bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Preclinical Characterization of RSM-932A, a Novel Anticancer Drug Targeting the Human Choline Kinase Alpha, an Enzyme Involved in Increased Lipid Metabolism of Cancer Cells
Authors: Lacal Juan Carlos , Campos Joaquín M.
Published: March 2024

Abstract
Choline kinase α (CHKA; here designated as ChoKα) is the first enzyme in the CDP-choline pathway, implicated in phospholipids metabolism. It is overexpressed in several human tumors such as breast, lung, bladder, colorectal, prostate, ovary, and liver. The overexpression of ChoKα has oncogenic potential and synergizes with other known oncogenes. It has been proposed as a novel cancer drug target with a distinct mechanism of action. We have generated a set of ChoKα inhibitors with potent in vitro antiproliferative and in vivo antitumoral activity against human xenografts in mice, showing high efficacy with low toxicity profiles. Among these inhibitors, RSM-932A has been chosen for further clinical development due to its potent antiproliferative activity in vitro against a large variety of tumor-derived cell lines, a potent in vivo anticancer activity, and lack of toxicity at the effective doses. Here, we provide the preclinical evidence to support the use of RSM-932A as a good candidate to be tested in clinical trials as the “first in humans” drug targeting ChoKα. Mol Cancer Ther; 14(1); 31–39. ©2014 AACR.
Data from Vemurafenib Resistance Signature by Proteome Analysis Offers New Strategies and Rational Therapeutic Concepts
Authors: Paulitschke Verena , Berger Walter , Paulitschke Philipp , Hofstätter Elisabeth , Knapp Bernhard , Dingelmaier-Hovorka Ruth , Födinger Dagmar , Jäger Walter , Szekeres Thomas , Meshcheryakova Anastasia , Bileck Andrea , Pirker Christine , Pehamberger Hubert , Gerner Christopher , Kunstfeld Rainer
Published: March 2024

Abstract
The FDA-approved BRAF inhibitor vemurafenib achieves outstanding clinical response rates in patients with melanoma, but early resistance is common. Understanding the pathologic mechanisms of drug resistance and identification of effective therapeutic alternatives are key scientific challenges in the melanoma setting. Using proteomic techniques, including shotgun analysis and 2D-gel electrophoresis, we identified a comprehensive signature of the vemurafenib-resistant M24met in comparison with the vemurafenib-sensitive A375 melanoma cell line. The resistant cells were characterized by loss of differentiation, induction of transformation, enhanced expression of the lysosomal compartment, increased potential for metastasis, migration, adherence and Ca2+ ion binding, enhanced expression of the MAPK pathway and extracellular matrix proteins, and epithelial–mesenchymal transformation. The main features were verified by shotgun analysis with QEXACTIVE orbitrap MS, electron microscopy, lysosomal staining, Western blotting, and adherence assay in a VM-1 melanoma cell line with acquired vemurafenib resistance. On the basis of the resistance profile, we were able to successfully predict that a novel resveratrol-derived COX-2 inhibitor, M8, would be active against the vemurafenib-resistant but not the vemurafenib-sensitive melanoma cells. Using high-throughput methods for cell line and drug characterization may thus offer a new way to identify key features of vemurafenib resistance, facilitating the design of effective rational therapeutic alternatives. Mol Cancer Ther; 14(3); 757–68. ©2015 AACR.
Data from Temozolomide Induces the Production of Epidermal Growth Factor to Regulate MDR1 Expression in Glioblastoma Cells
Authors: Munoz Jessian L. , Rodriguez-Cruz Vivian , Greco Steven J. , Nagula Vipul , Scotto Kathleen W. , Rameshwar Pranela
Published: March 2024

Abstract
Glioblastoma multiforme (GBM) commonly resists the frontline chemotherapy treatment temozolomide. The multidrug resistance gene (MDR1) and its protein, P-glycoprotein (P-gp), are associated with chemoresistance. This study investigated the mechanisms underlying MDR1-mediated resistance by GBM to temozolomide. P-gp trafficking was studied by flow cytometry and Western blot analysis. MDR1 expression was analyzed by real-time PCR and reporter gene assays. AP-1 interaction with MDR1 was studied by chromatin immunoprecipitation assay. EGF production was analyzed by ELISA, EGFR signaling was determined by Western blot analysis, and in vivo response to erlotinib and/or temozolomide was studied in nude mice. During the early phase of temozolomide treatment, intracellular P-gp was trafficked to the cell membrane, followed by conformational change into active P-gp. At the later phase, gene transcription of MDR1 was induced by temozolomide-mediated production of EGF. EGF activated ERK1/2-JNK-AP-1 cofactors (c-jun and c-fos). An inhibitor of EGFR kinase (erlotinib) given to nude mice with GBM prevented temozolomide-induced resistance. The results identified an essential role for activated EGFR in the resistance of GBM to temozolomide. Temozolomide resistance occurred through a biphasic response; first, by a conformational change in P-gp into the active form and, second, by releasing EGF, which caused autocrine stimulation of GBM cells to induce MDR1. Pharmacologic inhibition of EGFR kinase blunted the ability of GBM cells to resist temozolomide. These findings may explain reports on the common occurrence of mutant EGFR (EGFRvIII) and EGFR expansion in the resistance of GBM cells. Mol Cancer Ther; 13(10); 2399–411. ©2014 AACR.
Data from Inhibition of PI3Kβ Signaling with AZD8186 Inhibits Growth of PTEN-Deficient Breast and Prostate Tumors Alone and in Combination with Docetaxel
Authors: Hancox Urs , Cosulich Sabina , Hanson Lyndsey , Trigwell Cath , Lenaghan Carol , Ellston Rebecca , Dry Hannah , Crafter Claire , Barlaam Bernard , Fitzek Martina , Smith Paul D. , Ogilvie Donald , D'Cruz Celina , Castriotta Lillian , Wedge Stephen R. , Ward Lara , Powell Steve , Lawson Mandy , Davies Barry R. , Harrington Elizabeth A. , Foster Emily , Cumberbatch Marie , Green Stephen , Barry Simon T.
Published: March 2024

Abstract
Loss of PTEN protein results in upregulation of the PI3K/AKT pathway, which appears dependent on the PI3Kβ isoform. Inhibitors of PI3Kβ have potential to reduce growth of tumors in which loss of PTEN drives tumor progression. We have developed a small-molecule inhibitor of PI3Kβ and PI3Kδ (AZD8186) and assessed its antitumor activity across a panel of cell lines. We have then explored the antitumor effects as single agent and in combination with docetaxel in triple-negative breast (TNBC) and prostate cancer models. In vitro, AZD8186 inhibited growth of a range of cell lines. Sensitivity was associated with inhibition of the AKT pathway. Cells sensitive to AZD8186 (GI50 < 1 μmol/L) are enriched for, but not exclusively associated with, PTEN deficiency. In vivo, AZD8186 inhibits PI3K pathway biomarkers in prostate and TNBC tumors. Scheduling treatment with AZD8186 shows antitumor activity required only intermittent exposure, and that increased tumor control is achieved when AZD8186 is used in combination with docetaxel. AZD8186 is a potent inhibitor of PI3Kβ with activity against PI3Kδ signaling, and has potential to reduce growth of tumors dependent on dysregulated PTEN for growth. Moreover, AZD8186 can be combined with docetaxel, a chemotherapy commonly used to treat advanced TBNC and prostate tumors. The ability to schedule AZD8186 and maintain efficacy offers opportunity to combine AZD8186 more effectively with other drugs. Mol Cancer Ther; 14(1); 48–58. ©2014 AACR.
Data from Inhibition of mTORC2 Induces Cell-Cycle Arrest and Enhances the Cytotoxicity of Doxorubicin by Suppressing MDR1 Expression in HCC Cells
Authors: Chen Bryan Wei , Chen Wei , Liang Hui , Liu Hao , Liang Chao , Zhi Xiao , Hu Li-qiang , Yu Xia-Zhen , Wei Tao , Ma Tao , Xue Fei , Zheng Lei , Zhao Bin , Feng Xin-Hua , Bai Xue-li , Liang Ting-bo
Published: March 2024

Abstract
mTOR is aberrantly activated in hepatocellular carcinoma (HCC) and plays pivotal roles in tumorigenesis and chemoresistance. Rapamycin has been reported to exert antitumor activity in HCC and sensitizes HCC cells to cytotoxic agents. However, due to feedback activation of AKT after mTOR complex 1 (mTORC1) inhibition, simultaneous targeting of mTORC1/2 may be more effective. In this study, we examined the interaction between the dual mTORC1/2 inhibitor OSI-027 and doxorubicin in vitro and in vivo. OSI-027 was found to reduce phosphorylation of both mTORC1 and mTORC2 substrates, including 4E-BP1, p70S6K, and AKT (Ser473), and inhibit HCC cell proliferation. Similar to OSI-027 treatment, knockdown of mTORC2 induced G0–G1 phase cell-cycle arrest. In contrast, rapamycin or knockdown of mTORC1 increased phosphorylation of AKT (Ser473), yet had little antiproliferative effect. Notably, OSI-027 synergized with doxorubicin for the antiproliferative efficacy in a manner dependent of MDR1 expression in HCC cells. The synergistic antitumor effect of OSI-027 and doxorubicin was also observed in a HCC xenograft mouse model. Moreover, AKT was required for OSI-027–induced cell-cycle arrest and downregulation of MDR1. Our findings provide a rationale for dual mTORC1/mTORC2 inhibitors, such as OSI-027, as monotherapy or in combination with cytotoxic agents to treat HCC. Mol Cancer Ther; 14(8); 1805–15. ©2015 AACR.
Data from Synthetic Lethal Screens Identify Vulnerabilities in GPCR Signaling and Cytoskeletal Organization in E-Cadherin–Deficient Cells
Authors: Telford Bryony J. , Chen Augustine , Beetham Henry , Frick James , Brew Tom P. , Gould Cathryn M. , Single Andrew , Godwin Tanis , Simpson Kaylene J. , Guilford Parry
Published: March 2024

Abstract
The CDH1 gene, which encodes the cell-to-cell adhesion protein E-cadherin, is frequently mutated in lobular breast cancer (LBC) and diffuse gastric cancer (DGC). However, because E-cadherin is a tumor suppressor protein and lost from the cancer cell, it is not a conventional drug target. To overcome this, we have taken a synthetic lethal approach to determine whether the loss of E-cadherin creates druggable vulnerabilities. We first conducted a genome-wide siRNA screen of isogenic MCF10A cells with and without CDH1 expression. Gene ontology analysis demonstrated that G-protein–coupled receptor (GPCR) signaling proteins were highly enriched among the synthetic lethal candidates. Diverse families of cytoskeletal proteins were also frequently represented. These broad classes of E-cadherin synthetic lethal hits were validated using both lentiviral-mediated shRNA knockdown and specific antagonists, including the JAK inhibitor LY2784544, Pertussis toxin, and the aurora kinase inhibitors alisertib and danusertib. Next, we conducted a 4,057 known drug screen and time course studies on the CDH1 isogenic MCF10A cell lines and identified additional drug classes with linkages to GPCR signaling and cytoskeletal function that showed evidence of E-cadherin synthetic lethality. These included multiple histone deacetylase inhibitors, including vorinostat and entinostat, PI3K inhibitors, and the tyrosine kinase inhibitors crizotinib and saracatinib. Together, these results demonstrate that E-cadherin loss creates druggable vulnerabilities that have the potential to improve the management of both sporadic and familial LBC and DGC. Mol Cancer Ther; 14(5); 1213–23. ©2015 AACR.
Data from CD24+ Ovarian Cancer Cells Are Enriched for Cancer-Initiating Cells and Dependent on JAK2 Signaling for Growth and Metastasis
Authors: Burgos-Ojeda Daniela , Wu Rong , McLean Karen , Chen Yu-Chih , Talpaz Moshe , Yoon Euisik , Cho Kathleen R. , Buckanovich Ronald J.
Published: March 2024

Abstract
Ovarian cancer is known to be composed of distinct populations of cancer cells, some of which demonstrate increased capacity for cancer initiation and/or metastasis. The study of human cancer cell populations is difficult due to long requirements for tumor growth, interpatient variability, and the need for tumor growth in immune-deficient mice. We therefore characterized the cancer initiation capacity of distinct cancer cell populations in a transgenic murine model of ovarian cancer. In this model, conditional deletion of Apc, Pten, and Trp53 in the ovarian surface epithelium (OSE) results in the generation of high-grade metastatic ovarian carcinomas. Cell lines derived from these murine tumors express numerous putative stem cell markers, including CD24, CD44, CD90, CD117, CD133, and ALDH. We show that CD24+ and CD133+ cells have increased tumor sphere-forming capacity. CD133+ cells demonstrated a trend for increased tumor initiation while CD24+ cells versus CD24− cells had significantly greater tumor initiation and tumor growth capacity. No preferential tumor-initiating or growth capacity was observed for CD44+, CD90+, CD117+, or ALDH+ versus their negative counterparts. We have found that CD24+ cells, compared with CD24− cells, have increased phosphorylation of STAT3 and increased expression of STAT3 target Nanog and c-myc. JAK2 inhibition of STAT3 phosphorylation preferentially induced cytotoxicity in CD24+ cells. In vivo JAK2 inhibitor therapy dramatically reduced tumor metastases, and prolonged overall survival. These findings indicate that CD24+ cells play a role in tumor migration and metastasis and support JAK2 as a therapeutic target in ovarian cancer. Mol Cancer Ther; 14(7); 1717–27. ©2015 AACR.
Data from Efficacy of RG7787, a Next-Generation Mesothelin-Targeted Immunotoxin, against Triple-Negative Breast and Gastric Cancers
Authors: Alewine Christine , Xiang Laiman , Yamori Takao , Niederfellner Gerhard , Bosslet Klaus , Pastan Ira
Published: March 2024

Abstract
The RG7787 mesothelin-targeted recombinant immunotoxin (RIT) consists of an antibody fragment targeting mesothelin (MSLN) fused to a 24-kD fragment of Pseudomonas exotoxin A for cell killing. Compared with prior RITs, RG7787 has improved properties for clinical development including decreased nonspecific toxicity and immunogenicity and resistance to degradation by lysosomal proteases. MSLN is a cell surface glycoprotein highly expressed by many solid tumor malignancies. New reports have demonstrated that MSLN is expressed by a significant percentage of triple-negative breast and gastric cancer clinical specimens. Here, panels of triple-negative breast and gastric cancer cell lines were tested for surface MSLN expression, and for sensitivity to RG7787 in vitro and in animal models. RG7787 produced >95% cell killing of the HCC70 and SUM149 breast cancer cell lines in vitro with IC50 < 100 pmol/L. RG7787 was also effective against gastric cancer cell lines MKN28, MKN45, and MKN74 in vitro, with subnanomolar IC50s. In a nude mouse model, RG7787 treatment (2.5 mg/kg i.v. qod ×3–4) resulted in a statistically significant 41% decrease in volumes of HCC70 xenograft tumors (P < 0.0001) and an 18% decrease in MKN28 tumors (P < 0.0001). Pretreatment with paclitaxel (50 mg/kg i.p.) enhanced efficacy, producing 88% and 70% reduction in tumor volumes for HCC70 and MKN28, respectively, a statistically significant improvement over paclitaxel alone (P < 0.0001 for both). RG7787 merits clinical testing for triple-negative breast and gastric cancers. Mol Cancer Ther; 13(11); 2653–61. ©2014 AACR.
Data from Small Molecule Inhibition of MDM2–p53 Interaction Augments Radiation Response in Human Tumors
Authors: Werner Lauryn R. , Huang Shyhmin , Francis David M. , Armstrong Eric A. , Ma Fang , Li Chunrong , Iyer Gopal , Canon Jude , Harari Paul M.
Published: March 2024

Abstract
MDM2–p53 interaction and downstream signaling affect cellular response to DNA damage. AMG 232 is a potent small molecule inhibitor that blocks the interaction of MDM2 and p53. We examined the capacity of AMG 232 to augment radiation response across a spectrum of human tumor cell lines and xenografts. AMG 232 effectively inhibited proliferation and enhanced radiosensitivity via inhibition of damage repair signaling. Combined AMG 232 and radiation treatment resulted in the accumulation of γH2AX-related DNA damage and induction of senescence with promotion of apoptotic and/or autophagic cell death. Several molecules involved in senescence, autophagy, and apoptosis were specifically modulated following the combined AMG 232/radiation treatment, including FoxM1, ULK-1, DRAM, and BAX. In vivo xenograft studies confirmed more potent antitumor and antiangiogenesis efficacy with combined AMG 232/radiation treatment than treatment with drug or radiation alone. Taken together, these data identify the capacity of AMG 232 to augment radiation response across a variety of tumor types harboring functional p53. Mol Cancer Ther; 14(9); 1994–2003. ©2015 AACR.
Data from Repurposing the Antihelmintic Mebendazole as a Hedgehog Inhibitor
Authors: Larsen Andrew R. , Bai Ren-Yuan , Chung Jon H. , Borodovsky Alexandra , Rudin Charles M. , Riggins Gregory J. , Bunz Fred
Published: March 2024

Abstract
The hedgehog (Hh) signaling pathway is activated in many types of cancer and therefore presents an attractive target for new anticancer agents. Here, we show that mebendazole, a benzamidazole with a long history of safe use against nematode infestations and hydatid disease, potently inhibited Hh signaling and slowed the growth of Hh-driven human medulloblastoma cells at clinically attainable concentrations. As an antiparasitic, mebendazole avidly binds nematode tubulin and causes inhibition of intestinal microtubule synthesis. In human cells, mebendazole suppressed the formation of the primary cilium, a microtubule-based organelle that functions as a signaling hub for Hh pathway activation. The inhibition of Hh signaling by mebendazole was unaffected by mutants in the gene that encodes human Smoothened (SMO), which are selectively propagated in cell clones that survive treatment with the Hh inhibitor vismodegib. Combination of vismodegib and mebendazole resulted in additive Hh signaling inhibition. Because mebendazole can be safely administered to adults and children at high doses over extended time periods, we propose that mebendazole could be rapidly repurposed and clinically tested as a prospective therapeutic agent for many tumors that are dependent on Hh signaling. Mol Cancer Ther; 14(1); 3–13. ©2014 AACR.
Data from The Tyrosine Kinase Inhibitors Imatinib and Dasatinib Reduce Myeloid Suppressor Cells and Release Effector Lymphocyte Responses
Authors: Christiansson Lisa , Söderlund Stina , Mangsbo Sara , Hjorth-Hansen Henrik , Höglund Martin , Markevärn Berit , Richter Johan , Stenke Leif , Mustjoki Satu , Loskog Angelica , Olsson-Strömberg Ulla
Published: March 2024

Abstract
Immune escape mechanisms promote tumor progression and are hurdles of cancer immunotherapy. Removing immunosuppressive cells before treatment can enhance efficacy. Tyrosine kinase inhibitors (TKI) may be of interest to combine with immunotherapy, as it has been shown that the inhibitor sunitinib reduces myeloid suppressor cells in patients with renal cell carcinoma and dasatinib promotes expansion of natural killer–like lymphocytes in chronic myeloid leukemia (CML). In this study, the capacity of dasatinib and imatinib to reduce myeloid suppressor cells and to induce immunomodulation in vivo was investigated ex vivo. Samples from CML patients treated with imatinib (n = 18) or dasatinib (n = 14) within a Nordic clinical trial (clinicalTrials.gov identifier: NCT00852566) were investigated for the presence of CD11b+CD14−CD33+ myeloid cells and inhibitory molecules (arginase I, myeloperoxidase, IL10) as well as the presence of natural killer cells, T cells (naïve/memory), and stimulatory cytokines (IL12, IFNγ, MIG, IP10). Both imatinib and dasatinib decreased the presence of CD11b+CD14−CD33+ myeloid cells as well as the inhibitory molecules and the remaining myeloid suppressor cells had an increased CD40 expression. Monocytes also increased CD40 after therapy. Moreover, increased levels of CD40, IL12, natural killer cells, and experienced T cells were noted after TKI initiation. The presence of experienced T cells was correlated to a higher IFNγ and MIG plasma concentration. Taken together, the results demonstrate that both imatinib and dasatinib tilted the immunosuppressive CML tumor milieu towards promoting immune stimulation. Hence, imatinib and dasatinib may be of interest to combine with cancer immunotherapy. Mol Cancer Ther; 14(5); 1181–91. ©2015 AACR.
Data from Inhibition of the GTPase Rac1 Mediates the Antimigratory Effects of Metformin in Prostate Cancer Cells
Authors: Dirat Béatrice , Ader Isabelle , Golzio Muriel , Massa Fabienne , Mettouchi Amel , Laurent Kathiane , Larbret Frédéric , Malavaud Bernard , Cormont Mireille , Lemichez Emmanuel , Cuvillier Olivier , Tanti Jean François , Bost Frédéric
Published: March 2024

Abstract
Cell migration is a critical step in the progression of prostate cancer to the metastatic state, the lethal form of the disease. The antidiabetic drug metformin has been shown to display antitumoral properties in prostate cancer cell and animal models; however, its role in the formation of metastases remains poorly documented. Here, we show that metformin reduces the formation of metastases to fewer solid organs in an orthotopic metastatic prostate cancer cell model established in nude mice. As predicted, metformin hampers cell motility in PC3 and DU145 prostate cancer cells and triggers a radical reorganization of the cell cytoskeleton. The small GTPase Rac1 is a master regulator of cytoskeleton organization and cell migration. We report that metformin leads to a major inhibition of Rac1 GTPase activity by interfering with some of its multiple upstream signaling pathways, namely P-Rex1 (a Guanine nucleotide exchange factor and activator of Rac1), cAMP, and CXCL12/CXCR4, resulting in decreased migration of prostate cancer cells. Importantly, overexpression of a constitutively active form of Rac1, or P-Rex, as well as the inhibition of the adenylate cyclase, was able to reverse the antimigratory effects of metformin. These results establish a novel mechanism of action for metformin and highlight its potential antimetastatic properties in prostate cancer. Mol Cancer Ther; 14(2); 586–96. ©2014 AACR.
Data from Dual Targeting of Hypoxia and Homologous Recombination Repair Dysfunction in Triple-Negative Breast Cancer
Authors: Hunter Francis W. , Hsu Huai-Ling , Su Jiechuang , Pullen Susan M. , Wilson William R. , Wang Jingli
Published: March 2024

Abstract
Triple-negative breast cancer (TNBC) is an aggressive malignancy with poor clinical outcome and few validated drug targets. Two prevalent features of TNBC, tumor hypoxia and derangement of homologous recombination (HR) repair, are potentially exploitable for therapy. This study investigated whether hypoxia-activated prodrugs (HAP) of DNA-damaging cytotoxins may inhibit growth of TNBC by simultaneously addressing these two targets. We measured in vitro activity of HAP of DNA breakers (tirapazamine, SN30000) and alkylators (TH-302, PR-104, SN30548) in TNBC cell lines and isogenic models, and related this to measures of HR repair and expression of prodrug-activating enzymes. Antitumor activity of HAP was examined in isogenic BRCA2-knockout xenograft models and compared with platinum chemotherapy. All five HAP selectively inhibited growth of TNBC cell lines under hypoxia. Sensitivity to HAP was not strongly associated with BRCA1 genotype. However, HAP sensitivity was enhanced by suppression of HR (assessed by radiation-induced RAD51 focus formation) when BRCA1 and PALB2 were knocked down in a common (MDA-MB-231) background. Furthermore, knockout of BRCA2 markedly sensitized DLD-1 cells to the clinical nitrogen mustard prodrugs TH-302 and PR-104 and significantly augmented sterilization of clonogens by these agents in xenografts, both as monotherapy and in combination with radiotherapy, but had less effect on activity of the benzotriazine di-N-oxide SN30000. PR-104 monotherapy was more effective than cisplatin at inhibiting growth of BRCA2-knockout tumors at equitoxic doses. This study demonstrates the potential for HAP of nitrogen mustards to simultaneously exploit hypoxia and HR defects in tumors, with translational implications for TNBC and other HR-deficient malignancies. Mol Cancer Ther; 13(11); 2501–14. ©2014 AACR.
Data from Histone Deacetylase Inhibitor Entinostat Inhibits Tumor-Initiating Cells in Triple-Negative Breast Cancer Cells
Authors: Schech Amanda , Kazi Armina , Yu Stephen , Shah Preeti , Sabnis Gauri
Published: March 2024

Abstract
Mortality following breast cancer diagnosis is mainly due to the development of distant metastasis. To escape from the primary site, tumor cells undergo the epithelial-to-mesenchymal transition (EMT), which helps them acquire a more motile and invasive phenotype. In our previous study, we showed that class I selective HDAC inhibitor entinostat reverses the EMT phenotype through reversal of epigenetic repression of E-cadherin. Recent evidence suggests that a subset of cells within a breast tumor may drive the metastatic outgrowth following escape from the primary site. These cells, termed tumor-initiating cells (TIC), represent a great threat to overall prognosis. They are critical in terms of drug resistance and tumor initiation at metastatic sites. Acquisition of EMT traits has also been shown to impart TIC phenotype to the cells, making EMT a “dual-threat” for prognosis. In the current study, we show that entinostat treatment can reduce the percentage of TIC cells from triple-negative breast cancer (TNBC) cells. Entinostat treatment was able to reduce the CD44high/CD24low cell population, ALDH-1 activity, as well as protein and mRNA expression of known TIC markers such as Bmi-1, Nanog, and Oct-4. Next, we inoculated MDA-MB-231 cells transfected with firefly luciferase (231/Luc) in mammary fat pad of NSG mice. The mice were then treated with entinostat (2.5 mg/kg/d), and tumor development and formation of metastasis were assessed by bioluminescence imaging. Treatment with entinostat significantly reduced tumor formation at the primary site as well as lung metastasis. As such, entinostat may help prevent development of distant metastasis. Mol Cancer Ther; 14(8); 1848–57. ©2015 AACR.
Data from Bicyclic Peptides Conjugated to an Albumin-Binding Tag Diffuse Efficiently into Solid Tumors
Authors: Pollaro Lisa , Raghunathan Sandeep , Morales-Sanfrutos Julia , Angelini Alessandro , Kontos Stephan , Heinis Christian
Published: March 2024

Abstract
Monoclonal antibodies have long in vivo half-lives and reach high concentrations in tumors but cannot access all regions in the tissue, whereas smaller ligands such as peptides distribute better but are limited by low concentrations due to fast renal clearance. A potential solution to this problem might be offered by peptide-based ligands that are conjugated to an albumin-binding tag, and thus have a long plasma half-life. Herein, we tested if a small ligand based on a bicyclic peptide (1.9 kDa) conjugated to an albumin-binding peptide (2.3 kDa) can diffuse into tissues. Although the peptide conjugate (4.6 kDa) was most of the time bound to the large protein serum albumin (66.5 kDa), it diffused deeply into tissues and reached high nanomolar concentrations in wide areas of solid tumors. Most of the peptide conjugate isolated from tumor tissue was found to be fully intact 24 hours after administration. Because of its noncovalent interaction with albumin, the bicyclic peptide might dissociate to diffuse to tumor regions that are not accessible to larger ligands. Bicyclic peptides having high binding affinity for targets of interest and being proteolytically stable can be evolved by phage display; in conjunction with albumin-binding tags, they offer a promising format to access targets in solid tumors. Mol Cancer Ther; 14(1); 151–61. ©2014 AACR.
Data from Tissue Penetration and Activity of Camptothecins in Solid Tumor Xenografts
Authors: Kyle Alastair H. , Baker Jennifer H.E. , Gandolfo Maria-Jose , Reinsberg Stefan A. , Minchinton Andrew I.
Published: March 2024

Abstract
The ability of a panel of camptothecin derivatives to access the tumor compartment was evaluated to determine the mechanisms by which the architecture of solid tumors may act to limit their activity. Microregional localization and activity of members of the camptothecin class of topoisomerase I targeting agents, including topotecan, irinotecan, and irinophore C, a lipid-based nanoparticulate formulation of irinotecan, were evaluated over time in HCT116 and HT29 colorectal tumor xenografts. Using native drug fluorescence, their distributions in tissue cryosections were related to the underlying tumor vasculature, tumor cell proliferation, and apoptosis. Topotecan exhibited a relatively uniform tumor distribution; in tissue 100 μm away from vessels, it reached 94% ± 5% of levels seen around blood vessels, whereas irinotecan and irinophore C were found to reach only 41% ± 10% and 5% ± 2%, respectively. Surprisingly, all three agents were able to initially inhibit proliferation uniformly throughout the tumors, and it was their rate of washout (topotecan > irinotecan > irinophore C) that correlated with activity. To explain this discrepancy, we looked at SN38, the active metabolite of irinotecan, and found it to penetrate tissue similarly to topotecan. Hence, the poor access to the tumor compartment of irinotecan and irinophore C could be offset by their systemic conversion to SN38. It was concluded that all three agents were effective at reaching tumor cells, and that despite the poor access to the extravascular compartment of irinophore C, its extended plasma exposure and systemic conversion to the diffusible metabolite SN38 enabled it to effectively target solid tumors. Mol Cancer Ther; 13(11); 2727–37. ©2014 AACR.
Data from miR-185 Suppresses Tumor Proliferation by Directly Targeting E2F6 and DNMT1 and Indirectly Upregulating BRCA1 in Triple-Negative Breast Cancer
Authors: Tang Hailin , Liu Peng , Yang Lu , Xie Xinhua , Ye Feng , Wu Minqing , Liu Xiaoping , Chen Bo , Zhang Lijuan , Xie Xiaoming
Published: March 2024

Abstract
Breast cancer is a major public health problem all over the world, and the current treatment strategies are not potent enough for some patients, especially those with triple-negative breast cancer (TNBC). Recent studies have demonstrated that microRNAs (miRNA) play vital roles in the development of TNBC. In this study, we found that miR-185 was strongly downregulated in TNBC tissues and cell lines and that its expression levels were associated with lymph node metastasis, clinical stage, overall survival, and relapse-free survival in TNBC. We also found that ectopic expression of miR-185 inhibited TNBC cell proliferation in vitro and in vivo. We further identified that miR-185 directly targeted DNMT1 and E2F6, which resulted in a marked increase in the expression of BRCA1 at the mRNA and protein levels in TNBC. Our data suggest that miR-185 functions as a tumor suppressor in TNBC development. It is a promising prognostic biomarker and potential therapeutic target for TNBC. Mol Cancer Ther; 13(12); 3185–97. ©2014 AACR.
Data from AT2R Gene Delivered by Condensed Polylysine Complexes Attenuates Lewis Lung Carcinoma after Intravenous Injection or Intratracheal Spray
Authors: Alhakamy Nabil A. , Ishiguro Susumu , Uppalapati Deepthi , Berkland Cory J. , Tamura Masaaki
Published: March 2024

Abstract
Transfection efficiency and toxicity concerns remain a challenge for gene therapy. Cell-penetrating peptides (CPP) have been broadly investigated to improve the transfection of genetic material (e.g., pDNA and siRNA). Here, a synthetic CPP (polylysine, K9 peptide) was complexed with angiotensin II type 2 receptor (AT2R) plasmid DNA (pAT2R) and complexes were condensed using calcium chloride. The resulting complexes were small (∼150 nm) and showed high levels of gene expression in vitro and in vivo. This simple nonviral formulation approach showed negligible cytotoxicity in four different human cell lines (cervix, breast, kidney, and lung cell lines) and one mouse cell line (a lung cancer cell line). In addition, this K9-pDNA-Ca2+ complex demonstrated cancer-targeted gene delivery when administered via intravenous injection or intratracheal spray. The transfection efficiency was evaluated in Lewis lung carcinoma (LLC) cell lines cultured in vitro and in orthotopic cancer grafts in syngeneic mice. Immunohistochemical analysis confirmed that the complex effectively delivered pAT2R to the cancer cells, where it was expressed mainly in cancer cells along with bronchial epithelial cells. A single administration of these complexes markedly attenuated lung cancer growth, offering preclinical proof-of-concept for a novel nonviral gene delivery method exhibiting effective lung tumor gene therapy via either intravenous or intratracheal administration. Mol Cancer Ther; 15(1); 209–18. ©2015 AACR.
Data from MEK Inhibitor Selumetinib (AZD6244; ARRY-142886) Prevents Lung Metastasis in a Triple-Negative Breast Cancer Xenograft Model
Authors: Bartholomeusz Chandra , Xie Xuemei , Pitner Mary Kathryn , Kondo Kimie , Dadbin Ali , Lee Jangsoon , Saso Hitomi , Smith Paul D. , Dalby Kevin N. , Ueno Naoto T.
Published: March 2024

Abstract
Patients with triple-negative breast cancer (TNBC) have a poor prognosis because TNBC often metastasizes, leading to death. Among patients with TNBC, those with extracellular signal-regulated kinase 2 (ERK2)-overexpressing tumors were at higher risk of death than those with low-ERK2-expressing tumors (hazard ratio, 2.76; 95% confidence interval, 1.19–6.41). The MAPK pathway has been shown to be a marker of breast cancer metastasis, but has not been explored as a potential therapeutic target for preventing TNBC metastasis. Interestingly, when we treated TNBC cells with the allosteric MEK inhibitor selumetinib, cell viability was not reduced in two-dimensional culture. However, in three-dimensional culture, selumetinib changed the mesenchymal phenotype of TNBC cells to an epithelial phenotype. Cells that undergo epithelial–mesenchymal transition (EMT) are thought to contribute to the metastatic process. EMT leads to generation of mesenchymal-like breast cancer cells with stem cell–like characteristics and a CD44+CD24−/low expression pattern. We tested the hypothesis that targeted inhibition of the MAPK pathway by selumetinib inhibits acquisition of the breast cancer stem cell phenotype and prevents lung metastasis of TNBC. TNBC cells treated with selumetinib showed inhibition of anchorage-independent growth, an indicator of in vivo tumorigenicity (P < 0.005), and decreases in the CD44+CD24−/low fraction, ALDH1 activity, and mammosphere-forming efficiency. Mice treated with selumetinib formed significantly fewer lung metastases than control mice injected with vehicle (P < 0.05). Our data demonstrate that MEK inhibitors can inhibit breast cancer stem cells and may have clinical potential for the prevention of metastasis in certain cases in which tumors are MAPK dependent. Mol Cancer Ther; 14(12); 2773–81. ©2015 AACR.
Data from A Novel RAF Kinase Inhibitor with DFG-Out–Binding Mode: High Efficacy in BRAF-Mutant Tumor Xenograft Models in the Absence of Normal Tissue Hyperproliferation
Authors: Waizenegger Irene C. , Baum Anke , Steurer Steffen , Stadtmüller Heinz , Bader Gerd , Schaaf Otmar , Garin-Chesa Pilar , Schlattl Andreas , Schweifer Norbert , Haslinger Christian , Colbatzky Florian , Mousa Sien , Kalkuhl Arno , Kraut Norbert , Adolf Günther R.
Published: March 2024

Abstract
BI 882370 is a highly potent and selective RAF inhibitor that binds to the DFG-out (inactive) conformation of the BRAF kinase. The compound inhibited proliferation of human BRAF–mutant melanoma cells with 100× higher potency (1–10 nmol/L) than vemurafenib, whereas wild-type cells were not affected at 1,000 nmol/L. BI 882370 administered orally was efficacious in multiple mouse models of BRAF-mutant melanomas and colorectal carcinomas, and at 25 mg/kg twice daily showed superior efficacy compared with vemurafenib, dabrafenib, or trametinib (dosed to provide exposures reached in patients). To model drug resistance, A375 melanoma–bearing mice were initially treated with vemurafenib; all tumors responded with regression, but the majority subsequently resumed growth. Trametinib did not show any efficacy in this progressing population. BI 882370 induced tumor regression; however, resistance developed within 3 weeks. BI 882370 in combination with trametinib resulted in more pronounced regressions, and resistance was not observed during 5 weeks of second-line therapy. Importantly, mice treated with BI 882370 did not show any body weight loss or clinical signs of intolerability, and no pathologic changes were observed in several major organs investigated, including skin. Furthermore, a pilot study in rats (up to 60 mg/kg daily for 2 weeks) indicated lack of toxicity in terms of clinical chemistry, hematology, pathology, and toxicogenomics. Our results indicate the feasibility of developing novel compounds that provide an improved therapeutic window compared with first-generation BRAF inhibitors, resulting in more pronounced and long-lasting pathway suppression and thus improved efficacy. Mol Cancer Ther; 15(3); 354–65. ©2016 AACR.
Data from Acridine Derivatives as Inhibitors of the IRE1α–XBP1 Pathway Are Cytotoxic to Human Multiple Myeloma
Authors: Jiang Dadi , Tam Arvin B. , Alagappan Muthuraman , Hay Michael P. , Gupta Aparna , Kozak Margaret M. , Solow-Cordero David E. , Lum Pek Y. , Denko Nicholas C. , Giaccia Amato J. , Le Quynh-Thu , Niwa Maho , Koong Albert C.
Published: March 2024

Abstract
Using a luciferase reporter–based high-throughput chemical library screen and topological data analysis, we identified N-acridine-9-yl-N',N'-dimethylpropane-1,3-diamine (DAPA) as an inhibitor of the inositol requiring kinase 1α (IRE1α)–X-box binding protein-1 (XBP1) pathway of the unfolded protein response. We designed a collection of analogues based on the structure of DAPA to explore structure–activity relationships and identified N9-(3-(dimethylamino)propyl)-N3,N3,N6,N6-tetramethylacridine-3,6,9-triamine (3,6-DMAD), with 3,6-dimethylamino substitution on the chromophore, as a potent inhibitor. 3,6-DMAD inhibited both IRE1α oligomerization and in vitro endoribonuclease (RNase) activity, whereas the other analogues only blocked IRE1α oligomerization. Consistent with the inhibition of IRE1α-mediated XBP1 splicing, which is critical for multiple myeloma cell survival, these analogues were cytotoxic to multiple myeloma cell lines. Furthermore, 3,6-DMAD inhibited XBP1 splicing in vivo and the growth of multiple myeloma tumor xenografts. Our study not only confirmed the utilization of topological data analysis in drug discovery but also identified a class of compounds with a unique mechanism of action as potent IRE1α–XBP1 inhibitors in the treatment of multiple myeloma. Mol Cancer Ther; 15(9); 2055–65. ©2016 AACR.
Data from Preclinical Activity of the Novel Anti-Prolactin Receptor (PRLR) Antibody–Drug Conjugate REGN2878-DM1 in PRLR-Positive Breast Cancers
Authors: Kelly Marcus P. , Hickey Carlos , Makonnen Sosina , Coetzee Sandra , Jalal Sumreen , Wang Yu , Delfino Frank , Shan Jing , Potocky Terra B. , Chatterjee Ishita , Andreev Julian , Kunz Arthur , D'Souza Christopher , Giurleo Jason T. , Nittoli Thomas , Trail Pamela A. , Thurston Gavin , Kirshner Jessica R.
Published: March 2024

Abstract
The Prolactin Receptor (PRLR) is a type 1 cytokine receptor that is expressed in a subset of breast cancers and may contribute to its pathogenesis. It is relatively overexpressed in approximately 25% of human breast tumors while expressed at low levels in some normal human tissues including the mammary gland. We developed an anti-PRLR antibody-drug conjugate (ADC), to target PRLR-positive breast cancer. REGN2878-DM1 is comprised of a fully human high-affinity function-blocking anti-PRLR IgG1 antibody (REGN2878) conjugated via a noncleavable SMCC linker to the cytotoxic maytansine derivative DM1. Both unconjugated REGN2878 and conjugated REGN2878-DM1 block PRL-mediated activation in vitro and are rapidly internalized into lysosomes. REGN2878-DM1 induces potent cell-cycle arrest and cytotoxicity in PRLR-expressing tumor cell lines. In vivo, REGN2878-DM1 demonstrated significant antigen-specific antitumor activity against breast cancer xenograft models. In addition, REGN2878-DM1 showed additive activity when combined with the antiestrogen agent fulvestrant. These results illustrate promising antitumor activity against PRLR-positive breast cancer xenografts and support the evaluation of anti-PRLR ADCs as potential therapeutic agents in breast cancer. Mol Cancer Ther; 16(7); 1299–311. ©2017 AACR.
Data from Recombinant Immunotoxin with T-cell Epitope Mutations That Greatly Reduce Immunogenicity for Treatment of Mesothelin-Expressing Tumors
Authors: Mazor Ronit , Zhang Jingli , Xiang Laiman , Addissie Selamawit , Awuah Prince , Beers Richard , Hassan Raffit , Pastan Ira
Published: March 2024

Abstract
SS1P is a recombinant immunotoxin (RIT) that targets mesothelin. It consists of an antimesothelin Fv fused to a portion of Pseudomonas exotoxin A. In clinical studies, it has produced dramatic responses in patients with advanced mesothelioma, when combined with immunosuppressive therapy so that several treatment cycles could be given. Otherwise its activity is limited by its immunogenicity. In this work, we describe the development and characterization of LMB-T20, a highly potent RIT targeted at mesothelin-expressing cancers with low immunogenicity due to removal of its eight T-cell epitopes. LMB-T20 was more active than SS1P when tested on four different mesothelin-expressing cell lines as well as on cells obtained from patients with mesothelioma. It also has potent antitumor activity in mice, and has reduced immunogenicity as measured by cytokine secretion assays. In conclusion, LMB-T20 is a favorable candidate for evaluation in clinical trials due to its reduced immunogenicity and excellent activity. Mol Cancer Ther; 14(12); 2789–96. ©2015 AACR.
Data from Characterization of LY3023414, a Novel PI3K/mTOR Dual Inhibitor Eliciting Transient Target Modulation to Impede Tumor Growth
Authors: Smith Michele C. , Mader Mary M. , Cook James A. , Iversen Philip , Ajamie Rose , Perkins Everett , Bloem Laura , Yip Yvonne Y. , Barda David A. , Waid Philip P. , Zeckner Douglas J. , Young Debra A. , Sanchez-Felix Manuel , Donoho Gregory P. , Wacheck Volker
Published: March 2024

Abstract
The PI3K/AKT/mTOR pathway is among the most frequently altered pathways in cancer cell growth and survival. LY3023414 is a complex fused imidazoquinolinone with high solubility across a wide pH range designed to inhibit class I PI3K isoforms and mTOR kinase. Here, we describe the in vitro and in vivo activity of LY3023414. LY3023414 was highly soluble at pH 2–7. In biochemical testing against approximately 266 kinases, LY3023414 potently and selectively inhibited class I PI3K isoforms, mTORC1/2, and DNA-PK at low nanomolar concentrations. In vitro, inhibition of PI3K/AKT/mTOR signaling by LY3023414 caused G1 cell-cycle arrest and resulted in broad antiproliferative activity in cancer cell panel screens. In vivo, LY3023414 demonstrated high bioavailability and dose-dependent dephosphorylation of PI3K/AKT/mTOR pathway downstream substrates such as AKT, S6K, S6RP, and 4E-BP1 for 4 to 6 hours, reflecting the drug's half-life of 2 hours. Of note, equivalent total daily doses of LY3023414 given either once daily or twice daily inhibited tumor growth to similar extents in multiple xenograft models, indicating that intermittent target inhibition is sufficient for antitumor activity. In combination with standard-of-care drugs, LY3023414 demonstrated additive antitumor activity. The novel, orally bioavailable PI3K/mTOR inhibitor LY3023414 is highly soluble and exhibits potent in vivo efficacy via intermittent target inhibition. It is currently being evaluated in phase I and II trials for the treatment of human malignancies. Mol Cancer Ther; 15(10); 2344–56. ©2016 AACR.
Data from A Novel Inhibitor of Topoisomerase I Is Selectively Toxic for a Subset of Non–Small Cell Lung Cancer Cell Lines
Authors: Zubovych Iryna O. , Sethi Anirudh , Kulkarni Aditya , Tagal Vural , Roth Michael G.
Published: March 2024

Abstract
SW044248, identified through a screen for chemicals that are selectively toxic for non–small cell lung cancer (NSCLC) cell lines, was found to rapidly inhibit macromolecular synthesis in sensitive, but not in insensitive, cells. SW044248 killed approximately 15% of a panel of 74 NSCLC cell lines and was nontoxic to immortalized human bronchial cell lines. The acute transcriptional response to SW044248 in sensitive HCC4017 cells correlated significantly with inhibitors of topoisomerases and SW044248 inhibited topoisomerase 1 (Top1) but not topoisomerase 2. SW044248 inhibited Top1 differently from camptothecin and camptothecin did not show the same selective toxicity as SW044248. Elimination of Top1 by siRNA partially protected cells from SW044248, although removing Top1 was itself eventually toxic. Cells resistant to SW044248 responded to the compound by upregulating CDKN1A and siRNA to CDKN1A sensitized those cells to SW044248. Thus, at least part of the differential sensitivity of NSCLC cells to SW044248 is the ability to upregulate CDKN1A. Mol Cancer Ther; 15(1); 23–36. ©2015 AACR.
Data from Bruton's Tyrosine Kinase Inhibitors Prevent Therapeutic Escape in Breast Cancer Cells
Authors: Wang Xianhui , Wong Jason , Sevinsky Christopher J. , Kokabee Leila , Khan Faiza , Sun Yan , Conklin Douglas S.
Published: March 2024

Abstract
We have reported that a novel isoform of BTK (BTK-C) expressed in breast cancer protects these cells from apoptosis. In this study, we show that recently developed inhibitors of BTK, such as ibrutinib (PCI-32765), AVL-292, and CGI-1746, reduce breast cancer cell survival and prevent drug-resistant clones from arising. Ibrutinib treatment impacts HER2+ breast cancer cell viability at lower concentrations than the established breast cancer therapeutic lapatinib. In addition to inhibiting BTK, ibrutinib, but not AVL-292 and CGI-1746, efficiently blocks the activation of EGFR, HER2, ErbB3, and ErbB4. Consequently, the activation of AKT and ERK signaling pathways are also blocked leading to a G1–S cell-cycle delay and increased apoptosis. Importantly, inhibition of BTK prevents activation of the AKT signaling pathway by NRG or EGF that has been shown to promote growth factor–driven lapatinib resistance in HER2+ breast cancer cells. HER2+ breast cancer cell proliferation is blocked by ibrutinib even in the presence of these factors. AVL-292, which has no effect on EGFR family activation, prevents NRG- and EGF-dependent growth factor–driven resistance to lapatinib in HER2+ breast cancer cells. In vivo, ibrutinib inhibits HER2+ xenograft tumor growth. Consistent with this, immunofluorescence analysis of xenograft tumors shows that ibrutinib reduces the phosphorylation of HER2, BTK, Akt, and Erk and histone H3 and increases cleaved caspase-3 signals. As BTK-C and HER2 are often coexpressed in human breast cancers, these observations indicate that BTK-C is a potential therapeutic target and that ibrutinib could be an effective drug especially for HER2+ breast cancer. Mol Cancer Ther; 15(9); 2198–208. ©2016 AACR.