bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 1325: Overexpression of Tribbles 2 enhances prostate cancer cell growth and contributes to enzalutamide resistance
Authors: Monga Jitender , Sanghvi Parshva , Ghosh Jagadananda 
Published: July 2021

Abstract
Background: Enzalutamide, an FDA-approved androgen receptor blocker, is commonly prescribed for advanced prostate cancer which slows down prostate tumor growth. However, therapeutic benefit of enzalutamide is temporary because enzalutamide-resistant prostate cancer (ERPC) invariably develops which is incurable, primarily because currently available therapies cannot effectively kill ERPC cells. Molecular basis behind enzalutamide-resistance is not clearly understood, which is delaying progress towards development of new therapies. Thus, proper molecular characterization of ERPC cells is an urgent and unmet medical need to find appropriate targets to improve the current state of ERPC therapy.
Methods: We developed an ERPC model by chronically treating prostate cancer cells to mimic the clinical conditions of Enzalutamide resistance. These ERPC cells were used for comprehensive gene expression analysis by Illumina Hi-Seq whole genome gene-expression array. Hits were confirmed by RT-PCR and Western blot. Regulation of expression and pro-cancer effects of new hits were determined by overexpression and/or treating cells with shRNA and analyzing cell viability, soft-agar colony formation, apoptosis, and effects on downstream targets.
Results: Transcriptional profiling revealed that Tribbles 2 (Trib2), a pseudokinase, is overexpressed in ERPC cells. Elevated level of Trib2 was also observed in enzalutamide treated PDX tumors in mice, and in prostate tumors from patients who were treated with enzalutamide. Inhibition of Trib2 by shRNA effectively kills ERPC cells, suggesting that Trib2 plays an important role in ERPC. We found that the Trib2 protein level is especially higher in prostate cancer cells where the AR activity is either low, or absent due to genetic changes. Moreover, transfection and re-expression of the AR gene in AR-negative cells decreases Trib2 protein level, indicating that the expression of Trib2 is negatively regulated by androgenic signaling. Interestingly, forced overexpression of Trib2 results in faster prostate cancer cell growth and makes the cells completely resistant to enzalutamide, and inhibition of Trib2 by shRNA or chemical inhibitor decreases viability and re-sensitizes these cells to enzalutamide.
Conclusion: Collectively, our findings reveal that Trib2 is overexpressed in ERPC cells and tumors, and suggest that Trib2 may turn out to be a novel, promising molecular target for therapy of enzalutamide-resistant, lethal prostate cancer.
Citation Format: Jitender Monga, Parshva Sanghvi, Jagadananda Ghosh. Overexpression of Tribbles 2 enhances prostate cancer cell growth and contributes to enzalutamide resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1325.
Abstract 1331: Synthesis and evaluation of FPR1 inhibitors as a novel treatment for cancers
Authors: Aghamohammadi Amin , Lu Di , Salem Anwar , Cooper Patricia A. , Shnyder Steven D. , Vinader Victoria , Afarinkia Kamyar 
Published: July 2021

Abstract
The formyl peptide receptor-1 (FPR1) is a member of 7TM GPCRs. It was first identified in phagocytic leukocytes and has been found to play a role in innate immune response to bacterial infection. Recently FPR1 has been shown to be overexpressed in many malignant cancers and particularly in glioblastoma. Our more recent investigation has shown that increased expression of FPR1 in cancer is most notably prominent in the periphery of the necrotic foci. We have hypothesised that FPR1 activation by molecules released from the hypoxic/necrotic core of tumours (including Annexin-A1 and short chain-N-formylated peptides such as fMLF) leads to increased proliferation, invasion, resistance, and angiogenesis. Therefore, antagonism of FPR1 should prevent these key drivers of malignancy in cancer. Here we present the synthesis and biological evaluation of a series of pyrazole compounds that potently inhibit FPR1. In addition, we provide a computational rationale for their relative potency based on docking of the molecules inside a homology model of FPR1. We will also show the efficacy of our lead compound, ICT12035 (IC50 =30nM in calcium mobilisation assay) in a number 2D and 3D proliferation and invasion assays in vitro, and in an in vivo animal model where it arrests tumour growth. Furthermore, we demonstrate the significance of FPR1 in tumour resistance by showing that ICT12035 increases the efficacy of cytotoxic agents TMZ and BCNU, as well as radiation in vitro. ICT12035 significantly abrogates the effects fMLF induced resistance to TMZ and BCNU in in U87 cell lines. A similar effect is also observed in a cell viability assay where in the addition of ICT12035 significantly increased cell death following radiation. Our findings suggest that inhibiting FPR1 in combination with chemotherapy and radiotherapy could be a new treatment strategy against cancers.
Citation Format: Amin Aghamohammadi, Di Lu, Anwar Salem, Patricia A. Cooper, Steven D. Shnyder, Victoria Vinader, Kamyar Afarinkia. Synthesis and evaluation of FPR1 inhibitors as a novel treatment for cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1331.
Abstract 1332: Antiretroviral agent inhibits proliferation and motility of BT-20 cells through inhibition of human endogenous retrovirus type K
Authors: Lin John , Farris Mason , Robbins Lauren , Lee Matthew , Nong Serratt , Liu Yingguang 
Published: July 2021

Abstract
The purpose of the study was to establish the role of human endogenous retrovirus K (HERV-K) in cancer development and to explore the possibility of repurposing antiretroviral agents for cancer treatment. We screened different categories of antiretroviral agents and several breast cancer cell lines to study the ability of antiretroviral agents to inhibit cancer cell proliferation and to inhibit the natural expression of HERV-K in cancer cells. Cells were transduced with exogenous HERV-K genes or with HERV-K knockdown plasmids to investigate the relationship between cytotoxic effect of antiretroviral agents and HERV expression. We found that an integrase strand-transfer inhibitor, dolutegravir, inhibited HERV-K expression on both the RNA and protein levels in BT-20 cells. Transduction with both HERV-K env and pol genes rendered the cell line more resistant to dolutegravir. Knockdown of HERV-K with shRNA also increased resistance to dolutegravir compared to cells transduced with random double-stranded RNA. The cytotoxic effect of dolutegravir correlated with enhanced expression of E-cadherin and a reduction in cell motility. Interestingly, an HERV-K knockdown cell line also exhibited enhanced expression of E-cadherin and reduced motility. As a potential carcinogenic role of HERVs has raised interest in using antiretroviral agents as a new approach to treat cancer, we provide the first evidence that one antiretroviral agent actually inhibits the proliferation and motility of a cancer cell line through inhibiting an HERV.
Citation Format: John Lin, Mason Farris, Lauren Robbins, Matthew Lee, Serratt Nong, Yingguang Liu. Antiretroviral agent inhibits proliferation and motility of BT-20 cells through inhibition of human endogenous retrovirus type K [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1332.
Abstract 1346: Direct targeting of MAPK/ERK signaling pathway is a novel therapeutic approach for high-risk neuroblastoma
Authors: Chilamakuri Rameswari , Sharma Bharti , Rouse Danielle C. , Agarwal Saurabh 
Published: July 2021

Abstract
Neuroblastoma is a highly heterogenous pediatric tumor that develops during the early embryonic stages, and accounts for almost 15% of pediatric cancer related deaths. Despite advanced and intensive therapeutic approaches that combine surgery, radiation, and chemotherapy, high-risk neuroblastoma (NB) patients' long-term survival is still less than 50%. Tumor metastasis, relapse, drug-resistance, and treatment related toxicities mandate the development of novel therapeutic approaches to treat NB patients. MAPK/ERK pathway plays an important oncogenic role in different types of cancers, including NB. Activation of the MAPK/ERK pathway is known to induce cancer cell proliferation, progression, metabolism, and resistance to drug-induced apoptosis. In the present study, we investigated the effect of a small-molecule MEK inhibitor that targets MEK1 and MEK2 to block MAPK/ERK pathway in NB. Cytotoxicity assays using Cell-Titer One solution in different MYCN-amplified (NGP, LAN-5, CHLA-255-MYCN) and MYCN-non-amplified (SH-SY5Y, SK-N-AS, CHLA-255) NB cell lines show that MEK inhibitor significantly reduce the NB cell proliferation in a dose-dependent manner. We further performed clonogenic assays and 3D spheroidal assays to mimic the NB tumor growth, and our results show that MEK inhibitor significantly inhibit NB colony formation, inhibit 3D spheroidal tumor size by inducing cell death in 3D spheroidal tumors, in comparison to controls. Additionally, MEK inhibitor in a dose-dependent manner induces apoptosis and blocks cell cycle progression in NB cells in comparison to control, as determined by Annexin V apoptosis assays and Click-iT EdU cell proliferation assay respectively. Furthermore, gene expression analysis show that MEK inhibitor significantly reduce the mRNA expression of specific MAPK/ERK pathway targets such as MEK1, MEK2, and ERK2. Western blot assays further confirm the efficacy of MEK inhibitor in blocking MAPK/ERK pathway by significantly inhibiting the phosphorylation of key pathway proteins. Taken together, our results highlight that: a) MAPK/ERK pathway is implicated in NB growth, and b) direct targeting of MAPK/ERK signaling pathway by using a novel small molecule MEK inhibitor inhibit NB proliferation and 3D tumor growth. We will further combine this MEK inhibitor with current chemotherapy drugs to develop effective therapeutic approaches for NB patients.
Citation Format: Rameswari Chilamakuri, Bharti Sharma, Danielle C. Rouse, Saurabh Agarwal. Direct targeting of MAPK/ERK signaling pathway is a novel therapeutic approach for high-risk neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1346.
Abstract 1388: ATM inhibitor AZD1390 sensitizes breast cancer brain metastasis to radiation therapy
Authors: Tew Ben Yi , Durant Stephen , Salhia Bodour 
Published: July 2021

Abstract
Metastasis to the central nervous system (CNS) has remained a major source of morbidity and mortality for patients with breast cancer. This is mainly driven by the lack of therapeutic options, as traditional chemotherapy and targeted therapies have been shown to have limited efficacy in the brain. Ataxia-telangiectasia mutated (ATM) protein orchestrates the cellular DNA damage response (DDR) to cytotoxic DNA double-strand breaks induced by ionizing radiation (IR). ATM genetic ablation or pharmacological inhibition results in tumor cell hypersensitivity to IR.AZD1390 is a potent orally bioavailable ATM inhibitor, specifically optimized for blood brain barrier penetration and has shown to be an effective radiosensitizer in gliomas. We have shown that there are frequent alterations in DNA damage response (DDR) pathways in CNS metastasis (CM), which include frequent mutations in TP53. Incorrect repair of DNA lesions often leads to genomic instability. ATM, a core component of the DNA repair system, is activated to enhance the homologous recombination (HR) repair pathway upon DNA double-strand breaks. Here we show that AZD1390, when used in combination with radiation therapy, can inhibit the growth of breast cancer CM in patient derived xenograft (PDX) tumors. Three PDX models (2 Her2+ and one triple negative), all of which harbor TP53 mutations and other DDR alterations, were implanted into the flank or brain of immunocompromised mice. Pre-treatment with AZD1390 followed by a fractionated regime of radiation therapy (2Gy/day for 5 days) significantly inhibited growth of flank PDX tumors by an average of 81% (85% and 80% in the HER2+ and 77% in the triple negative PDX, p-value &lt; 0.05). This is compared to an average of 7% (8%, 13% and 0% respectively) for tumors treated with AZD1390 alone or 40% (39%, 21% and 58% respectively) for radiation therapy alone in all PDX models. Growth inhibition was sustained until the experiment endpoint at 90 days in 75% of the tumors, and 25% of the tumors regressed below their size at the beginning of treatment. About 31% of tumors across three models started to grow back and gene expression analysis comparing these tumors with complete responders demonstrated changes in oxidative phosphorylation, sirtuin signaling, and ERK/MAPK signaling. Adjuvant therapy of AZD1390 did not further decrease tumor growth. Our results demonstrate that AZD1390 can sensitize breast cancer CM with DDR pathway alterations to radiation therapy. This points to the potential of AZD1390 as a potential novel therapeutic agent for patients with breast cancer CM.
Citation Format: Ben Yi Tew, Stephen Durant, Bodour Salhia. ATM inhibitor AZD1390 sensitizes breast cancer brain metastasis to radiation therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1388.
Abstract 1402: HNRNPA2B1 increases the serine synthesis pathway in endocrine-resistant breast cancer cells
Authors: Klinge Carolyn M. , Petri Belinda J. , Piell Kellianne M. , Clem Brian C. 
Published: July 2021

Abstract
Despite the limited success of new combination therapies with fulvestrant improving survival of breast cancer patients with metastatic disease after initial response to endocrine therapies based on primary estrogen receptor alpha (ER+) tumors, mechanisms for acquired endocrine resistance remain to be fully elucidated. The RNA binding protein HNRNPA2B1, a reader of epitranscriptomic N(6)-methyladenosine (m6A) in transcribed RNA, is upregulated in endocrine-resistant, ER+ LCC9 and LY2 cells compared to parental MCF-7 endocrine-sensitive luminal A breast cancer cells. HNRNPA2B1 regulates pri- to pre- miRNA processing as well as splicing and transcript stability, depending on interacting proteins and cellular context. The miRNA-seq transcriptome of MCF-7 cells transiently overexpressing HNRNPA2B1 identified gene ontology (GO) pathways including cellular response to steroid hormone signaling and serine family amino acid metabolic processes, i.e., the serine synthesis pathway (SSP). Stable, modest (4.5-fold) overexpression of HNRNPA2B1 in MCF-7 cells (MCF-7-A2B1 cells) phenocopies the endocrine-resistance of LCC9 and LY2 cells including ablation of growth inhibition by 4-hydroxytamoxifen (4-OHT) and fulvestrant. This was not the result of decreased ER alpha; rather, ER alpha, and androgen receptor (AR), were increased. Conversely, transient knockdown of HNRNPA2B1 in LCC9 and LY2 cells sensitized the cells to growth inhibition by 4-OHT and fulvestrant. MCF-7-A2B1 cells, like LCC9 and LY2 cells, have higher expression of phosphoglycerate dehydrogenase (PHGDH) and phosphoserine aminotransferase (PSAT1) transcripts and proteins compared to MCF-7 cells. We identified two miRNAs, miR-424-5p and miR-145-5p downregulated in MCF-7-A2B1 cells that directly target the PSAT1 3'UTR in dual luciferase assays. Lower miR-424-5p and miR-145-5p in endocrine-resistant LCC9 and LY2 correlate with increased PSAT1 and higher PSAT1 is associated with reduced overall and metastasis-free survival in breast cancer patients. The correlation of HNRNPA2B1 and PSAT1 expression was examined by IHC in a breast tumor/tissue microarray. Overall, our data suggest a role for increased HNRNPA2B1 in endocrine-resistance and upregulation of the SSP to promote tumor progression in ER+ breast cancer.
Citation Format: Carolyn M. Klinge, Belinda J. Petri, Kellianne M. Piell, Brian C. Clem. HNRNPA2B1 increases the serine synthesis pathway in endocrine-resistant breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1402.
Abstract 1403: Efficacy of microtubule targeting agents on triple negative breast cancer cells influenced by adenomatous polyposis coli loss
Authors: Arenas Pamela D. , Maloney Sara M. , Prosperi Jenifer R. 
Published: July 2021

Abstract
Triple negative breast cancer (TNBC) accounts for about 20% of all breast cancers. TNBC is an aggressive subtype of breast cancer that lacks the expression of estrogen and progesterone receptors and HER2 protein. This lack of functioning receptors results in limited treatment options, usually resulting in the use of taxanes, platinums, and anthracyclines. Although TNBC often starts as being sensitive to traditional chemotherapies, tumor relapse and/or resistance often develops. Paclitaxel (PTX) is a commonly used taxane for TNBC, well known to induce mitotic arrest through stabilization of microtubules (MT) leading to an interference with the treadmilling function of MT through the activation of the spindle assembly checkpoint. We have previously shown that loss of the Adenomatous Polyposis Coli (APC) tumor suppressor significantly increases resistance to PTX in APC knockdown (APCKD) cells generated in two human TNBC cell lines, MDA-MB-157 and MDA-MB-231. Given this striking PTX resistance, we were interested in seeing if resistance in APCKD can be seen using other non-taxane MT targeting agents. To accomplish this, we have used an epothilone (Epothilone B) and a vinca alkaloid (Vinblastine), that function by stabilizing and destabilizing the MTs, respectively. Our previous investigations demonstrated that APC loss results in increased CDK1 and CDK6, so these have been used as markers of cell cycle progression after drug treatment. In addition, changes in apoptosis were measured through the use of Annexin V and PI staining, and cleaved caspase 3 expression. Examined together, a better understanding of how APC loss influences chemoresistance in TNBC can lead to more efficient treatments for TNBC patients resistant to taxanes. Given the critical interaction between APC and MTs, this may be an avenue for targeted therapies to overcome taxane resistance.
Citation Format: Pamela D. Arenas, Sara M. Maloney, Jenifer R. Prosperi. Efficacy of microtubule targeting agents on triple negative breast cancer cells influenced by adenomatous polyposis coli loss [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1403.
Abstract 1404: Loss of adenomatous polyposis coli induces DOX resistance through upregulation of ABC transporters
Authors: Stefanski Casey D. , Prosperi Jenifer R. , Milac Lauren 
Published: July 2021

Abstract
Chemoresistance is a leading cause of breast cancer related deaths. Therefore, understanding the molecular basis for chemoresistance is essential for novel therapeutic advancement improving patient outcome. The Adenomatous Polyposis Coli (APC) tumor suppressor is lost in up to 70% of sporadic breast cancer; however, little is known about how APC loss contributes to chemoresistance. Using mammary tumor cells isolated from the ApcMin/+ mouse crossed to the Polyoma middle T antigen (PyMT) transgenic model, we were the first to show that APC loss decreased doxorubicin (DOX) induced apoptosis. Therefore, we examined the mechanisms contributing to DOX resistance with APC loss to identify combination therapy options. We previously made the novel observation that APC loss in MMTV-PyMT;ApcMin/+ cells activated signal transducer and activator of transcription 3 (STAT3) thereby increasing the expression of the drug efflux pump, multidrug resistance protein 1 (MDR1). ATP-binding cassette (ABC) transporters, such as MDR1, are one of the most well-known contributors to drug resistance. These ABC transporters are capable of exporting drugs from the cell preventing apoptosis. Decreased intracellular DOX accumulation was observed in APC-deficient cells suggesting enhanced drug efflux. To investigate this decreased intracellular DOX accumulation, we measured the expression and activity of the drug export pumps, MDR1 and multidrug resistance protein 1 (MRP1). APC-deficient cells also have increased expression of MRP1. We used a calcein incorporation assay and demonstrated that APC loss increased MDR1 activity, which was restored by an MDR1 inhibitor. In addition, MDR1 inhibition sensitized the MMTV-PyMT;ApcMin/+ cells to DOX-mediated apoptosis. MRP1 inhibition through genetic manipulation will be used to assess MRP1 activity using the calcein AM assay and its contribution to DOX resistance. MDR1 and MRP1 inhibition will also be used to restore intracellular DOX accumulation. Future studies including evaluating human tumor protein lysates will for APC, MDR1, and MRP1 expression. Correlation studies will be used to determine whether loss of APC correlates with either high expression of MDR1 or MRP1. Taken together, APC loss mediates DOX resistance via exporting DOX demonstrating the potential use of combination therapy to overcome chemoresistance.
Citation Format: Casey D. Stefanski, Jenifer R. Prosperi, Lauren Milac. Loss of adenomatous polyposis coli induces DOX resistance through upregulation of ABC transporters [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1404.