bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 1167: MCM2-7 complex is a novel druggable target for neuroendocrine prostate cancer
Authors: Stoyanova Tanya Ivanova 
Published: July 2021

Abstract
Background: Neuroendocrine prostate cancer (NEPC) is a lethal subtype of prostate cancer that rarely develops de novo in primary tumors and is commonly acquired during the development of treatment resistance. NEPC is characterized by gain of neuroendocrine markers and androgen receptor (AR) loss, making it resistant to currently used therapeutic strategies targeting the AR signaling axis.
Methods: We utilized whole proteomic analysis of a previously characterized NEPC model and identified MCM2, MCM3, MCM4, and MCM6 proteins as novel targets to inhibit NEPC growth. High levels of MCM2/3/4/6 were significantly enriched in human NEPC when compared to castration-resistant prostate adenocarcinoma in multiple datasets. Colony formation, 3D Matrigel drop and subcutaneous xenograft models of NEPC were used to test the effect of MCM2-7 inhibition using ciprofloxacin in NEPC.
Results: Here, we report that MCM2, MCM3, MCM4, and MCM6 (MCM2/3/4/6) are elevated in human NEPC and high levels of MCM2/3/4/6 are associated with liver metastasis and poor survival in prostate cancer patients. MCM2/3/4/6 are four out of six proteins that form a core DNA helicase (MCM2-7) responsible for unwinding DNA forks during DNA replication. Inhibition of MCM2-7 helicase activity by treatment with ciprofloxacin inhibits NEPC cell proliferation and migration in vitro, significantly delays NEPC tumor xenograft growth, and partially reverses the neuroendocrine phenotype in vivo.
Conclusions: Our findings uncover that MCM2/3/4/6 are markedly elevated in NEPC and represent new druggable targets for therapeutic intervention. The study further reveals that inhibition of MCM2/3/4/6 complex using ciprofloxacin or other targeted approaches may represent a new effective therapy for NEPC. Our studies warrant further exploration of design and screening for MCM2-7 complex-specific inhibitors.
Citation Format: Tanya Ivanova Stoyanova. MCM2-7 complex is a novel druggable target for neuroendocrine prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1167.
Abstract 1182: The NEDD8 inhibitor pevonedistat blocks the repair of topoisomerase I (TOP1)-induced replication damage and synergizes with TOP1 inhibitors
Authors: Sun Yilun , Baechler Andrea , Factor Valentina , Okamoto Kanako , Pommier Yves 
Published: July 2021

Abstract
Genomic DNA is constantly challenged by various genotoxic substances, resulting in an array of DNA lesions including DNA-protein crosslinks (DPCs), one of the most detrimental forms of DNA damage. Topoisomerase I (TOP1) is the molecular target of anti-cancer agents camptothecin derivatives and indenoisoquinolines, which act by trapping TOP1 on genomic DNA. The resulting TOP1-DPCs interfere with DNA replication and transcription and trigger cell death if left unrepaired. In this work, we found that the ubiquitin-like protein NEDD8 plays a pivotal role in the repair of TOP1-DPCs by activating the cullin 4 (CUL4)-RING ubiquitin ligases (CRL4) for K48-linked polyubiquitylation of TOP1-DPCs and their subsequent proteasomal degradation. We identified DCAF13, an understudied family member of DDB1- and CUL4-asscoiated factors, as the receptor of TOP1-DPCs for CRL4. DCAF13 colocalizes with TOP1-DPCs at nascent replication forks and binds the TOP1 core domain with its WD40 domains, linking TOP1 to DDB1-CRL4 for ubiquitylation upon TOP1-induced replication damage. Prompted by these findings, we hypothesized that targeting this NEDD8-activated repair pathway can be developed as a strategy to overcome resistance to TOP1 inhibitors. To test this hypothesis, we performed pharmacological analyses using CellMiner (http://discover.nci.nih.gov/cellminercdb) and found that the activities of TOP1 inhibitors and pevonedistat, a first-in-class NEDD8-activating enzyme inhibitor in clinical trial, are highly correlated across cancer cell lines and with the expression of SLFN11. We also assessed the sensitivity of cultured cancer cells to combination of clinical TOP1 inhibitors and pevonedistat. The combination exhibited synergy in multiple cell lines particularly in human colon cancer cells HCT116 independently of SLFN11. We next investigated the efficacy of combination with TOP1 inhibitor topotecan and pevonedistat in HCT116 xenografts and observed supra-additive effect on tumor growth inhibition. Taken together, our work not only identifies a novel pathway for the repair of TOP1-DPCs but also provides translational evidence to support pevonedistat in combination with TOP1 inhibitors as a rationale therapeutic combination for cancer treatments.
Citation Format: Yilun Sun, Andrea Baechler, Valentina Factor, Kanako Okamoto, Yves Pommier. The NEDD8 inhibitor pevonedistat blocks the repair of topoisomerase I (TOP1)-induced replication damage and synergizes with TOP1 inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1182.
Abstract 121: A genetic signature of cancer dormancy: implications for human disease derived from a novel murine model
Authors: Casabianca Anthony S. , Dudgeon Crissy , Harris Chris , De Subhajyoto , Shah Mihir , Roberts Arthur , Collisson Eric , Balachandran Vinod , Carpizo Darren 
Published: July 2021

Abstract
Pancreatic cancer (PC) is a highly lethal malignancy characterized by local tumor aggressiveness and early metastatic dissemination. While surgical resection is used to treat localized cancers, the majority of patients do recur suggesting the presence of disseminated tumor cells (DTC) at the time of surgery. These DTC's represent minimal residual disease. While most patients recur early, a subset recur late due to the reactivation of dormant tumor cells. Currently, the mechanisms of cancer dormancy are poorly understood in part due to a lack of animal models that reflect human disease. Here we describe a murine model of PC dormancy that mimics outcomes in resected human patients. Using single-cell transcriptomics and an assay for chromatin accessibility, we found dormancy is a distinct cellular state from pre or post-dormant cancer cells. Mechanisms of dormancy include increased expression of transcriptional repressor Dec2, which functionally drives quiescence, and monoallelic suppression of mutant KRAS by DNA methylation. Pathway analysis of dormant tumor cell transcriptomics indicated an up-regulation of enzymes involved in linoleic acid metabolism among others. Linoleic acid treatment of tumor cells resulted in inhibited cell proliferation, decreased tumor growth, and an increase in Dec2 expression. We have identified a dormancy gene signature that is distinct from non-dormant PC cells and found that this correlates with human resected patients with long term survivals, and inversely in patients with short term survivals. We demonstrate that dormancy is characterized by large scale transcriptomic changes and global chromatin remodeling. We developed methods for isolating DTCs from the livers of early stage PC patients undergoing resection. Using these methods we have found that the murine dormancy signature correlated with the gene expression of the DTCs and not primary tumor cells indicating this dormancy signature has human relevance with potential novel therapeutic avenues.
Citation Format: Anthony S. Casabianca, Crissy Dudgeon, Chris Harris, Subhajyoto De, Mihir Shah, Arthur Roberts, Eric Collisson, Vinod Balachandran, Darren Carpizo. A genetic signature of cancer dormancy: implications for human disease derived from a novel murine model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 121.
Abstract 1231: Identification of selective Brd4 degrader for cancer treatment
Authors: Hu Biao , Hu Jiantao , Xu fuming , Huang Liyue , Wang Mi , Wang Shaomeng 
Published: July 2021

Abstract
Human BET family proteins consist of four members, termed Brd2, Brd3, Brd4 and testis-specific BrdT. They all contain two highly conserved tandem N-terminal bromodomains (BD1 and BD2) and a C-terminal extra-terminal (ET) domain. One of the major functions of the BET proteins is to recognize the acetylated lysine residues on histone proteins and transcriptional factors, thereby regulating the gene expression. Recent studies have implicated the BET proteins as a valid pharmaceutical target for treating cancers. Disrupting the interactions by pan-BET inhibitors have displayed beneficial prognosis in both the preclinical animal models and the clinic trials. Nevertheless, dose limiting adverse effects including mild to moderate gastrointestinal toxicity and fatigue, as well as reversible grade 3 thrombocytopenia, have been observed for some pan-BET inhibitors clinically. While the three BET proteins BRD2, BRD3 and BRD4 exhibit redundant and dynamic patterns in regulating gene transcription, the individual protein may have distinct functions. Thus developing of isoform-selective regulatory reagents is of interest to elucidate the biological function of the BET proteins and their applications in pharmaceutical development. Here, we describe our efforts for the development of selective Brd4 degraders with proteolysis-targeting chimera approaches. Our medicinal chemistry campaign led to the discovery of a series of highly potent Brd4 selective degraders. Treat the tumor cells with these selective Brd4 degraders resulted in rapid, sustained and selective degradation of Brd4. RNA-seq and real time RT-PCR analysis indicates the selective Brd4 degrader exhibits distinct regulation of gene expression in tumor cells comparing to pan-BET degraders and inhibitors. Further tests with flow cytometry analysis and WST-8 assays indicates that selective Brd4 degraders strongly suppress the tumor cells growth and induces the cell death through induction of apoptosis. Strong tumor suppression was also observed with treatment of selective Brd4 degrader in mouse xenograft models. These results suggest that the selective Brd4 degraders are strong candidates for potential tumor treatment.
Citation Format: Biao Hu, Jiantao Hu, fuming Xu, Liyue Huang, Mi Wang, Shaomeng Wang. Identification of selective Brd4 degrader for cancer treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1231.
Abstract 1232: Using mesoporous silica nanoparticles (MSNs) for delivering the mesoionic compound MIH 2.4Bl in treating breast cancer
Authors: Debnath Dipti , Nazzal Sami , Acharya Suchismita , Souza Helivaldo Diógenes da Silva , Filho Petrônio Filgueiras de Athayde , Fudala Rafal , Mathis J Michael 
Published: July 2021

Abstract
Breast cancer is the most frequently diagnosed cancer and the leading cause of cancer death in women worldwide, accounting for approximately 24% of all new cancer cases and is the leading cause of cancer death in over 100 countries. Thus, breast cancer is one of the most critical public health problems in the world facing women. There is a growing interest in studying the biological activity of mesoionic compounds, which possesses a 5-membered heterocyclic aromatic ring associated with a sextet of electrons. Mesoionic compounds have shown promising potential as anti-cancer agents due to their unique structure and reaction properties. We reported the synthesis of a new 1,3-thiazolium-5-thiolate derivative of a mesoionic compound (MIH 2.4Bl) and the characterization of its selective cytotoxicity on a panel of breast cancer cells lines. The results of our studies suggest a possible induction of apoptotic death through mitochondrial dysfunction by the treatment with MIH 2.4Bl. Based on our previous findings, MIH 2.4Bl is a promising candidate for treating breast cancer. However, a major challenge facing cancer therapy is the selective destruction of malignant cells while sparing normal cells to preserve tissue integrity. The development and use of drug delivery systems is a recognized approach to improve the efficacy of chemotherapy agents. Nonetheless, drug delivery systems have been unexplored in the context of mesoionic compounds. Drug delivery based on nanotechnology has flourished as a platform applicable to cancer therapy. Among various types of nanoparticles, mesoporous silica nanoparticles (MSNs) are more attractive nanomaterials for a broad range of functionality including gene/drug delivery, cancer therapy and bioimaging due to their broad surface area, less toxicity, low density, excellent biocompatibility, higher drug loading capacity, and impressive mechanical and thermal stability. In this preliminary work, we present an improved delivery strategy of a newly developed formulation of MIH 2.4BI compound with MSNs as the delivery agent. Also, physico-chemical characterization of the nanoparticles and cytotoxicity analyses using a panel of breast cancer cell lines were performed. These studies support the potential therapeutic use of MIH 2.4Bl in treating breast cancer.
Citation Format: Dipti Debnath, Sami Nazzal, Suchismita Acharya, Helivaldo Diógenes da Silva Souza, Petrônio Filgueiras de Athayde Filho, Rafal Fudala, J Michael Mathis. Using mesoporous silica nanoparticles (MSNs) for delivering the mesoionic compound MIH 2.4Bl in treating breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1232.
Abstract 1238: Treating estrogen receptor (ER)-negative and triple-negative breast cancer by targeting STAT3 signaling with putative STAT3 inhibitors
Authors: Kim Hyejin , Fricke Doerte R. , Xu Jimin , Chen Haiying , Zhou Jia , Shen Qiang 
Published: July 2021

Abstract
Approximately 20% to a quarter of breast cancer cases are estrogen receptor (ER)-negative breast cancer (ENBC), including the most aggressive subtype, triple-negative breast cancer (TNBC), which spreads early and shows poor prognosis. ENBCs do not respond to selective ER modulators such as tamoxifen. Therefore, there is an urgent need for non-ER-based therapies for ENBC. Recently, STAT3 was found to play an important role in maintaining cancer stem cells in vitro and in mouse models of human cancers. In addition, during mammary carcinogenesis, STAT3 is highly activated in mammary epithelial cells involving in mammary epithelial cell transformation, tumor initiation, progression, and metastasis. STAT3 has been traditionally considered as non-targetable or undruggable, and there is currently a lack of FDA-approved STAT3 inhibitors for clinical use. We recently developed a putative STAT3 inhibitor, HJC0152, and a series of HJC0152-based analogues as orally bioavailable STAT3 inhibitors. These small molecules have been evaluated and a number of them showed low micro-molar potency in inhibiting the proliferation of a panel of breast cancer cell lines. Compound JMX0804 showed improved anti-proliferative effects against the highly aggressive TNBC cell line MDA-MB-231 and other ER+ and ER- breast cancer cell lines in comparison to HJC0152. JMX0804 inhibited STAT3 phosphorylation at the Tyr705 residue and induced apoptosis in MDA-MB-231 cells. In vivo, mice treated with JMX0804 at a 10 mg/kg dose via i.p. showed reduced growth of xenograft tumors arisen from MDA-MB-231 cells, with minimal impact on general health and body weight. Our current research supports the notion that JMX0804 suppresses breast cancer growth by inhibiting breast cancer cell proliferation and inducing apoptosis via mediating STAT3 signaling. JMX0804 is currently undergoing further characterization for breast cancer metastasis and mechanisms of action as well as optimization to improve drug properties including potency and safety profile. This work is supported by NIH/NCI grant R01 CA231150.
Citation Format: Hyejin Kim, Doerte R. Fricke, Jimin Xu, Haiying Chen, Jia Zhou, Qiang Shen. Treating estrogen receptor (ER)-negative and triple-negative breast cancer by targeting STAT3 signaling with putative STAT3 inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1238.
Abstract 1304: AbYlinkTM: A site-selective labeling method for preclinical imaging of therapeutic antibodies
Authors: Postupalenko Viktoriia , Marx Léo , Viertl David , Gasilova Natalia , Plantin Mathilde , Gsponer Nadège , Johanssen Alexandre , Denoel Thibaut , Hagens Gerrit , Segura Jean-Manuel , Levy Frédéric , Garrouste Patrick , Prior John , Schottelius Margret , Schaefer Niklaus , Nyanguile Origene 
Published: July 2021

Abstract
Clinical development of therapeutic antibodies relies on robust and thorough preclinical evaluation of multiple pharmacodynamic and pharmacokinetic parameters of antibody candidates. While current methods are available for in vitro characterization of antibodies, in vivo determination of tissue distribution, tumor accumulation and retention and potential off-target effects cannot be performed non-invasively in vivo over a prolonged period of time.
Here, we used AbYlinkTM, a novel site-selective labeling method of native antibodies, enabling the single-step covalent conjugation of a radionuclide chelator to the Fc domain of any IgG antibody isotype. Given the selectivity of this reaction for the Fc region of the immunoglobulin, labeling of the antibody at this location should not compromise binding to the antigen. Chelators that are covalently attached to the antibody allows for the labeling with radioisotopes such as 68Ga, 177Lu, 111In and 89Zr, and for the sensitive and quantitative molecular in vivo measurement by Positron Emission Tomography (PET) or Single Photon Emission Computed Tomography (SPECT). AbYlinkTM also permits the conjugation of fluorescent dyes to antibodies with the aim to measure antibody pharmacodynamic parameters by intravital microscopy. In this work, we have validated the technology by labeling several antibodies and ADCs with different payloads. Importantly, antibodies conjugated with AbYlinkTM retained the same affinity to the antigen as the original, unconjugated antibodies, contrary to the randomly labelled antibodies. We will also present data on the specific radiolabeling of commercially available trastuzumab with 111Indium and the SPECT images obtained after injection of mice bearing HER2-positive tumors with 111In-trastuzumab.
The present data suggest that AbYlinkTM can be used to support preclinical drug discovery tools to assist in the selection of therapeutic antibody candidates and/or for pharmacodynamic assessment of commercial antibodies. Furthermore, the specificity of the chemical conjugation suggests that AbYlinkTM can help to control the chelator distribution on the antibody drug conjugates.
Citation Format: Viktoriia Postupalenko, Léo Marx, David Viertl, Natalia Gasilova, Mathilde Plantin, Nadège Gsponer, Alexandre Johanssen, Thibaut Denoel, Gerrit Hagens, Jean-Manuel Segura, Frédéric Levy, Patrick Garrouste, John Prior, Margret Schottelius, Niklaus Schaefer, Origene Nyanguile. AbYlinkTM: A site-selective labeling method for preclinical imaging of therapeutic antibodies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1304.
Abstract 1306: Primary NK cells and luciferase expressing reporter cell lines for use in developing ADCC assays for immuno-oncology drug screening
Authors: Liu Haiyun , Fera Brian Della , Foulke John , Chen Luping , Tian Fang 
Published: July 2021

Abstract
Immuno-oncology is one of the fastest growing fields in oncology, and cancer immunotherapy in recent years represents a milestone in the treatment of cancer. Natural killer (NK) cells are potent innate effectors capable of targeting and killing virally infected and malignant cells. The use of monoclonal antibodies (mAbs) targeting tumor antigens triggers antibody-dependent cellular cytotoxicity (ADCC) by NK cells, which has shown prominent clinical efficacy in clearing tumors in cancer patients. Therefore, the development of tumor cell targeting mAbs and biologics dictate a clear need for human cell-based models to evaluate antibody efficacy. In this study, human PBMCs and purified NK cells from healthy donors are used to develop an ADCC assay. The NK cells purified from PBMCs are &gt;90% CD45+ CD56+, express high levels of CD16, and NK activation markers such NKG2A, KIR2DL1, NKp44 upon activation. The activated NK cells exhibit both strong direct and antibody-dependent cytotoxicity. Genotyping for FcγRIIIa receptor F and V variant is also performed for cells isolated from different donors, which is the genetic polymorphism that affects ADCC response. In addition, we employ a portfolio of luciferase reporter tumor cell lines to evaluate NK cell direct killing and ADCC targeted killing. These include K562, Wil2S, BT474, A431, A375 parental, and CRISPR edited A375 KRAS mutant cell lines engineered to express luc2 reporter. The commonly targeted cell surface markers, such as CD20, Her2, and EGFR, are highly expressed within this panel of target tumor cell lines. We validate the ADCC assay system through testing the efficacy for some of the well-known mAb biologics such as anti-CD20, anti-HER2, and anti-EGFR. After co-culture of activated primary NK cells with luciferase reporter target cell lines and the addition of dilutions of ADCC and isotype control antibodies, we are able to show target cell specific and dose-dependent killing effects. The luciferase reporter provides great convenience in measuring target cell killing without having to use radioactive 51Cr release assay or pre-label the cells with calcein. This data demonstrates the utility of primary NK cells along with a portfolio of well characterized luciferase reporter tumor cell line to develop “custom” designed ADCC assays for studying NK cell immune response and screening for biological drugs for cancer immunotherapy.
Citation Format: Haiyun Liu, Brian Della Fera, John Foulke, Luping Chen, Fang Tian. Primary NK cells and luciferase expressing reporter cell lines for use in developing ADCC assays for immuno-oncology drug screening [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1306.