bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 4741: Re-evaluating the role of P-glycoprotein in the resistance of high-risk neuroblastoma to standard-of-care chemotherapies
Authors: Atkinson Caroline , Tactacan Carole M. , Kamili Alvin , Saletta Federica , Gana Christine , Eden Georgina L. , Mayoh Chelsea , Lock Richard B. , Norris Murray D. , Haber Michelle , Gifford Andrew J. , Trahair Toby N. , Fletcher Jamie I. 
Published: August 2019

Abstract
Background: Neuroblastoma is the most common extracranial solid malignancy in children, comprising 15% of cancer related deaths. Despite intensive treatment, patients with high-risk neuroblastoma (HR-NB) have a survival rate of ~50%, largely due to intrinsic or acquired drug resistance. The multidrug transporter P-glycoprotein (P-gp; ABCB1) effluxes several conventional agents used in HR-NB induction therapy, including doxorubicin, vincristine and etoposide, as well as the ALK inhibitor crizotinib. We observed high P-gp expression in HR-NB cell lines and patient-derived xenograft (PDX) models, so sought to assess the prevalence of P-gp expression and its role in resistance to standard-of-care chemotherapies and relevant targeted agents.
Methods and Results: Using RNA-sequencing, immunohistochemistry and western blot on panels of neuroblastoma tumour samples, PDX models and cell lines, we demonstrated that high ABCB1/P-gp expression is frequent in HR-NB. Analysis of ABCB1 levels in large patient tumor datasets suggests that high expression is attributable to the sympathoadrenal lineage of the disease, that high expression is more common in HR-NB than in most other cancers, and that high relative expression of ABCB1 in HR-NB tumours is associated with poorer outcome, consistent with its multidrug transporter function. We demonstrated that the P-gp inhibitor tariquidar and P-gp knockdown (shRNA) both strongly sensitize cultured high P-gp expressing neuroblastoma cells to vincristine, doxorubicin and etoposide but not to ALK inhibitors. Further, P-gp knockdown sensitized human neuroblastoma xenografts to vincristine, substantially extending survival.
Conclusions: Elevated P-gp expression is common in HR-NB and can be sufficient to confer resistance to standard-of-care chemotherapies in model systems. Our findings suggest that tumour P-gp levels might be used to guide treatment options for individual patients, and to avoid ineffective treatments. The potential of P-gp inhibitors as adjuncts to conventional chemotherapy for HR-NB should be further investigated.
Citation Format: Caroline Atkinson, Carole M. Tactacan, Alvin Kamili, Federica Saletta, Christine Gana, Georgina L. Eden, Chelsea Mayoh, Richard B. Lock, Murray D. Norris, Michelle Haber, Andrew J. Gifford, Toby N. Trahair, Jamie I. Fletcher. Re-evaluating the role of P-glycoprotein in the resistance of high-risk neuroblastoma to standard-of-care chemotherapies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4741.
Abstract 4743: Using genome-wide CRISPR screen to understand resistance mechanisms to PCA062, a P-cadherin targeting antibody-drug conjugate
Authors: Tam Angela , Zambrowski Mark , Seiss Katherine , Liu Si-Qi , Abrams Tinya , Caponigro Giordano , Tschantz William , Campbell Jennifer , DAlessio Tony , Sheng Qing 
Published: August 2019

Abstract
P-cadherin (PCAD) is a member of the cadherin family that mediates calcium dependent cell-cell contacts in adherens-type junctions of epithelium. Expression of P-cadherin is high in malignant tumors of epithelial origin, such as breast, esophagus, head and neck cancers, but low in normal tissues. This expression pattern makes P-cadherin a potential good target for antibody-drug conjugates (ADCs). PCA062 is a first-in-class antibody drug conjugate targeting P-cadherin. PCA062 consists of a fully human anti-P-cadherin antibody of the IgG1/κ subtype, a non-cleavable bi-functional linker (SMCC) and a maytansine-derived cytotoxic payload (DM1, with a target average drug to antibody ratio (DAR) of 3.8).
PCA062 activity was examined in a collection of cell lines expressing high level of PCAD. A subset of these PCAD high cell lines are resistant to PCA062 treatment while they remain sensitive to DM1, suggesting defects in the process of PCA062 uptake or the processing and release of DM1 into the cytoplasmic compartment. PCA062 internalization rate was measured by the uptake of a fluorescent dye labeled anti-PCAD antibody (CQY684, the Ab portion of PCA062) in both PCA062 sensitive and resistant lines. PCA062 resistant lines show slower CQY684 internalization as compared to PCA062 sensitive lines, indicating a defect in ADC internalization may contribute to PCA062 resistance. To explore additional resistance mechanisms to PCA062 as well as to find critical components for PCA062 internalization, a genome wide CRISPR screen was performed in PCA062 sensitive HCC1954 and in PCA062 resistant KYSE510 cell line in the presence and absence of PCA062 and DM1 to look for genes that when knocked out may specifically modulate PCA062 sensitivity. The multi-drug resistant gene MRP1 is a strong hit for PCA062 sensitization in both PCA062 resistant KYSE510 and PCA062 sensitive HCC1954 cells. Lysosomal transporter SLC46A3 and Saga transcription complex components are strong rescue hits for PCA062 in HCC1954. These data suggest that in addition to target expression level and cell intrinsic sensitivity to payload, genes involved in ADC internalization and payload cytoplasmic accumulation will also impact tumor cell sensitivity to ADCs.
Citation Format: Angela Tam, Mark Zambrowski, Katherine Seiss, Si-Qi Liu, Tinya Abrams, Giordano Caponigro, William Tschantz, Jennifer Campbell, Tony DAlessio, Qing Sheng. Using genome-wide CRISPR screen to understand resistance mechanisms to PCA062, a P-cadherin targeting antibody-drug conjugate [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4743.
Abstract 4748: RICTOR signaling modulates the activity of EGFR tyrosine kinase inhibitors (TKI) in EGFR-mutated non-small cell lung cancer (NSCLC)
Authors: Fan Ni , Zou Yiyu , Halmos Balazs , Perez-Soler Roman , Cheng Haiying 
Published: August 2019

Abstract
Background: Molecularly-targeted therapy has significantly improved the therapeutic efficiency and clinical outcome in a subgroup of NSCLC patients. However, drug resistance inevitably emerges, such as resistance to EGFR TKIs in EGFR-mutated NSCLC. RICTOR is a key component of the mTORC2 complex and plays important roles in cell survival, proliferation, migration and invasion. RICTOR has also been suggested to play a part in the regulation of drug resistance to HER2-targeted therapy in HER2-amplified breast cancer, a niche close to EGFR-targeted therapy. In our current study, we hypothesize that RICTOR modulates the activity of EGFR TKIs in EGFR-mutated NSCLC. Co-targeting RICTOR and EGFR signaling pathways could be a new therapeutic strategy for patients with EGFR-mutated lung cancer.
Results: Genetically modified EGFR-mutated NSCLC cell lines with different RICTOR expression levels have been developed. RICTOR knockdown significantly increases the sensitivity to all three generations of TKI inhibitors (erlotinib, afatinib and osimertinib), whereas overexpression of RICTOR renders the cells more resistant to EGFR TKIs. In addition, RICTOR knockdown restores the sensitivity of erlotinib-resistant HCC827 cells due to AXL overexpression (IC50: 216µM vs. 0.256 µM with RICTOR knockdown, P&lt;0.001). Pharmacological inhibition of the RICTOR signaling pathway with the mTOR1/2 inhibitor (sapanisertib) also improves EGFR TKI sensitivity. Taken together, RICTOR signaling modulates the efficacy of EGFR TKIs in the EGFR-mutated lung cancer models.
Conclusion: Our study provides a new insight into the role of RICTOR signaling modulation in increasing efficacy of EGFR TKI therapy in EGFR-mutated NSCLC. The combination of mTOR1/2 inhibitor and EGFR inhibitor could be a potential novel strategy leading to better therapeutic efficacy.
Note: This abstract was not presented at the meeting.
Citation Format: Ni Fan, Yiyu Zou, Balazs Halmos, Roman Perez-Soler, Haiying Cheng. RICTOR signaling modulates the activity of EGFR tyrosine kinase inhibitors (TKI) in EGFR-mutated non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4748.
Abstract 4749: Acquired resistance to BET-PROTACs caused by genomic alterations in core components of E3 ligase complexes
Authors: Riley-Gillis Bridget , Zhang Lu , Vijay Priyanka , Shen Yu 
Published: August 2019

Abstract
Proteolysis Targeting Chimeras (PROTACs) are bifunctional molecules that hijack endogenous E3 ubiquitin ligases to induce ubiquitination and subsequent degradation of protein of interest. Recently, it has been shown that PROTACs with robust in vitro and in vivo activities and, in some cases, drug-like pharmaceutical properties can be generated using small molecule ligands for the E3 ligases VHL and CRBN. These findings stoked tremendous enthusiasm on using PROTACs for therapeutics development. Innate and acquired drug resistance often underlies therapeutic failures, particularly for cancer therapy. With the PROTAC technology progressing rapidly towards therapeutic applications, it would be important to understand whether and how resistance to these novel agents may emerge. Using BET-PROTACs as a model system, we demonstrate that resistance to both VHL- and CRBN-based PROTACs can occur in cancer cells following chronic treatment. However, unlike what was often observed for many targeted therapeutics, resistance to BET-PROTACs did not result from secondary mutations that affect compound binding to the target. In contrast, acquired resistance to both VHL- and CRBN-based BET-PROTACs was primarily caused by genomic alterations that compromise core components of the relevant E3 ligase complexes.
Citation Format: Bridget Riley-Gillis, Lu Zhang, Priyanka Vijay, Yu Shen. Acquired resistance to BET-PROTACs caused by genomic alterations in core components of E3 ligase complexes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4749.
Abstract 4751: Overcoming cisplatin resistance of esophageal squamous cell carcinoma by targeting RAC1-regulated Warburg effect
Authors: Zeng Ruijie , Zheng Chunwen , Gu Jinge , Peng Liu , Zhang Haixia , Feng Pan , Chen Yang , Xu Xiue , Xu Liyan , Li Enmin 
Published: August 2019

Abstract
Esophageal squamous cell carcinoma (ESCC) is a highly aggressive malignancy with poor prognosis. Despite treatment advances, development of chemo-resistance remains a major challenge in treating ESCC patients. Ras-related C3 botulinum toxin substrate 1 (RAC1) is essential in regulating cancer progression. However, its role in chemo-resistance of ESCC and the underlying mechanisms are still unknown. In this study, we found that higher levels of RAC1 expression were associated with poorer disease-free survival (p=0.014) and overall survival (p=0.013) by immunohistochemistry in human ESCC samples (n=106). The over-expression of RAC1 was correlated with enhanced cell proliferation, migration, invasion and chemo-resistance in both KYSE150 and KYSE510 cells, while the knockdown of RAC1 produced the opposite results. The combination of RAC1 inhibitor EHop-016 with cisplatin significantly promoted cell viability reduction, cycle arrest at G2/M phase and apoptosis when compared with the single treatment. To examine the in vivo effects of RAC1 inhibition on chemo-resistance, we performed xenograft implantation studies in immunocompromised mice (n=10 per group). In the combination group, the tumor volume was significantly reduced to 21.4% (p&lt;0.001) as compared to the single treatment groups (cisplatin: 62.7%, RAC1 inhibitor: 58.5%). Mechanistically, the RNA-Seq data indicated that the glycolytic pathway was significantly down-regulated in the EHop-016-treated group (p&lt;0.001, Log2FC=1.86) and the combination group (p&lt;0.001, Log2FC=1.76), as compared to the control group. Moreover, the qRT-PCR and western blot results confirmed that RAC1 inhibitor alone or the combination treatment suppressed Akt/FOXO signaling and resulted in inhibition of key enzymes such as PKM2, LDH-A, ALDOA and HK1 for the Warburg effect. Overall, our study suggests that inhibition of RAC1 overcomes cisplatin resistance in ESCC both in vitro and in vivo, and provides a novel mechanism of chemo-resistance in ESCC. Therefore, targeting RAC1 might be a promising and potent strategy for treating ESCC in clinical practice.
Citation Format: Ruijie Zeng, Chunwen Zheng, Jinge Gu, Liu Peng, Haixia Zhang, Pan Feng, Yang Chen, Xiue Xu, Liyan Xu, Enmin Li. Overcoming cisplatin resistance of esophageal squamous cell carcinoma by targeting RAC1-regulated Warburg effect [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4751.
Abstract 4754: CHTOP is a novel therapeutic target for chemoresistant epithelial ovarian cancer therapy
Authors: Bai Xupeng , Feng Xiaojie , Ni Jie , Beretov Julia , Deng Junli , Zhu Ying , Graham Peter , Li Yong 
Published: August 2019

Abstract
Background: Chemotherapy is the mainstay treatment for ovarian cancer (OC). Chemoresistance is a major challenge in epithelial ovarian cancer (EOC) therapy. CHTOP was identified as a potential chemoresistant biomarker in chemoresistant EOC cell lines using label-free LC-MS/MS proteomic technique. However, the role of CHTOP in EOC chemoresistance is still unclear.
Aim: In this study, we aimed to investigate whether CHTOP can be used as a therapeutic target in chemoresistant EOC cells and to reveal the mechanism underlying chemosensitization.
Methods: The expression difference of CHTOP was detected in chemoresistant and metastatic EOC cell lines by immunofluorescence (IF) and Western blot (WB). The expression of CHTOP in human EOC tissues was examined using immunohistochemistry (IHC). The effect of CHTOP knockdown (KD) on metastasis was examined using the Transwell® matrigel invasion and wound healing assays. Flow cytometry and TUNEL assay were employed to determine the association of CHTOP with apoptosis, while mammary sphere formation assay and IF were used to evaluate its regulation on EOC-cis cell stemness.
Results: The higher expression of CHTOP was found in EOC-cis (A2780-cis and IGROV-1-cis) and metastatic EOC (SKOV-3 and OV-90) cells as compared to normal epithelial ovarian cells (HOSE) by IF and WB. Also, high expression of CHTOP was found in human EOC tissues and associated with poor prognosis in patients. In contrast, CHTOP KD significantly reduced the metastatic potential of EOC-cis cells and increased their apoptosis at the presence of cisplatin. Furthermore, CHTOP KD decreased the stemness of EOC-cis cells.
Conclusion: Our findings suggest that CHTOP is associated with metastasis, apoptosis, and stemness in chemoresistant EOC cells, the survival in EOC patients, and might be a promising therapeutic target to overcome chemoresistance in EOC treatment.
Keywords: ovarian cancer, chemoresistance, CHTOP, metastasis, apoptosis, stemness
Citation Format: Xupeng Bai, Xiaojie Feng, Jie Ni, Julia Beretov, Junli Deng, Ying Zhu, Peter Graham, Yong Li. CHTOP is a novel therapeutic target for chemoresistant epithelial ovarian cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4754.
Abstract 4756: Activation of AURKA contributes to TKI resistance in EGFR-mutant non-small lung cancer
Authors: Lee Meng-Hsuan , Hong Shiao-Ya , Kao Yu-Rung , Wu Cheng-Wen 
Published: August 2019

Abstract
The epithelial growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have been widely used to treat EGFR-mutant non-small cell lung cancer (NSCLC) in clinics. Several generations of TKI were invented to overcome the unfavorable response and acquired resistance after long-term usage of EGFR TKI. Several mechanisms of acquired resistance have been reported. The well-studied resistant mechanism results from EGFR secondary mutations including T790M and C797S, which are involved in the resistance to first and third generation TKI, respectively. Other mechanisms aside from secondary mutation on EGFR including Her2 and MET amplification or epithelial mesenchymal transition (EMT) also distribute to TKI resistance. However, the resistant mechanisms which are independent to these alterations have not been completely identified yet. Here, we generated resistant cells selected by three different generations of TKI and analyzed their gene expression profiles. We discovered that many signal pathways, especially involved in cell cycle regulation, are commonly upregulated in three TKI-resistant cell lines. Aurora kinase A (AURKA) was the upstream kinase of those pathways; however, neither RNA level nor protein level of AURKA was significant changed. Interestingly, we found that phosphorylation of Aurora A at Thr288 in its catalytic domain is higher in TKI resistant cells. This reveals the possibilities that AURKA activation plays a role in the occurrence of TKI-resistance and that TKI-resistant NSCLC patients have a better response rate to AURKA inhibitor treatments.
Citation Format: Meng-Hsuan Lee, Shiao-Ya Hong, Yu-Rung Kao, Cheng-Wen Wu. Activation of AURKA contributes to TKI resistance in EGFR-mutant non-small lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4756.
Abstract 4759: Antitumor activity of eribulin after fulvestrant plus palbociclib treatments in the HR(+) human breast PDx model
Authors: Asano Makoto , Nakagawa Takayuki , Semba Taro , Yokoi Akira , Matsui Junji , Funahashi Yasuhiro 
Published: August 2019

Abstract
Fulvestrant (FLV) and Palbociclib (Palb), which have an effect on degradation of estrogen receptor (ER) and inhibition of cyclin dependent kinases 4 and 6 (CDK4/6), respectively are used for treatments to postmenopausal breast cancer patients. However, there is not a clinical rationale to define a standard treatment regimen against breast cancer patients who are resistant to endocrine therapy plus Palb. Eribulin is a fully synthetic analog of the marine sponge natural product halichondrin B. Its clinical formulation is currently approved for advanced breast cancer (BC) and advanced liposarcoma in numerous countries. We examined the antitumor activity of eribulin after endocrine therapy (combination of FLV and Palb) compared with that of Capecitabine (Cape) in the luminal type breast cancer PDx model (OD-BRE-0438). OD-BRE-0438 is a patient derived xenograft (PDx) model developed from patient with luminal B breast cancer. Gene expression analysis by RNA-Seq showed that OD-BRE-0438 highly expressed ER and PR, but not ERBB2. OD-BRE-0438 tumor bearing mice were treated for 2 weeks of FLV (5mg/ head, Q7Dx2, sc) and Palb (10mg/kg, Q1Dx14, po), and treated mice were randomly divided using tumor volume around 350 mm3 as an index (day1). After that, mice were treated with eribulin (0.5 or 1 mg/kg, which are 1/4 MTD or 1/2 MTD in this model, Q7Dx2, iv) or Cape (125 or 250 mg/kg, which are 1/2 MTD or MTD in this model, Q1Dx14, po for 2 weeks). We measured tumor volume of each mouse after treatments (day 15) and analyzed the ratio of tumor volume at day 15 divided by that at day 1 (RTV: relative tumor volume). Treatments of FLV and Palb nearly completely inhibited in vivo growth of OD-BRE-0438 tumors, but didn’t cause tumor shrinkage. After two weeks of combination treatment with endocrine therapy, we started treatments with either eribulin or Cape, and compared the antitumor activity. Both drug showed strong antitumor activity with tumor shrinkage. In comparison of antitumor activity with either eribulin or Cape, that of eribulin was significantly greater than Cape. [eribulin 0.5mg/kg (RTV=0.42) vs Cape 125mg/kg (RTV=0.62, p=0.0068), eribulin 1.0mg/kg (RTV=0.32) vs Cape 250mg/kg (RTV=0.59, p=0.0008)]. Further investigation for mechanism of action of eribulin to show clear antitumor activity after treatments of FLV and Palb in the luminal type breast cancer PDx model are warranted.
Citation Format: Makoto Asano, Takayuki Nakagawa, Taro Semba, Akira Yokoi, Junji Matsui, Yasuhiro Funahashi. Antitumor activity of eribulin after fulvestrant plus palbociclib treatments in the HR(+) human breast PDx model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4759.
Abstract 4765: MERTK is a potential therapeutic target in osimertinib-resistant non-small cell lung cancer
Authors: Yan Dan , Huelse Justus , Parker Rebecca , Wang Xiaodong , Frye Stephen V. , Earp H. Shelton , DeRyckere Deborah , Graham Douglas 
Published: August 2019

Abstract
Non-small cell lung cancer (NSCLC) remains a global problem causing more deaths in both men and women than any other cancer worldwide with an urgent need for more efficacious treatments. During the last decade the therapeutic landscape for NSCLC has been profoundly changed with the discovery of activating mutations in Epidermal Growth Factor Receptor (EGFR) (EGFRMT). Osimertinib, a 3rd generation EGFR TKI, was recently FDA-approved as a front-line agent for newly diagnosed EGFRMT NSCLCs due to its superior efficacy relative to earlier-generation EGFR TKIs in the international FLAURA trial. However, unmet clinical needs have arisen in conjunction with osimertinib use, including understanding mechanisms of osimertinib resistance and developing novel approaches to prevent or reverse resistance and/or enhance osimertinib efficacy in responsive patients. Our group previously identified MERTK receptor tyrosine kinase as a potential therapeutic target in NSCLC and developed MRX-2843, a novel small molecule inhibitor with dual MERTK and FLT3 activity, which is currently in Phase I clinical trials. Here, we report upregulation of MERTK and its ligand PROS1 in xenograft tumors derived from the EGFRMT H4006 NSCLC cell line and treated with osimertinib relative to vehicle-treated tumors. MERTK expression was also increased in osimertinib-resistant derivatives of the H4006 and H4011 cell lines generated by culture in escalating doses of osimertinib. However, overexpression of exogenous MERTK in H4006 cells was not sufficient to confer osimertinib resistance. In contrast, stimulation with TAM kinase ligands GAS6 or PROS1 protected H4006 cells from osimertinib treatment, as indicated by restoration of AKT, ERK, and ribosomal S6 phosphorylation in the presence of osimertinib. Together these data implicate MERTK as a mediator of resistance to osimertinib. Indeed, combined treatment with osimertinib and MRX-2843 effectively blocked PI3K-AKT and MAPK-ERK signaling and mediated synergistic inhibition of colony formation in osimertinib-resistant H4006 cells. Thus, MERTK inhibition may be an effective therapeutic strategy to re-sensitize osimertinib-resistant NSCLCs to EGFR TKI treatment.
Citation Format: Dan Yan, Justus Huelse, Rebecca Parker, Xiaodong Wang, Stephen V. Frye, H. Shelton Earp, Deborah DeRyckere, Douglas Graham. MERTK is a potential therapeutic target in osimertinib-resistant non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4765.