bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 294: The role of the histone deacetylase HDAC 8 in mediating BRAF/MEK inhibitor metastatic dissemination and resistance
Authors: Emmons Michael , Rab Rashed , Sharma Ritin , Koomen John , Smalley Keiran 
Published: July 2016

Abstract
BRAF/MEK inhibitor resistance frequently results in increased phosphorylation of EphA2 at S897, which increases the invasive potential of melanoma cells in a ligand-independent manner. Through use of an unbiased phosphoproteomic screen, we identified HDAC phosphorylation as also being increased following the acquisition of BRAF/MEK inhibitor resistance. Treatment with the pan-HDAC inhibitor LBH 589 inhibited EphA2 phosphorylation at S897 and reduced tumor invasion, indicating a role for HDACs in the regulation of the resistance-associated metastatic phenotype. A comparison of HDAC protein levels in matched BRAF inhibitor sensitive/resistant cell lines showed that HDAC6, HDAC8, and HDAC11 protein levels were more highly expressed in BRAF resistant cell lines with HDAC8 being upregulated in 5 of 6 cell line pairs. shRNA knockdown of HDAC8 in the BRAF/MEK inhibitor resistant cell line WM164RR resulted in a decreased in pEphA2 as well as a decrease in pAKT at S473, which is known to directly bind to and phosphorylate EphA2 at S897. Reduced expression of HDAC8 in WM164RR cells resulted in a decrease in the invasive potential of the resistant phenotype as well as a resensitization of these cells to the BRAF inhibitor vemurafenib. HDAC8 overexpression in drug naïve cells led to increased melanoma cell invasion in a 3D spheroid and a matrigel invasion model. Overexpression of HDAC8 was also found to decrease the level of apoptosis following BRAF inhibitor treatment and was associated with increased number of clones in a colony formation assay. Conversely, knocking down HDAC8 with shRNA led to an increase in vemurafenib-mediated apoptosis. Mechanistically, it was found that HDAC8 overexpression increased the speed of adaptive MAPK signaling following BRAF inhibition and that this in turn limited the expression of pro-apoptotic BIM. Overall, these results indicate a dual role for HDAC8 in mediating BRAF/MEK inhibitor resistance and metastatic dissemination. Increased levels of HDAC8 caused an increase in invasion as well as a decrease in vemurafenib-induced apoptosis in BRAF inhibitor sensitive cell lines. Our studies suggest that selective HDAC8 inhibition may be one strategy to limit adaptation to both BRAF and BRAF/MEK inhibitor therapy.
Citation Format: Michael Emmons, Rashed Rab, Ritin Sharma, John Koomen, Keiran Smalley. The role of the histone deacetylase HDAC 8 in mediating BRAF/MEK inhibitor metastatic dissemination and resistance. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 294.
Abstract 2945: Cell stress during HIPEC causes heat shock protein induction and reduced chemosensitivity in human colon cancer
Authors: Grimmig Tanja , Kloos Kerstin , Thumm Rebecca , Moench Romana , Germer Christoph T. , Waaga-Gasser Ana Maria , Gasser Martin 
Published: July 2016

Abstract
Background: Hyperthermic intraperitoneal chemotherapy (HIPEC) is a promising procedure for the treatment of peritoneal carcinomatosis (PC). Heat shock proteins (HSPs) and other proteins involved in cellular repair mechanisms seem to induce cytoprotective processes during HIPEC therapy. Therefore, the aim of this study was to analyze the effects of HIPEC-related conditions on tumor cell proliferation and the expression of HSPs in human colon cancer.
Methods: Human colon cancer cell lines HT29, SW480 and SW620 were exposed to different temperatures (37°C, 41°C, and 43°C) as well as defined cytostatic agents (Oxaliplatin, Mitomycin C, and 5-Fluorouracil). After cellular regeneration (30 min, 24 h, 48 h and 72 h) RNA isolation and whole cell extraction was performed. Gene and protein expression analysis of HSP27, 70, 72 and 90 as well as PCNA, Ki-67, BCl-2 and BCl-Xl were carried out using RT-qPCR and Western blot. Additionally, MTS cell proliferation assays were performed 24 h, 48 h, 72 h and 96 h post treatment. Moreover, AnnexinV apoptosis assays were conducted.
Results: All colon cancer cells exposed to hyperthermic conditions showed initially up-regulated HSP gene expression. Highest expression was found after exposure to 43°C. Combined cytostatic and hyperthermic treatment demonstrated additional increase in HSP27 expression and in other HSPs to a lesser degree. Tumor cells exposed to cytostatic agents showed overall higher HSP gene expression compared to cells without chemotoxic treatment. Similar effects were detected for the expression of the proliferation marker PCNA and anti-apoptotic protein BCl-Xl. Apoptosis assay demonstrated decreased numbers of apoptotic cells at 43°C compared to normothermia. Additionally, proliferation assays revealed reduced chemosensitivity in cells treated with hyperthermia.
Conclusion: Desired effects of hyperthermia used in HIPEC therapy to achieve anti-proliferative and apoptosis inducing effects seem to be negatively influenced by cell stress mediated repair mechanisms in colon cancer. Our in vitro findings suggest analyzed HSPs to be significantly involved in this hyperthermia and chemotoxicity mediated cellular repair mechanisms. While initial increase in HSP expression can counteract cytotoxic effects during HIPEC therapy their prolonged expression may promote lasting resistance to cellular stress.
Citation Format: Tanja Grimmig, Kerstin Kloos, Rebecca Thumm, Romana Moench, Christoph T. Germer, Ana Maria Waaga-Gasser, Martin Gasser. Cell stress during HIPEC causes heat shock protein induction and reduced chemosensitivity in human colon cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2945.
Abstract 2949: REV3L, the catalytic subunit of pol ζ, is involved in the progression and chemoresistance of esophageal squamous cell cancer
Authors: Zhou Jundong , Zou Sitao , Ding Wei-Qun , Wu Jinchang 
Published: July 2016

Abstract
REV3L, the catalytic subunit of DNA ploymerse zeta, is well known to participate in error-prone translesion synthesis (TLS) with less stringent and lower processivity. Recent evidence demonstrated that REV3L is involved in carcinogenesis and tumor progression. However, the function of REV3L remains unclear in esophageal squamous cell cancer (ESCC). In this study, we examined REV3L expression in ESCC tissues and its association with clinicopathological parameters. REV3L was found to be significantly up-regulated in ESCC tissues, which is correlated with lymph node metastasis and clinical stages of the patients. To further investigate the potential role of REV3L in esophageal cancer, stable ESCC cell lines with the suppression of REV3L expression were established. Down regulation of REV3L expression led to a decrease in cell proliferation and invasive tendency partly through suppressing cyclinD1 and survivin expression, and an increase in cellular sensitivity to 5-Fu by inducing G1 phase arrest and apoptosis. Therefore, REV3L plays an important role in ESCC progression and chemoresistance, and is a potential diagnostic marker and therapeutic target for ESCC.
Citation Format: Jundong Zhou, Sitao Zou, Wei-Qun Ding, Jinchang Wu. REV3L, the catalytic subunit of pol ζ, is involved in the progression and chemoresistance of esophageal squamous cell cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2949.
Abstract 295: The cytosine deaminase APOBEC3B affects responses to therapy in estrogen receptor positive breast cancer cells
Authors: LaPara Kelly S. , Law Emily , Harris Reuben , Yee Douglas 
Published: July 2016

Abstract
Endocrine therapy, chemotherapy, or both represent the mainstay of therapy for estrogen receptor positive (ER+) breast cancer. However, acquired (secondary) drug resistance is a major clinical problem. We identified APOBEC3B (A3B), a DNA cytosine deaminase, as a source of DNA mutagenesis driving tumor evolution and contributing to poor clinical outcomes in several cancers by catalyzing genetic changes required for drug resistance and metastasis. A3B accounts for up to half of the mutational load in breast carcinomas expressing this enzyme. High levels of A3B correlate with poor clinical outcomes in tamoxifen treated patients. To evaluate the role for A3B in resistance to therapy, we used the ER+ MCF-7L breast cancer cell line. These cells have modestly elevated levels of endogenous A3B and we suppressed A3B levels by shRNA and enhanced levels by transduction. In vitro, alterations in A3B levels do not affect monolayer growth or cell doubling times. However, in vitro response to tamoxifen was prolonged in MCF-7L cells with suppressed A3B. In a xenograft model, MCF-7 cells with suppressed A3B remained responsive to tamoxifen for a longer period of time compared to wild type cells. Cells with overexpression of A3B had a very short period of tamoxifen suppression compared to wild-type cells. These data suggest high A3B levels are associated with a shorter period of response to tamoxifen. To evaluate the role for A3B in chemotherapy resistance, we treated cells with 5-fluorouracil. In contrast to tamoxifen therapy, cells with elevated A3B levels remained responsive to fluorouracil for longer periods of time compared to wild-type cells. Since A3B converts cytosine to uracil (C-to-U), we speculate that A3B enzymatic activity might enhance sensitivity to a fluoropyrimidine. Thus, the ability of A3B to affect therapeutic resistance in breast cancer may be dependent on the type and mechanism of drug treatment.
Citation Format: Kelly S. LaPara, Emily Law, Reuben Harris, Douglas Yee. The cytosine deaminase APOBEC3B affects responses to therapy in estrogen receptor positive breast cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 295.
Abstract 2952: Generation and molecular profiling of drug-resistant cancer cell lines
Authors: He Fang , Pan Pengwei , Yuan Zengjin , Huang Jingqi 
Published: July 2016

Abstract
Drug resistance is the main cause of ineffective chemotherapy in patients. Many cancers respond initially well to therapy but eventually the cancer recurs as drug-resistant disease leading to the patient death. Therefore, a better understanding of the molecular basis of the drug resistance is warranted in order to elucidate the mechanisms and markers underlying this drug-resistant phenotype In this study, we aimed to generate and characterize a panel of drug resistant cancer cell lines, providing a valuable tool with which to investigate the molecular pathways and putative markers that may be associated with this resistance phenotype in cancer.
Citation Format: Fang He, Pengwei Pan, Zengjin Yuan, Jingqi Huang. Generation and molecular profiling of drug-resistant cancer cell lines. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2952.
Abstract 2956: Optimal PEGylation of an auristatin linker provides ADCs with improved pharmacological properties
Authors: Burke Patrick J. , Hamilton Joseph Z. , Jeffrey Scott C. , Hunter Joshua H. , Cochran Julia H. , Chemuturi Nagendra , Anderson Martha E. , Senter Peter D. , Lyon Robert P. 
Published: July 2016

Abstract
As antibody-drug conjugates (ADCs) continue to emerge as an important therapeutic modality for the treatment of cancer, there is an increased effort to elucidate critical design parameters and devise improved linker technologies. The impact of drug-to-antibody ratio (DAR) on conjugate plasma pharmacokinetics (PK) is known to be an important attribute, and accelerated clearance induced by high levels of drug loading has served as a barrier to translating increased in vitro potency to in vivo xenografts. We have recently demonstrated that the incorporation of a discrete PEG24 unit into an auristatin drug-linker can greatly diminish the impact of drug loading on ADC PK. In an effort to optimize the antibody-mediated delivery of monomethylauristatin E (MMAE) as a homogeneous DAR 8 conjugate, we prepared a series of MMAE linkers using PEG units of varying lengths to identify constructs that preserve antibody PK properties and provide enhanced in vivo activity. The extent of PEGylation and linker chemistry was found to impact conjugate PK properties, biodistribution, antitumor activity, and tolerability. From that effort, a cleavable MMAE linker incorporating the glucuronide-based trigger, a self-stabilizing maleimide, and 12 PEG units emerged as the optimal design. ADCs prepared with this linker have now undergone further preclinical characterization in activity and toxicology models in which they have demonstrated an increase in therapeutic index relative to other MMAE-based ADCs.
Citation Format: Patrick J. Burke, Joseph Z. Hamilton, Scott C. Jeffrey, Joshua H. Hunter, Julia H. Cochran, Nagendra Chemuturi, Martha E. Anderson, Peter D. Senter, Robert P. Lyon. Optimal PEGylation of an auristatin linker provides ADCs with improved pharmacological properties. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2956.
Abstract 2959: Peptide-linked indolino-benzodiazepine DNA-alkylating agents for use in antibody-drug conjugates (ADCs)
Authors: Shizuka Manami , Wilhelm Alan , Archer Katie , Reid Emily , Yoder Nicholas C. , Bai Chen , Fishkin Nathan , Harris Luke , Maloney Erin , Hong Erica , Wu Rui , Ab Olga , Lai Kate , Sikka Surina , Jin Shan , Pinkas Jan , Chari Ravi , Miller Michael L. 
Published: July 2016

Abstract
As part of our efforts to expand the available toolbox of cytotoxic payloads for use in antibody-drug conjugates (ADCs), we have recently described the development of the mono-imine-containing indolino-benzodiazepine dimer, IGN-P1 (Miller, et al., AACR 2014 #652). IGN-P1 was conjugated via a protease-cleavable peptidic L-alanine-L-alanine linker to a folate receptor α (FRα)-binding antibody, and an EGFR-binding antibody. The resulting ADCs demonstrated high in vitro potency (IC50 ∼4-100 pM) and specificity towards several cancer cell lines. In vivo, anti-FRα-IGN-P1 induced complete regressions in NCI-H2110 non-small cell lung cancer xenografts following a single dose of 3 μg/kg (linked payload dose, equivalent to 0.18 mg/kg Ab dose).
Here we describe the structure-activity relationship of a number of peptide-linked IGN ADCs, leading to the selection of Ab-IGN-P1 for further advancement. The cytotoxic activities of these peptide-IGN conjugates were evaluated in vitro in cancer cell lines with both high and low target antigen expression. We also assessed bystander activity and identified in vitro and in vivo catabolites. We found that the stereochemistry of the peptide linker was crucial for bystander activity and in vivo efficacy. The IGN-P1 ADC exhibited strong bystander activity, which we believe is dictating the strong antitumor activity in vivo. Treatment of low to moderate antigen-expressing models with Ab-IGN-P1 further resulted in tumor regressions at doses as low as 3-10 μg/kg linked payload.
These data underscore the potential therapeutic benefit of highly active and specific IGN-P1 conjugates, even for the challenging subset of patients with solid tumors where the target antigen is expressed at lower levels.
Citation Format: Manami Shizuka, Alan Wilhelm, Katie Archer, Emily Reid, Nicholas C. Yoder, Chen Bai, Nathan Fishkin, Luke Harris, Erin Maloney, Erica Hong, Rui Wu, Olga Ab, Kate Lai, Surina Sikka, Shan Jin, Jan Pinkas, Ravi Chari, Michael L. Miller. Peptide-linked indolino-benzodiazepine DNA-alkylating agents for use in antibody-drug conjugates (ADCs). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2959.
Abstract 2964: An anti-CD20 extracellular antibody-drug conjugate for the treatment of B-cell malignancies
Authors: Prudent James R. , Hall Chad A. , Marshall David J. , Murphy John , Harried Scott 
Published: July 2016

Abstract
Purpose:
CD20 is known to be a therapeutic antibody drug target as it is expressed on the surface of most B-cell neoplasms. Here, we assessed the anti-tumor activity of EDC9, a novel extracellular drug conjugate composed of Rituximab (a well know and FDA approved anti-CD20 monoclonal antibody) conjugated to a steroidal glycoside via a long, flexible and stable linker.
Experimental Design:
The anti-cancer activity and safety of EDC9 were examined and compared to Rituximab using in vitro and in vivo techniques.
Results:
We found that EDC9 showed picomolar cytotoxic activity that was independent of effector functions and exhibited cytotoxic activity through a mechanism that was dependent on CD20 expression, as cells not expressing CD20 were resistant and Rituximab alone could compete with EDC9, rendering it inactive. After 72 hours of EDC9 treatment at levels between 100 and 200 picomolar, no cells were determined to be viable by CellTiter-Glo or high definition phase contrast imaging. Importantly, when compared on the basis of toxicity to PBMC, EDC9 was found not to be more toxic than Rituximab and the activity of EDC9 was dependent on specific steroid chemistry. In a tumor xenograft model, EDC9 provided complete long-term remission of diffuse large B-cell human lymphoma line SU-DHL-8 tumors, while Rituximab alone did not.
Conclusion:
These results support efforts to further evaluate EDC9 (a novel CD20 specific antibody drug conjugate) and may lead to phase I clinical trials in patients with certain B-cell related malignancies.
Citation Format: James R. Prudent, Chad A. Hall, David J. Marshall, John Murphy, Scott Harried. An anti-CD20 extracellular antibody-drug conjugate for the treatment of B-cell malignancies. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2964.
Abstract 2981: DNA damaging agent-induced apoptosis is controled by MCL-1 phosphorylation and degradation mediated by the Noxa/MCL-1/CDK2 complex
Authors: Nakajima Wataru , Lee June Y. , Maxim Nicolas , Sharma Kanika , Hicks Mark A. , Vu Thien-Trang , Luu Angela , Yeudall William Andrew , Tanaka Nobuyuki , Harada Hisashi 
Published: July 2016

Abstract
DNA damaging agents, such as cisplatin and etoposide, are employed for the treatment of a wide array of solid tumors, but the prolonged use of chemotherapeutic drugs is limited by their toxicity and by the development of resistance. To overcome these major roadblocks to improved prognosis requires mechanism-based therapeutic strategies that maximize the antitumor effect of drugs while limiting their toxicities. These agents exert anticancer effects via multiple mechanisms, yet their most prominent mode of action involves the generation of DNA lesions followed by activation of the DNA damage response and induction of the BCL-2 family-dependent mitochondrial apoptosis. However, the signaling pathways that connect to BCL-2-family-regulated cell death are not entirely clear.
Noxa, a BH3-only pro-apoptotic BCL-2 family protein, causes apoptosis by specifically interacting with the anti-apoptotic BCL-2 family protein MCL-1 to induce its proteasome-mediated degradation. We show here that the DNA damaging agents cisplatin and etoposide upregulate Noxa expression, which is required for the phosphorylation of MCL-1 at Ser64/Thr70 sites, proteasome-dependent degradation, and as a consequence, apoptosis. Noxa-induced MCL-1 phosphorylation at these sites occurs at the mitochondria and is primarily regulated by CDK2. MCL-1 and CDK2 form a stable complex and Noxa binds to this complex to facilitate the phosphorylation of MCL-1. When Ser64 and Thr70 of MCL-1 are substituted with alanine, the mutated MCL-1 is neither phosphorylated nor ubiquitinated, and becomes more stable than the wild-type protein. As a consequence, this mutant can inhibit apoptosis induced by Noxa overexpression or cisplatin treatment. These results indicate that Noxa-mediated MCL-1 phosphorylation followed by MCL-1 degradation is critical for apoptosis induced by DNA damaging agents through regulation of the Noxa/MCL-1/CDK2 complex. Of note, the identified phosphorylation sites are only observed in human MCL-1; thus, the regulatory mechanism shown here may be human-specific. It is of interest in the future to analyze whether CDK2 expression/activity correlates to cisplatin-resistance in patient samples.
Citation Format: Wataru Nakajima, June Y. Lee, Nicolas Maxim, Kanika Sharma, Mark A. Hicks, Thien-Trang Vu, Angela Luu, William Andrew Yeudall, Nobuyuki Tanaka, Hisashi Harada. DNA damaging agent-induced apoptosis is controled by MCL-1 phosphorylation and degradation mediated by the Noxa/MCL-1/CDK2 complex. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2981.
Abstract 299: Patient-derived tumor microenvironment models uncover non-autonomous TKI resistance mechanisms in NSCLC
Authors: Hu Haichuan , Niederst Matthew , Engelman Jeffrey 
Published: July 2016

Abstract
Background: Tyrosine kinase inhibitors (TKI) have yielded great responses in non-small-cell lung cancer (NSCLC) with EGFR mutations and ALK translocations, however these and other targeted therapies are limited by intrinsic and acquired drug resistance. Previous studies looking into relapsed samples largely expanded our understanding of tumor autonomous resistance mechanisms. In this study, we aimed to decipher the non-autonomous mechanisms in vitro by recapitulating the in vivo tumor microenvironment from patient-derived models.
Method: Cancer-associated fibroblast cells are isolated directly from EGFR mutant and ALK translocated NSCLC biopsies. Over 20 patient-derived fibroblast (PDF) models have been established for studying the tumor microenvironment's effect on TKI response.
Result: We found that many, but not all, PDF cells exert significant resistance to TKIs. Furthermore, there is considerable variability in the degree and secreted factor / mechanism by which they are protecting the tumor cells. These variations are further correlated with patient in vivo response.
Conclusion: Together, our results indicate that PDFs are clinically relevant models for deciphering non-autonomous resistance mechanisms, that they are heterogeneous in protecting cancer cells from TKI treatment, and that the resistance mediated by PDFs can be overcome by specific therapeutic combinations.
Citation Format: Haichuan Hu, Matthew Niederst, Jeffrey Engelman. Patient-derived tumor microenvironment models uncover non-autonomous TKI resistance mechanisms in NSCLC. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 299.