bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract B135: The mechanism of action of BT1718, a novel small-molecule drug conjugate for the treatment of solid tumors expressing MT1-MMP
Authors: Bennett Gavin , Rigby Mike , Lutz Bob , Park Peter , Keen Nicholas
Published: August 2018

BT1718 is a small-molecule drug conjugate, also called Bicycle drug conjugate (BDC), comprising a constrained bicyclic peptide (Bicycle) that binds with high affinity and specificity to membrane type 1-matrix metalloprotease (MT1-MMP; MMP14; MT1) covalently linked through a hindered disulfide linker to the potent antitubulin agent DM1. MT1 is naturally involved in tissue remodeling; however, its overexpression is linked to increased tumor aggressiveness and metastasis. Overexpression of MT1 is associated with poor survival in NSCLC, TNBC, and other solid tumors. MT1 expression can also be observed in tumor-associated stromal cells. The Bicycle binder for BT1718 was identified using a proprietary phage display peptide technology consisting of highly diverse phage libraries of linear amino acid sequences constrained into two loops by a central chemical scaffold. While binding with similar affinity and specificity to that observed with monoclonal antibodies, the small size of a Bicycle (1.5-3 kDa) aids in its rapid extravasation and tumor penetration, making it an ideal format for the targeted delivery of cytotoxic payloads. BT1718 shows profound antitumor activities as a single agent when given at doses as low as 3mg/kg biw, producing complete regression of tumors in cell-line and patient-derived xenograft models. BT1718 is also able to produce rapid complete regression of very large tumors (~1000 mm3). We have evaluated the target dependence of antitumor activities of BT1718 by evaluating tumor response in a range of xenograft models with varying expression of MT1, as measured by mRNA, FACS, and IHC. We evaluated a panel of cell-line derived xenograft (CDX) and patient-derived xenograft (PDX) tumors across various indications including lung, breast, colorectal, stomach, head and neck cancer, and multiple myeloma. In both CDX and PDX models, the efficacy of BT1718 was dependent on the MT1 expression levels. Moderate and high MT1-expressing cell lines showed partial or complete regression when treated with BT1718, while low MT1-expressing lines showed limited or no effect. BT1718 is a first-in-class, cytotoxic small-molecule drug conjugate with great potential for treatment of MT1-expressing solid tumors and is about to begin clinical testing.

Citation Format: Gavin Bennett, Mike Rigby, Bob Lutz, Peter Park, Nicholas Keen. The mechanism of action of BT1718, a novel small-molecule drug conjugate for the treatment of solid tumors expressing MT1-MMP [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 B135.
Abstract 1220: Integrative genomic analysis discovers the causative regulatory mechanisms of a breast cancer-associated genetic variant
Authors: Zhang Yi , Manjunath Mohith , Zhang Shilu , Chasman Deborah , Roy Sushmita , Song Jun S.
Published: August 2018

Genome-wide association studies (GWAS) have identified genetic variants that may significantly modulate breast cancer susceptibility. However, the precise molecular mechanisms behind these associations remain largely unknown; often, it is not even clear whether the GWAS variants are functional themselves or just genetically linked to other functional variants. We here provide an integrated method for identifying functional regulatory variants associated with breast cancer and their target genes by combining the analyses of expression quantitative trait loci (eQTL), a modified version of allele-specific expression (ASE) systematically utilizing haplotype information, transcription factor (TF) binding preference, and epigenetic information. Application of our method to the breast cancer susceptibility region in 5p12 demonstrates that the GWAS risk allele rs4415084-T is correlated with higher expression levels of the protein-coding gene MRPS30 and lncRNA RP11-53O19.1. We propose that an intergenic SNP, in linkage disequilibrium (LD) with the GWAS SNP rs4415084, is the predicted functional SNP. We provide multiple levels of evidence that the risk allele of the predicted functional SNP, in phase with the GWAS risk allele rs4415084-T, creates a GATA3 binding motif within a regulatory element, resulting in differential GATA3 binding and chromatin accessibility, which thereby promote the transcription of MRPS30 and RP11-53O19.1. MRPS30 encodes a member of the mitochondrial ribosomal proteins, implicating the risk SNP's role in modulating mitochondrial activities in breast cancer. Our computational framework can be extended to facilitate the rapid functional characterization of other genetic variants modulating cancer susceptibility and provides an effective way of integrating GWAS results with high-throughput genomic and epigenomic data.

Citation Format: Yi Zhang, Mohith Manjunath, Shilu Zhang, Deborah Chasman, Sushmita Roy, Jun S. Song. Integrative genomic analysis discovers the causative regulatory mechanisms of a breast cancer-associated genetic variant [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 1220.
Abstract 1238: International comparison of cancer risks for Lynch syndrome
Authors: Jenkins Mark A. , Reece Jeanette , Lee Grant , Win Aung K. ,   International Mismatch Repair Consortium
Published: August 2018

Aims: The International Mismatch Repair Consortium (IMRC) was formed in 2010 and comprises major worldwide consortia involved in the research and/or clinical treatment of Lynch syndrome (cancer predisposition caused by inherited mutations in mismatch repair (MMR) genes: MLH1, MSH2, MSH6, PMS2 and EPCAM); http://www.sphinx.org.au/imrc. The aim of this study was to determine cancer risks by geographic region.

Methods: For each cancer, we estimated the age-specific cumulative risks (penetrance) and the hazard ratios compared to the average population risk. We used a modified segregation analysis and adjusted for any ascertainment of families given this is an analysis of prospective data. We estimated penetrance by: cancer sex, mismatch repair gene, type of mutation, and geographic region.

Results: 43 investigators representing 53 different sites in 23 countries have submitted pedigree data. In total IMRC consists of 6,436 Lynch syndrome families (North America = 2,482, South America = 101, Europe = 3,307, Asia = 216, Australasia = 330). Of these, 2,214 were MLH1, 2,717 were MSH2, 1,118 were MSH6, 558 were PMS2, and 44 were EPCAM. The total number of distinct variants were 1,270 and the maximum size of families was 333 relatives. Of the distinct MMR variants submitted to the IMRC, 89% were classified as Class 4 (likely pathogenic) or 5 (pathogenic) by the InSiGHT Variant classification criteria (LOVD). Penetrance analyses were conducted only for the pathogenic or likely pathogenic variants. Preliminary analyses suggest that the risk of colorectal cancer to age 70 is highest for carriers in Australasia and North America and lowest for carriers in South America and Asia (Table 1).

Conclusion: Preliminary results suggest that cancer risks for people with Lynch syndrome differ by geographic region, which is consistent with environmental modifiers for the disease and might justify region-specific screening guidelines.

Risk (% to age 70) and hazard ratio (HR) of colorectal cancer by MMR gene and regionGeneRegionHR (95% CI)Risk MalesRisk FemalesMLH1Europe19 (14-26)50%32%MLH1Nth America32 (26-38)61%48%MLH1Australasia32 (22-46)68%55%MLH1Sth America6 (2-22)12%10%MLH1Asia7 (5-15)39%24%MSH2Europe14 (11-16)39%24%MSH2Nth America33 (28-40)61%50%MSH2Australasia36 (24-54)73%59%MSH2Sth America70 (10-490)82%75%MSH2Asia8 (5-17)21%15%

Citation Format: Mark A. Jenkins, Jeanette Reece, Grant Lee, Aung K. Win, International Mismatch Repair Consortium. International comparison of cancer risks for Lynch syndrome [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 1238.
Abstract 144: Dasatinib enhances the effects of paclitaxel on chemotherapy-resistant breast cancer through targeting breast cancer stem cells
Authors: Tian Jun , Lo Chieh , Raffa Fatmah Al , Dai Meiou , Lebrun Jean-Jacques
Published: August 2018

Many patients with triple negative breast cancer (TNBC) exhibit poor prognosis and are at high risk of tumor relapse and metastasis due to the resistance to conventional chemotherapy. These tumor recurrences have been attributed to the presence of breast cancer stem cells (BCSCs), a subpopulation of breast cancer cells that possesses stem-like properties and displays resistance to chemotherapy. Therefore, targeting BCSCs is a priority to overcoming chemotherapy failure in TNBCs. We generated chemotherapy-resistant TNBC cells through cyclic treatments with paclitaxel (pac). The pac-resistant cells displayed increased self-renewal potential compared to the parental TNBC cells, higher percentage BCSCs and increased phosphorylation of Src kinase at Tyr416. After performing a kinase library screening on BCSCs in chemotherapy-resistant cells, we identified dasatinib, a Src kinase family inhibitor, potently reduced BCSC self-renewal and two BCSC populations (ALDH+ and CD24lowCD44high) as well as phosphor-Src. We also demonstrated dasatinib to block pac-induced BCSC enrichment and Src activation in the parental TNBC cells. Interestingly, we found that dasatinib induced an epithelial differentiation of pac-resistant cells, resulting in their enhanced sensitivity to paclitaxel. The combination treatment of dasatinib and paclitaxel not only decreased the proportion of BCSCs and their self-renewal capacity but also synergistically reduced cell viability of pac-resistant cells. In vivo studies further demonstrated the effectiveness of dasatinib/paclitaxel combination treatment in inhibiting breast tumor growth. All these data suggest that dasatinib is a promising anti-BCSC agent and can be used in combination with paclitaxel to overcome chemotherapy resistance in TNBCs.

Citation Format: Jun Tian, Chieh Lo, Fatmah Al Raffa, Meiou Dai, Jean-Jacques Lebrun. Dasatinib enhances the effects of paclitaxel on chemotherapy-resistant breast cancer through targeting breast cancer stem 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 144.
Abstract 1586: Evaluation of AXL expression on circulating tumor cells from EGFR mutated lung cancer patients who have relapsed after the EGFR TKI treatment
Authors: Kim Young Hun , Kim Myoung Shin , Lee Jun Sup , Lee Hyun Kyung , Lee Jae Hyuk , Sohn Young Woong , Tazaki Koichi , Nakamaru Kenji , Wakita Kenichi , Jeon Byung Hee , Kim Seokhyung , Lee Se-Hoon
Published: August 2018

Background: The EGFR (epidermal growth factor receptor) TKI (tyrosine kinase inhibitor) has become the standard treatment in lung cancer patients with EGFR mutations. When these patients are treated with EGFR TKI, 80~90% of the patients show responses to the drug. However the tumor begins to progress again following the development of resistance about 1 year later on average. About a half of resistance mechanisms are caused by the additional mutation of the EGFR gene (T790M), and the other half of the resistance mechanisms are caused by various mechanisms, with one of them being the overexpression of the AXL protein. Confirming AXL overexpression in circulating tumor cells (CTCs) can be an alternative method for tissue biopsy, but almost no research has been conducted on this so far. Here, we evaluate the AXL expression in CTC in case resistance occurs after the EGFR inhibitor treatment.

Materials and Methods: The blood samples (10 ml) were collected from 10 EGFR TKI treated and relapsed lung cancer patients (TKI group) and 10 non-treated patients (control group). The blood samples were processed through Cytogen protocol to enrich CTCs. The enriched cells were immunofluorescent stained for CTC markers (EpCAM or Vimentin), AXL and WBC marker (CD45). The immunofluorescent stained cells were analyzed for each markers using Image Analysis program.

Result: CTCs were detected by CTC markers in all patients from TKI group (range 0-210) and control group (range 1-42). AXL positive CTCs were detected in 9 out of 10 cases from TKI group and in all cases from control group. Interestingly, the quantification of AXL staining intensity in CTCs showed that AXL overexpression (3 fold or greater than baseline) was in 50% of TKI group and 20 % of control group.

Conclusion: We have tested a new approach to evaluate the AXL overexpression in tumor cells of EGFR TKI resistant patients, and showed the feasibility of the this method. Most of lung cancer patients who undergo biopsy require hospitalization and some degree of complication due to biopsy is inevitable. Here we suggested that the blood-based method as a good alternative to the tissue biopsy in patients with tolerance.

Citation Format: Young Hun Kim, Myoung Shin Kim, Jun Sup Lee, Hyun Kyung Lee, Jae Hyuk Lee, Young Woong Sohn, Koichi Tazaki, Kenji Nakamaru, Kenichi Wakita, Byung Hee Jeon, Seokhyung Kim, Se-Hoon Lee. Evaluation of AXL expression on circulating tumor cells from EGFR mutated lung cancer patients who have relapsed after the EGFR TKI treatment [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 1586.
Abstract 1724: Evaluation of niraparib in combination with anti-PD1/anti-PD-L1 in preclinical models
Authors: Wang Sarah , Sun Kaiming , Xiao Yonghong , Feng Bin , Mikule Keith , Ramaswamy Sridhar , Hanke Jeffrey , Wang Jing
Published: August 2018

Niraparib is an orally available and selective poly(ADP-ribose) polymerase (PARP)-1/-2 inhibitor approved for maintenance treatment of adult patients with recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer who are in complete or partial response to platinum-based chemotherapy. PARP inhibition may enhance the immune response in tumors treated with anti-PD-1 therapy via generation of cytosolic DNA that activates T cells through the stimulator of interferon gene (STING) pathway, rendering tumors immunologically “hot” with an increase in infiltrating lymphocytes.

In this study, we explored the responses and mechanism of action of niraparib and anti-PD-1/anti-PD-L1 combination therapy in preclinical models. Out of a cohort of 14 immune-competent mouse tumor models, the combination treatment demonstrated enhanced anti-tumor activity in eight tumor models derived from BRCA-proficient and BRCA-deficient genetic backgrounds. Substantial increases compared to monotherapies in anti-tumor activity was observed in 5 models, indicative of synergy between niraparib and anti-PD-1/anti-PD-L1 therapy. The combination triggered durable responses that were coincident with induction of immune memories in a BRCA-deficient ovarian syngeneic model. Mechanistically, niraparib treatment increased the number of infiltrating CD8+ and CD4+ cells within the intratumoral region. The enhanced immune cell infiltration was accompanied by elevated interferon-stimulated gene expression. Pathway analyses using transcriptome profiling identified interferon response gene signatures as the significantly differentially-upregulated gene sets following niraparib treatment. Consistently, niraparib treatment activated the STING pathway in vitro in BRCA-deficient MDA-MB-436 human triple negative breast cancer cells. STING pathway markers including p-STING(Ser366), p-TBK1(Ser172) and p-NFκB p65 were elevated following niraparib treatment and was accompanied by an increase in IFNB mRNA expression. In summary, our data suggested that niraparib treatment in combination with anti-PD-1/anti-PD-L1 therapy enhanced immune cell infiltration, interferon-stimulated gene expression and tumor responses.

Citation Format: Sarah Wang, Kaiming Sun, Yonghong Xiao, Bin Feng, Keith Mikule, Sridhar Ramaswamy, Jeffrey Hanke, Jing Wang. Evaluation of niraparib in combination with anti-PD1/anti-PD-L1 in preclinical 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 1724.
Abstract 1763A: Single-cell RNA-sequencing reveals the immune contexture of triple-negative breast cancer tumors
Authors: Qiu Si , Hong Ruoxi , Zhuang Zhenkun , Wang Shusen
Published: August 2018

Triple-negative breast cancer (TNBC) is aggressive and associated with a higher risk of early relapse. The lack of estrogen receptor, progesterone receptor, and HER2 expression precludes the use of targeted therapies, and the high level of immune cell infiltration suggests that TNBC patients may benefit from immunotherapy. The design of immunomodulatory strategies for the TNBC treatment will tremendously benefit from a comprehensive understanding of the tumor infiltrated immune cell landscape of this cancer. To this end, we performed deep single cell RNA sequencing to 7,066 immune cells collected from 8 TNBC patients using the MIRALCS platform. We identified 13 immune cell subsets according to their transcriptome features. We found that the frequency of identified T cells and macrophages varied greatly across patients. We explored the diversity of tumor-infiltrating T lymphocytes and their functional states, and described the complicated and patient specific macrophage phenotypes. We also examined the single-cell expression level of immunotherapeutic target molecules in different immune cell subgroups. Our study gives an insight into the heterogeneity of the immune cell contexture of TNBC tumors, provides a valuable resource to understand the immune ecosystem of TNBC and may accelerate immunotherapies development on this breast cancer subtype.

Citation Format: Si Qiu, Ruoxi Hong, Zhenkun Zhuang, Shusen Wang. Single-cell RNA-sequencing reveals the immune contexture of triple-negative breast cancer 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 1763A.
Abstract 1773: HPN424, a half-life extended, PSMA/CD3-specific TriTAC for the treatment of metastatic prostate cancer
Authors: Lemon Bryan , Aaron Wade , Austin Richard , Baeuerle Patrick , Barath Manasi , Jones Adrie , Jones Susan D. , Kwant Kathryn , Law Che-Leung , Muchnik Anna , Sexton Kenneth , Tatalick Laurie , Wesche Holger , Yu Timothy
Published: August 2018

Metastatic, castrate-resistant prostate cancer (mCRPC) is diagnosed in up to 50,000 patients each year in the US alone, and roughly 27,000 patients will succumb to it every year. Once metastasized beyond regional lymph nodes, the 5-year survival rate is 30%. While novel therapeutics like abiraterone and enzalutamide have improved the treatment options for mCRPC, no curative treatment is available, and new therapies are urgently needed. HPN424 is a ~50-kDa antibody derivative called TriTAC (Tri-specific T cell Activating Construct) under development for the treatment of mCRPC. It is designed to simultaneously bind to CD3ε on T cells and to prostate specific membrane antigen (PSMA, FOLH1) on prostate cancer cells. A third domain of HPN424 binds non-covalently to serum albumin for extension of serum half-life. PSMA is expressed in >90% of malignant lesions of patients, and outside the central nervous system, its expression on normal tissue is largely restricted to the prostate. HPN424 binds human PSMA with sub-nanomolar affinity. When incubated in co-cultures with resting, human T cells and prostate cancer cells, it activates T cells and induces cytokine production, proliferation and redirected target cell killing with EC50 values in the single digit picomolar range. When administered to mice bearing human prostate cancer xenografts and human T cells, HPN424 eradicates subcutaneous tumors. The affinities of HPN424 for human and cynomolgus monkey CD3 and albumin are comparable, while HPN424 binds only marginally to cynomolgus PSMA. HPN424 is very well tolerated in non-human primates, even at high doses, indicating that CD3-binding has little if any pharmacological effect in the absence of target binding. Pharmacokinetic analysis supports weekly administration in humans. Our preclinical data suggest that HPN424 will be highly efficacious, safe and convenient for the treatment of patients with mCRPC.

Citation Format: Bryan Lemon, Wade Aaron, Richard Austin, Patrick Baeuerle, Manasi Barath, Adrie Jones, Susan D. Jones, Kathryn Kwant, Che-Leung Law, Anna Muchnik, Kenneth Sexton, Laurie Tatalick, Holger Wesche, Timothy Yu. HPN424, a half-life extended, PSMA/CD3-specific TriTAC for the treatment of metastatic prostate 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 1773.
Abstract 1932: Discovery of ENPP1 inhibitors as agonists of STING pathway
Authors: Sharma Sunil , Weston Alexis , Thode Trason , Gomez Eric , Kaadige Mohan , Vankayalapti Hariprasad
Published: August 2018

The discovery of STING (Stimulator of interferon genes) pathway and the second messenger 2′3′-cGAMP that activate it opened up several new possibilities for the development of anti-cancer and anti-pathogen therapeutics. STING is a pattern-recognition receptor anchored on endoplasmic reticulum and has pivotal roles in surveillance and innate immune response. Binding of 2′3′-cGAMP with STING induces conformational changes, which subsequently leads to perinuclear migration of STING and recruitment of TANK-binding kinase 1 (TBK1) and IFN regulatory factor 3 (IRF3). TBK1 phosphorylates IRF3, which then translocates to the nucleus and drives the transcription of innate immune genes, including IFN-β. Ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) is a dominant hydrolyzing enzyme of 2′3′-cGAMP. In ENPP-/- cells, 2′3′-cGAMP is more active in stimulating STING activation, and this is predicted to be due to increased half-life. Similarly, hydrolysis resistant 2′3′-cGAMP analogs are reported to be potent STING agonists. We hypothesized that inhibition of ENPP1 activity with an orally available small molecule would be a novel approach to activate STING pathway when compared with the cyclic dinucleotides (CDNs) due to their parenteral route of administration. We have utilized computational methods successfully discovered small molecule candidates that showed a strong binding affinity towards ENPP1. With the help of in vitro enzymatic inhibition and direct binding assays we have identified few lead candidates with an IC50 of <100 nM. Cellular assays further showed target specific inhibition of ENPP1 activity and subsequent activation of STING pathway. Additionally, our lead series of compounds showed no effect on other members of the ENPP family, a kinome panel, and several epigenetic regulators, suggesting the specificity towards ENPP1. In summary, we have developed small molecule inhibitors of ENPP1 and one of our lead candidate's is currently under investigation for ADME-Tox, PK and efficacy. The results from these studies will be presented.

Citation Format: Sunil Sharma, Alexis Weston, Trason Thode, Eric Gomez, Mohan Kaadige, Hariprasad Vankayalapti. Discovery of ENPP1 inhibitors as agonists of STING pathway [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 1932.
Abstract 1987: Expansion of pancreatic cancer stem-like cells through PGE2 accumulation in inflammatory environment
Authors: Ishimoto Takatsugu , Arima Kota , Bu Luke , Uchihara Tomoyuki , Miyake Keisuke , Eto Tsugio , Itoyama Rumi , Baba Hideo
Published: August 2018

Chronic inflammation has a crucial role in cancer development and the progression of various tumors, including pancreatic ductal adenocarcinoma (PDAC). The arachidonate cascade is a major inflammatory pathway that produces several metabolites, such as prostaglandin E2 (PGE2). 15-hydroxyprostaglandin dehydrogenase (15-PGDH) participates in the degradation of PGE2 and has attracted attention in recent years. Although inhibition of 15-PGDH is reported to lead to PGE2 accumulation and expand tissue stem cell fraction, the role for pancreatic tumor progression is still unknown. The aim of this study is to elucidate the regulatory mechanism and functional role of 15-PGDH for cancer stem-like cell expansion during tumor progression in pancreas. We found that 15-PGDH expression is frequently down-regulated in PDAC cells and significantly correlated with the number of infiltrating macrophages in human PDAC tissues. Moreover, direct co-culture assay revealed that macrophage derived interleukin-1 beta down-regulates 15-PGDH expression in PDAC cells. Furthermore, pharmacological blockade of 15-PGDH led to PGE2 accumulation, and promoted growth and sphere formation through the expansion of ALDH1-positive cells. We also elucidated the molecular mechanism that PGE2 accumulation by 15-PGDH inhibition increases CYP26A1 expression and subsequently depletes all-trans retinoic acid, and results in ALDH1 up-regulation. Finally, genetic ablation of 15-Pgdh promoted tumorigenesis in KrasLSL-G12D; Ptf1aCre/+ mice through the expansion of ALDH1-positive cells. Our findings highlight the role and significance of PGE2 degradation pathway for PDAC tumor progression.

Citation Format: Takatsugu Ishimoto, Kota Arima, Luke Bu, Tomoyuki Uchihara, Keisuke Miyake, Tsugio Eto, Rumi Itoyama, Hideo Baba. Expansion of pancreatic cancer stem-like cells through PGE2 accumulation in inflammatory environment [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 1987.
Abstract 2: CXCR2+ tumor cells mediate vascular mimicry driving anti-angiogenic therapy (AAT) resistance in glioblastoma (GBM)
Authors: Angara Kartik P. , Borin Thaiz F. , Rashid Mohammad H. , Ara Roxan , Achyut Bhagelu R. , Arbab Ali S.
Published: August 2018

Glioblastoma (GBM) is a hypervascular and hypoxic neoplasia of the central nervous system with an extremely high rate of mortality. Owing to its hypervascularity, anti-angiogenic therapies (AAT) have been used as an adjuvant to the traditional surgical resection, chemotherapy, and radiation to normalize blood vessels and control abnormal vasculature. The benefits of AAT have been transient, and evidence of relapse exemplified in the progressive tumor growth following AAT reflects development of resistance and alternative neovascularization mechanisms in these resilient tumors to counter the AAT therapy insult. Vascular mimicry (VM) is the uncanny ability of tumor cells to acquire endothelial-like properties and lay down vascular patterned networks reminiscent of host endothelial blood vessels. The VM channels serve as an irrigation system for the tumors to meet with the increasing metabolic and nutrient demands of the tumor. In our current studies to understand the tumor-inherent mechanisms of AAT resistance, we identified a crucial pro-migratory and pro-angiogenic chemokine, CXCL8 or IL-8, to be highly upregulated in the GBM tumors treated with AAT. AAT-treated groups had significantly higher populations of CXCR2+ stem and endothelial-like subpopulations and these cells lined the VM-like vascular structures carrying functional RBCs in the tumors. These stem cell-like and endothelial-like populations were decreased following treatment with HET0016 or SB225002. Furthermore, knocking down CXCR2 led to smaller tumor size in the animals and improperly developed vascular structures without CXCR2+ GBM cells lining them. Also, HET0016 and SB225002 disrupt the tube-forming capability of U251 GBM cells in an in vitro Matrigel angiogenesis assay. This confirms our hypothesis that CXCR2+ GBM cells initiate VM and contribute to AAT resistance in GBM. Our present study suggests that tumor cell autonomous IL-8/CXCR2 pathway contributes to VM-mediated AAT resistance in GBM and that HET0016 and SB225002 have a great potential to target therapeutic resistance and can be combined with other chemotherapeutic agents in preclinical and clinical trials.

Citation Format: Kartik P. Angara, Thaiz F. Borin, Mohammad H. Rashid, Roxan Ara, Bhagelu R. Achyut, Ali S. Arbab. CXCR2+ tumor cells mediate vascular mimicry driving anti-angiogenic therapy (AAT) resistance in glioblastoma (GBM) [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 2.
Abstract 2019: Extracellular ATP induces EMT and metastatic activities in non-small cell lung cancer cells
Authors: Cao Yanyang , Wang Xuan , Chen Xiaozhuo
Published: August 2018

Cancer is a leading cause of death worldwide. Metastasis, the spread of cancer cells from the primary tumors to distant organs, is responsible for approximately 90% of all cancer-related deaths. Metastasis is a multistep process in which loss of cell-cell adhesion, increased proteolysis, and cell motility have been shown to be critical steps. Recent studies have indicated that intratumoral ATP concentration is ~1,000 times higher than normal tissues of the same cell origins in the range of at least several hundred μM. Extracellular ATP (eATP), a tumor microenvironment molecule, potentially has a crucial role in supporting tumor invasion and metastasis. Our previous studies showed that eATP is internalized by cancer cells through macropinocytosis and other endocytosis and promotes cancer cell growth, survival, and drug resistance (1-4). Based on all these, we hypothesize that eATP functions as both a signaling molecule and an energy source to stimulate epithelial mesenchymal transition (EMT) and metastasis. Various bioassays were used in human non-small cell lung cancer (NSCLC) A549 and HOP-92 cells to test our hypothesis. Our results reveal that eATP treatment led to a substantially increased number of floating cancer cells, and these cells were viable and formed clones in clonogenic assays. Fence assay indicated that eATP not only induces cancer cell detachment but also increases the number of secondary colonies formed. Moreover, treatment of eATP induces a dose- and time-dependent increase in the migration and invasive capacities of the A549 and HOP-92 cells. Confocal images demonstrated that eATP induces the formation of F-actin-dependent filopodia necessary for cell migration. Using Western blot analysis, we found that the expression of epithelial markers was significantly reduced, while the mesenchymal markers were increased after eATP treatment. Purinergic receptor (PR) inhibitors and P2X7 receptor knockdown only slightly attenuated these effects, suggesting PR signaling is only partially responsible for eATP-induced migration and invasion. These results indicate eATP is an EMT and metastasis stimulator and imply novel targets for inhibiting/preventing metastasis.

References:

1. Qian Y et al. Cancer Lett 2014;351:242-51.

2. Chen X, Qian Y, Wu S. Free Radical Biol Med 2015;79;253-63.

3. Qian Y et al. Mol Cancer Res 2016;14(11):1087-96.

4. Wang X et al. Oncotarget 2017;8:87860-77.

Citation Format: Yanyang Cao, Xuan Wang, Xiaozhuo Chen. Extracellular ATP induces EMT and metastatic activities in non-small cell lung 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 2019.
Abstract 2332: Necroptosis induction in triple negative breast cancer therapy
Authors: Nyinawabera Angelique , Gupta Smiti , Chandrabose Karthikeyan , Tiwari Amit K.
Published: August 2018

“Triple-negative” breast cancer (TNBC), is the most aggressive form of malignant mammary tumors that do not express three cell-surface receptors (estrogen receptor-α, progesterone receptor, and HER2/ERBB3). TNBC accounts for about 15 percent of breast cancer cases, with >42,000 new cases each year and approximately 21,000 deaths. Currently there are no targeted treatments available for TNBC. We found an interesting target associated with TNBC, the mitochondrial fission protein GTPase, dynamin-related protein-1 (Drp1), for which one inhibitor (mdivi-1) is under active investigation. However, mdivi-1 has shown inconsistent antineoplastic activity, low potency and selectivity. This led us to use a 200,000-compound library of commercially available small molecules (Specs), in conjunction with the likely structure of the Drp1-mdivi-1 inhibitory complex, resulting in the identification of twelve thieno-pyrimidin-4-yl-hydrazinylidene class of compounds that were highly potent and selective Drp1 inhibitors. In our preliminary work we found one compound ANT4 with IC50 value of 180-220 nM that has up to 100-fold selectivity in different TNBC cells compared to normal breast cells and up to 30-fold compared to other normal cells. We discovered that ANT4 is a selective inhibitor of Drp1 and has a 100-fold greater affinity for the Drp1 complex. ANT4 inhibited TNBC colony formation, invasion and metastasis,150-fold more potently than Mdivi-1. Interestingly, we discovered that ANT4, in nanomolar range, selectively induced a unique non-apoptotic, necroptotic inducing (NANI) cell death in TNBC cells by increasing the expression of necroptotic cell death markers (RIP, p-RIP, MLKL, p-MLKL). Further, ANT4, inhibited the expression of pro-apoptotic proteins and enhanced the expression of anti-apoptotic proteins. In addition, ANT4 arrested the TNBC cells in S-phase without producing any significant nuclear condensation or release of reactive oxygen species (ROS). Further studies are underway to understand the Drp1 mediated NANI induction process in TNBC cells and to identify the structural requirements that are necessary for targeting cancers refractory to apoptosis. The findings of these studies will allow us to understand the biology of necroptosis-induced Drp1 inhibition and to develop this new class of small molecules for the treatment of TNBC patients.

Citation Format: Angelique Nyinawabera, Smiti Gupta, Karthikeyan Chandrabose, Amit K. Tiwari. Necroptosis induction in triple negative breast cancer therapy [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 2332.
Abstract 2386: Identification of SIK1 as a potential therapeutic target for desmoplastic small round cell tumor
Authors: Hartono Alifiani B. , Lee Sean B.
Published: August 2018

Desmoplastic Small Round Cell Tumor (DSRCT) is a rare and aggressive malignant cancer caused by the chromosomal translocation of t(11;22)(p13;q12) that produces a novel, aberrant transcription factor, EWS-WT1. EWS-WT1 is essential in the formation of DSRCT as well as for maintaining DSRCT cell growth. However, current research has not elucidated how EWS-WT1 leads to the oncogenesis of DSRCT. Through our integrative gene expression data, we identified Salt Inducible Kinase 1 (SIK1) as one of direct target genes of EWS-WT1 in JN-DSRCT-1 cell line. SIK1 is a member of the AMPK related kinases and is involved in gluconeogenesis and lipogenesis regulation, skeletal myocytes development, p53 dependent anoikis, and cell cycle regulation. Through our ChIP analysis, we showed that EWS-WT1 directly binds to a 2kb proximal promoter region of SIK1. Following SIK1 depletion, JN-DSRCT-1 cell proliferation sharply decreased, similar to the growth inhibition observed when EWS-WT1 is depleted. We further showed that cells do not transit to S phase when SIK1 is depleted, suggesting a critical role of SIK1 in cell cycle regulation in DSRCT. Taken together, we have established that EWS-WT1 directly activates SIK1 expression and promotes cell proliferation through SIK1. Therefore, our work identified SIK1 as a new potential therapeutic target in DSRCT.

Citation Format: Alifiani B. Hartono, Sean B. Lee. Identification of SIK1 as a potential therapeutic target for desmoplastic small round cell tumor [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 2386.
Abstract 2403: SGK-1-mediated ATP generation: A novel metabolic pathway that supports ECM-detached cell survival
Authors: Cockfield Jordan A. , Mason Joshua A. , Schafer Zachary T.
Published: August 2018

Successful metastasis requires cancer cells to overcome both anoikis -caspase dependent cell death triggered by extracellular matrix (ECM) detachment—and ECM-detachment-induced metabolic defects that compromise cell survival. While studies have begun to elucidate signal transduction cascades responsible for anoikis evasion, less is known about the precise signals cancer cells use to overcome ECM-detachment induced metabolic deficiencies. Previously, we discovered that oncogenic Ras utilizes a PI(3)K/SGK-1 signaling cascade in order to promote glucose-mediated ATP generation and survival of ECM-detached cells. We have expanded these studies and found that SGK-1 signaling is required in a variety of cell types and oncogenic backgrounds (during ECM-detachment) for glucose-derived ATP production and anchorage independent growth. Our data demonstrate that SGK-1 is required for glucose uptake due to its regulation of the GLUT1 transporter. SGK-1 appears to not only promote GLUT1 localization at the plasma membrane, but also to dramatically promote its transcription. Once inside the cell, SGK-1 promotes the flux of glucose into the glycolytic and pentose phosphate pathways (PPP). When further examining the mechanism by which SGK-1 promotes ATP generation, we surprisingly found that uncoupling the mitochondria did not impact the ability of SGK-1 to promote ATP generation. These data suggest that the TCA cycle is not required for SGK-1 mediated ATP generation. Intriguingly, ATP generation instead requires flux through the PPP and consequent production of glyceraldehyde-3-phosphate (G3P). PPP-derived G3P is shuttled back to glycolysis where ATP production robustly occurs. This metabolic pathway appears to be critical for the anchorage-independent growth of cancer cells as genetic or pharmacological disruption of glucose flux through the PPP significantly abrogates colony formation in soft agar in a variety of distinct cell lines. Overall, these data uncover a novel metabolic pathway downstream of SGK-1 that is highly conserved across multiple epithelial cancer cell lines during ECM detachment.

Citation Format: Jordan A. Cockfield, Joshua A. Mason, Zachary T. Schafer. SGK-1-mediated ATP generation: A novel metabolic pathway that supports ECM-detached cell survival [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 2403.
Abstract 2488: Functional characterization of nuclear TYRO3 in colorectal cancer
Authors: Tsai Shaw-Jenq , Chien Chun-Wei , Chen Sih-Yu , Lin Shao-Chieh , Lin Bo-Wen , Lee Jenq-Chang
Published: August 2018

Colorectal cancer is one of most common death-related cancers worldwide. Aberrant expression of oncogenes is regarded as a predominant factor in colorectal cancer development. TYRO3 belongs to TAM (TYRO3, AXL, and MER) family, which is a subfamily of receptor tyrosine kinases. Our previous study discovered TYRO3, an oncogene overexpressed in colorectal cancer, promotes cell proliferation, metastasis, and tumor progression. Herein, we further identified that TYRO3 is present in nucleus of colon cancer cells using immunofluorescence staining in conjunction with confocal microscopy. By staining with three different antibodies recognizing N-terminal, central region, and C-terminal of TYRO3, respectively, we identified that central and C-terminal of TYRO3 is the fragment to be translocated to the nucleus. Transfection of exogenous Myc-TYRO3-GFP fusion protein further confirmed this finding. By bioinformatic tool prediction, we found there is a nuclear localization signal (NLS) and a nuclear export signal (NES) in TYRO3. To evaluate the function of nuclear TYRO3, we mutated NLS of TYRO3 and performed several functional studies. Results of immunofluorescent staining showed that after NLS mutation, TYRO3 cannot be translocated to nucleus, which was accompanied by distorted morphology. Furthermore, cancer cells transfected with NLS-mutated TYRO3 increased activated caspase-3 and number of apoptotic cells, suggesting nuclear localization of TYRO3 is essential for cell survival. Clinical data further support that levels of nuclear TYRO3 are a poor prognostic marker that is positively associated with colon cancer treatment failure and malignancy. These data support that nuclear TYRO3 is important for colon cancer cell survival and is a valuable biomarker for prognosis.

Citation Format: Shaw-Jenq Tsai, Chun-Wei Chien, Sih-Yu Chen, Shao-Chieh Lin, Bo-Wen Lin, Jenq-Chang Lee. Functional characterization of nuclear TYRO3 in colorectal 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 2488.
Abstract 2542: c-Jun and FOXO1 play key roles in the overexpression of oncogenic PKC-ι in human prostate and melanoma cell lines
Authors: Apostolatos Andre H. , Ratnayake Wishrawana S. , Islam Anisul , Apostolatos Christopher , Smalley Tracess , Acevedo-Duncan Mildred
Published: August 2018

Protein Kinase C-ι (PKC-ι) is an anti-apoptotic oncogene overexpressed in multiple cancers including prostate, melanoma, ovarian, breast, and glioma. We have previously shown that PKC-ι is part of a cycle that helps cancer cells avoid senescence by releasing the transcription factor NF-kB. Additionally, PKC-ι has an anti-apoptotic effect while promoting epithelial-mesenchymal transition in melanoma {Ratnayake, et al. Int. J. Oncol. 51(5), (2017), 1370-1382}. PKC-ι is activated externally by factors like loss of PTEN and TGFβ stimulation. However treatment with PKC-ι specific inhibitors downregulate expression of both PKC-ι and phosphorylated PKC-ι, suggesting PKC-ι plays a role in regulating its own expression. A previous study showed the ELK1 transcription factor to be a regulator of PKC-ι (Gustafson, et al. J. Biol. Chem 279(10), (2003), 9400-8}. In this study, transcription factors c-Jun, ISGF3, PAX3, EGR1, and FOXO1 which bind on or near the promoter sequence of the PRKCI gene, were analyzed for their role in PKC-ι regulation in prostate cancer cell lines (DU145 and PC3) and melanoma cell lines (SK-MEL-2 and MeWo). Each transcription factor was systematically silenced. Western blots revealed that treatment with either c-Jun or FOXO1 siRNA significantly altered expression of PKC-ι. Results showed c-Jun followed by FOXO1 are the two major transcription factors which involve in PKC-ι expression in prostate cells compared to FOXO1 in melanoma cells. This suggests that these transcription factors act as activators that regulate PKC-ι expression and can be downstream targets of PKC-ι. We found that regulation of PKC-ι expression was governed mainly through NF-κB pathway. siRNA knockdown of NF-κB p65 and application of NF-κB inhibitors confirmed the above observation. We have also used immuno-paired-antibody detection assay to determine which pathways were affected with PKC-ι inhibitor treatments other than NF-κB pathway. qPCR and microarray were performed to analyze the transcriptome of treated cells to match protein levels with mRNA levels. We have analyzed multiple targets both up and downstream of PKC-ι to determine the mechanism of PKC-ι self-regulation. Overall results suggest that PKC-ι inhibition downregulates its own expression making it a novel target in prostate and melanoma cancer treatment.

Citation Format: Andre H. Apostolatos, Wishrawana S. Ratnayake, Anisul Islam, Christopher Apostolatos, Tracess Smalley, Mildred Acevedo-Duncan. c-Jun and FOXO1 play key roles in the overexpression of oncogenic PKC-ι in human prostate and melanoma cell lines [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 2542.
Abstract 2720: The CD47-blocking innate immune checkpoint inhibitor, TTI-621, triggers CD47-mediated tumor cell apoptosis
Authors: Izrailit Julia Bershadsky , Viller Natasja Nielsen , Pang Xinli , Petrova Penka S. , Uger Robert A. , Winston Jeff , Linderoth Emma
Published: August 2018

CD47 is a cell surface glycoprotein of the immunoglobulin superfamily that is utilized by tumor cells to avoid immune destruction. Overexpression of the CD47 ligand on tumor cells provides a “do-not-eat” signal when bound to its receptor, signal regulatory protein α (SIRPα), on macrophages, resulting in inhibition of phagocytosis and tumor survival. TTI-621 is a soluble SIRPα recombinant fusion protein with an IgG1 Fc tail that triggers macrophage phagocytosis of tumor cells in vitro, and potently inhibits tumor growth in vivo. It is currently being evaluated in two clinical studies in patients with hematologic and solid cancers (NCT02663518 and NCT02890368). TTI-621's pro-phagocytic effect has been shown to be a result of blockade of the CD47-SIRPα pathway as well as activation of Fc gamma receptors (FcγR) on macrophages. However, engagement of CD47 has also been shown to directly induce apoptosis in tumor cells. Therefore, the objective of this study was to further examine the pro-apoptotic potential of TTI-621.

The induction of apoptosis in tumor cells by TTI-621 was evaluated using flow cytometry and protein expression assays. Ligating CD47 with immobilized TTI-621 efficiently induced apoptosis in malignant T-ALL and DLBCL cells but had no effect on apoptosis in normal peripheral blood mononuclear cells. Immobilized TTI-621 or anti-CD47 mAb promoted caspase-independent but PLCγ-1-dependent apoptosis. Under conditions of cellular stress, both soluble and immobilized TTI-621 induced apoptosis in T-ALL cells. In contrast to immobilized TTI-621, treatment of stressed tumor cells with soluble TTI-621 triggered caspase-dependent but PLCγ-1-independent apoptosis. In addition, anchoring the IgG1 Fc tail of TTI-621 to FcγR-expressing cells enhanced tumor cell apoptosis in a dose-dependent and CD47-dependent manner.

These results suggest that in addition to blocking the anti-phagocytic “do-not-eat” signal on tumor cells and activating FcγR on macrophages, binding of TTI-621 to FcγRs on tumor-infiltrating immune cells may provide a cross-linking scaffold to enhance TTI-621-mediated apoptosis via CD47 on cancer cells. Additionally, under conditions of cellular stress, TTI-621 may induce tumor cell death directly via binding to CD47 on malignant cells, in a cell-autonomous, cytotoxic mechanism. Thus, TTI-621 may employ multiple mechanisms to elicit its anti-tumor effects.

Citation Format: Julia Bershadsky Izrailit, Natasja Nielsen Viller, Xinli Pang, Penka S. Petrova, Robert A. Uger, Jeff Winston, Emma Linderoth. The CD47-blocking innate immune checkpoint inhibitor, TTI-621, triggers CD47-mediated tumor cell 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 2720.