bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract A105: Checkpoint kinase 1 and 14-3-3 proteins inhibit atypical E2Fs to prevent a permanent cell cycle arrest
Authors: Yuan Ruixue
Published: August 2018

The atypical E2Fs, E2F7 and E2F8, act as potent transcriptional repressors of DNA replication genes, providing them with the ability to induce a permanent S-phase arrest and suppress tumorigenesis. Surprisingly in human cancer, transcript levels of atypical E2Fs are frequently elevated in proliferating cancer cells, suggesting that the tumor suppressor functions of atypical E2Fs might be inhibited through unknown post-translational mechanisms. Here, we show that E2F7 and E2F8 can be directly phosphorylated by Checkpoint kinase 1 (Chk1) to prevent a permanent cell cycle arrest. We found that multiple 14-3-3 protein isoforms interact with both E2Fs in a Chk1-dependent manner. We show that 14-3-3 proteins inhibit E2F7 and E2F8 repressor function without disrupting their binding to target gene promoters or subcellular translocation. In addition, we observed that high levels of 14-3-3 strongly correlate with upregulated transcription of atypical E2Fs target genes in human cancer. Thus, we reveal that Chk1 and 14-3-3 proteins cooperate to inactivate the transcriptional repressor functions of atypical E2Fs. This mechanism might be of particular importance to cancer cells, since they are exposed frequently to replication stress and DNA-damaging therapeutic reagents, which are both known inducers of Chk1 activity.

Citation Format: Ruixue Yuan. Checkpoint kinase 1 and 14-3-3 proteins inhibit atypical E2Fs to prevent a permanent cell cycle arrest [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A105.
Abstract A107: Development of polymerase theta inhibitors for precision medicine in BRCA-deficient cancers
Authors: Pomerantz Richard T.
Published: August 2018

DNA polymerase theta (Polq) is important for the proliferation of BRCA-deficient cancer cells, but is dispensable for normal cell growth. Thus, Polq is widely considered to be an important new drug target for BRCA-deficient cancers, such as those in the breast, ovary, prostate, pancreas, and blood. We have identified "expanded-size" nucleoside analogs that are uniquely incorporated by Polq and inhibit its activity. We have also identified small-molecule inhibitors of Polq through a random high-throughput screening approach. Consistent with the ability of Polq to promote the survival of BRCA-deficient cells, preliminary studies show that a newly identified Polq small-molecule inhibitor selectively kills cells deficient in BRCA2, while sparing wild-type cells. We are currently further advancing Polq nucleoside analog and small-molecule inhibitors via structure activity relationship (SAR) and medicinal chemistry studies with the goal of testing these inhibitors in BRCA-deficient PDX mouse models.

Citation Format: Richard T. Pomerantz. Development of polymerase theta inhibitors for precision medicine in BRCA-deficient cancers [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A107.
Abstract A114: SIRT2 directs DNA-PKcs in the DNA damage response
Authors: Head Pamelasara E. , Zhang Hui , Yu David S.
Published: August 2018

DNA Damage Response (DDR) pathways, including DNA repair and cell-cycle checkpoints, are critical for maintaining genome integrity and preventing disease including cancer. Deficiencies in the DDR result in increased susceptibility to cancer, a leading cause of morbidity and mortality worldwide. However, the mechanisms mediating the activities of the DDR and how their dysregulation leads to genomic instability and a tumor-permissive phenotype are not fully understood. Sirtuin 2 (SIRT2) is a class III NAD+ dependent histone deacetylase implicated in maintaining genomic stability and tumor suppression in that genetic loss of Sirt2 results in both genomic instability and specific murine breast and liver tumors. SIRT2 deficiency in human cells results in hypersensitivity to DNA damage, impaired recovery from replication arrest, and a defect in the G2/M checkpoint in response to ionizing radiation (IR). Preliminary data demonstrate a strong interaction between SIRT2 and DNA-PKcs following IR in human cell lines. DNA-PKcs is a well-established nonhomologous end-joining (NHEJ) mediator kinase that is capable of self-regulation by autophosphorylation at serine 2056 to promote end ligation. SIRT2 knockdown inhibits localization of DNA-PKcs to sites of microirradiation and co-immunoprecipitation with the KU complex in response to IR. Inhibition of localization leads to decreased self-activation of DNA-PKcs at serine 2056 and decreased interaction with KU in SIRT2 knockout lines in response to IR. DNA-PKcs self-phosphorylation and interaction with KU is rescued following damage with wild-type SIRT2 but not with deacetylase dead SIRT2 H187Y, indicating that SIRT2 enzymatic function is necessary for regulation. Overexpression of SIRT2 leads to premature autophosphorylation of DNA-PKcs a serine 2056 without induction of DNA damage. We also demonstrate SIRT2 is capable of deacetylating DNA-PKcs in vitro and in cells. SIRT2 overexpression leads to increased DNA-PKcs self-phosphorylation before and after IR. In addition SIRT2 knockout cell lines exhibit increased sensitivity to IR and CPT. Overall, these data demonstrate that SIRT2 could be a strong potential cancer therapeutic target.

Citation Format: Pamelasara E. Head, Hui Zhang, David S. Yu. SIRT2 directs DNA-PKcs in the DNA damage response [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A114.
Abstract A115: Targeting glycolysis and RAD51-dependent repair in B-lymphoid cancers
Authors: Hasham Muneer G. , Chow Kin-hoe , Wilson John , LaBrie Nathan , Perkins Bryant , Branca Jane , Sproule Thomas , Roopenian Derry
Published: August 2018

Activation-Induced Cytidine Deaminase (AID) mutates and modifies the IgH locus. However, it also initiates double-strand breaks (DSBs) throughout the genome. This effect of AID is balanced by RAD51-dependent homologous recombination repair. Importantly, we previously showed that inhibition of RAD51 function by a small-molecule inhibitor leads to cell death of AID-positive neoplastic cells. While we have used AID-RAD51 imbalance as a potential chemotherapy approach, the efficacy of current RAD51 inhibitors can be further improved. Studies have shown a relationship between glycolysis and RAD51 function, and therefore targeting the glycolytic pathway is a viable strategy to enhance RAD51 inhibitor efficacy. Here we show that glycolytic inhibitor 2DG and RAD51 inhibitor DIDS act synergistically to reduce B-lymphocyte human chronic lymphocytic leukemia proliferation ex vivo, and mice xenografted with this cell line showed significant reduction in the tumor burden in the presence of both 2DG and DIDS. These data suggest that the glycolytic pathway and DNA repair can be simultaneously targeted to produce better chemotherapies against B-lymphoid cancers.

Citation Format: Muneer G. Hasham, Kin-hoe Chow, John Wilson, Nathan LaBrie, Bryant Perkins, Jane Branca, Thomas Sproule, Derry Roopenian. Targeting glycolysis and RAD51-dependent repair in B-lymphoid cancers [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A115.
Abstract A171: Epigenetic modification of α-N-acetylgalactosaminidase (NAGA) enhances cisplatin resistance in ovarian cancer
Authors: Ju Woong , Sung Hye Youn , Ahn Jung-Hyuck
Published: August 2018

Although cisplatin is one of the most effective antitumor drugs for ovarian cancer, the emergence of chemoresistance to cisplatin in over 80% of initially responsive patients is a major barrier to successful therapy. The precise mechanisms underlying the development of cisplatin resistance are not fully understood, but alteration of DNA methylation associated with aberrant gene silencing may play a role. To identify epigenetically regulated genes directly associated with ovarian cancer cisplatin resistance, we compared the expression and methylation profiles of cisplatin-sensitive and -resistant human ovarian cancer cell lines. We identified α-N-acetylgalactosaminidase (NAGA) as one of the key candidate genes for cisplatin drug response. Interestingly, in cisplatin-resistant cell lines, NAGA was significantly downregulated and hypermethylated at a promoter CpG site at position +251 relative to the transcriptional start site. Low NAGA expression in cisplatin-resistant cell lines was restored by treatment with a DNA demethylation agent, indicating transcriptional silencing by hyper-DNA methylation. Furthermore, overexpression of NAGA in cisplatin-resistant lines induced cytotoxicity in response to cisplatin, whereas depletion of NAGA expression increased cisplatin chemoresistance, suggesting an essential role of NAGA in sensitizing ovarian cells to cisplatin. These findings indicate that NAGA acts as a cisplatin sensitizer and its gene silencing by hypermethylation confers resistance to cisplatin in ovarian cancer. Therefore, we suggest NAGA may be a promising potential therapeutic target for improvement of sensitivity to cisplatin in ovarian cancer.

Citation Format: Woong Ju, Hye Youn Sung, Jung-Hyuck Ahn. Epigenetic modification of α-N-acetylgalactosaminidase (NAGA) enhances cisplatin resistance in ovarian cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A171.
Abstract A173: Long-term responders to epigenetic modulators: abexinostat and pazopanib
Authors: Aggarwal Rahul , Pawlowsk Nela , Grabowsky Jennifer , Harb Armand , Abri-Lavasani Kamran , Thomas Scott , Munster Pamela N.
Published: August 2018

Characterization of long-term responders in a phase I trial evaluating the role of epigenetic modulation of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor by using a histone deacetylase abexinostat in combination with pazopanib to enhance response and reverse resistance. Patients and Methods: Pazopanib was administered once a day on days 1 to 28 and abexinostat was administered orally twice a day on days 1 to 5, 8 to 12, and 15 to 19 (schedule A) or on days 1 to 4, 8 to 11, and 15 to 18 (schedule B). Dose escalation (3 + 3 design) in all solid tumors was followed by dose expansion in renal cell carcinoma (RCC). Histone acetylation and HDAC2 expression were correlated long-term responders, >1y). Results: Fifty-one patients including RCC (N = 22) were enrolled, including 30 (59%) with one or more lines of prior VEGF-targeting therapy. Toxicities and PK studies were reported previously. 7 pts had response > 23 months (23-60+), including 5/22 patients with RCC, and one patient with medullary thyroid and thymic neurondocrine cancer. Long-term response was associated with high HDAC2 expression in PBMCs, increased histone acetylation, and modulation of VEGF level. Conclusion: Epigenetic modulation with HDAC inhibitors is strongly dependent on host factors to promote long-term benefit to abexinostat and pazopanib in pretreated patients.

Citation Format: Rahul Aggarwal, Nela Pawlowsk, Jennifer Grabowsky, Armand Harb, Kamran Abri-Lavasani, Scott Thomas, Pamela N. Munster. Long-term responders to epigenetic modulators: abexinostat and pazopanib [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A173.
Abstract A177: Role of promoter methylation in regulation of Notch4 and JAG2 gene expression in human glioblastoma
Authors: Aithal Madhuri G S , Narayanappa Rajeswari
Published: August 2018

In cancer, DNA methylation causes alteration in gene expression affecting important signal transduction pathways. Since methylation occurs at a very early stage and is reversible, hypermethylated promoters hold great promise as biomarkers for early detection and effective drug targets for gene reactivation. The Notch signaling pathway is one such important developmental pathway governing cell fate decisions. Dysregulated Notch signaling is found to have a prominent role in the development of various cancers. Glioblastoma (GBM) is the most common primary brain tumor, with a very poor prognosis despite advanced treatment facilities due to poor molecular stratification. It is therefore important to study genetic and epigenetic events leading to gliomagenesis and to guide new treatment strategies. The aim of this study was to detect Notch pathway genes potentially regulated by promoter methylation in human GBM. We used real-time PCR and quantitative methylation-specific PCR to study methylation status of underexpressed Notch pathway genes from human GBM formalin-fixed, paraffin-embedded sections. 50% of samples showed methylation at Notch4 gene promoter at levels higher than 25 % (P < 0.05). However, JAG2 gene promoter was estimated to be methylated at a negligible level (<2 %) (P < 0.05). Our study showed poor gene expression and high-level methylation of Notch4 gene, suggesting a possibility of epigenetic silencing. However, low JAG2 gene expression despite not being highly methylated suggests lack of correlation between gene expression and promoter methylation and the presence of alternative regulatory mechanisms. This study for the first time provides gene expression and DNA methylation profiles of Notch pathway genes from GBM patient samples. We have identified genes whose expression may be regulated by epigenetic mechanisms and thus can be used as potential biomarkers. This study will eventually give clues to improve diagnosis, prognosis, and treatment of GBM.

Citation Format: Madhuri G S Aithal, Rajeswari Narayanappa. Role of promoter methylation in regulation of Notch4 and JAG2 gene expression in human glioblastoma [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A177.
Abstract A185: Combining unbiased network analysis and cancer genomics to guide precision medicine-oriented early-phase clinical trials
Authors: Torres-Ayuso Pedro , Sahoo Sudhakar , Chester Christopher , Hodgkinson Cassandra , Galvin Melanie , Leong Hui Sun , Frese Kristopher , Marais Richard , Dive Caroline , Krebs Matthew , Brognard John
Published: August 2018

Background: Precision medicine aims to tailor cancer therapies to target specific tumor-promoting aberrations. For tumors that lack actionable drivers, extensive molecular characterization and preclinical drug efficacy studies will be required to match a patient with the appropriate targeted therapy. Patients and Methods: Next-generation sequencing, high-throughput signaling network analysis, and drug efficacy trials were used in a tumor-derived cell line and a patient-derived xenograft (PDX) model to identify actionable targets for therapeutic intervention. Results: A patient-derived xenograft (PDX) model for preclinical research was successfully established and no actionable mutations were identified after whole exome sequencing of the patient’s DNA. Whole genome sequencing revealed amplification of the 3q and 5p chromosomal arms, which include the PIK3CA and RICTOR genes, respectively. Consistent with amplification of these genes, pathway analysis revealed activation of the AKT pathway. Based on this analysis, efficacy of PIK3CA and AKT inhibitors were evaluated, and response to the AKT inhibitor AZD5363 was observed in in vitro and in vivo models established from the patient’s biopsy, indicating the patient would benefit from targeted therapies directed against the serine/threonine kinase AKT. Conclusion: High-throughput signaling pathway analysis complements next-generation sequencing approaches for detection of actionable alterations and will aid in patient stratification into early-phase clinical trials.

Citation Format: Pedro Torres-Ayuso, Sudhakar Sahoo, Christopher Chester, Cassandra Hodgkinson, Melanie Galvin, Hui Sun Leong, Kristopher Frese, Richard Marais, Caroline Dive, Matthew Krebs, John Brognard. Combining unbiased network analysis and cancer genomics to guide precision medicine-oriented early-phase clinical trials [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A185.
Abstract A186: Dual CRISPRi and CRISPRa screening reveals phenotypic switches in response to BRAF inhibition
Authors: le Sage Carlos , Panckier Prince , Cross Bendict CS
Published: August 2018

Functional genomic screening with CRISPR-Cas9 has provided a powerful and precise new way to interrogate the phenotypic consequences of gene manipulation in high-throughput, unbiased analyses. Rapid development of pooled lentivirus and deep-sequencing-led approaches has allowed us and others to exploit this technology in target ID, target validation, drug MOA analysis, and patient stratification. To date, the majority of screens have been conducted using loss-of-function perturbation driven by CRISPR-Cas9 enacted gene knockout. While powerful, this approach does not allow for the examination of activating gene function, leaving a salient hole in the functional genomic analysis. To address this, we have developed two new paired pooled screening platforms using catalytically inactivated Cas9 (dCas9) to control gene expression in both loss- and gain-of-function cell reprogramming. Our CRISPRi platform uses a streamlined and high-performance approach with an improved tracrRNA sequence incorporated into a single-shot transduction protocol. Our CRISPRa platform is based on the synergistic activation mediator (SAM) system and both platforms have been adapted to use next-generation, highly optimized whole-genome libraries in order to enact maximum gene expression modulation. Validation analysis of both tools revealed outstanding performance and sensitivity, with greater than ten-fold improvement in detection rates compared to existing platforms. We used these paired tools to explore the development of resistance mechanisms to the BRAF V600E inhibitor, vemurafenib. Unambiguous discovery of both expected hits and multiple novel genes involved in drug resistance was determined by both platforms. Those novel hits arising from the CRISPRi screen represented an enriched cohort of essential genes that have been missed by previous screens using RNAi and CRISPR-KO technologies. Most interestingly, simultaneous evaluation of both activating and inhibiting perturbations revealed direct and opposing phenotypic effects within complex gene networks, switching the response of affected cells to either sensitization or resistance. Thus, in contrast to loss-of-function-only analysis, this paired approach allows the discovery of key genes that control the drug response, but through an inhibitory mechanism. These genes were found to sit in the center of the hit nexus and revealed as key components only by the assimilation of both datasets, demonstrating the unique power of bidirectional functional genomic screening approaches.

Citation Format: Carlos le Sage, Prince Panckier, Bendict CS Cross. Dual CRISPRi and CRISPRa screening reveals phenotypic switches in response to BRAF inhibition [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A186.
Abstract A193: Quantitative global profiling reveals how RB-loss changes the metabolome, transcriptome, and proteome of cells and provides new opportunities to target RB-deficient cancer cells
Authors: Dowdle James , Nicolay Brandon , Haas Wilhelm , Dyson Nicholas , Miles Wayne O.
Published: August 2018

Disruption of the RB/E2F pathway is one of the hallmarks of cancer cells. There are, however, very few treatment options available to specifically target RB-deficient tumor cells. We hypothesized that was likely due to gaps in our knowledge about how RB-inactivation reprograms cells. To fill this void, we used a doxycycline-inducible shRNA system to deplete either RB or a negative control from non-tumorigenic human cells and profiled how RB-loss changed the metabolome (LCMS), transcriptome (RNA-seq), and proteome (mass spectrometry). By combining these quantitative approaches, we have identified statistically significant changes in 84 metabolites, 1257 mRNAs, and 527 proteins in RB-deficient cells, suggesting that RB-depletion results in widespread cellular reprogramming. Our analysis has identified (1) a number of new RB/E2F responsive pathways including the Interferon Response genes, extracellular matrix (ECM) proteins, and the Golgi apparatus; (2) significant increases in glucose metabolites and glucose metabolism proteins, independent of mRNA changes; (3) E2F target genes, which are well transcribed but show poor protein correlations; and (4) widespread increases in the purine and pyrimidine scavenging and synthesis pathways and their products. We have extended these experiments to confirm that these new pathways contribute to the phenotypes of RB-deficient cancer cells. Importantly, we then determined whether these mRNA and protein changes caused by RB-loss in cells are also seen in tumors. To do this we profiled RB1-/- retinoblastomas and normal retinal tissue. From these samples, we were able to characterize a number of highly homologous changes to the Interferon Response, purine/pyrimidine biosynthesis, ECM, glucose metabolism, and the RB/E2F target genes. Our results show that RB-loss effects many more biologic and potentially targetable pathways other than just pro-proliferation and apoptotic genes in both cell lines and tumors. We hope that this in-depth profiling of how RB-deficiency changes cells will provide new opportunities to develop methods to exploit the biologic dependencies caused by RB-loss.

Citation Format: James Dowdle, Brandon Nicolay, Wilhelm Haas, Nicholas Dyson, Wayne O. Miles. Quantitative global profiling reveals how RB-loss changes the metabolome, transcriptome, and proteome of cells and provides new opportunities to target RB-deficient cancer cells [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A193.
Abstract A194: Transcriptome evaluation of papillary thyroid cancer with TERT promoter mutation
Authors: Cheng Shih-Ping , Chien Ming-Nan , Liu Chien-Liang , Hsu Yi-Chiung , Yang Po-Sheng , Lee Jie-Jen
Published: August 2018

Background: Mutations in the promoter region of the telomerase reverse transcriptase (TERT) gene have recently been described in thyroid cancer and have been linked with poor prognosis. The mutations result in cancer-specific telomerase reactivation. However, functional effects of TERT promoter mutations other than telomere maintenance remain elusive. Methods: We examined papillary thyroid cancer data from The Cancer Genome Atlas. Clinicopathologic characteristics were compared between patients with or without TERT promoter mutations. A control cohort was selected from patients without TERT promoter mutations by propensity score matching. Differentially expressed genes were generated by comparing transcriptome profiling between the two groups. Results: A total of 382 patients with papillary thyroid cancer were included for analysis. TERT promoter mutations were identified in 36 patients. TERT promoter mutations were associated with older age, larger tumor size, the presence of extrathyroidal extension, more advanced TNM stage, and high risk of recurrence. Following propensity score matching, pathway analysis of differentially expressed genes indicated that TERT promoter mutations were associated with upregulation of DNA damage response and downregulation of nitric oxide signaling and fatty acid β-oxidation. Conclusion: Our results confirmed that acquisition of TERT promoter mutations in papillary thyroid cancer leads to bypass of replicative senescence. Furthermore, the mutations may be associated with other signaling and metabolic alterations. Our findings can potentially identify extended therapeutic targets.

Citation Format: Shih-Ping Cheng, Ming-Nan Chien, Chien-Liang Liu, Yi-Chiung Hsu, Po-Sheng Yang, Jie-Jen Lee. Transcriptome evaluation of papillary thyroid cancer with TERT promoter mutation [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A194.
Abstract A196: Nano-diamino-tetrac (NDAT) enhances resveratrol-induced antiproliferation by reducing RRM2 expression in colorectal cancer cells
Authors: Chin Yu-Tang , Lin Chi-Yu , Shih Ya-Jung , Lin Shin-Ying , Chen YiRu , Mousa Shaker A. , Tang Heng-Yun , Lin Hung-Yun , Davis Paul J.
Published: August 2018

Tetraiodothyroacetic acid (tetrac) and its nanoparticulate derivative (Nano-diamino-tetrac, NDAT) inhibit cancer cell proliferation by multiple mechanisms. Resveratrol causes inducible COX-2-dependent antiproliferation in multiple types of cancer cells. Both agents suppress tumorigenesis in xenograft models. In the current study, we demonstrated the potentiating effect of NDAT on resveratrol-induced antiproliferation in human colorectal cancer cells. Induction of antiproliferation by resveratrol was shown by induction of COX-2, by increased expression of of antiproliferative genes and by reduction of transcription of pro-proliferative genes. Antiproliferation induced by NDAT was associated with downregulation of ribonucleoside-diphosphate reductase subunit 2 (RRM2), an inhibitor of resveratrol-induced COX-2 accumulation. Interestingly, resveratrol itself induced RRM2 expression in a concentration-dependent manner that was variable among different colorectal cancer cells. Knockdown of RRM2 by shRNA increased resveratrol-induced COX-2 expression. Combined treatment with resveratrol and NDAT in shRNA-transfected colorectal cancer cells resulted in further enhancement of COX-2 accumulation and antiproliferation. In summary, RRM2 is a target of NDAT and may contribute to increased resveratrol-induced antiproliferation in colorectal cancer cells in the presence of NDAT. From these studies, we expect to develop a cellular and molecular mechanistic framework for better delineation of the chemotherapeutic activities of NDAT with resveratrol against colorectal carcinogenesis. Novel biomarkers may also emerge from such studies.

Citation Format: Yu-Tang Chin, Chi-Yu Lin, Ya-Jung Shih, Shin-Ying Lin, YiRu Chen, Shaker A. Mousa, Heng-Yun Tang, Hung-Yun Lin, Paul J. Davis. Nano-diamino-tetrac (NDAT) enhances resveratrol-induced antiproliferation by reducing RRM2 expression in colorectal cancer cells [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A196.
Abstract A205: Q701, a selective Axl and Mer inhibitor as an immune checkpoint inhibitor
Authors: Yang Yeong-In , Kang Hwankyu , Park Dongsik , Ahn Jiye , Choi Jinho , Ahn Seohyun , Kim Jaeseung , Nam Kiyean
Published: August 2018

Axl and Mer receptors are reported to have many functions, including promotion of epithelial-mesenchymal transition (EMT), resistance to antitumor therap,y and negative regulation of the innate immune response. Particular attention has been given to Axl and Mer receptor tyrosine kinase's (RTK) roles in regulating macrophage and NK cell activation as tumor cells exploit Axl and Mer signaling pathway to downregulate antitumor immunity, constituting an immune checkpoint. Q701 is a highly potent, selective, orally available Axl and Mer RTK inhibitor that can relieve immune suppression through innate immunity activation leading to T-cell activation. In various syngeneic mouse models, Q701 shows tumor regression activities by treatment of compound alone or in combination with other treatments, while Q701 has no direct cytotoxic activity against tested cell lines. Q701 treatment also show immune activation profile in tumor leading to T-cell activation. Q701 is under IND-enabling studies and a back-up program with Axl, Mer, and CSF1R inhibitors is in candidate nomination stage.

Citation Format: Yeong-In Yang, Hwankyu Kang, Dongsik Park, Jiye Ahn, Jinho Choi, Seohyun Ahn, Jaeseung Kim, Kiyean Nam. Q701, a selective Axl and Mer inhibitor as an immune checkpoint inhibitor [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A205.
Abstract A210: Evaluation and comparison of the CDK 4/6 inhibitor palbociclib in a panel of PDX models representing hormone-positive and -negative breast cancer
Authors: Moriarty Alyssa , Mangold Amanda , Munoz Ileana , Groves Megan , Guerra Marcus , Rundle Melissa , Papadopoulos Kyriakos P. , Rasco Drew , Tolcher Anthony W. , Patnaik Amita , Wick Michael J.
Published: August 2018

Background: Palbociclib is a CDK 4/6 inhibitor approved in combination with letrozole in hormone-positive breast cancer. The START PDX platform comprises over 1300 fully annotated models, including a breast cancer panel of over 100 models representing each disease subtype: ~35 ER+, 20 HER2+, and 45 TNBC models. To better understand activity of CDK 4/6 inhibitors in breast cancer we screened our breast panel with single-agent palbociclib. The goal of this study was to determine and compare efficacy of a CDK 4/6 inhibitor in models representative of relevant subtypes of human breast cancer. Methods: START-PDX models were established from tissue biopsies or tissue samples taken from breast cancer patients. Sensitivity of 100 breast tumor models to single-agent palbociclib administered orally once daily at 75 mg/kg for a minimum of twenty-eight days was evaluated in a coclinical screen format. Study endpoints included mean tumor volume and time from treatment initiation with %T/C values and tumor regression reported at study completion. Results: ER+ models showed variable sensitivity to palbociclib treatment, including ST897, ST986, and ST313, which reported tumor regressions. Interestingly, two ER+ harboring an ESR1 mutation and developed in the presence (ST941 and ST2177) or absence (ST941/HI and ST2177/HI) of exogenous estradiol reported differential sensitivity with the hormone-independent (HI) models more sensitive. Several TNBC models including ST319 and ST1394 reported sensitivity to palbociclib with %T/C values of 20% and 25%, respectively. Conclusion: We screened a panel of breast PDX models with the CDK 4/6 inhibitor palbociclib and identified activity in all breast cancer subtypes. In addition, we found a differential response in ER+, ESR1-mutant models developed in the presence and absence of exogenous estradiol. Exploration of biomarkers of sensitivity is ongoing.

Citation Format: Alyssa Moriarty, Amanda Mangold, Ileana Munoz, Megan Groves, Marcus Guerra, Melissa Rundle, Kyriakos P. Papadopoulos, Drew Rasco, Anthony W. Tolcher, Amita Patnaik, Michael J. Wick. Evaluation and comparison of the CDK 4/6 inhibitor palbociclib in a panel of PDX models representing hormone-positive and -negative breast cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A210.
Abstract B015: An approach to suppress the evolution of resistance in BRAFV600E-mutant cancer
Authors: Xue Yaohua , Martelotto Luciano , Baslan Timour , Vides Alberto , Solomon Martha , Chadalavada Kalyani , DeStanchina Elisa , Nanjangud Gouri , Berger Michael , Lowe Scott , Reis-Filho Jorge S. , Rosen Neal , Lito Piro
Published: August 2018

Tumors evolve as they adapt to environmental cues. The principles governing evolution of tumors under the selective pressure of targeted therapy are not well understood. We aimed to evaluate the evolution of resistance and to identify therapeutic modalities that prevent this process in BRAFV600E-mutant tumors. We modeled the selection and propagation of BRAFV600E amplification (BRAFamp) in patient-derived tumor xenografts (PDX) treated with a direct ERK inhibitor. Single-cell sequencing and multiplex-fluorescence in situ hybridization mapped the emergence of extra-chromosomal amplification in multiple subclones of the same tumor shortly after treatment. The evolutionary selection of BRAFamp is determined by the fitness threshold, the barrier subclonal populations need to overcome to regain fitness in the presence of therapy. This differed for ERK signaling inhibitors, and single-cell sequencing of a melanoma PDX model showed that drugs of the same pathway do not necessarily select for the same subclones. These data suggest that sequential monotherapy is not optimal, but concurrent targeting of RAF, MEK, and ERK, however, imposes a sufficiently high fitness threshold to prevent the propagation of subclones with high-level amplification. Administered on an intermittent schedule, this treatment inhibited tumor growth without apparent toxicity in 11/11-lung cancer and melanoma PDX models with various additional alterations. Thus, gene amplification can be acquired and expanded through parallel evolution, enabling tumors to adapt while maintaining their intratumoral heterogeneity. Treatments that impose a high fitness threshold, such as our intermittent triple therapy, will likely prevent the evolution of resistance-causing alterations and merit testing in patients.

Citation Format: Yaohua Xue, Luciano Martelotto, Timour Baslan, Alberto Vides, Martha Solomon, Kalyani Chadalavada, Elisa DeStanchina, Gouri Nanjangud, Michael Berger, Scott Lowe, Jorge S. Reis-Filho, Neal Rosen, Piro Lito. An approach to suppress the evolution of resistance in BRAFV600E-mutant cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B015.
Abstract B021: Inhibition of β-catenin impairs triple-negative breast cancer (TNBC) cell migration and invasion by modulating aerobic glycolysis components
Authors: Prasad Chandra P. , Andersson Tommy
Published: August 2018

In the present study, we investigated the role of β-catenin on aerobic glycolysis in breast cancer cells and further evaluated its effects on triple-negative breast cancer (TNBC) cell migration and invasion. We used two metastatic TNBC cell lines, i.e., MDA-MB-468 and MDA-MB-231, and treated them with β-catenin antagonists (WNT5A and XAV939). Evaluation of glycolytic markers in WNT5A-expressing cell lines showed selective downregulation in the expression of β-catenin, platelet type-phosphofructokinase (PFKP), and lactate secretion, without affecting cell proliferation. Of the three phosphofructokinase isoform, we found that only PFKP expression was associated with decreased survival in breast cancer patients. We also found that the cause of PKFP and lactate downregulation was mediated by inhibition of β-catenin signaling, which is in accordance with the finding that β-catenin signaling positively regulates lactate production. Functionally, we showed that specific downregulation of β-catenin resulted in reduced lactate production accompanied by impaired TNBC cells migration and invasion. Finally, we demonstrated that apart from its inhibitory effect on lactate production, inhibition of β-catenin can also impair TNBC cell migration induced by exogenous lactate via downregulating monocarboxylate transporter 1 (MCT1). Overall, we demonstrated that inhibition of β-catenin-PFKP signaling axis impaired lactate production as well as its uptake from tumor microenvironment (via MCT1), thereby impairing TNBC cells' migration.

Citation Format: Chandra P. Prasad, Tommy Andersson. Inhibition of β-catenin impairs triple-negative breast cancer (TNBC) cell migration and invasion by modulating aerobic glycolysis components [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B021.
Abstract B030: Neoadjuvant chemotherapy promotes macrophage-induced MenaINV-dependent pro-metastatic changes in breast tumors
Authors: Karagiannis George S. , Sharma Ved P. , Brizio Sara , Burt Joseph , Wang Yarong , Entenberg David , Smith Bryan , Flynn Daniel , Oktay Maja H. , Condeelis John
Published: August 2018

Neoadjuvant chemotherapy (NAC) is used for treatment of localized breast cancer to decrease tumor size and improve surgical outcome. However, our recent study has uncovered a previously unrecognized side effect of NAC, which involves the induction of pro-metastatic changes in the primary breast cancer microenvironment. In particular, NAC promotes the assembly of structures that serve as doorways for intravasation of tumor cells called tumor microenvironment of metastasis (TMEM), and increases the proportion of the highly invasive and migratory MenaINV-hi/Mena11alo (MenaCalc+) tumor cells, which utilize the TMEM sites for hematogenous dissemination (1). MenaINV expression in particular is associated with decreased sensitivity of cancer cells to receptor tyrosine-kinase (RTK) and tyrosine-kinase (TK) inhibitors and with dramatically increased TMEM-dependent intravasation. The mechanism behind these pro-metastatic changes was not known. Here we report that NAC induces increased levels of Tie2Hi macrophages in the tumors, resulting in increased contact between macrophages and tumor cells leading to MenaINV expression in the cancer cells, and MenaINV-dependent TMEM assembly and tumor cell intravasation. Furthermore, we demonstrate that the Tie2 switch control inhibitor rebastinib sufficiently suppresses Tie2 signaling in macrophages, thereby inhibiting increased levels of Tie2Hi macrophages in the tumor, resulting in decreased MenaINV expression in the cancer cells and decreased TMEM-associated tumor cell intravasation. Our work has uncovered a previously unrecognized mechanism behind pro-metastatic changes in response to cytotoxic chemotherapy, the markers that predict these changes (TMEM, MenaCalc and MenaINV), and shows that this mechanism could be addressed by combining chemotherapy with rebastinib. Reference: 1. Karagiannis GS, et al. Neoadjuvant chemotherapy induces breast cancer metastasis through a TMEM-mediated mechanism. Sci Transl Med 2017;9:aeen0026.

Citation Format: George S. Karagiannis, Ved P. Sharma, Sara Brizio, Joseph Burt, Yarong Wang, David Entenberg, Bryan Smith, Daniel Flynn, Maja H. Oktay, John Condeelis. Neoadjuvant chemotherapy promotes macrophage-induced MenaINV-dependent pro-metastatic changes in breast tumors [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B030.
Abstract B053: GPER signaling inhibits melanoma and improves response to PD-1 blockade
Authors: Natale Christopher A. , Li Jinyang , Zhang Junqian , Dahal Ankit , Stanger Ben , Ridky Todd
Published: August 2018

Female sex and pregnancy are associated with reduced risk of melanoma and improved stage-specific survival; however, the mechanism underlying this apparent clinical benefit is unknown. We previously discovered that pregnancy-associated 17β-estradiol drives melanocyte differentiation by activating the nonclassical G-protein coupled estrogen receptor (GPER). Here, we show that pregnancy inhibits melanoma, and that transient GPER activation induces long-term changes in melanocytes, which are associated with increased cellular differentiation and resistance to melanoma. A selective GPER agonist induced c-Myc protein degradation, slowed tumor growth, and inhibited expression of immune-suppressive proteins, including PD-L1, suggesting that GPER signaling may render melanoma cells more vulnerable to immunotherapy. Systemically delivered GPER agonist was well tolerated, and cooperated with PD-1 blockade in melanoma-bearing mice to dramatically extend survival. These results thus define GPER as a target for differentiation-based melanoma therapy.

Citation Format: Christopher A. Natale, Jinyang Li, Junqian Zhang, Ankit Dahal, Ben Stanger, Todd Ridky. GPER signaling inhibits melanoma and improves response to PD-1 blockade [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B053.
Abstract B076: A DREAM-world of approaches for predicting combination synergies in cancer
Authors: Dry Jonathan R. , Menden Michael , Saez Rodriguez Julio , Guinney Justin
Published: August 2018

Selecting the right drug combination for the right patient is a complex problem. Some success has been seen from preclinical screening and computational approaches combining molecular, drug and tumor properties to predict combination benefit within the tumor cell. However the context specificity and heterogeneity of drug resistance is often overlooked, leading to inappropriate assumptions of statistical power and resulting in poor translatability. Knowledge-aware approaches will be needed to augment pre-clinical statistical discovery but a huge variety of techniques exist, each offering different strengths. To test this world of methods, AstraZeneca partnered with DREAM, Sage Bionetworks and the Sanger Institute. We released over 11,000 test results from drug combinations in cancer cell lines for an incentivized crowd-sourcing challenge to develop computational models predicting synergistic drug combinations and biomarkers determining response. This became the highest participated of any DREAM challenge, with >700 participants from diverse geographies and knowledge/skill specialties collectively contributing >50,000 hours to the problem. Over 70 models were submitted, testing most machine learning algorithms alongside knowledge-driven approaches. The best models out-performed the state of the art, consistently predicting at an equivalent level to biological replication. Network techniques to select molecular markers most relevant to drug target biology improved prediction the most. Amongst results that could be validated in independent data, ERBB2/EGFR/EP300 variants were predictive for combinations inhibiting AKT+EGFR/ERBB, KRAS for BRAF+MAP2K, AR for AKT/SGK+MAP2K, and ESR1 for ESR1+AKT/PI3K. Alongside revealing interesting biology in our data and providing predictive models, the challenge has given clear direction to our future investment in computational methods for combination pharmacogenomics.

Citation Format: Jonathan R. Dry, Michael Menden, Julio Saez Rodriguez, Justin Guinney. A DREAM-world of approaches for predicting combination synergies in cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B076.
Abstract B100: Mutant KRAS-induced macrophage migration inhibitory factor (MIF) secretion promotes resistance to cetuximab in colorectal cancer
Authors: Jang Jee Eun , Kim Hwang-Phill , Han Sae Won , Kim Tae You
Published: August 2018

The tumor microenvironment is recognized as developing crosstalk between different cells by secretion of growth factors and cytokines, thus providing oncogenic signals enhancing tumor progression and drug resistance. Here, we hypothesized that tumor cells carrying KRAS mutation-induced cytokines may have a critical role in intercellular communication between microenvironment and tumor cells. We first investigated biologic evidence of secreted cytokines in KRAS mutant type (KRAS MT) cell lines. We explored the roles of cytokine that cell morphology, colony-formation ability, and wound-healing ability were enhanced when KRAS wild-type (KRAS WT) cell lines were exposed to conditioned media (CM) from KRAS MT cells, and we found macrophage migration inhibitory factor (MIF) was highly expressed in KRAS MT cells by analysis of proteomics. We also observed secreted MIF level between KRAS WT and MT cell lines, and it was highly secreted in KRAS MT cell lines. In addition, compared with patients whose KRAS mutation was not harbored, MIF expression was higher in patients who have KRAS mutation. The predictive marker of KRAS mutation in colorectal cancer patients is associated with resistance to antiepidermal growth factor receptor (EGFR) antibody cetuximab. Following the hypothesis, we investigated that secreted cytokines have an effect on the cetuximab resistance to surrounding cells including KRAS WT cells. Treatment of CM from KRAS MT cells led to cetuximab resistance in KRAS WT cells and MIF blockade prevented cetuximab resistance. Also, CM from knockout in KRAS MT cells by using CRISPR/Cas9 system resulted in sensitizing to cetuximab resistance compared with CM from KRAS MT cells. In conclusion, we demonstrated for the first time that MIF promotes the cetuximab resistance of KRAS WT colorectal cancer cells, and this effect is mediated by paracrine and autocrine signaling-induced activation of the intracellular AKT signaling pathways and regulated by NF-kb transcription factor through oncogenic KRAS mutation and MIF overexpression, respectively. These findings suggest that MIF may be a promising predictive biomarker for the cetuximab resistance of KRAS wild-type colorectal cancer patients.

Citation Format: Jee Eun Jang, Hwang-Phill Kim, Sae Won Han, Tae You Kim. Mutant KRAS-induced macrophage migration inhibitory factor (MIF) secretion promotes resistance to cetuximab in colorectal cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B100.
Abstract B121: The benefits of bispecific mAb2 antibodies targeting EGFR and HGF
Authors: Leung Kin-Mei
Published: August 2018

F-star’s Modular Antibody TechnologyTM platform introduces a novel antigen binding site into the constant (Fc) region of an antibody to create a so-called FcabTM (an Fc-domain with antigen binding activity). The resulting Fcab is then combined with variable region (Fab) of an existing antibody to generate a full-length bispecific antibody or mAb2TM. Here we show how Fcabs targeting epidermal growth factor receptor (EGFR) are utilized to generate mAb2 molecules that bind specifically EGFR and hepatocyte growth factor (HGF). The EGFR/HGF bispecifics inhibit cell proliferation in vitro and show antitumor activity in patient-derived xenograft (PDX) models in vivo. The mAb2 molecules show superior inhibition of tumor growth compared to combination treatments in tumors with specific molecular profiles, suggesting novel biology of the bispecific.

Citation Format: Kin-Mei Leung. The benefits of bispecific mAb2 antibodies targeting EGFR and HGF [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B121.