bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 2899: Antitumor activity of CIGB-300, a peptide CK2 inhibitor, in breast cancer models
Authors: Gottardo Maria F. , Capibianco Carla S. , Sidabra Johanna E. , Perera Yasser , Perea Silvio , Alonso Daniel F. , Farina Hernan G.
Published: August 2018

CK2 is a serine-threonine kinase that has been involved in growth, proliferation and cell apoptosis. CK2 has a constitutive expression and it has more than 300 substrates. In recent years, CK2 became an interesting target for anticancer therapies. Inhibition of CK2 showed antitumor activity in different types of cancer. Because breast cancer is one of the main tumor types in which CK2 is overexpressed, we focus on the effect of CK2 inhibition as a modulator of key features of breast cancer cell biology. The aim of the present study was to evaluate the role of inhibition of CK2 by CIGB-300 in murine and human mammary carcinoma cell lines. For this purpose, we evaluated the action of CIGB-300 on viability, apoptosis, cell cycle, clonogenic capacity and migration using three different breast tumor cell lines, MCF7 (positive for estrogen, progesterone and HER2-neu receptors), MDA MB 231 (representative of triple negative tumors) and F3II, a murine mammary carcinoma. As compared the potential of CK2 inhibition in these models we included another chemical inhibitor of the enzyme, CX-4945. Our results showed that CIGB-300 reduced the viability of MDA MB 231 (IC50=120 μM) and MCF-7 (IC50=140 μM) (p<0.05, ANOVA). We observed that in both human and murine cell lines CIGB-300 exerts a pro-apoptotic action (TUNEL assay, p<0.05, χ2) and arrest cell cycle. We also found that the inhibition of CK2 by CIGB-300 decreased the clonogenic capacity and migration of F3II, MCF-7 and MDA-MB-231 (p<0.05, ANOVA). In vivo studies using the syngeneic F3II breast cancer model in BalB/c mice showed a decrease in the number of lung metastases in mice treated systemically with CIGB-300 after primary tumor surgery (Mann Whitney test, p<0.05). However, CK2 inhibition did not affect the growth of local recurrences. Also, intravenous administration of CIGB-300 decreased lung metastasis development of F3II cells. These results demonstrate an antimetastatic effect of CIGB-300 in a systemic inoculation model after surgical removal of primary tumors. In this work we demostrated the antitumor effect of CIGB-300 in breast cancer models such as those reported in myeloid leukemia, lung and cervix and head cancer.

Citation Format: Maria F. Gottardo, Carla S. Capibianco, Johanna E. Sidabra, Yasser Perera, Silvio Perea, Daniel F. Alonso, Hernan G. Farina. Antitumor activity of CIGB-300, a peptide CK2 inhibitor, in breast cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2899.
Abstract 2903: A novel compound induces synthetic lethality for p53 mutations in osteosarcoma cells
Authors: Iwakuma Tomoo , Parrales Alejandro , McDonald Peter , Roy Anuradha , Braun Mitchell W. , Schoenen Frank J. , Wang Jenna , Rogers Steve , Broward Melinda , Bruns Tyce , Anant Shrikant , Dixon Dan A. , Meyer Fred , Chastain Katherine M. , Thamm Douglas H. , Weir Scott J. , Neville Kathleen , Fulbright Joy M.
Published: August 2018

Osteosarcoma is the second-highest cause of cancer-related death in children and adolescents. Despite advances in chemotherapy and surgery, the survival rate for metastatic osteosarcoma remains below 30% for the last three decades. Discovery of new chemotherapy agents would be crucial for improving outcomes of osteosarcoma patients. Here, using high-throughput screening, we have found a new compound, called 2-{2-[(3,5-dimethoxybenzyl)sulfanyl]-1,3-thiazol-4-yl}-N-(2-thienylmethyl)acetamide (referred to as KU0171032), as an inducer of apoptosis in various canine and human osteosarcoma cells. This compound shows minimal effects on non-transformed osteoblast and fibroblast cells. Intriguingly, KU0171032-induced apoptosis is more robust in osteosarcoma cells having mutant p53 or null for p53, as compared to cells with wild-type p53. Knockdown of wild-type p53 in U2OS and SJSA-1 cells significantly enhances sensitivity to KU0171032 with increase in DNA damage and caspase-3 cleavage. Moreover, KU0171032 significantly reduces in vivo tumor growth of osteosarcoma cells with p53 knockdown or carrying mutant p53. Our results strongly suggest that KU0171032 shows synthetic lethality with p53 mutations in osteosarcoma cells. Given that loss of p53 activity is frequent event in many cancer types including osteosarcoma while normal cells usually retain wild-type p53, this compound could be used to develop novel therapeutic strategies that capitalize on vulnerabilities in osteosarcoma and other types of cancer.

Citation Format: Tomoo Iwakuma, Alejandro Parrales, Peter McDonald, Anuradha Roy, Mitchell W. Braun, Frank J. Schoenen, Jenna Wang, Steve Rogers, Melinda Broward, Tyce Bruns, Shrikant Anant, Dan A. Dixon, Fred Meyer, Katherine M. Chastain, Douglas H. Thamm, Scott J. Weir, Kathleen Neville, Joy M. Fulbright. A novel compound induces synthetic lethality for p53 mutations in osteosarcoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2903.
Abstract 2923: BET inhibitors synergize with HDAC inhibitors and downregulate expression of interferon response genes in glioblastoma
Authors: Gusyatiner Olga , Pham Minh Diêu Thanh , Lei Yvonne , Park Jungyeon , Bady Pierre , Delorenzi Mauro , Hegi Monika
Published: August 2018

Glioblastoma (GBM) is the most aggressive brain tumor in adults with a median overall survival of only 15 months. Despite multiple attempts, single agent therapies have failed in clinical trials and new strategies for combination treatments are urgently needed.

Here, our aim was to predict rational combination therapies with BET inhibitors (BETi) that target bromodomain and extra-terminal tail (BET) proteins and are currently evaluated as anti-cancer drugs. In order to identify BETi-induced vulnerabilities in cancer relevant pathways that may be targeted with a second drug, we obtained differential expression profiles of glioma sphere lines (GS-lines) treated with the BETi JQ1. Gene set enrichment analysis revealed several significantly disturbed pathways that included IFN-alpha response genes and signatures of response to histone deacetylase inhibitors (HDACi).

In order to validate the observed down regulation of the interferon response gene signature, we primed the GS-lines with IFN-alpha and confirmed that interferon-stimulated genes (ISGs), such as MX1, OAS1, and CD274 are down regulated after a 4-hour exposure to JQ1. Importantly, the levels of pSTAT1 in the nucleus remained unchanged upon JQ1 treatment, suggesting that JQ1 was acting directly on the transcriptional level of ISGs and not on the canonical JAK-STAT pathway. Similar results were obtained in adherent GBM cell lines that constitutively express ISGs. Moreover, in U87MG orthotropic xenografts in mice, a single i.p. injection of JQ1 downregulated OAS1 and CD274 expression. Currently we are studying the mechanism of how BETi represses transcription of ISGs by chromatin immuno-precipitation.

Finally, we show that HDACi and JQ1 synergize to reduce cell viability of GS-lines in vitro. Further experiments will test HDACi and BETi drug combinations in mouse orthotopic xenografts of GS-lines.

Citation Format: Olga Gusyatiner, Minh Diêu Thanh Pham, Yvonne Lei, Jungyeon Park, Pierre Bady, Mauro Delorenzi, Monika Hegi. BET inhibitors synergize with HDAC inhibitors and downregulate expression of interferon response genes in glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2923.
Abstract 2925: Tandem targeting of poly (ADP-ribose) polymerase (PARP) and epidermal growth factor receptor (EGFR) as a novel strategy for enhancing radio- and chemosensitivity of refractory tumors
Authors: Rupp Martin , Mouhri Zhor Senhaji , Stochaj Ursula , Jean-Claude Bertrand
Published: August 2018

Poly (ADP-ribose) polymerase (PARP) inhibitors are a novel therapeutic approach for the selective targeting of tumours with BRCA1/2 hereditary deficiencies. BRCA1/2 are two key proteins involved in homologous recombination (HR) repair. Although the therapeutic benefit of PARP inhibitors has now been proven in the clinic in patients with BRCA1/2 mutations, much effort has been deployed to expand the use of PARP inhibitors beyond tumours harbouring inherited deficiencies in HR- mediated DNA repair. Several combination modalities with agents that can induce HR deficiency and exploit the concept of “contextual synthetic lethality” have been reported for PARP inhibitors. Here we exploited the contextual synthetic lethality between PARP and the epidermal growth factor receptor (EGFR) to design and synthesize a novel dual EGFR targeted PARP inhibitor, termed ZSMR06. The results showed that: a) ZSMR06 is capable of inhibiting EGFR and PARP in whole cells in the nanomolar range (36-63 nM); b) it was selectively potent against BRCA2 mutant and EGFR expressing isogenic cells; c) as monotherapy, ZSMR06 was extremely potent with growth inhibitory activities superior to that of an equimolar combination of olaparib (a clinical PARP inhibitor) and gefitinib (a clinical EGFR inhibitor) in a large panel of tumour cell lines; d) ZSMR06 strongly potentiated the effect of temozolomide (TMZ) and induced significantly stronger (p<0.05-0.001) growth inhibition than olaparib + TMZ combination in cells expressing O6-methylguanine-DNA methyltransferase (MGMT), an enzyme that confers a robust resistance to TMZ; e) ZSMR06 selectively potentiated TMZ on EGFR expressing cells; f) it was able to strongly sensitize bladder cancer cells to radiation (DMF50= 2.96-9.5). These results in toto showed that ZSMR06 due to its dual mechanism of action is capable of behaving as a strong potentiator of TMZ and radiation in resistant cells. Its potency in non-BRCA1/2 mutant tumour cells indicates that it may be the first prototype of hybrid molecules capable of expanding the use of PARP inhibition beyond BRCA1/2 mutations.

Citation Format: Martin Rupp, Zhor Senhaji Mouhri, Ursula Stochaj, Bertrand Jean-Claude. Tandem targeting of poly (ADP-ribose) polymerase (PARP) and epidermal growth factor receptor (EGFR) as a novel strategy for enhancing radio- and chemosensitivity of refractory tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2925.
Abstract 2955: A radiomic-based MRI phenotype is uniquely associated with hypermutated genotype in gliomas
Authors: Hassan Islam , Kotrotsou Aikaterini , Matsuoka Carlos Kamiya , Alfaro-Munoz Kristin D. , Elshafeey Nabil , Shafei Nancy El , Zinn Pascal O. , Groot John F. de , Colen Rivka R.
Published: August 2018

INTRODUCTION Hypermutation is the excessive accumulation of DNA mutation in cancer cells. This specific hypermutated genotype has been reported in low and high grade gliomas, specifically post-temozolomide treatment and is associated with treatment-resistance. Herein, we sought to identify an imaging-based signature for hypermutated gliomas using a radiomics-based approach.

MATERIALS AND METHODS In this IRB-approved retrospective study, we analyzed a total of 101 patients with primary gliomas from the University of Texas MD Anderson Cancer Center. Next generation sequencing (NGS) platforms (T200 and Foundation 1) were used to determine the Mutation burden status in post-biopsy (stereotactic/excisional). Patients were dichotomized based on their mutation burden; 77 hypomutated (<30 mutations) and 24 hypermutated (>=30 mutations or <30 with MMR gene or POLE/POLD gene mutations). Radiomic analysis was performed on the conventional MR images (FLAIR and T1 post-contrast) obtained prior to tumor tissue surgical sampling; and a total of 2480 rotation-invariant radiomic features were extracted using: (i) the first-order histogram and (ii) grey level co-occurrence matrix. The Maximum Relevance Minimum Redundancy technique was used to select the most relevant radiomic features. ROC analysis and leave-one-out cross-validation (LOOCV) were used to assess the performance of the Support Vector Machine (SVM) classifier as and AUC, Sensitivity, Specificity, and p-value were obtained.

RESULTS We found 100 radiomic features that can discriminate between hypermutated versus hypomutated gliomas, AUC 96.3% (CI: 90.2%-98.9%), Sensitivity 100%, Specificity 95%, p-value=3.769e-6.

CONCLUSION Hypermutated gliomas has a unique radiomic quantitative signature that can be used to predict mutation burden regardless of tumor grade or histopathology.

Citation Format: Islam Hassan, Aikaterini Kotrotsou, Carlos Kamiya Matsuoka, Kristin D. Alfaro-Munoz, Nabil Elshafeey, Nancy El Shafei, Pascal O. Zinn, John F. de Groot, Rivka R. Colen. A radiomic-based MRI phenotype is uniquely associated with hypermutated genotype in gliomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2955.
Abstract 2956: Mechanisms of resistance for osimertinib for patients with EGFR-mutant lung cancer: MD Anderson Cancer Center single institution experience with osimertinib resistance
Authors: Le Xiuning , Negrao Marcelo Vailati , Nilsson Monique , Robichaux Jacqulyne , Roarty Emily , Rinsurongkawong Waree , Glisson Bonnie , Zhang Jianjun , Heymach John V.
Published: August 2018

PURPOSE: Osimertinib was initially approved for treating epidermal growth factor receptor (EGFR) T790M positive non-small cell lung cancer (NSCLC), and recently is moving forward as the first-line treatment for EGFR sensitizing mutation positive NSCLC. However, the types and frequencies of resistance mechanisms to osimertinib have been incompletely described, and currently there are no guidelines for managing these patients. We evaluated clinical and genetic characteristics of patients who received osimertinib for EGFR-mutant NSCLC. We also provide treatment experience after progression on osimertinib.

PATIENTS AND METHODS: Using the MD Anderson Lung Cancer Moon Shot GEMINI database, we identified patients treated with osimertinib and performed clinical outcome analysis. Molecular profiling analysis was performed at the time of progression when available.

RESULTS: Eighty two patients were identified. Median PFS on osimertinib was 8.8 months (95% CI, 6.7 to 10.9). Fifty three of the 82 patients had disease progression on osimertinib. Among them, 30 had molecular profiling upon progression. Other than two cases with germline T790M, 11 cases preserved and 17 cases lost T790M mutation. In T790M preserved cases, tertiary mutations of C797S (5 cases) and L792H (2 cases) in EGFR gene, as well as MET amplification (4 cases), were the most common mechanisms of resistance. In T790M lost cases, 12 cases were without known resistance mechanisms. Upon progression, osimertinib was continued in 34 of 51 patients and 17 (50%) of them received local consolidation radiation. The osimertinib continued patients had longer PFS2 compared to the patients who discontinued on osimertinib upon first progression.

CONCLUSION: T790M loss is common (61%) in osimertinib resistance cases. In T790M-preserved cases, tertiary mutation within EGFR was the most common mechanism of resistance. MET amplification was observed in both T790M preserved and loss cases. In T790M loss cases, the mechanisms of resistance were mostly EGFR independent, highlighting the importance of understanding T790M-negative resistance mechanisms in the osimertinib era.

Citation Format: Xiuning Le, Marcelo Vailati Negrao, Monique Nilsson, Jacqulyne Robichaux, Emily Roarty, Waree Rinsurongkawong, Bonnie Glisson, Jianjun Zhang, John V. Heymach. Mechanisms of resistance for osimertinib for patients with EGFR-mutant lung cancer: MD Anderson Cancer Center single institution experience with osimertinib resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2956.
Abstract 298: Identifying mechanisms of anti-apoptotic adaptation to enhance BAX activation and overcome resistance to apoptosis
Authors: Lopez-Arroyo Andrea G. , Gavathiotis Evripidis
Published: August 2018

The BCL-2 protein family includes both pro- and anti-apoptotic proteins, which have a central role in regulating apoptosis during tumor formation and in response to chemotherapy. Cancer cells can evade apoptosis through upregulation of the BCL-2 anti-apoptotic proteins and/or the downregulation or inhibition of the BCL-2 pro-apoptotic proteins. BAX is a crucial pro-apoptotic BCL-2 family protein that upon activation translocates from the cytosol to the mitochondria to execute mitochondrial outer membrane permeabilization, the “point of no return” for mitochondrial apoptosis. BH3 mimetics, small molecules that have been developed to bind specific anti-apoptotic BCL-2 proteins, such as Venetoclax, have shown efficacy in hematologic cancers but generally are less effective in solid tumors. Here we explored a panel of non-small cell lung cancer (NSCLC) cell lines for elucidating their mechanism of anti-apoptotic adaptation and identify novel therapeutic strategies to overcome resistance to apoptosis. We used the BH3 profiling approach in NSCLC cell lines, as a tool to understand addiction to specific BCL-2 family members, and identified cells that depend on one or more anti-apoptotic proteins for their survival. Furthermore, these cell lines have low expression levels of the activators BH3-only proteins suggesting that downregulation of BH3-only proteins could be a second apoptotic block. Using size-exclusion chromatography of cytosolic cellular extracts we found that NSCLC cell lines contain BAX in dimeric conformation, which is previously characterized to provide resistance to BAX activation, suggesting that this could be a third factor increasing the apoptotic threshold. Our laboratory recently developed a lead BAX activator small molecule, BTSA1, that mimics BIM BH3 helix and interacts with the BAX activation site inducing apoptosis in vitro and in vivo in hematological cancers. We hypothesized that availability of increased amounts of cytosolic BAX monomers in addition to direct BAX activation by BTSA1 would be sufficient to broadly overcome resistance to apoptosis in NSCLC cells. To systematically identify such mechanisms, we have performed combinatorial high-throughput screens using a library of FDA-approved and investigational chemotherapeutic drugs. We identified drugs that significantly enhanced apoptosis when are combined with direct BAX activation. Our work highlights three different mechanisms of anti-apoptotic adaptation and resistance in NSCLC and provides novel pharmacological strategies that may lead to effective therapies for cancer patients.

Citation Format: Andrea G. Lopez-Arroyo, Evripidis Gavathiotis. Identifying mechanisms of anti-apoptotic adaptation to enhance BAX activation and overcome resistance to apoptosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 298.
Abstract 2985: Radiotherapy and αCD40 non-redundantly augment immunity to checkpoint blockade in refractory pancreatic ductal adenocarcinoma
Authors: Dada Hannah , Rech Andrew J. , Victor Christina Twyman-Saint , Minn Andy J. , Vonderheide Robert H.
Published: August 2018

Despite the success of cancer immunotherapy in many disease types, pancreatic ductal adenocarcinoma (PDA) is notably unresponsive to immune checkpoint blockade (ICB) with αPD1 and/or αCTLA4. The mechanism of resistance is poorly understood, but tumor epitopes and the microenvironment, which is immunosuppressive and excludes T cells, are thought to be contributory. To improve response to ICB, we used subcutaneous and orthotopic murine models of PDA to investigate the effect of combination therapy with ICB (CTLA-4 and PD-1 antagonist antibodies), CD40 agonist antibody and radiation therapy (RT). Combination therapy with CD40 agonist antibody, ICB and RT resulted in decrease tumor burden, increase overall survival, and generation of long-term immunity. Response is dependent on T and short-lived myeloid cells, while it is independent of innate activation pathways. Together, these results suggest a dual role for both the innate and adaptive immune response in treating PDA.

Citation Format: Hannah Dada, Andrew J. Rech, Christina Twyman-Saint Victor, Andy J. Minn, Robert H. Vonderheide. Radiotherapy and αCD40 non-redundantly augment immunity to checkpoint blockade in refractory pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2985.
Abstract 2989: BET inhibitors induce Rac1-dependent MNK and eIF4E phosphorylation in cancer cells
Authors: Pham Thao , Decant Brian T. , Kumar Krishan , Shang Meng , Matsangou Maria , Ebine Kazumi , Munshi Hidayatullah G.
Published: August 2018

Patients with recurrent differentiated thyroid cancers (DTCs) have poor prognosis and suffer from multiple complications from progressive symptomatic disease. Here we show that eukaryotic translation initiation factor 4E (eIF4E), an oncogene that is overexpressed in aggressive thyroid cancers, is required for growth of DTC cells in collagen microenvironment. We show that inhibitors targeting bromodomain and extra-terminal domain (BET) family of proteins also decrease growth of DTC cells in the collagen microenvironment. Unexpectedly, we have found that BET inhibitors induce MNK and eIF4E phosphorylation in cancer cells. Mechanistically, BET inhibitors induce Rac1-mediated cytoskeletal changes and targeting Rac1 blocks these changes as well as MNK and eIF4E phosphorylation. Functionally, we show that MNK inhibitors potentiate the effects of BET inhibitors at suppressing cancer cell proliferation and limiting sphere-forming ability. Together, these results demonstrate crosstalk between BET proteins and the MNK-eIF4E pathway, suggesting that combination therapy with BET and MNK inhibitors has the potential for synergistic inhibition of cancer cells.

Citation Format: Thao Pham, Brian T. Decant, Krishan Kumar, Meng Shang, Maria Matsangou, Kazumi Ebine, Hidayatullah G. Munshi. BET inhibitors induce Rac1-dependent MNK and eIF4E phosphorylation in cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2989.
Abstract 2993: A switch in epigenetic silencing mechanisms of endogenous retroviruses during human genome evolution
Authors: Ohtani Hitoshi , Liu Minmin , Zhou Wanding , Liang Gangning , Jones Peter A.
Published: August 2018

Approximately 9% of the human genome is derived from Endogenous Retroviruses (ERVs), which are a type of transposable element. ERVs started to become integrated into the ancestral human genome about 100 million years ago. Recent studies have reported that silencing mechanisms of long terminal repeats regions (LTRs), which are the putative promoters of ERVs, depend on DNA methylation, heterochromatin conformation (H3K9me3) and the PRC2 complex (H3K27me3). However, extensive maps of LTR distribution and the associated epigenetic marks have not yet been provided in human cancer cells. Here we report a switch in epigenetic silencing mechanisms of the approximately 450,000 LTR elements present in the non-genic regions of human DNA. Total RNA-seq in human colon cancer HCT116 cells following DNA methylation inhibitor treatment or knockdown of individual H3K9me2/3 histone methyltransferases (G9a, SETDB1, SETDB2, SUV39H1 and SUV39H2), H3K27me3 (EZH2) or a scaffold protein TRIM28 revealed that about 1,000 of evolutionary young LTRs were predominantly silenced by DNA methylation, whereas about 800 of intermediate age LTRs were silenced by histone methylation. They therefore have undergone an “epigenetic switch” in silencing mechanism during host genome evolution. Eventually, evolutionary old LTRs become inactive by accumulation of loss-of-function mutations. Consistent with these results, CpG sites in evolutionary young LTRs were methylated at higher levels than in intermediate age LTRs, whereas H3K9me2 and H3K9me3 marks were enriched on intermediate age LTRs. Interestingly, knockdowns of EZH2 showed limited upregulation of LTRs by itself, but multiple LTRs were upregulated by combination treatment with DNA methylation inhibitor. This is probably due to a process, in which removal of DNA methylation leads to the subsequent recruitment of EZH2 resulting in suppression by the polycomb repressive complex PRC2. Our earlier studies showed that LTR expressions lead to activation of viral defense pathways and apoptosis, however the species of LTRs was not characterized. We found that the activation of viral defense pathway was correlated with the upregulation of evolutionary young, but not intermediate age LTRs. Dual inhibition of DNA methylation and histone modifications by knockdown of G9a, SUV39H1 and EZH2 showed further upregulation of evolutionary young LTRs. Therefore, combination treatment targeting DNA methylation and the histone methyltransferases (G9a, SUV39H1 and EZH2) inhibitor may be useful in epigenetic therapy for cancer patients.

Citation Format: Hitoshi Ohtani, Minmin Liu, Wanding Zhou, Gangning Liang, Peter A. Jones. A switch in epigenetic silencing mechanisms of endogenous retroviruses during human genome evolution [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2993.
Abstract 302: Selective Mcl-1 inhibition by AZD5991 induces on-target cell death and achieves antitumor activity in multiple myeloma and acute myeloid leukemia
Authors: Tron Adriana E. , Belmonte Matthew A. , Criscione Steven , Clark Edwin A. , Gangl Eric , Gibbons Francis D. , Tyner Jeffrey W. , Kurtz Stephen E. , Ye Qing , Hird Alexander W. , Schuller Alwin , Secrist J. Paul
Published: August 2018

Mcl-1 is a member of the Bcl/Mcl family of proteins that promotes cell survival by preventing induction of apoptosis in a broad range of cancers. High expression of Mcl-1 has been linked to tumor development and resistance to anticancer therapies, underscoring the potential of Mcl-1 inhibitors as anticancer drugs. We have previously shown that AZD5991, a rationally designed macrocycle with sub-nanomolar affinity for Mcl-1 and high selectivity, induces rapid and irreversible commitment to apoptosis in Mcl-1-dependent cancer cells in a manner dependent on proapoptotic BAK. Here, we demonstrate that AZD5991 exhibits cytotoxic activity (GI50<100nM) in various MM and AML cell lines in vitro with an activity profile distinct from the selective Bcl2 inhibitor venetoclax. In vivo, AZD5991 shows potent antitumor activity with complete (100%) tumor regression in several mouse MM and AML xenograft models after a single tolerated dose. AZD5991 shows enhanced efficacy in vivo when combined with standard-of-care agents. Pharmacodynamic studies confirmed that AZD5991 kills cancer cells by activation of the mitochondrial apoptotic pathway. Ex vivo analysis indicates that AZD5991 has single agent activity in primary AML patient samples with LC50 values in the low nanomolar range. Consistent with our findings in AML cell lines, the activity profile for AZD5991 in AML primary samples was distinct from venetoclax, highlighting the unique therapeutic opportunity for AZD5991. Based on these data a phase I clinical trial has been launched for evaluation of AZD5991 in patients with MM and other hematologic malignancies (NCT03218683).

Citation Format: Adriana E. Tron, Matthew A. Belmonte, Steven Criscione, Edwin A. Clark, Eric Gangl, Francis D. Gibbons, Jeffrey W. Tyner, Stephen E. Kurtz, Qing Ye, Alexander W. Hird, Alwin Schuller, J. Paul Secrist. Selective Mcl-1 inhibition by AZD5991 induces on-target cell death and achieves antitumor activity in multiple myeloma and acute myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 302.
Abstract 3021: Plexin-B3 regulates cellular motility, invasiveness and metastasis in pancreatic cancer
Authors: Saxena Sugandha , Hayashi Yuri , Rachagani Satyanarayana , Batra Surinder Kumar , Singh Rakesh Kumar
Published: August 2018

Cancer metastasis significantly worsens the survival of pancreatic cancer (PC) patients. Currently, semaphorins and their high-affinity receptors plexins are considered versatile regulators of cancer cell migration, angiogenesis, invasion and metastasis. Our group identified semaphorin-5A (SEMA5A) as a putative cell adhesion molecule involved in organ-specific homing of PC cells and playing a significant role in PC angiogenesis and metastasis. Thus, SEMA5A and its receptor plexin-B3 represents an attractive targetable axis in PC metastasis. However, for a better understanding of the SEMA5A-initiated downstream signaling events and regulation of cellular phenotypes, it is necessary to delineate the function of its receptor plexin-B3 in PC as well. Thus, understanding the pathologic expression and functional role of plexin-B3 is essential for characterization of SEMA5A/plexin-B3 axis in PC. In the present study, we analyzed plexin-B3 expression in PC disease progression model of PDX-Cre-Kras(G12D) (KC) mice and evaluated the functional role by utilizing plexin-B3 knockdown T3M-4 and CD18/HPAF cells. We observed a reduction of plexin-B3 expression with disease progression in KC mice model and also the poor survival of pancreatic adenocarcinoma stage II patients (n = 24) with lower plexin-B3 expression. Functionally, knockdown of plexin-B3 enhanced in vitro cellular migration and invasiveness of PC cells. Furthermore, plexin-B3 knockdown cells showed a significant increase in cellular size with impaired colony formation in three-dimensional culture. Cell proliferation analysis demonstrated that plexin-B3 knockdown cells showed lower proliferation in comparison with the control cells. We also observed higher metastasis with lower tumor burden in nude mice injected with CD18/HPAF-sh plexin-B3 cells than CD18/HPAF-control cells. Furthermore, the tumors formed by CD18/HPAF-plexin-B3 cells showed higher fibrosis, a higher number of vimentin-positive cells, and lower number of proliferation marker Ki-67-positive cells in comparison with the CD18/HPAF-control tumors. In addition, we observed similar phenotypic changes in PC cells with loss of SEMA5A-ligand of plexin-B3. In summary, our data demonstrate that impairment in SEMA5A/plexin-B3 axis enhances cellular motility and invasiveness of PC cells, thereby resulting in higher metastasis.

Citation Format: Sugandha Saxena, Yuri Hayashi, Satyanarayana Rachagani, Surinder Kumar Batra, Rakesh Kumar Singh. Plexin-B3 regulates cellular motility, invasiveness and metastasis in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3021.
Abstract 303: Novel role of nuclear BH3-only protein BNIP3 in regulation of cellular proliferation
Authors: Singh Amandeep , Azad Meghan , Gibson Spencer
Published: August 2018

The objective of this study is to investigate the role of Bcl-2 nineteen kilodalton interacting protein 3 (BNIP3) in regulating cellular proliferation and identifying the proliferation pathways mediated by BNIP3. BNIP3 is a BH3-only proapoptotic member of Bcl-2 family of cell death regulating proteins. The function of BNIP3 is dependent on its localization and expression levels. Under normal conditions, low levels of BNIP3 are present in the nucleus of cells. Low oxygen or hypoxic conditions lead to increased expression of BNIP3, and high levels of BNIP3 are found in the cytoplasm. Cytoplasmic BNIP3 is associated with caspase-independent apoptotic cell death through mitochondria. If, however, BNIP3 levels are increased in the nucleus, it promotes survival of cells by transcriptionally inhibiting several apoptosis-inducing factors. High levels of BNIP3 in nucleus are seen in majority of glioblastoma tumors, where hypoxic environment of tumor core causes an increase in expression of BNIP3 but high amounts of BNIP3 localize to the nucleus, possibly aiding in the survival of the tumor cells. In this study, we found that BNIP3 knockout mice brains have increased cellularity compared to wild-type brains. We also found that both mouse primary astrocytes and embryonic fibroblasts (MEFs) lacking BNIP3 expression have an increased capacity for proliferation compared to wild-type MEFs. Overexpressing BNIP3 in the nucleus of HEK 293 cells also resulted in reduced proliferation. In contrast, both astrocytes and MEFs lacking BNIP3 failed to show differences in cell death compared to wild-type cells. This reveals a novel function for BNIP3 in regulating cellular proliferation that may lead to new targets for cancer therapy. In future studies, we will identity genes regulated by nuclear BNIP3 that may lead to suppression of cellular proliferation in cancer cells.

Citation Format: Amandeep Singh, Meghan Azad, Spencer Gibson. Novel role of nuclear BH3-only protein BNIP3 in regulation of cellular proliferation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 303.
Abstract 3049: Dexamethasone pretreatment impairs the TS inhibition-mediated flare in thymidine salvage pathway activity
Authors: Katz Sharyn I. , Chen Xiao , Yang Yizeng
Published: August 2018

Introduction: Inhibition of thymidylate synthase (TS) by pemetrexed, an inhibitor of thymidylate synthase, results in an early transient burst or “flare” in thymidine salvage pathway activity at 2 hrs of therapy, which, we have demonstrated in prior publications, can be measurable with FLT ([18F]thymidine)-positron emission tomography (PET) in non-small cell lung cancer (NSCLC). Administration of dexamethasone with pemetrexed-based therapy, as typically practiced in the clinic, could potentially confound this imaging approach since dexamethasone is known to inhibit expression of thymidine kinase 1, a key enzyme in the thymidine salvage pathway. Here we examine the potential impact of dexamethasone on the TS inhibition-mediated thymidine salvage pathway “flare” in NSCLC.

Materials and Methods: In order to determine NSCLC cell line sensitivity to dexamethasone and pemetrexed, IC50 studies were performed on NSCLC cell lines H23, H1975, H460, H1299. TS inhibition-mediated “flare” in thymidine salvage pathway activity was then measured at 2hrs of exposure to pemetrexed and cisplatin in NSCLC cells lines following using 3H-thymidine incorporation assays under the following conditions: control (no chemotherapy or dexamethasone), treated with pemetrexed and cisplatin without dexamethasone, with 24 pretreatment of dexamethasone, or with dexamethasone administered together with chemotherapy. These conditions were chosen to model the delivery of pemetrexed-based therapy in the clinic.

Results: The IC50 of H23, H1975, H460, H1299 for dexamethasone and pemetrexed were 40, 5.9, 718, 362 uM and 0.22, 0.73, 0.14 and 0.66 uM, respectively. Significant blunting of the thymidine salvage pathway “flare” is observed at 2hrs of pemetrexed-based therapy when dexamethasone-sensitive cell lines H23 and H1975 were pretreated with dexamethasone but not when dexamethasone was given together with pemetrexed therapy or in the setting of dexamethasone resistance (H460 and H1299).

Conclusion: Imaging of TS inhibition may be impacted by pretreatment with dexamethasone but not administration of dexamethasone on the same day of therapy delivery.

Citation Format: Sharyn I. Katz, Xiao Chen, Yizeng Yang. Dexamethasone pretreatment impairs the TS inhibition-mediated flare in thymidine salvage pathway activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3049.
Abstract 3050: Imaging tissue extracellular pH for the differential diagnosis of coccidioidomycosis and lung cancer
Authors: Lindeman Leila Renee , Randtke Edward A. , Shubitz Lisa F. , Howison Christine M. , Jones Kyle M. , Pagel Mark D.
Published: August 2018

Introduction: Our objective was to determine whether acidoCEST MRI—a novel, non-invasive MRI method that measures extracellular pH (pHe)—can differentiate between lung tumors and coccidioidomycosis (valley fever) granulomas within in vivo mouse models of lung cancer and valley fever.

Methods: To develop a spontaneous murine lung tumor model, A/J mice received orthotopic injections of urethane to induce formation of lung adenocarcinomas. The Valley Fever Center for Excellence at the University of Arizona infected SW mice with a BSL 2-compatible mutant Coccidioides strain, Δcps1, to develop our preclinical valley fever model. All scans were performed with a Bruker BioSpin 7T MRI system. For all MRI scans, mice were anesthetized with 2.0% isofluorane, respiration and body temperature were monitoreduring scans, and body temperature was maintained at 37 °C. Respiration-triggering (gating) was used in all imaging sequences to compensate for motion artifacts in the lung. For optimal gating, the mouse's respiration rate was maintained at < 50 breaths per minute. Each mouse was scanned with acidoCEST MRI using 370 mg/mL Iopamidol (200 μL IV bolus, 400 μL/hr IV infusion). AcidoCEST MRI (3.5 μT, 300 ms imaging time, 6000 ms presaturation pulse) was performed according to previously published methods, updated with improved respiration gating. For acidoCEST MRI, the saturation pulse continued until terminated by the gating trigger. Spatial pHe maps of tumor and granuloma ROI were produced using Bloch fitting in Matlab 2014a. Average lesion pHe and iopamidol concentration we also recorded.

Results: AcidoCEST MRI was successfully applied to the in vivo imaging of murine lung tumors and coccidioidomycosis granulomas. Lung tumors demonstrated successful uptake of the iopamidol contrast agent, with an average concentration of approximately 40 mM. pHe values in the tumor ROI ranged from 6.5 to 7.2 with an average value of 6.64. Granulomas demonstrated successful uptake of iopamidol with an average concentration of about 75 mM. pHe values in granulomas ranged from 7.2 to 7.4 with an average value of 7.29.

Conclusion: AcidoCEST MRI may be used to quantify the pHe of murine lung tumors and coccidioidomycosis granulomas in vivo. Our results show that pHe is a promising biomarker for the differential diagnosis of coccidioidomycosis and lung cancer.

Citation Format: Leila Renee Lindeman, Edward A. Randtke, Lisa F. Shubitz, Christine M. Howison, Kyle M. Jones, Mark D. Pagel. Imaging tissue extracellular pH for the differential diagnosis of coccidioidomycosis and lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3050.
Abstract 3054: High-throughput microfluidic Labyrinth for the label-free isolation of circulating tumor cells
Authors: Lin Eric
Published: August 2018

Circulating tumor cells (CTCs) present in the blood are the instruments of metastasis and are of high biologic and clinical relevance. Single-cell technologies are playing an increasing role in profiling CTCs in the peripheral blood for detection and real-time monitoring of cancer metastasis. CTCs also help in identifying its distinct drivers. However, current approaches are limited to manual selection of CTCs, which hinders the unbiased comprehensive study of CTCs on a single-cell level. We present a unique label-free microfluidic “Labyrinth” device to isolate CTCs at a high throughput of 2.5mL/min, offering the first biomarker-independent single-cell isolation and genomic characterization platform to study heterogeneous CTC subpopulations in cancer patients. The Labyrinth takes advantage of inertial forces on the microscale in curved geometries to differentially focus cells based on their size. This novel strategy of multicourse path traversing across inner loops to outer loops yielding highest hydrodynamic path length enables focusing of white blood cells (WBCs), leading to high recoveries (> 90%) and efficient separation of WBCs from CTCs, resulting in high purity (~ 200 WBCs/mL), even in whole blood samples without any preprocessing. CTCs were successfully isolated from 56 breast cancer (9.1 CTCs/mL average, range 2-31/mL) and 20 pancreatic cancer (51.6 CTCs/mL average, range 11-115/mL) patients. We detected not only CTCs typically defined by epithelial markers, but also significant numbers of CTCs (>50%) lacking epithelial markers but expressing mesenchymal and cancer stem cell (CSC) markers. Patient samples were then analyzed using single-cell multiplex gene expression. Seventy single cells were successfully recovered and used to identify different subpopulations of CTCs based on their genetic signature, unlike other methods where a positive or negative selection based on protein expression is used. Interestingly, both inter- and intrapatient molecular heterogeneity at the single-cell level in CTCs were observed with cells expressing genes uniquely related to epithelial, MET, and EMT phenotypes. The Labyrinth platform allows a thorough molecular understanding of the heterogeneity among CTCs. This platform also shows CTCs' potential as a biomarker to noninvasively evaluate tumor progression and response to treatment in cancer patients.

Citation Format: Eric Lin. High-throughput microfluidic Labyrinth for the label-free isolation of circulating tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3054.
Abstract 3085: Epithelial S100A2 reduced upper aerodigestive track carcinogenesis by immunomodulation
Authors: Wu Li-Wha
Published: August 2018

Upper aerodigestive track cancer (UATC) including oral and esophageal cancer is the 3rd leading cause of cancer death in the world. Most of these patients demonstrate compromised immunity systems. Myeloid-derived suppressor cells (MDSCs), a population of cells exerting immunosuppressive effects, can sustain cancer progression by providing a pro-tumor microenvironment through the enhancement of T-cell suppressive factors like arginase 1 (ARG1). MDSCs can subsequently facilitate the development of immunosuppressive regulatory T cells (Tregs). Tumor-associated macrophages (TAMs) produce multiple inflammation modulators and are other key players in tumor microenvironment and divided into M1 and M2 phenotypes with specific expression of different cytokines in each type. Several S100 proteins are recently shown to participate in tumor promotion or suppression through both autocrine and least known receptor-mediated paracrine release. RAGE and TLR4, frequently expressed on immune cells, are two known receptors for S100 proteins. Among many S100 proteins, we previously showed a tumor suppressor role of S100A2 in oral cancer. Whether S100A2 functions as a tumor suppressor in mice and plays any role in regulating these immune cell populations during upper aerodigestive track carcinogenesis remains elusive. Due to lack of S100A2 expression in mice, epithelial-specific human S100A2 transgenic mice and their wildtype littermates were used for tumor induction in upper areodigestive track by the co-treatment of 4NQO and arecoline. Epithelial S100A2 significantly repressed tumor formation in esophagus. To understand the involvement of immune cell recruitment in these mice, flow cytometry and qRT-PCR analyses were used. Among the key molecules associated with MDSCs, Tregs and TAMs, S100A2 preferentially induced tumor macrophage polarization to M1 phenotype with a marginal decrease of Tregs recruitment at 7 month post tumor induction. Together, epithelial S100A2 exerts anti-tumor effect in part through differential impact on immune cell recruitment although more studies are needed to underscore the action mechanism.

Citation Format: Li-Wha Wu. Epithelial S100A2 reduced upper aerodigestive track carcinogenesis by immunomodulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3085.
Abstract 3099: Hydrocarbon carcinogenicity reexamined: An extremly potent direct-acting mutagen is common to smoke, soot and ash from a variety of combustion sources, including cigarette tobacco
Authors: Blackburn Gary R.
Published: August 2018

Percivall Pott (1714-1788), an English surgeon, is generally credited with being the first to suggest that cancer may be induced by exposure to environmental carcinogens – in his case, cancer of the scrotum in London chimney sweeps occupationally exposed to soot. It is perhaps not surprising, therefore, that combustion products became a primary focus of later research into the mechanisms of chemical carcinogenesis. Early on, those studies pointed toward a particular class of compounds as being primarily responsible for cancer induction by such materials, a group of environmentally ubiquitous compounds called polycyclic aromatic hydrocarbons, or PAHs. One such PAH, benzo[a]pyrene (BaP), is perhaps the most studied compound in all of cancer research. While there is little doubt that BaP and its congeners are the primary carcinogens in incomplete combustion products like coal tar, their concentrations in other hydrocarbon mixtures are too low to fully account for their overall carcinogenic potency. It is possible that other factors such as tumor promotion contribute to the additional potency, but it might also be expected that there are significant contributions from nitro-PAH derivatives, in particular the isomers of dinitropyrene (DNP) found in carbon black, diesel exhaust and other combustion products. One such isomer, 1,6-dinitropyrene was shown by Iwagawa et al. to have three-times the carcinogenic potency of BaP when injected directly into the lungs of rats. In order to indirectly test nitroaromatic contribution to combustion product carcinogenicity, extracts of smoke soot, ash and food products exposed to smoke during processing were fractionated by HPLC, and the fractions tested in the Ames Test without metabolic activation. All showed a common peak of extremely potent direct-acting mutagenicity at a retention time similar to that of dinitropyrene. Efforts are currently underway to fully characterize the mutagen by a combination of standard analytical means.

Citation Format: Gary R. Blackburn. Hydrocarbon carcinogenicity reexamined: An extremly potent direct-acting mutagen is common to smoke, soot and ash from a variety of combustion sources, including cigarette tobacco [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3099.