bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Combination of Rad001 (Everolimus) and Propachlor Synergistically Induces Apoptosis through Enhanced Autophagy in Prostate Cancer Cells
Authors: Tai Sheng , Sun Yin , Liu Nan , Ding Boxiao , Hsia Elaine , Bhuta Sunita , Thor Ryan K. , Damoiseaux Robert , Liang Chaozhao , Huang Jiaoti
Published: April 2023

Abstract
PI3K/AKT/mTOR pathway plays a key role in the tumorigenesis of many human cancers including prostate cancer. However, inhibitors of this pathway, such as Rad001, have not shown therapeutic efficacy as a single agent. Through a high-throughput screen of 5,000 widely used small molecules, we identified compounds that can synergize with Rad001 to inhibit prostate cancer cells. One of the compounds, propachlor, synergizes with Rad001 to induce apoptosis of castration-resistant prostate cancer cells via enhanced autophagy. This enhanced autophagic cell death is accompanied by increased Beclin1 expression as well as upregulation of Atg5–Atg12 conjugate and LC3-2. Rad001 and propachlor can also synergistically inhibit tumors in a xenograft animal model of prostate cancer. These findings provide a novel direction to develop combination therapies for advanced and metastatic prostate cancer that has failed the currently available therapies. Mol Cancer Ther; 11(6); 1320–31. ©2012 AACR.
Data from Interpreting Mammalian Target of Rapamycin and Cell Growth Inhibition in a Genetically Engineered Mouse Model of Nf1-Deficient Astrocytes
Authors: Banerjee Sutapa , Gianino Scott M. , Gao Feng , Christians Uwe , Gutmann David H.
Published: April 2023

Abstract
The identification of mammalian target of rapamycin (mTOR) as a major mediator of neurofibromatosis-1 (NF1) tumor growth has led to the initiation of clinical trials using rapamycin analogs. Previous studies from our laboratory have shown that durable responses to rapamycin treatment in a genetically engineered mouse model of Nf1 optic glioma require 20 mg/kg/day, whereas only transient tumor growth suppression was observed with 5 mg/kg/day rapamycin despite complete silencing of ribosomal S6 activity. To gain clinically relevant insights into the mechanism underlying this dose-dependent effect, we used Nf1-deficient glial cells in vitro and in vivo. First, there was an exponential relationship between blood and brain rapamycin levels. Second, we show that currently used biomarkers of mTOR pathway inhibition (phospho-S6, phospho-4EBP1, phospho-STAT3, and Jagged-1 levels) and tumor proliferation (Ki67) do not accurately reflect mTOR target inhibition or Nf1-deficient glial growth suppression. Third, the incomplete suppression of Nf1-deficient glial cell proliferation in vivo following 5 mg/kg/day rapamycin treatment reflects mTOR-mediated AKT activation, such that combined 5 mg/kg/day rapamycin and PI3-kinase (PI3K) inhibition or dual PI3K/mTOR inhibition recapitulates the growth suppressive effects of 20 mg/kg/day rapamycin. These new findings argue for the identification of more accurate biomarkers for rapamycin treatment response and provide reference preclinical data for comparing human rapamycin levels with target effects in the brain. Mol Cancer Ther; 10(2); 279–91. ©2011 AACR.
Data from Dual Inhibition of Tumor Energy Pathway by 2-Deoxyglucose and Metformin Is Effective against a Broad Spectrum of Preclinical Cancer Models
Authors: Cheong Jae-Ho , Park Eun Sung , Liang Jiyong , Dennison Jennifer B. , Tsavachidou Dimitra , Nguyen-Charles Catherine , Wa Cheng Kwai , Hall Hassan , Zhang Dong , Lu Yiling , Ravoori Murali , Kundra Vikas , Ajani Jaffer , Lee Ju-Seog , Ki Hong Waun , Mills Gordon B.
Published: April 2023

Abstract
Tumor cell proliferation requires both growth signals and sufficient cellular bioenergetics. The AMP-activated protein kinase (AMPK) pathway seems dominant over the oncogenic signaling pathway suppressing cell proliferation. This study investigated the preclinical efficacy of targeting the tumor bioenergetic pathway using a glycolysis inhibitor 2-deoxyglucose (2DG) and AMPK agonists, AICAR and metformin. We evaluated the in vitro antitumor activity of 2DG, metformin or AICAR alone, and 2DG in combination either with metformin or AICAR. We examined in vivo efficacy using xenograft mouse models. 2DG alone was not sufficient to promote tumor cell death, reflecting the limited efficacy showed in clinical trials. A combined use of 2DG and AICAR also failed to induce cell death. However, 2DG and metformin led to significant cell death associated with decrease in cellular ATP, prolonged activation of AMPK, and sustained autophagy. Gene expression analysis and functional assays revealed that the selective AMPK agonist AICAR augments mitochondrial energy transduction (OXPHOS) whereas metformin compromises OXPHOS. Importantly, forced energy restoration with methyl pyruvate reversed the cell death induced by 2DG and metformin, suggesting a critical role of energetic deprivation in the underlying mechanism of cell death. The combination of 2DG and metformin inhibited tumor growth in mouse xenograft models. Deprivation of tumor bioenergetics by dual inhibition of energy pathways might be an effective novel therapeutic approach for a broad spectrum of human tumors. Mol Cancer Ther; 10(12); 2350–62. ©2011 AACR.
Data from A Molecular Screening Approach to Identify and Characterize Inhibitors of Glioblastoma Stem Cells
Authors: Visnyei Koppany , Onodera Hideyuki , Damoiseaux Robert , Saigusa Kuniyasu , Petrosyan Syuzanna , De Vries David , Ferrari Denise , Saxe Jonathan , Panosyan Eduard H. , Masterman-Smith Michael , Mottahedeh Jack , Bradley Kenneth A. , Huang Jing , Sabatti Chiara , Nakano Ichiro , Kornblum Harley I.
Published: April 2023

Abstract
Glioblastoma (GBM) is among the most lethal of all cancers. GBM consist of a heterogeneous population of tumor cells among which a tumor-initiating and treatment-resistant subpopulation, here termed GBM stem cells, have been identified as primary therapeutic targets. Here, we describe a high-throughput small molecule screening approach that enables the identification and characterization of chemical compounds that are effective against GBM stem cells. The paradigm uses a tissue culture model to enrich for GBM stem cells derived from human GBM resections and combines a phenotype-based screen with gene target-specific screens for compound identification. We used 31,624 small molecules from 7 chemical libraries that we characterized and ranked based on their effect on a panel of GBM stem cell-enriched cultures and their effect on the expression of a module of genes whose expression negatively correlates with clinical outcome: MELK, ASPM, TOP2A, and FOXM1b. Of the 11 compounds meeting criteria for exerting differential effects across cell types used, 4 compounds showed selectivity by inhibiting multiple GBM stem cells-enriched cultures compared with nonenriched cultures: emetine, n-arachidonoyl dopamine, n-oleoyldopamine (OLDA), and n-palmitoyl dopamine. ChemBridge compounds #5560509 and #5256360 inhibited the expression of the 4 mitotic module genes. OLDA, emetine, and compounds #5560509 and #5256360 were chosen for more detailed study and inhibited GBM stem cells in self-renewal assays in vitro and in a xenograft model in vivo. These studies show that our screening strategy provides potential candidates and a blueprint for lead compound identification in larger scale screens or screens involving other cancer types. Mol Cancer Ther; 10(10); 1818–28. ©2011 AACR.
Data from Human Monoclonal Antibodies Targeting Nonoverlapping Epitopes on Insulin-like Growth Factor II as a Novel Type of Candidate Cancer Therapeutics
Authors: Chen Weizao , Feng Yang , Zhao Qi , Zhu Zhongyu , Dimitrov Dimiter S.
Published: April 2023

Abstract
Soluble ligands are important targets for therapy of cancers and other diseases. Therapeutic monoclonal antibodies (mAb) against such ligands block their interactions with corresponding receptors but do not enhance their removal from the circulation and can increase their half-lives because of the long half-lives of the antibodies. We have hypothesized that mAbs targeting two or more nonoverlapping epitopes on the same ligand could form oligomeric antibody–ligand complexes that can bind to cells expressing Fc gamma receptors (FcγRs) with high avidity leading to their fast and irreversible removal from the circulation. Insulin-like growth factor II (IGF-II) is an example of such ligands and an important target for human cancer therapy. We identified two mAbs, m610.27 and m630.3, which bound to nonoverlapping epitopes on IGF-II with nanomolar affinity, and generated a bispecific antibody, m660. m660 inhibited the interaction of human IGF-II (hIGF-II) with the human breast cancer cell line MCF-7, hIGF-II–mediated IGF receptor type I and insulin receptor phosphorylation, and cell growth. In the presence of hIGF-II, large complexes of m660 were formed that bound to FcγRII-expressing BJAB cells much more efficiently than the monospecific antibody–hIGF-II complexes and were presumably phagocytosed by phorbol 12-myristate 13-acetate–stimulated macrophage-like U937 cells. A mixture of m610.27 and m630.3 exhibited similar properties. To our knowledge, these mAbs are the first reported to target nonoverlapping epitopes on a cancer-related ligand and could represent a novel class of candidate therapeutics against cancers. This approach could also be used to irreversibly eliminate other disease-related soluble ligands. Mol Cancer Ther; 11(7); 1400–10. ©2012 AACR.
Data from Triggering Fbw7-Mediated Proteasomal Degradation of c-Myc by Oridonin Induces Cell Growth Inhibition and Apoptosis
Authors: Huang Hui-Lin , Weng Heng-You , Wang Lu-Qin , Yu Chun-Hong , Huang Qiao-Juan , Zhao Pan-Pan , Wen Jun-Zhi , Zhou Hui , Qu Liang-Hu
Published: April 2023

Abstract
The transcription factor c-Myc is important in cell fate decisions and is frequently overexpressed in cancer cells, making it an attractive therapeutic target. Natural compounds are among the current strategies aimed at targeting c-Myc, but their modes of action still need to be characterized. To explore the mechanisms underlying the anticancer activity of a natural diterpenoid, oridonin, we conducted miRNA expression profiling and statistical analyses that strongly suggested that c-Myc was a potential molecular target of oridonin. Furthermore, experimental data showed that oridonin significantly reduced c-Myc protein levels in vitro and in vivo and that this reduction was mediated by the ubiquitin-proteasome system. Fbw7, a component of the ubiquitin-proteasome system and an E3 ubiquitin ligase of c-Myc, was upregulated rapidly in K562 cells and other leukemia and lymphoma cells, resulting in the rapid turnover of c-Myc. In cell lines harboring mutations in the WD domain of Fbw7, the degradation of c-Myc induced by oridonin was attenuated during short-term treatment. GSK-3, an Fbw7 priming kinase, was also activated by oridonin, along with an increase in T58-phosphorylated c-Myc. Furthermore, the knockdown of Fbw7 or the forced expression of stable c-Myc resulted in reduced sensitization to oridonin-induced apoptosis. Our observations help to clarify the anticancer mechanisms of oridonin and shed light on the application of this natural compound as an Fbw7-c-Myc pathway targeting agent in cancer treatment. Mol Cancer Ther; 11(5); 1155–65. ©2012 AACR.
Data from Targeting Sarcoplasmic/Endoplasmic Reticulum Ca2+-ATPase 2 by Curcumin Induces ER Stress-Associated Apoptosis for Treating Human Liposarcoma
Authors: Wang Lu , Wang Lingxian , Song Ran , Shen Yan , Sun Yang , Gu Yanhong , Shu Yongqian , Xu Qiang
Published: April 2023

Abstract
Human liposarcoma is the most common soft tissue sarcoma. There is no effective therapy so far except for surgery. In this study, we report for the first time that curcumin induces endoplasmic reticulum (ER) stress in human liposarcoma cells via interacting with sarcoplasmic/endoplasmic reticulum Ca2+-ATPase 2 (SERCA2). Curcumin dose-dependently inhibited the cell survival of human liposarcoma cell line SW872 cells, but did not affect that of human normal adipose-derived cells. Curcumin-mediated ER stress via inhibiting the activity of SERCA2 caused increasing expressions of CHOP and its transcription target death receptor 5 (TRAIL-R2), leading to a caspase-3 and caspase-8 cascade-dependent apoptosis in SW872 cells in vitro and in vivo. Moreover, 70% of human liposarcoma tissues showed an elevated SERCA2 expression compared with normal adipose tissues. Curcumin dose-dependently inhibited the activity of SERCA2, and the interaction of molecular docking and colocalization in ER of curcumin with SERCA2 were further observed. These findings suggest that curcumin may serve as a potent agent for curing human liposarcoma via targeting SERCA2. Mol Cancer Ther; 10(3); 461–71. ©2011 AACR.
Data from Identification of a Natural Compound by Cell-Based Screening That Enhances Interferon Regulatory Factor-1 Activity and Causes Tumor Suppression
Authors: Gao Jinbo , Wang Yujun , Xing Quanhua , Yan Jin , Senthil Maheswari , Akmal Yasir , Kowolik Claudia M. , Kang Julia , Lu David M. , Zhao Ming , Lin Zhixiu , Cheng Christopher H.K. , Yip M.L. Richard , Yim John H.
Published: April 2023

Abstract
The transcription factor interferon regulatory factor-1 (IRF-1) is induced by many tumor-suppressive stimuli and can mediate antiproliferative and proapoptotic effects in cancer cells. Thus, identifying agents that enhance IRF-1 activity may be an effective approach to cancer therapy. A cell-based screening assay was developed to identify extracts and compounds that could enhance IRF-1 activity, using an IRF-1–dependent luciferase reporter cell line. Through this approach, we identified a natural product extract and a known active component of this extract, baicalein, which causes a marked increase in IRF-1–dependent reporter gene expression and IRF-1 protein, with modulation of known IRF-1 targets PUMA and cyclin D1. Baicalein causes suppression of growth in vitro in multiple cancer cell lines in the low micromolar range. IRF-1 plays a role in this growth suppression as shown by significant resistance to growth suppression in a breast cancer cell line stably transfected with short hairpin RNA against IRF-1. Finally, intraperitoneal administration of baicalein by repeated injection causes inhibition of growth in both xenogeneic and syngeneic mouse models of cancer without toxicity to the animals. These findings indicate that identifying enhancers of IRF-1 activity may have utility in anticancer therapies and that cell-based screening for activation of transcription factors can be a useful approach for drug discovery. Mol Cancer Ther; 10(10); 1774–83. ©2011 AACR.
Data from Integrin α6high Cell Population Functions as an Initiator in Tumorigenesis and Relapse of Human Liposarcoma
Authors: Wang Lu , Wang Lingxian , Gu Yanhong , Shu Yongqian , Shen Yan , Xu Qiang
Published: April 2023

Abstract
The relapse and resistance to chemo- and radiotherapy are main problems in the treatment of human liposarcoma. It is important to find a functional marker existing in the liposarcoma cells for targeting. In this article, we established a new sub-cell line SW872-S cells with high tumorigenicity from human liposarcoma SW872 cells by repeated inoculation approach. The characteristic of the sub-cell line is linked to the high levels of integrin α6 on the surface. The integrin α6high cells show much higher tumor initiation and self-renewal potential in vivo than integrin α6low cells do. Targeting integrin α6 with its specific short interfering RNA and antibody significantly inhibits the cell adhesion to laminin and the tumor growth in vitro and in vivo, respectively. Interestingly, integrin α6 marks almost all of the surgical biopsy specimens of patients with liposarcoma relapse. Moreover, integrin α6 is found to coexpress with CD13, which might contribute to the antiapoptosis ability of integrin α6high cells. Consistently, integrin α6high cells are more sensitive to the CD13 inhibitor bestatin, and 61% of 23 other human tumor cell lines also contain integrin α6high CD13high subgroup. These results provide evidence, for the first time, to our knowledge, that integrin α6 and CD13 can serve as functional markers of the tumor-initiation subcell population in human liposarcoma as well as other cancers for therapeutic targeting. Mol Cancer Ther; 10(12); 2276–86. ©2011 AACR.
Data from Determinants of Mitotic Catastrophe on Abrogation of the G2 DNA Damage Checkpoint by UCN-01
Authors: On Kin Fan , Chen Yue , Tang Ma Hoi , Chow Jeremy P.H. , Poon Randy Y.C.
Published: April 2023

Abstract
Genotoxic stress such as ionizing radiation halts entry into mitosis by activation of the G2 DNA damage checkpoint. The CHK1 inhibitor 7-hydroxystaurosporine (UCN-01) can bypass the checkpoint and induce unscheduled mitosis in irradiated cells. Precisely, how cells behave following checkpoint abrogation remains to be defined. In this study, we tracked the fates of individual cells after checkpoint abrogation, focusing in particular on whether they undergo mitotic catastrophe. Surprisingly, while a subset of UCN-01–treated cells were immediately eliminated during the first mitosis after checkpoint abrogation, about half remained viable and progressed into G1. Both the delay of mitotic entry and the level of mitotic catastrophe were dependent on the dose of radiation. Although the level of mitotic catastrophe was specific for different cell lines, it could be promoted by extending the mitosis. In supporting this idea, weakening of the spindle-assembly checkpoint, by either depleting MAD2 or overexpressing the MAD2-binding protein p31comet, suppressed mitotic catastrophe. Conversely, delaying of mitotic exit by depleting either p31comet or CDC20 tipped the balance toward mitotic catastrophe. These results underscore the interplay between the level of DNA damage and the effectiveness of the spindle-assembly checkpoint in determining whether checkpoint-abrogated cells are eliminated during mitosis. Mol Cancer Ther; 10(5); 784–94. ©2011 AACR.
Data from Synergistic Antitumor Activity of Gemcitabine and ABT-737 In Vitro and In Vivo through Disrupting the Interaction of USP9X and Mcl-1
Authors: Zhang Chong , Cai Tian-yu , Zhu Hong , Yang Liu-qing , Jiang Hai , Dong Xiao-wu , Hu Yong-zhou , Lin Neng-ming , He Qiao-jun , Yang Bo
Published: April 2023

Abstract
The Bcl-2 antagonist ABT-737 targets Bcl-2/Bcl-xL, but not Mcl-1, which may confer resistance to this agent in various cancers with high levels of Mcl-1. Here, we showed that the combination of gemcitabine and ABT-737 exhibited synergistic cytotoxicity and induced significant apoptosis in multiple cancer types, including lung, renal, bladder, and prostate cancers. The enhanced apoptosis induced by gemcitabine plus ABT-737 was accompanied by the greater extent of mitochondrial depolarization, caspases-3 activation, and PARP cleavage in 95-D and 5637 cell lines. Importantly, in ABT-737–resistant cancer cells, the interaction between USP9X and Mcl-1, which was increased by ABT-737 treatment, could be disrupted by gemcitabine, thus resulting in enhanced ubiquitination and the subsequent degradation of Mcl-1 and ultimately in the synergism of these two drugs. Moreover, the increased anticancer efficacy of gemcitabine combined with ABT-737 was further validated in a human lung cancer 95-D xenograft model in nude mice. Taken together, our data first showed the synergistic anticancer capabilities achieved by combining gemcitabine and ABT-737 and, second, opened new opportunities to use antiapoptotic Bcl-2 family members, which drive tumor cell resistance in current anticancer therapies, therapeutically. Mol Cancer Ther; 10(7); 1264–75. ©2011 AACR.
Data from Targeting Tyrosine Phosphorylation of PCNA Inhibits Prostate Cancer Growth
Authors: Zhao Huajun , Lo Yuan-Hung , Ma Li , Waltz Susan E. , Gray Jerilyn K. , Hung Mien-Chie , Wang Shao-Chun
Published: April 2023

Abstract
The proliferation cell nuclear antigen (PCNA) is a critical protein required for DNA replication in proliferating cells including cancer cells. However, direct inhibition of PCNA in cancer cells has been difficult due to the lack of targetable sites. We previously reported that phosphorylation of tyrosine 211 (Y211) on PCNA is important for the proliferative function of PCNA when this protein is associated with the chromatin in cancer cells. Here, we show that the Y211 phosphorylation of PCNA is a frequent event in advanced prostate cancer. To explore the potential of this signaling event in inhibition of cancer cell growth, we used a synthetic peptide, the Y211F peptide, which when present inhibits phosphorylation of Y211 on endogenous PCNA. Treatment with this peptide, but not a scrambled control peptide, resulted in S-phase arrest, inhibition of DNA synthesis, and enhanced cell death in a panel of human prostate cancer cell lines. In addition, treatment with the Y211F peptide led to decreased tumor growth in PC3-derived xenograft tumors in vivo in nude mice. Our study shows for the first time that PCNA phosphorylation at Y211 is a frequent and biologically important signaling event in prostate cancer. This study also shows a proof of concept that Y211 phosphorylation of PCNA may be used as a therapeutic target in prostate cancer cells, including cells of advanced cancers that are refractory to standard hormonal therapies. Mol Cancer Ther; 10(1); 29–36. ©2011 AACR.
Data from MiR-196a Is Upregulated in Gastric Cancer and Promotes Cell Proliferation by Downregulating p27kip1
Authors: Sun Ming , Liu Xiang-hua , Li Jin-hai , Yang Jin-song , Zhang Er-bao , Yin Dan-dan , Liu Zhi-li , Zhou Jing , Ding Ying , Li Su-qin , Wang Zhao-xia , Cao Xiu-feng , De Wei
Published: April 2023

Abstract
Aberrant expression of miR-196a has been frequently reported in cancer studies. However, the expression and mechanism of its function in gastric cancer remains unclear. Quantitative real-time PCR was carried out to detect the relative expression of miR-196a in gastric cancer cell lines and tissues. SGC7901 cells were treated with miR-196a inhibitors, mimics, or pCDNA/miR-196a to investigate the role of miR-196a in cell proliferation. Higher expression of miR-196a in gastric cancer tissues was associated with tumor size, a higher clinical stage, and was also correlated with shorter overall survival of patients with gastric cancer. Exogenous downregulation of miR-196a expression significantly suppressed the in vitro cell-cycle progression, proliferation, and colony formation of gastric cancer cells, and ectopic miR-196a expression significantly enhanced the development of tumors in nude mice. Luciferase assays revealed that miR-196a inhibited p27kip1 expression by targeting one binding site in the 3′-untranslated region (3′-UTR) of p27kip1 mRNA. qPCR and Western blot assays verified that miR-196a reduced p27kip1 expression at both mRNA and protein levels. The p27kip1-mediated repression in cell proliferation was reverted by exogenous miR-196a expression. A reverse correlation between miR-196a and p27kip1 expression was noted in gastric cancer tissues. Our study shows that aberrant overexpression of miR-196a and consequent downregulation of p27kip1 could contribute to gastric carcinogenesis and would be targets for gastric cancer therapies and further developed as potential prognostic factors. Mol Cancer Ther; 11(4); 842–52. ©2012 AACR.
Data from Glycolytic Inhibition Alters Anaplastic Thyroid Carcinoma Tumor Metabolism and Improves Response to Conventional Chemotherapy and Radiation
Authors: Sandulache Vlad C. , Skinner Heath D. , Wang Yuan , Chen Yunyun , Dodge Cristina T. , Ow Thomas J. , Bankson James A. , Myers Jeffrey N. , Lai Stephen Y.
Published: April 2023

Abstract
Anaplastic thyroid carcinoma (ATC) accounts for more than 50% of thyroid cancer mortality and is generally refractory to conventional treatment. On the basis of recent studies, we hypothesized that ATC metabolism can be targeted to improve response to chemoradiotherapy. Eight established and authenticated ATC cell lines were sequenced at 140 sites contained within 26 commonly mutated genes to identify novel potential therapeutic targets. Cellular proliferation, energy, and reducing potential stores were measured under conditions of specific nutrient deprivation. Tumor metabolism was evaluated using hyperpolarized 13C MRI in a murine orthotopic xenograft model of ATC. Sensitivity to chemotherapeutic agents and radiation (XRT) was assayed using cytotoxicity assays. We identified mutations in BRAF, NRAS, and KIT but failed to identify generalized novel targets for therapeutic intervention. ATC cell lines exhibited a mesenchymal phenotype and generalized dependence on glucose for energy, reducing potential and survival. Glycolytic inhibition using 2-deoxyglucose (2-DG) sensitized ATC cells to conventional chemotherapy and external beam radiation. In vivo, 2-DG induced a transient, but significant reduction in ATC metabolic activity. Generalized dependence of ATC cells on glucose catabolism makes them susceptible to the sensitizing effects of 2-DG for radiation therapy and chemotherapy. Under in vivo conditions, 2-DG can inhibit ATC metabolism. However, the modest magnitude and transient nature of this effect suggest the need for antimetabolic agents with more favorable pharmacodynamics to achieve therapeutic effects. Mol Cancer Ther; 11(6); 1373–80. ©2012 AACR.
Data from Targeting Subcellular Localization through the Polo-Box Domain: Non-ATP Competitive Inhibitors Recapitulate a PLK1 Phenotype
Authors: McInnes Campbell , Estes Kara , Baxter Merissa , Yang Zhengguan , Farag Doaa Boshra , Johnston Paul , Lazo John S. , Wang Jianjun , Wyatt Michael D.
Published: April 2023

Abstract
The polo-box domain (PBD) has critical roles in the mitotic functions of polo-like kinase 1 (PLK1). The replacement with partial ligand alternative through computational enrichment (REPLACE) strategy to develop inhibitors of protein–protein interactions has identified alternatives for the N-terminal tripeptide of a Cdc25C substrate. In addition, a peptide structure–activity relationship described key determinants and novel information useful for drug design. Fragment-ligated inhibitory peptides (FLIP) were generated with comparable affinity to peptide PBD inhibitors and possessed antiproliferative phenotypes in cells consistent with the observed decrease in PLK1 centrosomal localization. These FLIPs showed evidence of enhanced PLK1 inhibition in cells relative to peptides and induced monopolar and multipolar spindles, which stands in contrast to previously reported small-molecule PBD inhibitors that display phenotypes only partially representative of PLK1 knockdown. Progress obtained applying REPLACE validates this approach for identifying fragment alternatives for determinants of the Cdc25C-binding motif and extends its applicability of the strategy for discovering protein–protein interaction inhibitors. In addition, the described PBD inhibitors retain high specificity for PLK1 over PLK3 and therefore show promise as isotype selective, non-ATP competitive kinase inhibitors that provide new impetus for the development of PLK1-selective antitumor therapeutics. Mol Cancer Ther; 11(8); 1683–92. ©2012 AACR.
Data from Contrary Regulation of Bladder Cancer Cell Proliferation and Invasion by Dexamethasone-Mediated Glucocorticoid Receptor Signals
Authors: Zheng Yichun , Izumi Koji , Li Yi , Ishiguro Hitoshi , Miyamoto Hiroshi
Published: April 2023

Abstract
In patients with advanced bladder cancer, glucocorticoids are frequently given to reduce acute toxicity, particularly hyperemesis, during chemotherapy, as well as to improve cachectic conditions. However, it remains unclear whether glucocorticoids directly affect the development and progression of bladder cancer through the glucocorticoid receptor pathway. Glucocorticoid receptor expression was first investigated in human bladder cancer lines and tissue microarrays. Then, the effects of dexamethasone on glucocorticoid receptor transcription, cell proliferation, apoptosis/cell cycle, and invasion were examined in bladder cancer lines. Finally, mouse xenograft models for bladder cancer were used to assess the efficacy of dexamethasone on tumor progression. All the cell lines and tissues examined were found to express glucocorticoid receptor. Dexamethasone increased glucocorticoid receptor–mediated reporter activity and cell proliferation, and inhibited apoptosis in the presence or absence of cisplatin. In contrast, dexamethasone suppressed cell invasion, the expression of its related genes [MMP-2/MMP-9, interleukin (IL)-6, VEGF], and the activity of MMP-2/MMP-9, and also induced mesenchymal-to-epithelial transition. In addition, dexamethasone increased IκBα protein levels and cytosolic accumulation of NF-κB. In xenograft-bearing mice, dexamethasone slightly augmented the growth of the inoculated tumors but completely prevented the development of bloody ascites, suggestive of peritoneal dissemination of tumor cells, and actual metastasis. In all these assays, dexamethasone effects were abolished by a glucocorticoid receptor antagonist or glucocorticoid receptor knockdown via RNA interference. Thus, glucocorticoid receptor activation resulted in promotion of cell proliferation via inhibiting apoptosis yet repression of cell invasion and metastasis. These results may provide a basis of developing improved chemotherapy regimens, including or excluding glucocorticoid receptor agonists/antagonists, for urothelial carcinoma. Mol Cancer Ther; 11(12); 2621–32. ©2012 AACR.
Data from DNA Methyltransferase Inhibitor, Zebularine, Delays Tumor Growth and Induces Apoptosis in a Genetically Engineered Mouse Model of Breast Cancer
Authors: Chen Min , Shabashvili Daniel , Nawab Akbar , Yang Sherry X. , Dyer Lisa M. , Brown Kevin D. , Hollingshead Melinda , Hunter Kent W. , Kaye Frederic J. , Hochwald Steven N. , Marquez Victor E. , Steeg Patricia , Zajac-Kaye Maria
Published: April 2023

Abstract
Zebularine is a novel potent inhibitor of both cytidine deaminase and DNA methylation. We examined the effect of zebularine on mammary tumor growth in genetically engineered MMTV-PyMT transgenic mice that develop mammary tumors at 60 days of age with 100% penetrance. The MMTV-PyMT transgenic mice were randomized at 46 days of age into control (n = 25) and zebularine (n = 25) treatment groups and monitored for parameters of tumor growth. Zebularine was administered at 5 mg/mL in drinking water. We observed a significant delay in the growth of mammary tumors in zebularine-treated mice with a statistically significant reduction (P = 0.0135) in total tumor burden at 94 days of age when the mice were sacrificed. After 48 days of zebularine treatment, the tumors were predominantly necrotic compared with untreated animals. In addition, a high apoptotic index by terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling assay was observed as early as 13 days following treatment. Immunoblot analysis showed depletion of DNMT1 and partial depletion of DNMT3b after zebularine treatment. Microarray analyses of global gene expression identified upregulation of twelve methylation-regulated genes as well as a set of candidate cancer genes that participate in cell growth and apoptosis. In summary, zebularine inhibits the growth of spontaneous mammary tumors and causes early onset of tumor cell necrosis and apoptosis in a genetically engineered mouse model of breast cancer. Defining the parameters of zebularine-mediated tumor inhibition may advance the future development of DNA methyltransferase inhibitors as an effective cancer treatment. Mol Cancer Ther; 11(2); 370–82. ©2011 AACR.
Data from Another Surprise from Metformin: Novel Mechanism of Action via K-Ras Influences Endometrial Cancer Response to Therapy
Authors: Iglesias David A. , Yates Melinda S. , van der Hoeven Dharini , Rodkey Travis L. , Zhang Qian , Co Ngai Na , Burzawa Jennifer , Chigurupati Sravanthi , Celestino Joseph , Bowser Jessica , Broaddus Russell , Hancock John F. , Schmandt Rosemarie , Lu Karen H.
Published: April 2023

Abstract
Metformin is an oral biguanide commonly used for the treatment of type II diabetes and has recently been demonstrated to possess antiproliferative properties that can be exploited for the prevention and treatment of a variety of cancers. The mechanisms underlying this effect have not been fully elucidated. Using both in vitro and in vivo models, we examined the effects of metformin on endometrial tumors with defined aberrations in the PI3K/PTEN/mTOR and MAPK signaling pathways to understand metformin mechanism of action and identify clinically useful predictors of response to this agent. In vitro assays of proliferation, cytotoxicity, and apoptosis were used to quantify the effects of metformin on endometrial cancer cell lines with mutations in the PI3K/PTEN/mTOR and MAPK signaling pathways. The in vivo effects of oral metformin on tumor progression were further examined using xenograft mouse models of endometrial cancer. K-Ras localization was analyzed by confocal microscopy using GFP-labeled oncogenic K-Ras and by immunoblot following subcellular fractionation. Metformin inhibited cell proliferation, induced apoptosis, and decreased tumor growth in preclinical endometrial cancer models, with the greatest response observed in cells harboring activating mutations in K-Ras. Furthermore, metformin displaces constitutively active K-Ras from the cell membrane, causing uncoupling of the MAPK signaling pathway. These studies provide a rationale for clinical trials using metformin in combination with PI3K-targeted agents for tumors harboring activating K-Ras mutations, and reveal a novel mechanism of action for metformin. Mol Cancer Ther; 12(12); 2847–56. ©2013 AACR.
Data from In Vitro and In Vivo Therapeutic Efficacy of Carfilzomib in Mantle Cell Lymphoma: Targeting the Immunoproteasome
Authors: Zhang Liang , Pham Lan V. , Newberry Kate J. , Ou Zhishuo , Liang Rong , Qian Jianfei , Sun Luhong , Blonska Marzenna , You Yun , Yang Jing , Lin Xin , Rollo Alex , Tamayo Archito T. , Lee John , Ford Richard J. , Zhao Xiurong , Kwak Larry W. , Yi Qing , Wang Michael
Published: April 2023

Abstract
Mantle cell lymphoma (MCL) remains incurable due to its inevitable pattern of relapse after treatment with current existing therapies. However, the promise of a cure for MCL lies in the burgeoning area of novel agents. In this study, we elucidated the therapeutic effect and mechanism of carfilzomib, a novel long-acting second-generation proteasome inhibitor, in MCL cells. We found that carfilzomib induced growth inhibition and apoptosis in both established MCL cell lines and freshly isolated primary MCL cells in a dose-dependent manner. In contrast, carfilzomib was less toxic to normal peripheral blood mononuclear cells from healthy individuals. The carfilzomib-induced apoptosis of MCL cells was mediated by the activation of JNK, Bcl-2, and mitochondria-related pathways. In addition, carfilzomib inhibited the growth and survival signaling pathways NF-κB and STAT3. Interestingly, we discovered that expression of immunoproteasome (i-proteasome) subunits is required for the anti-MCL activity of carfilzomib in MCL cells. In MCL-bearing SCID mice/primary MCL-bearing SCID-hu mice, intravenous administration of 5 mg/kg carfilzomib on days 1 and 2 for 5 weeks slowed/abrogated tumor growth and significantly prolonged survival. Our preclinical data show that carfilzomib is a promising, potentially less toxic treatment for MCL. Furthermore, an intact i-proteasome, especially LMP2, appears to be necessary for its anti-MCL activity, suggesting that i-proteasome could serve as a biomarker for identifying patients who will benefit from carfilzomib. Mol Cancer Ther; 12(11); 2494–504. ©2013 AACR.
Data from A Novel Monoclonal Antibody to Secreted Frizzled-Related Protein 2 Inhibits Tumor Growth
Authors: Fontenot Emily , Rossi Emma , Mumper Russell , Snyder Stephanie , Siamakpour-Reihani Sharareh , Ma Ping , Hilliard Eleanor , Bone Bradley , Ketelsen David , Santos Charlene , Patterson Cam , Klauber-DeMore Nancy
Published: April 2023

Abstract
Secreted frizzled-related protein 2 (SFRP2) is overexpressed in human angiosarcoma and breast cancer and stimulates angiogenesis via activation of the calcineurin/NFATc3 pathway. There are conflicting reports in the literature as to whether SFRP2 is an antagonist or agonist of β-catenin. The aims of these studies were to assess the effects of SFRP2 antagonism on tumor growth and Wnt-signaling and to evaluate whether SFRP2 is a viable therapeutic target. The antiangiogenic and antitumor properties of SFRP2 monoclonal antibody (mAb) were assessed using in vitro proliferation, migration, tube formation assays, and in vivo angiosarcoma and triple-negative breast cancer models. Wnt-signaling was assessed in endothelial and tumor cells treated with SFRP2 mAb using Western blotting. Pharmacokinetic and biodistribution data were generated in tumor-bearing and nontumor-bearing mice. SFRP2 mAb was shown to induce antitumor and antiangiogenic effects in vitro and inhibit activation of β-catenin and nuclear factor of activated T-cells c3 (NFATc3) in endothelial and tumor cells. Treatment of SVR angiosarcoma allografts in nude mice with the SFRP2 mAb decreased tumor volume by 58% compared with control (P = 0.004). Treatment of MDA-MB-231 breast carcinoma xenografts with SFRP2 mAb decreased tumor volume by 52% (P = 0.03) compared with control, whereas bevacizumab did not significantly reduce tumor volume. Pharmacokinetic studies show the antibody is long circulating in the blood and preferentially accumulates in SFRP2-positive tumors. In conclusion, antagonizing SFRP2 inhibits activation of β-catenin and NFATc3 in endothelial and tumor cells and is a novel therapeutic approach for inhibiting angiosarcoma and triple-negative breast cancer. Mol Cancer Ther; 12(5); 685–95. ©2013 AACR.
Data from A Polymeric Nanoparticle Encapsulated Small-Molecule Inhibitor of Hedgehog Signaling (NanoHHI) Bypasses Secondary Mutational Resistance to Smoothened Antagonists
Authors: Chenna Venugopal , Hu Chaoxin , Pramanik Dipankar , Aftab Blake T. , Karikari Collins , Campbell Nathaniel R. , Hong Seung-Mo , Zhao Ming , Rudek Michelle A. , Khan Saeed R. , Rudin Charles M. , Maitra Anirban
Published: April 2023

Abstract
Aberrant activation of the hedgehog (Hh) signaling pathway is one of the most prevalent abnormalities in human cancer. Tumors with cell autonomous Hh activation (e.g., medulloblastomas) can acquire secondary mutations at the Smoothened (Smo) antagonist binding pocket, which render them refractory to conventional Hh inhibitors. A class of Hh pathway inhibitors (HPI) has been identified that block signaling downstream of Smo; one of these compounds, HPI-1, is a potent antagonist of the Hh transcription factor Gli1 and functions independent of upstream components in the pathway. Systemic administration of HPI-1 is challenging due to its minimal aqueous solubility and poor bioavailability. We engineered a polymeric nanoparticle from [poly(lactic-co-glycolic acid); (PLGA)] conjugated with polyethylene glycol (PEG), encapsulating HPI-1 (NanoHHI). NanoHHI particles have an average diameter of approximately 60 nm, forms uniform aqueous suspension, and improved systemic bioavailability compared with the parent compound. In contrast to the prototype targeted Smo antagonist, HhAntag (Genentech), NanoHHI markedly inhibits the growth of allografts derived from Ptch−/+; Trp53−/− mouse medulloblastomas that harbor a SmoD477G binding site mutation (P < 0.001), which is accompanied by significant downregulation of mGli1 as well as bona fide Hh target genes (Akna, Cltb, and Olig2). Notably, NanoHHI combined with gemcitabine also significantly impedes the growth of orthotopic Pa03C pancreatic cancer xenografts that have a ligand-dependent, paracrine mechanism of Hh activation when compared with gemcitabine alone. No demonstrable hematologic or biochemical abnormalities were observed with NanoHHI administration. NanoHHI should be amenable to clinical translation in settings where tumors acquire mutational resistance to current Smo antagonists. Mol Cancer Ther; 11(1); 165–73. ©2011 AACR.
Data from Aryl Hydrocarbon Receptor Agonists Induce MicroRNA-335 Expression and Inhibit Lung Metastasis of Estrogen Receptor Negative Breast Cancer Cells
Authors: Zhang Shu , Kim KyoungHyun , Jin Un Ho , Pfent Catherine , Cao Huojun , Amendt Brad , Liu Xinyi , Wilson-Robles Heather , Safe Stephen
Published: April 2023

Abstract
The aryl hydrocarbon receptor (AHR) was initially identified as a receptor that bound 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related environmental toxicants; however, there is increasing evidence that the AHR is an important new drug target for treating multiple diseases including breast cancer. Treatment of estrogen receptor (ER)-negative MDA-MB-231 and BT474 breast cancer cells with TCDD or the selective AHR modulator 6-methyl-1,3,-trichlorodibenzofuran (MCDF) inhibited breast cancer cell invasion in a Boyden chamber assay. These results were similar to those previously reported for the antimetastic microRNA-335 (miR-335). Both TCDD and MCDF induced miR-335 in MDA-MB-231 and BT474 cells and this was accompanied by downregulation of SOX4, a miR-335-regulated (inhibited) gene. The effects of TCDD and MCDF on miR-335 and SOX4 expression and interactions of miR-335 with the 3′-UTR target sequence in the SOX4 gene were all inhibited in cells transfected with an oligonucleotide (iAHR) that knocks down the AHR, thus confirming AHR-miR-335 interactions. MCDF (40 mg/kg/d) also inhibited lung metastasis of MDA-MB-231 cells in a tail vein injection model, showing that the AHR is a potential new target for treating patients with ER-negative breast cancer, a disease where treatment options and their effectiveness are limited. Mol Cancer Ther; 11(1); 108–18. ©2011 AACR.
Data from Quantitative Proteomic Profiling Identifies Protein Correlates to EGFR Kinase Inhibition
Authors: Kani Kian , Faca Vitor M. , Hughes Lindsey D. , Zhang Wenxuan , Fang Qiaojun , Shahbaba Babak , Luethy Roland , Erde Jonathan , Schmidt Joanna , Pitteri Sharon J. , Zhang Qing , Katz Jonathan E. , Gross Mitchell E. , Plevritis Sylvia K. , McIntosh Martin W. , Jain Anjali , Hanash Samir , Agus David B. , Mallick Parag
Published: April 2023

Abstract
Clinical oncology is hampered by lack of tools to accurately assess a patient's response to pathway-targeted therapies. Serum and tumor cell surface proteins whose abundance, or change in abundance in response to therapy, differentiates patients responding to a therapy from patients not responding to a therapy could be usefully incorporated into tools for monitoring response. Here, we posit and then verify that proteomic discovery in in vitro tissue culture models can identify proteins with concordant in vivo behavior and further, can be a valuable approach for identifying tumor-derived serum proteins. In this study, we use stable isotope labeling of amino acids in culture (SILAC) with proteomic technologies to quantitatively analyze the gefitinib-related protein changes in a model system for sensitivity to EGF receptor (EGFR)-targeted tyrosine kinase inhibitors. We identified 3,707 intracellular proteins, 1,276 cell surface proteins, and 879 shed proteins. More than 75% of the proteins identified had quantitative information, and a subset consisting of 400 proteins showed a statistically significant change in abundance following gefitinib treatment. We validated the change in expression profile in vitro and screened our panel of response markers in an in vivo isogenic resistant model and showed that these were markers of gefitinib response and not simply markers of phospho-EGFR downregulation. In doing so, we also were able to identify which proteins might be useful as markers for monitoring response and which proteins might be useful as markers for a priori prediction of response. Mol Cancer Ther; 11(5); 1071–81. ©2012 AACR.
Data from miRNA-100 Inhibits Human Bladder Urothelial Carcinogenesis by Directly Targeting mTOR
Authors: Xu Chuanliang , Zeng Qinsong , Xu Weidong , Jiao Li , Chen Yanqiong , Zhang Zhensheng , Wu Chengyao , Jin Taile , Pan Anyin , Wei Rongchao , Yang Bo , Sun Yinghao
Published: April 2023

Abstract
miRNAs are involved in cancer development and progression, acting as tumor suppressors or oncogenes. In this study, miRNA profiling was conducted on 10 paired bladder cancer tissues using 20 GeneChip miRNA Array, and 10 differentially expressed miRNAs were identified in bladder cancer and adjacent noncancerous tissues of any disease stage/grade. After being validated on expanded cohort of 67 paired bladder cancer tissues and 10 human bladder cancer cell lines by quantitative real-time PCR (qRT-PCR), it was found that miR-100 was downregulated most significantly in cancer tissues. Ectopic restoration of miR-100 expression in bladder cancer cells suppressed cell proliferation and motility, induced cell-cycle arrest in vitro, and inhibited tumorigenesis in vivo both in subcutaneous and in intravesical passage. Bioinformatic analysis showed that the mTOR gene was a direct target of miR-100. siRNA-mediated mTOR knockdown phenocopied the effect of miR-100 in bladder cancer cell lines. In addition, the cancerous metastatic nude mouse model established on the basis of primary bladder cancer cell lines suggested that miR-100/mTOR regulated cell motility and was associated with tumor metastasis. Both mTOR and p70S6K (downstream messenger) presented higher expression levels in distant metastatic foci such as in liver and kidney metastases than in primary tumor. Taken together, miR-100 may act as a tumor suppressor in bladder cancer, and reintroduction of this mature miRNA into tumor tissue may prove to be a therapeutic strategy by reducing the expression of target genes. Mol Cancer Ther; 12(2); 207–19. ©2012 AACR.
Data from Bortezomib Sensitizes Human Acute Myeloid Leukemia Cells to All-Trans-Retinoic Acid–Induced Differentiation by Modifying the RARα/STAT1 Axis
Authors: Ying Meidan , Zhou Xinglu , Zhong Like , Lin Nengming , Jing Hui , Luo Peihua , Yang Xiaochun , Song Hua , Yang Bo , He Qiaojun
Published: April 2023

Abstract
All-trans-retinoic acid (ATRA) has held great promise for differentiation-based therapy but reportedly downregulates retinoic acid receptor-α (RARα) in a proteasome-dependent manner, which leads to decreased acute myeloid leukemia (AML) cell differentiation efficiency. Therefore, research strategies that seek to further sensitize cells to retinoids and extend the range of retinoid-affected myeloid malignancies beyond acute promyelocytic leukemia (APL) are key investigative avenues. Here, we show that bortezomib, the first proteasome inhibitor approved for newly diagnosed and relapsed multiple myeloma, exhibited strong synergism with ATRA to promote HL60 and NB4 AML cell differentiation. We observed that bortezomib sensitized AML cells to ATRA-induced morphologic, biochemical, and functional changes, indicative of myeloid differentiation without cell death. In addition, treatment of human leukemia HL60 xenografts with bortezomib and ATRA together did not increase bortezomib-induced progressive weight loss but resulted in significant tumor growth inhibition in addition to increased differentiation (P < 0.05). These enhanced differentiation effects were accompanied by RARα stabilization and STAT1 activation. Taken together, our study was the first to evaluate bortezomib and ATRA synergy in AML cell differentiation and to assess new opportunities for bortezomib and ATRA combination as a promising approach for future differentiation therapy. Mol Cancer Ther; 12(2); 195–206. ©2012 AACR.