs permitted efficient NK cell–mediated killing even at concentrations comparable with or higher than the maximally achieved therapeutic concentration in vivo in humans: asparaginase, bevacizumab, bleomycin, doxorubicin, epirubicin, etoposide, 5-fluorouracil, hydroxyurea, streptozocin, and 6-mercaptopurine. [Mol Cancer Ther 2007;6(2):644–54]
Optimizing the development of targeted agents in pancreatic cancer: tumor fine-needle aspiration biopsy as a platform for novel prospective ex vivo drug sensitivity assays
Authors: Rubio-Viqueira Belen , Mezzadra Heather , Nielsen Matthew E. , Jimeno Antonio , Zhang Xianfeng , Iacobuzio-Donahue Christine , Maitra Anirban , Hidalgo Manuel , Altiok Soner
Published: February 2007

At the present time, the optimal development of molecularly targeted anticancer agents is limited by the lack of clinically applicable tools to predict drug effects. This study aimed to develop methods that might be useful in predicting the efficacy of targeted agents in a novel model system of human pancreatic cancer. A series of xenografts were established in nude mice by implanting human pancreatic cancer tissue surgically resected from cancer patients. Animals were treated with the epidermal growth factor receptor inhibitor erlotinib, the mammalian target of rapamycin inhibitor temsirolimus, or vehicle. Tumor cells were sampled by fine-needle aspiration biopsy (FNAB) before (baseline, day 0) and at the completion of 28 days of treatment. Cells obtained at baseline were exposed to erlotinib or temsirolimus in short-term cell culture conditions (ex vivo). Western blot analysis was done to determine the degree of inhibition in the phosphorylation of extracellular signal-regulated kinase 1/2 and S6-ribosomal protein (downstream effectors of epidermal growth factor receptor and mammalian target of rapamycin, respectively) ex vivo and in vivo. Five of six xenografted tumors responded to temsirolimus, whereas only one tumor responded to erlotinib. The results of the ex vivo studies correctly predicted the pharmacodynamic effect of the agents in vivo as well as their gross antitumor effects. Finally, we showed the clinical feasibility of this approach, performing ex vivo assessment of drug-target response in FNAB samples from three patients with pancreatic cancer. Cancer cells obtained by FNAB, an established minimally invasive diagnostic procedure, can be used to test ex vivo the effects of targeted anticancer agents. These effects correlate with antitumor activity in vivo and may therefore provide an important tool applicable to clinical trials. Ultimately, an approach of this nature may facilitate the further refinement of patient selection in favor of individuals with molecular profiles, predicting a greater likelihood of therapeutic benefit. [Mol Cancer Ther 2007;6(2):515–23]
Treatment of prostate cancer with Ad5/3Δ24hCG allows non-invasive detection of the magnitude and persistence of virus replication in vivo
Authors: Rajecki Maria , Kanerva Anna , Stenman Ulf-Håkan , Tenhunen Mikko , Kangasniemi Lotta , Särkioja Merja , Ala-Opas Martti Y. , Alfthan Henrik , Sankila Anna , Rintala Erkki , Desmond Renee A. , Hakkarainen Tanja , Hemminki Akseli
Published: February 2007

Hormone refractory metastatic prostate cancer is a deadly disease that currently lacks curative treatments. Conditionally replicating adenoviruses (CRAds) are promising new agents against cancer due to their innate capability to cause oncolysis of tumor cells. Their antitumor effect is determined in part by their capacity for infecting cancer cells. However, the respective primary receptor, the coxsackie-adenovirus receptor (CAR), is variably expressed in many cancer types. We created Ad5/3Δ24hCG, a novel CRAd retargeted to the adenovirus serotype 3 receptor, which has been reported to be highly expressed in tumors. Furthermore, we added a transgene for the β-chain of human chorionic gonadotropin (hCGβ), whose expression was tightly coupled to virus replication. Ad5/3Δ24hCG was found effective in killing prostate cancer cells, and oncolysis was seen in concordance with hCGβ production. In a s.c. in vivo model of hormone refractory prostate cancer, Ad5/3Δ24hCG treatment resulted in statistically significant tumor growth inhibition. Moreover, i.v. injection of Ad5/3Δ24hCG prolonged the survival of mice with hormone refractory prostate cancer metastatic to the lung. Detection of hCGβ in serum samples confirmed viral replication in vivo. Infection of human clinical samples of cancerous and normal prostatic tissue resulted in effective hCGβ production in cancer tissue, whereas it remained low in nonmalignant tissue, suggesting cancer-specific replication. These results suggest that Ad5/3Δ24hCG is a potent virus for the treatment of hormone refractory prostate cancer in vitro and in vivo. These preclinical data set the stage for translation into clinical studies. [Mol Cancer Ther 2007;6(2):742–51]
Hypoxia-inducible factor-1 confers resistance to the glycolytic inhibitor 2-deoxy-d-glucose
Authors: Maher Johnathan C. , Wangpaichitr Medhi , Savaraj Niramol , Kurtoglu Metin , Lampidis Theodore J.
Published: February 2007

Hypoxic regions within solid tumors harbor cells that are resistant to standard chemotherapy and radiotherapy. Because oxygen is required to produce ATP by oxidative phosphorylation, under hypoxia, cells rely more on glycolysis to generate ATP and are thereby sensitive to 2-deoxy-d-glucose (2-DG), an inhibitor of this pathway. Universally, cells respond to lowered oxygen tension by increasing the amount of glycolytic enzymes and glucose transporters via the well-characterized hypoxia-inducible factor-1 (HIF). To evaluate the effects of HIF on 2-DG sensitivity, the following three models were used: (a) cells treated with oligomycin to block mitochondrial function in the presence (HIF+) or absence (HIF−) of hypoxia, (b) cells treated with small interfering RNA specific for HIF-1α and control cells cultured under hypoxia, and (c) a mutant cell line unable to initiate the HIF response and its parental HIF+ counterpart under hypoxic conditions. In all three models, HIF increased resistance to 2-DG and other glycolytic inhibitors but not to other chemotherapeutic agents. Additionally, HIF reduced the effects of 2-DG on glycolysis (as measured by ATP and lactate assays). Because HIF increases glycolytic enzymes, it follows that greater amounts of 2-DG would be required to inhibit glycolysis, thereby leading to increased resistance to it under hypoxia. Indeed, hexokinase, aldolase, and lactate dehydrogenase were found to be increased as a function of HIF under the hypoxic conditions and cell types we used; however, phosphoglucose isomerase was not. Although both hexokinase and phosphoglucose isomerase are known to interact with 2-DG, our findings of increased levels of hexokinase more likely implicate this enzyme in the mechanism of HIF-mediated resistance to 2-DG. Moreover, because 2-DG is now in phase I clinical trials, our results suggest that glycolytic inhibitors may be more effective clinically when combined with agents that inhibit HIF. [Mol Cancer Ther 2007;6(2):732–41]
Targeted therapy of orthotopic human lung cancer by combined vascular endothelial growth factor and epidermal growth factor receptor signaling blockade
Authors: Wu Wenjuan , Onn Amir , Isobe Takeshi , Itasaka Satoshi , Langley Robert R. , Shitani Tomoaki , Shibuya Keiko , Komaki Ritsuko , Ryan Anderson J. , Fidler Isaiah J. , Herbst Roy S. , O'Reilly Michael S.
Published: February 2007

The outcome for patients with lung cancer has not changed significantly for more than two decades. Several studies show that the overexpression of vascular endothelial growth factor (VEGF)/vascular permeability factor and epidermal growth factor (EGF) and their receptors correlates with the clinical outcome for lung cancer patients. However, clinical trials of agents that target either of these pathways alone have been disappointing. We hypothesize that targeting both the tumor and its vasculature by simultaneously blocking the VEGFR and EGFR pathways will improve the treatment of locoregional lung cancer. Human lung cancer specimens were first examined for the activation of VEGF receptor 2 (VEGFR2) and EGF receptor (EGFR) for tumor and tumor-associated endothelial cells, and both were found to be activated. The effects of ZD6474 (ZACTIMA), a small-molecule inhibitor of VEGFR2 and EGFR tyrosine kinases, were then studied in vitro using human lung cancer and microvascular endothelial cells. In vitro, ZD6474 inhibited EGFR, VEGFR2, mitogen-activated protein kinase and Akt phosphorylation, EGF- and VEGF-induced proliferation, and endothelial cell tube formation and also induced apoptosis. ZD6474 was further studied in vivo using an orthotopic mouse model of non–small cell lung cancer using NCI-H441 human lung adenocarcinoma cells. The inhibition of both VEGFR2 and EGFR signaling pathways by ZD6474 resulted in profound antiangiogenic, antivascular, and antitumor effects. These results provide a basis for the development of clinical strategies for the combination of selective protein tyrosine kinase inhibitors that block both EGFR and VEGFR signaling as part of the management of locally advanced lung cancer. [Mol Cancer Ther 2007;6(2):471–83]
Plasminogen Kringle 5 blocks tumor progression by antiangiogenic and proinflammatory pathways
Authors: Perri Sabrina R. , Martineau Daniel , François Moïra , Lejeune Laurence , Bisson Louis , Durocher Yves , Galipeau Jacques
Published: February 2007

Proteolytic processing of human plasminogen generates potent antiangiogenic peptides such as angiostatin. The plasminogen kringle 5 (K5) domain, which is distinct from angiostatin, possesses potent antiangiogenic properties on its own, which can be exploited in cancer therapy. It has been recently observed that antiangiogenic agents promote leukocyte-vessel wall interaction as part of their antitumor effect. Although we have previously shown that K5 suppresses cancer growth in tumor xenograft models, its modulation of inflammation in experimental mice with intact immune systems is unknown. To determine whether K5 possesses immune proinflammatory properties, we investigated the effects of K5 in an immune competent model of breast cancer and observed that tumor rejection is substantially reduced in nonobese diabetic/severe combined immunodeficient and BALB/c nude when compared with wild-type BALB/c mice, suggesting an important role for T-lymphoid cells in the antitumor effect of K5. Tumor explant analysis shows that K5 enhances tumor recruitment of CD3+ lymphoid cells, in particular, the NKT phenotype. We also observed a significant decrease in tumor-associated microvessel length and density consistent with antiangiogenic activity. Histologic analysis of K5 tumors also revealed a robust neutrophilic infiltrate, which may be explained by the neutrophil chemotactic activity of K5 as well as its ability to promote CD64 up-regulation within the CD11b+ adhesive neutrophil population. In sum, our findings confirm that the K5 protein acts as a potent angiostatic agent and possesses a novel proinflammatory role via its ability to recruit tumor-associated neutrophils and NKT lymphocytes, leading to a potent antitumor response. [Mol Cancer Ther 2007;6(2):441–9]
Prediction of drug combination chemosensitivity in human bladder cancer
Authors: Havaleshko Dmytro M. , Cho HyungJun , Conaway Mark , Owens Charles R. , Hampton Garret , Lee Jae K. , Theodorescu Dan
Published: February 2007

The choice of therapy for metastatic cancer is largely empirical because of a lack of chemosensitivity prediction for available combination chemotherapeutic regimens. Here, we identify molecular models of bladder carcinoma chemosensitivity based on gene expression for three widely used chemotherapeutic agents: cisplatin, paclitaxel, and gemcitabine. We measured the growth inhibition elicited by these three agents in a series of 40 human urothelial cancer cell lines and correlated the GI50 (50% of growth inhibition) values with quantitative measures of global gene expression to derive models of chemosensitivity using a misclassification-penalized posterior approach. The misclassification-penalized posterior–derived models predicted the growth response of human bladder cancer cell lines to each of the three agents with sensitivities of between 0.93 and 0.96. We then developed an in silico approach to predict the cellular growth responses for each of these agents in the clinically relevant two-agent combinations. These predictions were prospectively evaluated on a series of 15 randomly chosen bladder carcinoma cell lines. Overall, 80% of the predicted combinations were correct (P = 0.0002). Together, our results suggest that chemosensitivity to drug combinations can be predicted based on molecular models and provide the framework for evaluation of such models in patients undergoing combination chemotherapy for cancer. If validated in vivo, such predictive models have the potential to guide therapeutic choice at the level of an individual's tumor. [Mol Cancer Ther 2007;6(2):578–86]