tbuckley/cabot-search huggingface dataset:
Abstract LB303: Suppression of stress granule formation is a novel vulnerability imposed by mutant p53
Authors: Elizabeth Thoenen, Atul Ranjan, Alejandro Parrales, Shigeto Nishikawa, Dan Dixon, Sugako Oka, Tomoo Iwakuma
Journal: Cancer Research (2024)

Abstract Mutation of the tumor suppressor p53 is the most common cancer specific event. Most of these mutations are missense mutations in the DNA-binding domain of p53, causing loss of wild-type p53 (wtp53) transcriptional activity. Missense mutant p53 (mutp53) also enhances cancer malignancy in a manner independent of wtp53. Hence, mutp53 is an ideal therapeutic target due to its uniqueness and high expression levels in cancers; however, directly targeting mutp53 protein itself has been challenging. To better understand the mechanism of oncogenic function of mutp53, we performed in silico TCGA database analysis and found that patients with missense mutp53-carrying hepatocellular carcinoma (HCC), but not other types of cancer, had unexpectedly better overall survival than patients with p53-null HCC. Since sorafenib (SOR) has historically been used as a single agent chemotherapy for HCC, unlike other cancer types, we hypothesized that SOR treatment may have yet unappreciated advantages for treating mutp53-expressing tumors. Indeed, knockdown of mutp53 rendered HCC cells and xenografts more resistant to SOR. Consistent with a report showing that SOR induces ER stress-mediated pro-survival stress granule (SG) formation, mutp53-expressing HCC cells, treated with SOR or other ER stress inducers, formed significantly fewer SGs with increased apoptosis, as compared with mutp53-knockdown cells. This result was partly due to mutp53’s ability to interact with an eIF2α kinase PERK and a key SG core protein, G3BP1. Moreover, the oligomerization domain of mutp53 was required for the interaction of mutp53 with G3BP1 and subsequent suppression of ER-stress-mediated SG formation and survival. These results suggest that inhibition of SG formation is a novel vulnerability imposed by mutp53, leading to sensitization of cancer cells to ER stress. Our results also emphasize the use of ER stress inducers to treat mutp53-expressing tumors and mutp53 as a biomarker of SOR sensitivity. Citation Format: Elizabeth Thoenen, Atul Ranjan, Alejandro Parrales, Shigeto Nishikawa, Dan Dixon, Sugako Oka, Tomoo Iwakuma. Suppression of stress granule formation is a novel vulnerability imposed by mutant p53 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB303.
Abstract LB190: Cancer-stromal cells interaction dominates the expression of pro-tumor decreted protein chitinase-3-like-1 in pancreatic cancer
Authors: Pei-Chia (Peggy) Su, Yi-Ching Wang
Journal: Cancer Research (2024)

Abstract In the context of the tumor microenvironment (TME), a substantial increased secreted protein, chitinase-3 like-protein-1 (CHI3L1) has been observed, emanating from various cell types such as cancer cells, macrophages, and T cells. The development of an immunosuppressive and fibrotic TME has been implicated in CHI3L1-mediated cancer progression. Despite recognizing the potential for CHI3L1 blockade to facilitate cancer regression, there remains a limited understanding of the regulatory mechanisms governing the expression of this tumor-promoting protein within cancer cells. Our investigations, along with others, have identified low levels of CHI3L1 protein in normal epithelial cells, in stark contrast to its abundant presence in pancreatic cancer tumor specimens. We propose that the interaction between cancer and stromal cells in the TME induces CHI3L1 expression within cancer cells. To test this hypothesis, we established a co-culture system involving cancer and stromal cells including pancreatic stellate cells, macrophages and T cells to emulate the TME of pancreatic cancer. Subsequently, we observed a ten-fold increase in CHI3L1 expression in cancer cells upon exposure to co-culture media. Through secretomic analysis, C-X-C motif chemokine ligand 10 (CXCL10) emerged as a potential inducer of CHI3L1 expression in response to co-culture media. CXCL10/CXCR3 signaling has been reported to correlate with poor prognosis in pancreatic cancer, while their role in disease development is still unclear. Concurrently, Gene Set Enrichment Analysis (GSEA) identified the activation of TNFα signaling via NF-κB and TGF-β pathways in pancreatic cancer patients with high CHI3L1 expression. Notably, chromatin-immunoprecipitation and promoter activity assays validated the direct binding and transcriptional regulatory role of NF-κB, a downstream transcription factor of CXCL10, on CHI3L1 gene in cancer cells. In addition, epigenetic reprogramming occurred during co-culture media education. Our observations indicated demethylation of the CHI3L1 promoter during co-culture media exposure, a phenomenon confirmed to be mediated by STAT3 activation. In summary, this study elucidates, for the first time, the intricate crosstalk between cancer and stromal cells within the TME of pancreatic cancer as a pivotal factor for the transcriptional and epigenetic dysregulation of CHI3L1, which then contributes to TME remodeling and malignant pancreatic cancer progression. Citation Format: Pei-Chia (Peggy) Su, Yi-Ching Wang. Cancer-stromal cells interaction dominates the expression of pro-tumor decreted protein chitinase-3-like-1 in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB190.
Abstract SY37-03: Leveraging the complexities of tumor associated macrophages for effective anti-cancer therapy
Authors: Jennifer L. Guerriero
Journal: Cancer Research (2024)

Abstract Macrophages are innate immune cells that play a critical role in host defense and maintaining tissue homeostasis, however their infiltration into tumors is associated with disease progression and resistance to therapy. Tumor associated macrophages (TAMs) represent a significant proportion of solid tumors, including breast cancer. TAMs play a major role in tumorigenesis as they can enhance tumor cell growth, angiogenesis and metastasis. In addition, TAMs can inhibit anti-tumor responses of T cells. Our recent work has shown that removal or conversion of TAMs to an anti-tumor phenotype enhances chemo- and immuno-therapy establishing TAMs as targets for anti-cancer therapy. Using high-dimensional single-cell and multi-omics profiling of murine and human breast tumors we reveal multiple subsets of TAMs with distinct transcriptional and activity profiles that correlate with progression of disease and response to therapy. This work has revealed the complexity of TAMs and major gaps in our knowledge of the functional and phenotypic characterization of TAM subsets associated with cancer, before and after treatment. Here we will discuss the complexity of TAMs in solid tumors including characterizing TAM subsets, location, and crosstalk with neighboring cells, as well as novel TAM-modulating strategies and combinations that are likely to enhance current therapies and overcome chemo- and immuno-therapy resistance. Our findings support the idea that targeting TAMs offers great potential to enhance both chemo- and immuno-therapy. Citation Format: Jennifer L. Guerriero. Leveraging the complexities of tumor associated macrophages for effective anti-cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr SY37-03.
Abstract LB411: Investigating the dependency of androgen receptor-positive prostate cancer on class I myosins
Authors: Anoushka Kadam, Shivani Kumar, Varsha Vakkala, Rajendra Kumar, Angelo M. De Marzo, Edward J. Pearce, Laura A. Sena
Journal: Cancer Research (2024)

Abstract Prostate adenocarcinoma is characterized by high expression and activity of the androgen receptor (AR). AR is a nuclear hormone receptor that stimulates anabolic cell metabolism. We hypothesized that the high activity of AR in prostate cancer creates unique dependencies on cellular machinery to support this high rate of anabolism. We observed that androgen treatment of patients with metastatic castration-resistant prostate cancer resulted in increased abundance of MYO1E, a class I myosin that facilitates intracellular vesicular trafficking, in tumor biopsies. Similarly, MYO1E protein increased in AR+ prostate cancer cell lines upon treatment with androgens. Notably, a specific small molecule inhibitor of MYO1E, pentachloropseudilin (PClP), induced cell death of AR-positive prostate cancer cell lines with an IC50 of 2-4uM, but was non-toxic to AR-negative prostate cancer cell lines. Expression of AR in these AR-negative lines conferred sensitivity to PClP, while deletion of AR in an AR-positive line conferred resistance to PClP, indicating that AR expression was required and sufficient for sensitivity of prostate cancer cell lines to PClP. Previous studies have suggested that AR globally increases protein synthesis and proteotoxic stress, and we asked whether this may create a dependency on MYO1E for secretion of protein-containing vesicles to manage proteotoxic stress. Initial experiments suggest that AR increases global rates of protein synthesis, as assessed by puromycin-incorporation assays, and inhibition of MYO1E increases phosphorylation of EIF2A, suggestive of activation of the integrated stress response. Further experiments will determine the essential function of MYO1E in AR-positive prostate cancer. Altogether our studies suggest that the class I myosin MYO1E is an essential protein in AR-positive cell lines and may represent a novel drug target for prostate adenocarcinoma. Citation Format: Anoushka Kadam, Shivani Kumar, Varsha Vakkala, Rajendra Kumar, Angelo M. De Marzo, Edward J. Pearce, Laura A. Sena. Investigating the dependency of androgen receptor-positive prostate cancer on class I myosins [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB411.
Abstract SY05-01: Targeting chromatin adaptor proteins in cancer
Authors: Yadira Soto-Feliciano
Journal: Cancer Research (2024)

Abstract Menin interacts with oncogenic fusion proteins produced by MLL1 rearrangements, and small molecules capable of disrupting these interactions are currently under investigation in clinical trials for the treatment of leukemia. Our research, which combines chromatin-focused and genome-wide CRISPR screenings with a range of genetic, pharmacological, and biochemical strategies in both mouse and human models, has led to the discovery of a molecular mechanism that acts as a switch between the MLL1-Menin and MLL3/4-UTX chromatin modifying complexes, influencing the efficacy of Menin-MLL inhibitors. We demonstrate that the MLL1-Menin complex plays a critical role in maintaining leukemia cell survival by preventing the MLL3/4-UTX complex from binding to certain gene promoters. Interruption of the Menin-MLL1 interaction results in the UTX-dependent transcriptional activation of a tumor suppressor gene program, which significantly influences therapeutic outcomes in both murine and human leukemia models. Notably, the therapeutic activation of this gene program through CDK4/6 inhibitors can overcome resistance in leukemia cells that do not respond to Menin inhibitors. The identification of this molecular switch between MLL1-Menin and MLL3/4-UTX complexes on chromatin highlights the complex roles of these evolutionarily conserved epigenetic regulators and underscores their importance in understanding and addressing the molecular mechanisms underlying response and resistance in leukemia treatment trials. Citation Format: Yadira Soto-Feliciano. Targeting chromatin adaptor proteins in cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr SY05-01.
Abstract LB367: Effects of modulation of ERAP1 activity in antigen processing and presentation
Authors: Shami Alvarez Mourid, Edward James, Dario Guglietta, Emma Reeves
Journal: Cancer Research (2024)

Abstract ERAP1 is an enzyme that plays a key role in the antigen processing and presentation pathway as an editor of the peptide repertoire, allowing for the binding of neoantigens to MHC I. ERAP1 is polymorphic, with the different allelic variants showing various degrees of peptide trimming function expressed in humans. However, the trimming mechanism by which ERAP1 trims peptides is still not fully understood. The purpose of the study is to characterize the effect of the different ERAP1 variants and their inhibition on the peptide repertoire presented by tumor cells, enabling us to gain valuable insights into how this process works. This characterization will also enhance the pharmacological modulation of ERAP1, which has already been proven to promote T cell and NK-mediated anti-tumor cytotoxic response. By specifically targeting the activity levels of the ERAP1 variant expressed, we can adopt a personalized approach that maximizes the potential production of neoantigens, crucial for activating an anti-tumor immune response. We CRISPR knocked out the ERAP1 gene in the CT26 cell line and assessed the MHC I kinetics and stability by investigating the dissociation of pMHC complexes at the cell surface, using a Brefeldin-A decay assay and an acid-stripping test compared to wild-type. The assessment of MHC I assembly and cell surface expression kinetics showed higher MHC I in the ERAP1 KO cell line, highlighting that the lack of ERAP1 translated into a faster recovery time of peptide/MHC complexes at the cell surface. After assessing the kinetics, we re-expressed different human ERAP1 allotypes in CT26 ERAP1KO cell line through retroviral transduction and characterized MHC I expression levels through flow cytometry. Interestingly, MHC I expression levels varied across the transduced samples, with specific variants showing much higher expression levels indicating more peptide availability for loading onto the MHC molecules. Immunopeptidomic analysis comparing the WT, ERAP1 KO and the CT26 human ERAP1 transduced cell lines, showed distinct subsets of neoantigens presented in the KO cell line. ERAP1 plays a significant role in the assembly and recovery of peptide/MHC complexes. The reintroduction of different ERAP1 allelic variants greatly alters MHC I expression levels suggesting the formation of new peptide-MHC complexes responsible for the increase in MHC I expression. Modulation of ERAP1 activity significantly alters the presented peptide repertoire , uncovering neoantigens which are potentially immunogenic. Citation Format: Shami Alvarez Mourid, Edward James, Dario Guglietta, Emma Reeves. Effects of modulation of ERAP1 activity in antigen processing and presentation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB367.
Abstract LB362: Systematic development and characterization of orthotopic animal tumor models: A proactive approach to mimic patients' tumor microenvironments for drug discovery
Authors: WenQing Yang, Xusheng Yuan, Guangliang Yang, Xiaojun Tong, Weiqun Ding, Qiuxia Zhang, Feng Lu, Zhijian Yang
Journal: Cancer Research (2024)

Abstract Preclinical in vivo tumor models are crucial in translational research and the pharmaceutical industry, particularly for evaluating novel anti-cancer agents. While animal tumor models are widely used in both drug development and academic research, the majority of investigations have relied on subcutaneous (SC) transplantable tumor models. These models often fail to consider the orthotopic organ origin or the unique microenvironmental differences, leading to significant limitations. Despite many publications highlighting the advantages of orthotopic tumor models (ORTH) over SC models, there is a lack of systematic analysis and comparative characterization of these formats. In this study, we have systematically developed a comprehensive ORTH tumor model platform comprising over 80 orthotopic tumor models and covering more than 25 tumor types. ORTH tumor models have been enhanced for non-invasive monitoring and increased sensitivity of tumor growth and metastasis detection through labeling with multimodality imaging markers such as GFP, RFP, and bioluminescence or imaging with micro-CT or ultrasound. We optimized and streamlined technical procedures, throughput, and reproducibility of ORTH model development, facilitating the use of these models to assess anticancer agents in a large-scale format. To mimic the clinical situation, our characterization of these models includes growth profiles, metastatic features, and survival status. Additionally, ORTH models were compared with SC models regarding the efficacy of standard-of-care (SOC) drugs through side-by-side comparison studies. As expected, inconsistent responses to SOC therapeutics were observed in some models when comparing ORTH versus SC tumors. For models yielding inconsistent results, molecular analysis and model selection recommendations will be discussed. To date, this is the first study describing the generation of a considerably large orthotopic tumor model collection and conducting a comprehensive side-by-side characterization of ORTH and SC models. This proactive approach aims to improve the mimicry of patients' tumor microenvironments and enhance the clinical relevance and potentially increase the efficiency of translational research processes. Citation Format: WenQing Yang, Xusheng Yuan, Guangliang Yang, Xiaojun Tong, Weiqun Ding, Qiuxia Zhang, Feng Lu, Zhijian Yang. Systematic development and characterization of orthotopic animal tumor models: A proactive approach to mimic patients' tumor microenvironments for drug discovery [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB362.
Abstract LB275: Reactivation of mitotic arrest upon targeting TACC3 restores immunogenic cell death and T-DM1 response in HER2-positive breast cancer
Authors: Ozge Saatci, Mustafa Emre Gedik, Nathaniel Oberholtzer, Meral Uner, Ozge Akbulut, Metin Cetin, Mertkaya Aras, Kubra Ibis, Burcu Caliskan, Erden Banoglu, Stefan Wiemann, Aysegul Uner, Sercan Aksoy, Shikhar Mehrotra, Ozgur Sahin
Journal: Cancer Research (2024)

Abstract Immunogenic cell death (ICD) is a specific form of cell death that is characterized by the release of danger-associated molecular patterns (DAMPs), such as cell surface exposure of calreticulin, ATP and HMGB1 release, and can be induced by several different anti-cancer therapies. This, in turn, evokes a strong anti-tumor immune response, leading to reduced tumor growth. Despite being the first and one of the most successful antibody-drug conjugates (ADCs) approved for refractory HER2-positive breast cancer, little is known if response and resistance to trastuzumab emtansine (T-DM1) involves ICD modulation that can be leveraged to enhance T-DM1 response. Here we report that T-DM1 induces spindle assembly checkpoint (SAC)-dependent ICD in sensitive cells, mediated by its payload by inducing eIF2α phosphorylation, surface exposure of calreticulin, ATP and HMGB1 release, and secretion of ICD-related cytokines, all of which are lost in resistance. Accordingly, ICD-related gene signatures correlate with clinical response to T-DM1-containing therapy in pre-treatment samples, and increased infiltration of anti-tumor CD8+ T cells is correlated with better T-DM1 response in post-treatment samples. We found that transforming acidic coiled-coil containing 3 (TACC3) is overexpressed in T-DM1 resistant cells, and that T-DM1 responsive patients have reduced TACC3 protein while the non-responders exhibited increased TACC3 expression during T-DM1 treatment. Notably, genetic or pharmacological inhibition of TACC3 revives T-DM1-induced SAC activation and induction of ICD markers in vitro. TACC3 inhibition elicits ICD in vivo as shown by vaccination assay. It also potentiates T-DM1 in the human HER2-overexpressing MMTV-huHER2#5 (Fo5) transgenic model by activating ICD markers, release of cytokines and inducing dendritic cell (DC) maturation and enhancing infiltration of cytotoxic T cells. Together, our results show that ICD is a key mechanism of action of T-DM1 which is lost in resistance, and that targeting TACC3 restores T-DM1-mediated ICD and overcomes resistance. Citation Format: Ozge Saatci, Mustafa Emre Gedik, Nathaniel Oberholtzer, Meral Uner, Ozge Akbulut, Metin Cetin, Mertkaya Aras, Kubra Ibis, Burcu Caliskan, Erden Banoglu, Stefan Wiemann, Aysegul Uner, Sercan Aksoy, Shikhar Mehrotra, Ozgur Sahin. Reactivation of mitotic arrest upon targeting TACC3 restores immunogenic cell death and T-DM1 response in HER2-positive breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB275.