bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 5440: Novel PD-1 blockade bioassay to assess therapeutic antibodies in PD-1 and PD-L1 immunotherapy programs
Authors: Cheng Zhi-Jie Jey , Karassina Natasha , Grailer Jamison , Hartnett Jim , Fan Frank , Cong Mei 
Published: August 2015

Abstract
Programmed death receptor-1 (PD-1) and its ligand (PD-L1) are among the few important immunotherapy targets for cancer. Current PD1 assays measure cell proliferation or cytokine production in primary T cells which are tedious, have high assay variation and small assay window. To enable quantitative potency measurement for key anti-PD-1 drugs in the market or in clinical trials such as pembrolizumab and nivolumab, as well as anti-PD-L1 drugs in clinical trials such as MPDL3280A and BMS-936559, here we report the development of a robust bioluminescent cell-based PD1 blockade bioassay. For this, we built a PD-1 effector cells in Jurkat cells which stably express human PD-1 and a NFAT-RE-luciferase reporter, and a PD-L1 positive artificial Antigen Presenting Cells (PD-L1+ aAPC) in CHO-K1 cells which stably express PD-L1 and an engineered TCR activator. Once these two cell types were co-cultivated, transcriptional activation of NFAT pathway in PD-1 effector cells, mediated by binding of TCR complex with TCR activator in PD-L1+ aAPC, is significantly suppressed by PD-1/PD-L1 engagement. This inhibition can then be specifically reversed by co-incubation of PD-1 or PD-L1 blocking antibodies in dose-dependent manner, but not by the antibody for other immune checkpoint receptors such as anti-CTLA4 ipilimumab. We further developed both PD-1 effector cells and PD-L1+ aAPC in Thaw-and-Use format so the cells can be plated for assay without the need of cell culture. The resultant PD-1 assay using Thaw-and-Use cells brings the benefit of convenience, low day-to-day variation, and easy lab-to-lab assay transfer. We demonstrate the assay is able to measure relative potency for antibody biologics, and also can detect potency changes for stressed antibody samples. In summary, the reporter-based PD-1 blockade assay provides a valuable tool for both drug screening and characterization in early drug discovery, and lot release and stability study in drug manufacture for therapeutic antibody drug candidates in PD-1 and PD-L1 immunotherapy programs.
Citation Format: Zhi-Jie Jey Cheng, Natasha Karassina, Jamison Grailer, Jim Hartnett, Frank Fan, Mei Cong. Novel PD-1 blockade bioassay to assess therapeutic antibodies in PD-1 and PD-L1 immunotherapy programs. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5440. doi:10.1158/1538-7445.AM2015-5440
Abstract 5455: Surface accumulation of receptor tyrosine kinases upon treatment with tyrosine kinase inhibitors and resulting enhancement of activity upon treatment cessation
Authors: Bjerregaard Anne-Mette , Grandal Michael V. , Frohlich Camilla , Lindsted Trine , Egebjerg Christina , Horac Ivan D. , Kragh Michael , Pedersen Mikkel W. 
Published: August 2015

Abstract
Receptor tyrosine kinases (RTKs) constitute the largest family of structurally related oncogenes and are often involved in the initiation, maintenance and/or metastasis of various human cancers. The genes encoding RTKs are frequently amplified, fused, mutated, or the ligands are expressed at high levels, causing abnormal activation and downstream signaling. Two major types of drugs have been used with success to treat cancers with abnormal RTK activation, recombinant monoclonal antibodies (mAbs) and small molecule inhibitors of the tyrosine kinases (TKIs). TKIs have proven most successful against cancers driven by gene fusions or mutations, whereas mAbs dominate in cancers driven by gene amplifications or ligand-mediated RTK activation. Recent studies show that the two types of treatment modalities may often be synergistic, but the reason for this is not well characterized.
Here, we demonstrate that surface levels of various RTKs increase in cancer cell lines upon treatment with TKIs specific for the individual RTKs. The effect was most pronounced in cell lines with amplification or autocrine ligand production and occurred at inhibitor concentrations suboptimal for inhibition of growth. Removal of the TKIs resulted in an increase in RTK activity and cancer cell proliferation as a result of the increased RTK levels.
MAbs, especially mAb mixtures, when given in combination with the TKIs were found to prevent RTK accumulation and led to enhanced efficacy. Due to the increased number of receptors, the combination also resulted in enhancement of secondary effector functions, such as ADCC.
In conclusion, our results demonstrate that in certain contexts TKI treatment leads to RTK accumulation and that this accumulation has the potential to enhance tumor growth. Antibody mixtures, when given together with the TKIs, can prevent RTK accumulation and even enhance the TKI activity.
Citation Format: Anne-Mette Bjerregaard, Michael V. Grandal, Camilla Frohlich, Trine Lindsted, Christina Egebjerg, Ivan D. Horac, Michael Kragh, Mikkel W. Pedersen. Surface accumulation of receptor tyrosine kinases upon treatment with tyrosine kinase inhibitors and resulting enhancement of activity upon treatment cessation. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5455. doi:10.1158/1538-7445.AM2015-5455
Abstract 5456: FGF9 gene amplification can induce resistance to anti-EGFR therapy in colorectal cancer
Authors: Mizukami Takuro , Togashi Yosuke , Banno Eri , Terashima Masato , de velasco Marco A , Sakai Kazuko , Fujita Yoshihiko , Tomida Shuta , Eguchi Nakajima Takako , Boku Narikazu , Nishio Kazuto 
Published: August 2015

Abstract
The prognosis of advanced colorectal cancer (CRC) remains dismal. Fibroblast growth factor (FGF) signals are potent mitogens, morphogens, and inducers of angiogenesis. Abnormal expression of FGF9 has been observed in several malignancies and might result in uncontrolled cell proliferation and carcinogenesis. However, limited information is available regarding the role of FGF9 in CRC. In this study, amplification of FGF9 gene was observed in 14/146 (9.6%) CRC specimens, using a TaqMan copy number assay. FGF9-overexpressed CRC cell lines were created, and FGF9-overexpression induced the resistance to anti-epidermal growth factor receptor (EGFR) therapy (cetuximab or lapatinib) via the FGF receptor (FGFR) signal, which was cancelled by BGJ398, a pan-FGFR inhibitor. In vivo, FGF9-overexpressed xenograft tumors were resistant to cetuximab monotherapy and the combination with BGJ398 overcame the resistance. Considering these results, FGF9 gene amplification may play an important role in the resistance to anti-EGFR therapy in CRC and the combination with an anti-FGFR inhibitor could overcome this resistance.
Citation Format: Takuro Mizukami, Yosuke Togashi, Eri Banno, Masato Terashima, Marco A de velasco, Kazuko Sakai, Yoshihiko Fujita, Shuta Tomida, Takako Eguchi Nakajima, Narikazu Boku, Kazuto Nishio. FGF9 gene amplification can induce resistance to anti-EGFR therapy in colorectal cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5456. doi:10.1158/1538-7445.AM2015-5456
Abstract 5457: MAD2γ, a new MAD2 isoform, is ubiquitously expressed in distinct cell lines, reduces mitotic arrest, and associates with resistance to cisplatin-based chemotherapy in testicular germ cell tumors
Authors: Lopez-Saavedra Alejandro , Caceres Rodrigo , Luna Fernando , Hernandez Irwin , Herrera Luis Alonso 
Published: August 2015

Abstract
The mitotic spindle assembly checkpoint (SAC) signaling has been emerging as an important promising mechanism in cancer therapy. A prolonged mitotic arrest in response to cancer chemotherapy induces apoptosis, mitotic catastrophe, mitotic slippage and senescence, depending on what cell line and/or inhibitor is studied. In consequence, a weakened or disturbed SAC signaling in human cancers might contribute to drug resistance both to spindle inhibitors and to DNA damaging agents. In several studies the mitotic arrest deficient 2 (MAD2α) has been implicated in the association between failure in the SAC signaling and chemotherapy response. In this study, we identified a novel splicing variant of MAD2, designated as MAD2γ. This isoform was ubiquitously expressed in several cancer cell lines and non-cancerous primary foreskin fibroblasts. When it was ectopically expressed, MAD2γ localized in the nucleus. Its overexpression in a fully functional SAC-competent cancer cell line, HCT116, reduced the mitotic index, suggesting SAC impairment. Furthermore, the endogenous overexpression of MAD2γ in testicular germ cell tumor patients was associated with a resistant response to cisplatin-based chemotherapy, whereas expression of MAD2α was not significantly different between resistant and sensitive patients. In addition, HCT116 raised significantly its endogenous expression of MAD2γ only in response to cisplatin, but not that of MAD2α. Our data suggest that MAD2γ may have an opposing role to MAD2α in the activation of the SAC signaling, and that its expression is associated to a resistant response to DNA-damaging agents, such as cisplatin-based chemotherapy. This highlight the importance to study alternative splicing that may compromise the SAC function, which has been regarded as a promise for cancer therapy.
Citation Format: Alejandro Lopez-Saavedra, Rodrigo Caceres, Fernando Luna, Irwin Hernandez, Luis Alonso Herrera. MAD2γ, a new MAD2 isoform, is ubiquitously expressed in distinct cell lines, reduces mitotic arrest, and associates with resistance to cisplatin-based chemotherapy in testicular germ cell tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5457. doi:10.1158/1538-7445.AM2015-5457
Abstract 5458: Elevated level of Fibrillarin induces chemoresistance by interfering p53 pathway in cancers
Authors: Xu Teng , Ganapathy Suthakar , Long Meijun , Ha Chul , Yuan Zhi-Min , Su Hang 
Published: August 2015

Abstract
Fibrillarin (FBL), an rRNA 2′-O-methyltransferase, has long been recognized as the enzymatic unit of the C/D box small nucleolar ribonucleoprotein (snoRNP) involved in the first step of pre-rRNA processing. It is not until recently that the link between FBL and cancers has been unveiled. As a direct regulatory target of Myc and p53, FBL is frequently upregulated in breast cancers and prostate cancers. High expression of FBL has also been shown to be associated with poor survival in patients with breast cancer. Our recent study found that FBL overexpression contributes to tumorigenesis and confers cellular resistance to chemodrugs. However, the underlying mechanism of chemoresistance elicited by FBL upregulation is still elusive. Here, we studied the molecular roles of FBL on p53 response. The p53 pathway in response to etoposide and actinomycin D were examined in a variety cell lines including U-2OS, MCF7, H1299, ZR75-1, A549 and an FBL inducible cell line. Western blotting and immunofluorescent staining were employed to examine protein level and their cellular localization. We found that ectopic expression of FBL enhanced the protein level of MDM2, resulting in decreased p53 accumulation and activity in response to chemodrugs. Interestingly, MDM2 was partially recruited to the nucleoli under stimuli. FBL depletion abrogated the nucleolar recruitment of MDM2 and subsequently dampened p53 activation. In conclusion, physiological level of FBL sequesters and stabilizes MDM2 in the nucleoli, therefore inhibits p53 degradation. When upregulated in cancers, FBL stabilizes nucleus MDM2 and promotes the degradation of p53
Citation Format: Teng Xu, Suthakar Ganapathy, Meijun Long, Chul Ha, Zhi-Min Yuan, Hang Su. Elevated level of Fibrillarin induces chemoresistance by interfering p53 pathway in cancers. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5458. doi:10.1158/1538-7445.AM2015-5458
Abstract 546: Soluble EphA2 is a potential serum biomarker for lung cancer
Authors: Kondo Tadanori , Yumoto Hiroki , Usui Kento , Kato Kazunori 
Published: August 2015

Abstract
EphA2 is a cell surface glycoprotein expresses in various tumor tissues including lung, breast and pancreas carcinoma. As the patients with a highly positive surface expression of EphA2 carcinomas have the poor prognosis, therefore, preclinical and clinical studies using antibody targeting to EphA2 are underlying. Previous study has reported that EphA2 fragment is also released in a soluble form by the proteolytic cleavage from tumor cell surface. In this study, we tried to detect the soluble form of EphA2 (sEphA2) in the serum specimens of lung cancer patients. By using antibodies to EphA2, we developed a new sandwich ELISA system detecting human sEphA2 with high sensitivity and specificity. With this system, we measured the concentration of sEphA2 in the serum of normal healthy donors and lung cancer patients. The concentration of sEphA2 was significantly higher in sera of 15 lung cancer patients than 15 healthy donors (p&lt;0.01). We also examined the other diagnostics biomarkers such as CYFRA and CEA. The levels of sEphA2 in serum of lung cancer patients are correlated with CYFRA and CEA. These data indicate that the diagnosis of the lung cancer enabled by measuring the concentration of sEphA2. However, detail clinicopathological characteristics are necessary for the feasible diagnosis for sEphA2 as a biomarker of lung cancer.
Citation Format: Tadanori Kondo, Hiroki Yumoto, Kento Usui, Kazunori Kato. Soluble EphA2 is a potential serum biomarker for lung cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 546. doi:10.1158/1538-7445.AM2015-546
Abstract 5462: Extracellular ATP promotes cancer cell drug resistance to tyrosine kinase inhibitors by competing for the ATP-binding site of tyrosine kinase
Authors: Wang Xuan , Qian Yanrong , Li Yunsheng , Chen Xiaozhuo 
Published: August 2015

Abstract
ATP plays important roles in cellular processes in cancer cells, which are a heterogeneous population in tumors regarding their genetic background and oxygen and energy supplies. The fact that cancer cells undergo rapid proliferation suggests that they must possess mechanisms, which may not be present in normal cells, to meet their high energy needs. Studies by others revealed that extracellular ATP levels of various cancer types are 10^3 to 10^4 times higher than those in their corresponding normal tissues (1). We recently reported that extracellular ATP can be taken up directly by cancer cells by macropinocytosis (2). Based on these results, we hypothesized that the internalized extracellular ATP not only promotes cancer cell growth and survival, but also drug resistance. In this study, human lung cancer A549 and breast cancer MCF7 cells were used as cell models to determine the effects of extracellular ATP on drug resistance to tyrosine kinase inhibitors (TKIs) in cancer cells. Cancer cell viability and intracellular ATP measurement results showed that extracellular ATP substantially increased intracellular ATP levels and promoted cancer cell drug resistance to TKIs. Viability of TKI treated cancer cells was significantly increased in the presence of extracellular ATP, compared to cancer cells with TKI treatment alone. Administration of macropinocytosis inhibitors significantly reduced the drug resistance induced by extracellular ATP, suggesting that extracellular ATP promoted drug resistance by contributing to the intracellular ATP pool. Protein and protein phosphorylation analyses results suggested that the increased intracellular ATP reversed the inhibition of TKIs by competing with the inhibitor for the ATP-binding site of platelet-derived growth factor receptor (PDGFR) and enhancing Akt and MAPK signaling pathways. These findings identify, for the first time, new biological functions of extracellular ATP in tumors and may lead to novel anti-cancer strategies combating drug resistance in cancers.
1. Pellegatti P, et al. PLoS ONE 2008;3:e2599.
2. Qian Y, et al. Cancer Lett 2014;351:242-51.
Citation Format: Xuan Wang, Yanrong Qian, Yunsheng Li, Xiaozhuo Chen. Extracellular ATP promotes cancer cell drug resistance to tyrosine kinase inhibitors by competing for the ATP-binding site of tyrosine kinase. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5462. doi:10.1158/1538-7445.AM2015-5462
Abstract 5465: Systematic interrogation of druggable pathways in pancreatic adenocarcinomas using pooled gene-knockdown lentiviral libraries
Authors: Ferrer-Lorenzo Edgar , Nussbaum Daniel P. , Winter Peter , Wood Kris 
Published: August 2015

Abstract
Despite significant advances in the development of cancer treatment in the last 20 years the best available therapies have marginally improved the survival rate of treated pancreatic cancer patients (from 3% to 6% five-year survival), making it still one the deadliest malignancies. Single standard of care cytotoxic and targeted therapies demonstrate little to no effect on patient survival. Even though we now understand some of the main genetic factors that are mutatated in pancreatic tumors, their role in drug response remains poorly understood. To identify drug-sensitizing genetic targets in cancer cells we have developed a high-throughput screening platform. In this methodology, pooled lentiviral libraries containing hundreds of knockout constructs specific for cancer-related genes are used to infect cancer cells. By treating the infected populations with therapeutic agents we are able to identify genetic targets that when inhibited synergize with existing drugs to cause increased cell death. We piloted this type of screening platform in HCT-116 cells, a KRAS mutant, MEK inhibitor resistant colorectal cancer cell line, using the MEK-inhibitor AZD-2644 and a pooled shRNA library. This study identified 4-7 target genes that when knocked down sensitized the previously resistant HCT-116 cells to AZD-2644. To conduct a more robust and representative sensitization screen we developed a lentiviral CRISPR-Cas9 library. By performing screens in a panel of pancreatic cancer cell lines, we have identified both cell line dependencies and sensitizers to targeted and cytotoxic chemotherapies. The findings from these screens provide potential mechanistic insights into the key survival signaling programs in pancreatic cancer as well as new therapeutic strategies.
Citation Format: Edgar Ferrer-Lorenzo, Daniel P. Nussbaum, Peter Winter, Kris Wood. Systematic interrogation of druggable pathways in pancreatic adenocarcinomas using pooled gene-knockdown lentiviral libraries. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5465. doi:10.1158/1538-7445.AM2015-5465
Abstract 5473: Human cancer cells acquire chemoresistance to gemcitabine mainly through loss-of-function mutations in the DCK gene
Authors: Horii Akira , Saiki Yuriko , Nakano Tomohiro , Kudo Chiharu , Sunamura Makoto 
Published: August 2015

Abstract
Gemcitabine (GEM) has shown clinical activity in several solid tumors such as pancreatic and biliary tract cancers, urinary cancer, and non-small cell lung cancers, but a substantial number of patients acquire GEM chemoresistance. GEM functions after phosphorylation by deoxycytidine kinase (DCK) and its inactivation is one of the important mechanisms for acquisition of gemcitabine resistance. We established eight GEM resistant cell lines including four pancreatic, two biliary tract, and two gastrointestinal cancers and investigated mechanisms for acquisition of GEM resistances; six GEM resistant cell lines harbored complete inactivating mutations of DCK by protein-truncating mutation or complete or partial loss of the gene, and one gastric cancer cell line harbored a missense mutation that inactivate DCK activity. One pancreatic cancer cell line lost GEM sensitivity by unknown mechanism. Our present results strongly suggest that genetic alteration of DCK can be the major cause of acquisition of GEM resistance. Further studies analyzing primary tumors will give us (1) the fully understanding of acquisition of GEM resistance, and (2) desirable clues to overcome the acquisition of GEM resistance.
Citation Format: Akira Horii, Yuriko Saiki, Tomohiro Nakano, Chiharu Kudo, Makoto Sunamura. Human cancer cells acquire chemoresistance to gemcitabine mainly through loss-of-function mutations in the DCK gene. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5473. doi:10.1158/1538-7445.AM2015-5473
Abstract 5477: MERIT40 is an Akt substrate that promotes resolution of DNA damage induced by chemotherapy
Authors: Brown Kristin K. , Montaser-Kouhsari Laleh , Beck Andrew H. , Toker Alex 
Published: August 2015

Abstract
Resistance to cytotoxic chemotherapy agents is a common phenomenon in breast cancer and has a drastic impact on patient survival. Characterization of the mechanisms that contribute to chemotherapy resistance, and identification of strategies to circumvent resistance, would provide more effective therapies for the management of breast cancer. In this study we show that in addition to inflicting DNA damage, the cytotoxic chemotherapy agent doxorubicin triggers rapid and sustained activation of Akt in breast cancer cells. Pharmacological inhibitors of PI 3-K or Akt effectively block Akt signaling downstream of DNA damage and render cells markedly more sensitive to doxorubicin. We sought to identify mechanisms by which Akt promotes resistance to doxorubicin and have identified MERIT40, a component of the nuclear BRCA1-A DNA damage repair complex, as a novel Akt substrate that is phosphorylated when cells are exposed to doxorubicin. We have demonstrated that MERIT40 phosphorylation is necessary for BRCA1-A complex assembly and is required for resolution of DNA damage. We propose that inhibition of MERIT40 phosphorylation contributes to the efficacy of combination therapy with PI 3-K or Akt inhibitors and doxorubicin. We also show that MERIT40 phosphorylation is associated with ER status in breast tumor tissue samples, suggesting that MERIT40 phosphorylation could be used as a biomarker in ER-positive breast cancer patients to predict sensitivity to cytotoxic chemotherapy agents. Our data also indicates that patients with high levels of phosphorylated MERIT40 would likely benefit from combination therapy with Akt inhibitors and doxorubicin. We are currently investigating additional mechanisms by which Akt activation downstream of DNA damage promotes chemotherapy resistance with the aim of identifying novel combination therapy regimens to circumvent chemotherapy resistance.
Citation Format: Kristin K. Brown, Laleh Montaser-Kouhsari, Andrew H. Beck, Alex Toker. MERIT40 is an Akt substrate that promotes resolution of DNA damage induced by chemotherapy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5477. doi:10.1158/1538-7445.AM2015-5477