bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 5451: FOXC2 influences EMT-induced stem cell properties through regulation of FABP4 in breast cancer
Authors: Demestichas Breanna R. , Shivakumar Vinita , Ramirez-Peña Esmeralda , Taube Joseph , Hollander Petra den , Mani Sendurai A.
Published: March 2024

Cancer stem cells (CSCs) pose a significant clinical challenge due to their inherent resistance to therapies and prevalence in cancer recurrence. CSCs have the ability for self-renewal and to adapt to different microenvironments during dissemination and seeding into distal organs, and these properties are critical in metastasis. We and others have shown that epithelial to mesenchymal transition (EMT) drives the acquisition of stem cell properties, particularly via the forkhead box protein C2 (FOXC2) transcription factor. FOXC2 is a master regulator of EMT and is necessary for the induction and maintenance of CSC properties. Importantly, FOXC2 is not expressed in most adult tissues except adipocytes, in which it dictates several aspects of lipid metabolism. Additionally, metabolic changes during EMT can equip cancer cells with enhanced survival mechanisms during tumor progression and metastasis. We hypothesized that FOXC2 regulates metabolism in EMT-induced cells, facilitating stem cell properties and metastatic competence.

To determine the downstream metabolic genes regulated by FOXC2 and that enhance stemness properties in cancer cells, we performed gene expression profiling and identified fatty acid binding protein 4 (FABP4), which is known to be involved in lipid metabolism, especially in adipocytes and macrophages. We demonstrate that inhibition of FOXC2 expression using shRNA in EMT-induced cells markedly reduces FABP4 expression. In agreement with this, we found that the overexpression of FOXC2 expression rescues the expression of FABP4. In addition, FOXC2 binds to the FABP4 promoter and regulates its expression suggesting that FABP4 is a direct target of FOXC2. We demonstrate that both lipid uptake and CSC formation is inhibited in a dose-dependent manner using a FABP4-specific small molecule inhibitor. Additional experiments are underway to assess the role of FABP4 in CSC formation in vivo and in contributions to metastasis, using our small molecule inhibitor in mouse models of metastatic breast cancer.

Overall, our data indicate that FABP4 is a key regulator of stemness in breast cancer cells and targeting the FOXC2—FABP4 axis may provide therapeutic benefits for breast cancer. This work also provides insights into the metabolic shifts that occur during EMT and CSC formation, which warrants further investigation into these mechanisms.

Citation Format: Breanna R. Demestichas, Vinita Shivakumar, Esmeralda Ramirez-Peña, Joseph Taube, Petra den Hollander, Sendurai A. Mani. FOXC2 influences EMT-induced stem cell properties through regulation of FABP4 in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5451.
Abstract 5512: Cerebral endothelial FAK paradoxically inhibits brain metastasis in vivo
Authors: Noda-Narita Shoko , Aiba Atsu
Published: March 2024

Introduction: In cancer metastasis in the trunk, the secreted proteins from tumors, such as VEGFs and TNF-α, activate focal adhesion kinase (FAK) in vascular endothelial cells (VECs). The activated FAK promotes VE-cadherin phosphorylation and the expression of cell adhesion molecules, and it facilitates the extravasation of cancer cells. In the cerebral blood vessels, the VECs maintain very strong cell adhesion supported by the surrounding pericytes and astrocytes. The strong barrier of cerebral VECs is called the blood-brain barrier (BBB) and is regulated differently from trunk VECs. Although the role of FAK in trunk metastasis is shown in many studies, its importance in brain metastasis is not verified. In this study, we focused on the role of the cerebral endothelial FAK and compared the role of FAK in brain metastasis with that in trunk metastasis.

Methods: We generated tamoxifen-inducible VEC-specific FAK knockout (FAK-cKO) mice (VEcad-CreERT2; Ptk2-flox/flox) and brain metastatic (BrM) cell lines of Ex3LL (murine lung cancer cell line). We intracardially injected BrM cells of Ex3LL into the FAK-cKO mice and analyzed the tumor development using in vivo bioluminescence imaging and a CUBIC tissue clearing system. We also analyzed the intracranially injected mice of the parental and BrM cell lines to evaluate the tumor angiogenesis, which is reported to be promoted by the endothelial FAK.

Results: Although FAK-cKO in VECs has been reported to inhibit lung metastasis, brain metastasis was accelerated in FAK-cKO mice compared with control mice. The number of brain metastatic sites increased in FAK-cKO mice, but there was no difference in the individual tumor size. It suggests that the brain metastasis was promoted by FAK-cKO, but that the proliferation of brain metastasis was not promoted by FAK-cKO. Blood vessel density was decreased with irregular shape in the brain tumors of FAK-cKO mice, suggesting that the angiogenesis was inhibited by FAK-cKO. It indicates that the angiogenic function of endothelial FAK in the brain vasculature was not different from that in the trunk.

Conclusion: FAK-cKO in VECs exacerbated the brain metastasis of the BrM cells although it has been reported to inhibit the metastasis in the trunk. FAK-cKO in VECs decreased tumor angiogenesis both in the brain and the trunk. It suggests that the regulatory mechanism of cell adhesion and the FAK function in the brain vasculature is partly different from that in the other organs in the body trunk. We need further investigation to elucidate the function of endothelial FAK in brain metastasis.

Citation Format: Shoko Noda-Narita, Atsu Aiba. Cerebral endothelial FAK paradoxically inhibits brain metastasis in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5512.
Abstract 552: Non-canonical disulfide isomerases are strongly selective, understudied targets for cancer therapy
Authors: Law Mary E. , Dulloo Zaafir M. , Yaaghubi Elham , Alexandrow Grace M. , Forsyth Bianca , Su Hanyu , Castellano Ronald K. , Law Brian K.
Published: March 2024

A major challenge in cancer therapy is the identification of drug targets that are essential for cancer cells but not non-transformed cells. The Broad Institute’s Dependency Map (DepMap) evaluates whether knocking down or knocking out expression of specific genes is “strongly selective” against subsets of cancer cells, in contrast with genes that are “common essential.” Of the 22 human Protein Disulfide Isomerases (PDIs), only four, ERp44, TMX1, AGR2, and AGR3, were identified as strongly selective in the DepMap. Importantly, our team previously identified ERp44, AGR2, and AGR3 as targets of bicyclic thiosulfonate compounds termed Disulfide bond Disrupting Agents (DDAs). DDAs exhibit striking anti-cancer activity in xenograft tumor studies. DDA treatment of cancer cells blocks ERp44, AGR2, and AGR3 active site Cys residues, ablating their catalytic activity and binding to client proteins. Evaluation of cancer cell lines predicted to be sensitive to DDAs, based on their AGR2, AGR3, or ERp44 dependence, accurately predicts DDA sensitivity. Cell lines from a variety of tumor types exhibit AGR2, AGR3, or ERp44 dependencies. Our previous work identified HER-family members (i.e., EGFR, HER2, and HER3) and TRAIL receptors (Death Receptors 4 and 5) as important clients of DDA-sensitive PDIs in breast cancer cells, but it was unknown if these observations extend to other tumor types. Initial studies indicate that AGR2 DepMap dependencies are a strong predictor of sensitivity of cancer cells to DDAs, irrespective of their site of origin. It will be important in future studies to determine what the key client proteins for these DDA-sensitive PDIs are and whether they vary across tumor types.

Citation Format: Mary E. Law, Zaafir M. Dulloo, Elham Yaaghubi, Grace M. Alexandrow, Bianca Forsyth, Hanyu Su, Ronald K. Castellano, Brian K. Law. Non-canonical disulfide isomerases are strongly selective, understudied targets for cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 552.
Abstract 5529: Mimicking CAFs, pial cells support leptomeningeal metastasis
Authors: Snyder Jenna , Remsik Jan , Boire Adrienne
Published: March 2024

Leptomeningeal metastasis (LM), the spread of cancer into cerebrospinal fluid (CSF)-filled coverings of the brain and spinal cord, is a dismal complication of cancer leading to rapid neurologic disability and death. While a diverse array of primary tumors may result in LM, recent work from our laboratory (Chi Y et al 2020 Science) demonstrates a conserved transcriptional signature, independent of primary tumor, suggesting that tumor-microenvironmental interactions play a dominant role in this pathology. We have proteomically interrogated CSF collected from breast (n = 45), lung (n = 30), and melanoma (n = 27) patients with and without LM. We detect robust expression of inflammatory cytokines in all LM+ samples, 15 of these cytokines including IL8, IL6, and CXCL1 are conserved across tumor types in the presence of LM. Because cancer cells in the CSF do not express mRNA associated with these cytokines, we hypothesized that these inflammatory cytokines may originate from the microenvironment. Within the leptomeninges, LM cells adhere to and interact with the innermost layer of the meninges, the pia mater, which contains fibroblast-like cells. Co-culture of cancer cells with pial cells induced changes in the pial cell transcriptome and secretome, leading to increased IL8, IL6, and CXCL1 production. This communication between cancer cells and pial cells is preserved in the absence of direct cell-cell contact. These pial cells support cancer cell growth in vivo, as measured by co-implantation experiments. In addition, bulk RNA sequencing of mouse pial cells shows an inflammatory signature upregulated in the presence of LM. Taken together, these observations support a cancer-associated-fibroblast like role for pial cells in the setting of LM. Our work extends the CAF phenotype beyond classical fibroblasts to include pial cells, suggesting novel therapeutic opportunities within CNS malignancies.

Citation Format: Jenna Snyder, Jan Remsik, Adrienne Boire. Mimicking CAFs, pial cells support leptomeningeal metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5529.
Abstract 5530: Metastasis founder cells activate immunsuppression early in human metastatic colonization
Authors: Guetter Severin , Koenig Courtney , Koerkel-Qu Huiqin , Markiewicz Aleksandra , Scheitler Sebastian , Katzer Marie , Berneburg Mark , Renner Philipp , Cucuruz Beatrix , Guttenberger Leonhard , Naimer Veronika , Weidele Kathrin , Treitschke Steffi , Werno Christian , Jaser Hanna , Bargmann Tonia , Braun Armin , Weber Florian , Limm Katharina , Rachel Reinhard , Baumann Felix , Schmidleithner Lisa , Schambeck Kathrin , Ulmer Anja , Haferkamp Sebastian , Klein Christoph , Werner-Klein Melanie
Published: March 2024

Metastatic dissemination occurs very early in melanoma, often before diagnosis, rendering prevention of metastasis formation an important therapeutic goal. However, the earliest steps of lethal metastasis in patients are incompletely understood. Therefore, in this study we searched for the earliest detectable disseminated cancer cells (DCC) in sentinel lymph node biopsies of 492 stage I-III melanoma patients. We used micromanipulator-assisted isolation and single-cell transcriptome analysis of these extremely rare DCC and identified melanoma -associated chondroitin sulfate proteoglycan (MCSP) expressing melanoma cells as strong candidates for metastasis founder cells in lymph nodes. Based on a median follow-up time of 6 years, their detection was the strongest predictor of systemic metastasis and death upon multivariable analysis. Single-cell transcriptome analysis revealed that melanoma DCC were exposed to CD8 T cell attack during the transition from single cells to metastasis-initiating clusters, activated the extracellular vesicular exosomal pathway, and expressed the immunomodulatory proteins CD155 and CD276, but rarely PD-L1. CD155- and CD276-positive extracellular vesicles from patient-derived DCC models showed an immunosuppressive activity on CD8 T cells. In conclusion, our data suggest that either direct targeting of metastasis-founder cell with MCSP or their immune escape mechanisms may be key to curing early-stage melanoma.

Citation Format: Severin Guetter, Courtney Koenig, Huiqin Koerkel-Qu, Aleksandra Markiewicz, Sebastian Scheitler, Marie Katzer, Mark Berneburg, Philipp Renner, Beatrix Cucuruz, Leonhard Guttenberger, Veronika Naimer, Kathrin Weidele, Steffi Treitschke, Christian Werno, Hanna Jaser, Tonia Bargmann, Armin Braun, Florian Weber, Katharina Limm, Reinhard Rachel, Felix Baumann, Lisa Schmidleithner, Kathrin Schambeck, Anja Ulmer, Sebastian Haferkamp, Christoph Klein, Melanie Werner-Klein. Metastasis founder cells activate immunsuppression early in human metastatic colonization [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5530.
Abstract 554: Determining the role of PROX1 in prostate cancer neuroendocrine trans-differentiation
Authors: Raj Sonam , Capaldo Brian , Bowman Joel , White Margaret , Moore Xavier , Gryder Berkley , Alilin Aian N. , Takeda David , Kelly Kathleen
Published: March 2024

Nonbiased mutational screening to identify essential genes and pathways in cancer is a powerful approach for understanding underlying biology as well as the identification of potential therapeutic targets. Epigenetic (EPI) and transcriptional factors (TF) play an important role in the change of phenotype and lineage plasticity from adenocarcinoma to castration resistant prostate cancer (CRPC), double negative (DN) or treatment-induced neuroendocrine prostate cancer (NEPC). When RB1 loss occurs in combination with TP53 alterations, stemness and lineage plasticity increase with one consequence being differentiation to a neuroendocrine (NE) lineage. Here, we are identifying and testing the functional role of epigenetic and transcription factors required for the viability of CRPC, DN and NEPC relative to a matrix of genotypic and phenotypic characteristics. We applied CRISPR-CAS9 dropout screens in prostate organoids and cell lines to identify gene/s associated with CRPC, DN and NEPC viability. We successfully CRISPR-engineered LNCaP clones of single (LNCaP-TP53-SKO, LNCaP-RB1-SKO) and double (LNCaP-TP53-RB1-DKO) gene knockouts, which were subsequently characterized for immuno-phenotype and transcriptome. Our dropout screens, targeting all TFs and EPIs, identified 117 TF and 40 EPI genes responsible for the viability of DN, NEPC and LNCaP models. We found known genes such as FOXA1 and ASCL1, as well as novel genes including PROX1 and KLF3, which were validated through guide RNA competition assays. Our results showed PROX1 is essential for cell viability in a DN organoid model, and its expression is associated with increased aggressiveness, indicating PROX1 has role in stemness/lineage plasticity in treatment resistant adenocarcinoma. RNA-seq analysis following overexpression of PROX1 in the LNCaP-TP53-RB1 null adenocarcinoma model, with and without enzalutamide, identified pathways enriched for cell proliferation, differentiation, neuronal development, and prostate gland development. In summary, our study has suggested an important role for PROX1 in the growth and differentiation of poorly differentiated prostate cancer, which may lead to the identification of potential therapeutic targets.

Citation Format: Sonam Raj, Brian Capaldo, Joel Bowman, Margaret White, Xavier Moore, Berkley Gryder, Aian N. Alilin, David Takeda, Kathleen Kelly. Determining the role of PROX1 in prostate cancer neuroendocrine trans-differentiation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 554.
Abstract 5557: Stem-like T cells maintain latent anticancer activity and underly therapy resistance
Authors: Tao Fang , McElroy Sara , Nemechek Jacqelyn , Pushel Irina , Szarejko John , Khanal Santosh , Bradley Todd , Myers Doug , Perry John M.
Published: March 2024

Pre-cancerous cells are normally recognized and eliminated by immune cells. Cancer progresses only when this immunosurveillance system fails. Although immunotherapy has driven the most significant and exciting advances in cancer treatment in modern times, current approaches are running into barriers. An emerging area of interest includes evidence for rare but highly potent stem cell-like T cells. Stem-like T cells combine long-term persistence and high potency with immunological memory. Our recent findings reveal insights into the nature and regulation of stem-like T cells and their potential anticancer activity. Minimal residual disease (MRD) underlies therapeutic resistance, dictates treatment escalation, and predicts patient outcomes. We have shown that the Wnt and PI3K pathways promote the transformation of hematopoietic stem cells (HSCs) into chemoresistant leukemia stem cells (LSCs), which form the root of leukemia initiation and post-treatment recurrence. High-throughput screening revealed that LSCs could be targeted by low dose anthracycline treatment. Mechanistically, low dose, but not high dose anthracyclines indirectly target LSCs by inhibiting their unique properties of immune escape, allowing for their elimination by CD8+ T cells. We employed single-cell genomic and proteomic analysis to investigate immunological changes during development of HSCs, LSCs, and their progeny in response to low dose anthracycline treatment. While leukemia progression results in exhaustion of differentiated CD8+ T cells, stem-like T cells accumulate. However, low dose anthracycline treatment reverses this imbalance. Comparing MRD+ and MRD- patient samples, we found that differential proportions of stem-like T cells persist in the bone marrow of leukemia patients. While T cells of MRD- patients recover following chemotherapy induction, T cell recovery is severely attenuated in MRD+ patients. Furthermore, failure of immunological recovery is driven at least partially by a lack of stem-like T cells in MRD+ leukemia patients. Overall, our studies have revealed that low dose anthracyclines, in contrast to high dose, induce opposing, dichotomous effects on LSCs vs. HSCs and stem-like vs. differentiated T cells.

Citation Format: Fang Tao, Sara McElroy, Jacqelyn Nemechek, Irina Pushel, John Szarejko, Santosh Khanal, Todd Bradley, Doug Myers, John M. Perry. Stem-like T cells maintain latent anticancer activity and underly therapy resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5557.
Abstract 5559: The anti-tumor efficacy and immune effects of combining of ceralasertib, an oral ATR kinase inhibitor, with imipridones, in prostate cancer treatment in vitro and in vivo
Authors: Xia Yutong Linda , Zhang Leiqing , Ghandali Maryam , Schwermann Maximilian P. , El-Deiry Wafik
Published: March 2024

Prostate cancer is the most common cancer and the second leading cause of cancer death among men in the United States. There is an estimated 10% to 50% of cases progress to metastatic castration resistant prostate cancer (mCRPC) state within 3 years of diagnosis. mCPRC remains lethal despite therapeutic advances. There is approximately 20% of mCRPC patients present somatic DNA damage repair (DDR) gene mutations. Ceralasertib, formerly known as AZD6738, is a potent and selective orally bioavailable inhibitor of the ataxia tenlangiectasia and Rad3-related (ATR) kinase, which is involved in DNA repair in response to DNA damage and replication stress. Preclinical studies have demonstrated ATRi sensitizing alterations in DNA damage response (DDR) genes. Ceralasertib’s antitumor activity as a monotherapy in treating prostate cancer is moderate. Thus, we combined ceralasertib with imipridones (ONC201 and ONC206), which target mitochondrial caseinolytic protease P (ClpP) and the integrated stress response, resulting in enhanced antitumor efficacy in vitro. Prior data have demonstrated sensitivity of 4 prostate cancer lines to ceralasertib and imipridones monotherapies, synergistic activities with the combination treatments, and immune enhancement effects with the combination treatments when co-cultured with NK92MI cell line. We proceeded to a short term in-vivo study validating the combination treatment efficacy. Preliminary results include cytokine profiling using the Luminex 200 technology to understand treatment induced changes in the tumor microenvironment (TME) from both in vitro and in vivo studies. Our results guide novel clinical trials for effective clinical responses in mCPRC patients.

Citation Format: Yutong Linda Xia, Leiqing Zhang, Maryam Ghandali, Maximilian P. Schwermann, Wafik El-Deiry. The anti-tumor efficacy and immune effects of combining of ceralasertib, an oral ATR kinase inhibitor, with imipridones, in prostate cancer treatment in vitro and in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5559.
Abstract 557: Clofarabine inhibits U87MG glioblastoma cell line proliferation through CD99 signaling pathway
Authors: de Souza Camila Cristina , Soares Roseli da Silva , Lerario Antonio Marcondes , Marie Suely Kazue , Oba-Shinjo Sueli Mieko
Published: March 2024

The present work aimed to test the efficacy of clofarabine in glioblastoma (GBM) cells that express high levels of CD99. GBMs are the most malignant with the poorest prognosis among tumors of the central nervous system. Patients have a median survival of 12 to 15 months despite surgical, radio, and chemotherapy. CD99 is a cell surface receptor overexpressed in several types of tumors, including GBMs, justifying the interest of studies in CD99 as a possible therapeutic target. Our group has previously demonstrated that knockout of CD99 in the U87MG GBM cell line promoted a decrease in cell adhesion, migration, and invasion. Clofarabine is a third-line drug used in the treatment of refractory/relapsed childhood acute lymphoblastic leukemia. It is a purine analog that is transported into intracellular space, phosphorylated, and incorporated into DNA chain, inhibiting DNA synthesis and ultimately inducing cell death by apoptosis. The clofarabine effect has also been demonstrated in cells from solid tumors, such as breast, gastric, and bladder. Clofarabine action on the proliferation of Ewing sarcoma cells in vitro and in vivo was proved to be by direct binding to CD99 and independent of the drug internalization. In addition, clofarabine also had an effect on cells from other tumor types that express CD99. The present work demonstrated the significant action of clofarabine on the high CD99-expressing U87MG cells by inhibiting cell proliferation, adhesion, and migration, and by inducing cell cycle arrest and apoptosis. U87MG cells knocked out for CD99 expression were more resistant to clofarabine action on proliferation. RNAseq analysis of U87MG cells treated with clofarabine and compared to control showed downregulated genes involved in cell cycle regulation and mitosis, while upregulated genes were enriched in extracellular proteins, cell adhesion, locomotion, p53 signaling pathway, and apoptosis. Our data indicates clofarabine as a potential CD99 inhibitor to treat GBM patients.

Citation Format: Camila Cristina de Souza, Roseli da Silva Soares, Antonio Marcondes Lerario, Suely Kazue Marie, Sueli Mieko Oba-Shinjo. Clofarabine inhibits U87MG glioblastoma cell line proliferation through CD99 signaling pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 557.
Abstract 558: Stearoyl-CoA desaturase is a synthetic lethal target in SMAD4-deficient cancers
Authors: Lu Alvin , Fenoglio Silvia , Wu Hsin-Jung , Zhang Minjie , Tsai Alice , Ferdinez Maria L. , Grove Lauren , Liu Shangtao , Wu Edward , Choi Ashley , Throner Scott , Meier Samuel , Yu Yi , Zhang Wenhai , Maxwell John , Andersen Jannik N. , Teng Teng , Haines Brian B. , Chen Yingnan P.
Published: March 2024

Mothers against decapentaplegic homolog 4, or SMAD4, is a member of the SMAD family of transcription factors that mediate TGF-β signal transduction. SMAD4 loss of function mutation or deletion is found in about 30% of PDAC and 15% of COAD and EAC patients, and it is associated with their poor prognosis. Over the past two decades, its tumor suppressor role has been elucidated, and the loss of SMAD4 is sufficient to promote tumorigenesis in multiple GEM models. To identify novel therapeutic vulnerabilities for SMAD4-deficient cancers, a CRISPR dropout screening approach was employed in SMAD4 isogenic PDAC models. We identified stearoyl-CoA desaturase, SCD, as a synthetic lethal target in SMAD4-deficient context. SCD is critical for de novo lipid biogenesis and catalyzes the rate-limiting step in the production of monounsaturated fatty acid. Genetic and pharmacologic studies in vitro confirmed this synthetic lethal relationship. Additionally, drug-anchored CRISPR dropout screening and RNA expression profiling demonstrated that accumulation of saturated fatty acid in response to SCD inhibition drives cytotoxicity in SMAD4-deficient cells. Mouse studies with CRISPR-based knockout of SCD and a well-characterized SCD inhibitor (A939572) demonstrated anti-tumor efficacy in SMAD4-mutant xenograft models. However, compared to genetic KO of SCD the pharmacological inhibitor was less effective at inhibiting tumor proliferation in vivo. Together, these data identify SCD as a selective vulnerability in SMAD4-mutant cancers.

Citation Format: Alvin Lu, Silvia Fenoglio, Hsin-Jung Wu, Minjie Zhang, Alice Tsai, Maria L. Ferdinez, Lauren Grove, Shangtao Liu, Edward Wu, Ashley Choi, Scott Throner, Samuel Meier, Yi Yu, Wenhai Zhang, John Maxwell, Jannik N. Andersen, Teng Teng, Brian B. Haines, Yingnan P. Chen. Stearoyl-CoA desaturase is a synthetic lethal target in SMAD4-deficient cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 558.
Abstract 5596: Exploring BRCA1-Y1853ter and potential therapeutic targets in BRCA1-BRCT mutated cancers
Authors: Chen Jingjing
Published: March 2024

The breast cancer gene BRCA1 plays a pivotal role as a tumor suppressor gene. Despite the use of poly (ADP-ribose) polymerase inhibitors (PARPi) in treating BRCA1 mutation carriers, the lack of response or the development of acquired drug resistance underscores the pressing need for new therapeutic targets. One intriguing BRCA1 mutation, BRCA1-Y1853ter, characterized by a minimal truncation, has been identified in multiple individuals with Hereditary Breast and Ovarian Cancer (HBOC) syndrome. We have developed a Halo Tag and adenovirus-based system where wild-type BRCA1 (WT BRCA1) and mutant BRCA1 protein complexes can be studied in multiple cell types. Here, we used this system to affinity purify BRCA1 wild-type and mutant complexes, followed by label-free quantitative proteomics to investigate the dynamic interactome variations between WT BRCA1 and BRCA1 mutant. Contrary to the assumed loss of function, our preliminary findings suggest a potential gain of function, as a significant number of candidate proteins exhibit enhanced binding affinity with the mutant BRCA1. We are currently exploring whether these distinct binding characteristics are shared among various BRCA1-BRCT mutants, which may hint at a common tumorigenesis mechanism. Our overarching hypothesis is that identifying a specific binding partner, shared among various BRCA-BRCT mutants, could unveil a novel therapeutic target with broader applicability in treating BRCA1-related malignancies.

Citation Format: Jingjing Chen. Exploring BRCA1-Y1853ter and potential therapeutic targets in BRCA1-BRCT mutated cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5596.
Abstract 5640: Unlocking the therapeutic potential of SF3B1 inhibitors for bladder cancer treatment
Authors: Columbres Rod Carlo , Chakraborty Arup , Apolo Andrea , Banday Rouf
Published: March 2024

RNA splicing dysregulation is a hallmark of cancer, occurring in multiple solid and hematological malignancies. Splicing factor 3 subunit B1 (SF3B1), a key component of the U2 small nuclear ribonucleoprotein (snRNP) complex that regulates RNA splicing, is frequently altered in a variety of cancer types, including non-muscle-invasive and muscle-invasive bladder cancer, where the E902K mutation is common. In this study, we investigated the therapeutic potential of the SF3B1 inhibitor, pladienolide B, in bladder cancer using in vitro models. We used a recombinant plasmid containing the SF3B1E902K mutation and established an UMUC3E902K mutant urothelial cell line. Both UMUC3WT and UMUC3E902K cells were treated with pladienolide B alone or in combination with cisplatin to evaluate differences in cell viability. Flow cytometry using annexin V staining and propidium iodide exclusion was utilized to assess the cell death mechanism. RNAseq was performed after RNA extraction from UMUC3WT, UMUC3E902K, RT4, and HT1376 bladder cancer cell lines were treated with pladienolide alone or combined with cisplatin. We determined that the IC50 for pladienolide B is 5nM for UMUC3 cells observed 72 hours post-treatment. Treatment with pladienolide B halted the cell cycle and caused cell death by apoptosis for both UMUC3WT and UMUC3E902K cell lines. We also observed that UMUC3E902K cells were significantly more sensitive to pladienolide B compared to UMUC3WT cells (p≤0.05). Furthermore, there was a synergistic effect observed after co-treatment with low-dose pladienolide B (2 nM) and cisplatin (3 µM) for both UMUC3WT and UMUC3E902K cell lines, with UMUC3E902K cells showing greater sensitivity to combination treatment. Our results provide insights into the potential use of splicing inhibitors, alone or in combination with chemotherapy, for treating bladder cancer, specifically for tumors that bear driver mutations in splicing factors. Currently, we are evaluating the mechanism by which SF3B1 mutations make cells sensitive to pladienolide B in vitro and in vivo, with the goal of identifying specific mRNA splicing vulnerabilities that can be targeted by anti-sense or splice-switching oligonucleotides to achieve anti-tumor outcomes. Additional differential splicing patterns and preliminary in vivo results will be presented.

Citation Format: Rod Carlo Columbres, Arup Chakraborty, Andrea Apolo, Rouf Banday. Unlocking the therapeutic potential of SF3B1 inhibitors for bladder cancer treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5640.
Abstract 5680: Circular MALAT1 - the new kid on the block in breast-to-brain metastatic cancer
Authors: Szczepaniak Adrian , Bronisz Agnieszka , Godlewski Jakub
Published: March 2024

Introduction: Breast-to-brain metastatic (BTB met) cancer constitutes a great challenge for modern medicine and science. As the research on protein-coding genes brought only incremental progress in developing anticancer therapy, much attention is devoted to understanding the role of non-coding RNAs, including a relatively recently discovered group - of circular RNAs. This project aimed to determine the relationship between BTB met cancer cells and cells derived from a deadly brain tumor - glioblastoma stem-like cells (GSCs), considering the circular RNA signatures and selecting a reliable candidate for mechanistic study - a circular form of non-coding oncogene MALAT1 (circMALAT1).

Methods: The circular RNA expression profile in patient-derived BTB met cancer cells (n=4), GSCs (n=8), and neural progenitor cells (NPC) as a non-malignant control (n=3) was evaluated by the microarray approach. Expression of circMALAT1 was also validated in non-malignant breast epithelial cells by digital PCR and data mining in the GEO database. CircMALAT1 knockdown by antisense oligonucleotides was followed by functional analysis.

Results: 12,660 circular RNAs were detected using the Arraystar platform, and upon applying the cutoff of FC ≥2 and p-value <0.05, 547 circular RNAs were selected as significantly deregulated in all cancer groups compared to NPC. CircMALAT1 was elevated in BTB met compared to NPC and normal breast epithelial cells. Knockdown of circMALAT1 affected cancer cell viability and proliferation while promoting p21 expression, thus decelerating the cell cycle manifested by a reduction in 3D spheroids volume.

Conclusions: The analysis of the circular RNA landscape showed for the first time some striking similarities between BTB mets and GSCs despite different tissue-of-origin. Of note, the circRNAome of BTB mets clustered especially closely with mesenchymal GSC - the most aggressive and therapy-resistant subtype of GSCs. These results also demonstrated the role of circMALAT1 in shaping the oncogenic traits of these cells. Therefore, circular RNAs can serve as valuable biomarkers and promising novel mechanistic candidates whose modulation may become a paradigm-shifting therapeutic approach.

Citation Format: Adrian Szczepaniak, Agnieszka Bronisz, Jakub Godlewski. Circular MALAT1 - the new kid on the block in breast-to-brain metastatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5680.
Abstract 5709: PF-07104091, a first-in-class CDK2-selective inhibitor for the treatment of HR+/HER2- breast cancer and CCNE1high ovarian cancer
Authors: Shen Chen , Qiu Ming , Huser Nanni , Pascual Bernadette , Zhang Qin , VanArsdale Todd , Murtaza Anwar , Almaden Jonathan , Kim berly , Anders Lars , Eisele Koleen
Published: March 2024

The selective inhibition of Cyclin\CDK complexes controlling cell cycle progression has been established as cancer therapy by selective CDK4/6 inhibitors in HR+/HER2- breast cancer. Expanding control of the cell cycle through selective inhibition of CDK2 offers novel therapeutic opportunities in cancer, including targeting CCNE1 amplified tumors and countering resistance to CDK4\6 inhibitors in ER+ breast cancer. PF-07104091 is a first-in-class CDK2-selective inhibitor under clinical investigation in patients with HR+/HER2- breast cancer and ovarian cancer. Preclinical studies using PF-07104091 establish the therapeutic impact of CDK2 inhibition in both diseases and highlight distinct mechanistic roles for CDK2 in control of cancer cell proliferation. In models of CCNE1 amplified ovarian cancer, CDK2 plays the dominant role in control of RB1 phosphorylation and the G1 checkpoint. CDK2 inhibition with PF-07104091 induces G1 growth arrest and controls tumor xenograft growth as single agent therapy. In ER+ breast models CDK2 plays a supportive role in the control of RB1 phosphorylation cooperating with CDK4\6. Whole genome CRISPR KO and CRISPR activation screens in conjunction with CDK4\6 inhibition establish CDK2 KO as a primary sensitizer to CDK4\6 inhibition, and support Cyclin E\CDK2 complexes as the driver of resistance to CDK4\6 inhibitors in ER+ breast models. PF-07104091 combined with CDK4\6 inhibitor Palbociclib or CDK4-selective inhibitor PF-0060 synergistically controls proliferation of ER+ BC cells in vitro and induces tumor regression in ER+ BC xenograft models, including PDX models with acquired resistance to CDK4\6 inhibitors and endocrine therapy.

Citation Format: Chen Shen, Ming Qiu, Nanni Huser, Bernadette Pascual, Qin Zhang, Todd VanArsdale, Anwar Murtaza, Jonathan Almaden, berly Kim, Lars Anders, Koleen Eisele. PF-07104091, a first-in-class CDK2-selective inhibitor for the treatment of HR+/HER2- breast cancer and CCNE1high ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5709.
Abstract 5712: Functional dissection of CDK7 in transcription using a highly selective CDK7 inhibitor Q901
Authors: Jung Hyerim , Um Dahun , Lee Yoonji , Yu Donghoon , Lee Dayoung , Ahn Jiye , Kim Jeongjun , Lee Seung-Joo , Kim Jaeseung , Nam Kiyean , Kim Tae-Kyung
Published: March 2024

CDK7 is a well-known regulator of both the cell cycle and transcription and plays a crucial role in cell cycle progression by catalyzing T-loop phosphorylation of other CDKs. CDK7 is also an integral subunit of the general transcription factor, TFIIH and regulates transcription through phosphorylation of RNA Polymerase II (Pol II) at CTD Ser5 and CDK9. We used Q901, a highly selective CDK7 inhibitor to further investigate the molecular function of CDK7 in the transcriptional process. Q901 is currently being evaluated in a phase 1 clinical study for selected advanced solid tumors. Compared to previously reported CDK7 inhibitors, Q901 has increased specificity and efficacy, but the impact on transcription have not been studied in detail. In our study, we combined RNA Pol II (pan, Ser5P, Ser2P) ChIP-seq and PRO-seq techniques in the MCF7 breast cancer cell line. The findings demonstrated that the Q901 effectively altered transcription and the RNA Pol II profile in a subset of genes, leading to a significant reduction in Ser5 phosphorylation levels in RNA Pol II. The downregulated genes were associated with critical pathways including downstream of oncogenic genes (MYC and E2F), DNA damage repair, cell cycle checkpoint, and gene expression. To verify whether these genes were the direct targets of CDK7, we performed CDK7 ChIP-seq analysis. CDK7 binding exclusively to the genes that were downregulated by Q901, without any detectable binding to upregulated genes. Despite the universal role of general transcription machinery in transcription, the data demonstrated that the highly selective inhibition of CDK7 in transcription of various oncogenic pathways underlies the potent in vitro and in vivo anti-cancer efficacy of this specific CDK7 inhibitor.

Citation Format: Hyerim Jung, Dahun Um, Yoonji Lee, Donghoon Yu, Dayoung Lee, Jiye Ahn, Jeongjun Kim, Seung-Joo Lee, Jaeseung Kim, Kiyean Nam, Tae-Kyung Kim. Functional dissection of CDK7 in transcription using a highly selective CDK7 inhibitor Q901 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5712.
Abstract 5736: Sonochemical preparation of SP94 peptide-decorated pH-responsive biodegradable biopolyester nanoparticles for targeted therapy in hepatocellular carcinoma
Authors: Wu Mingfang , Wang Qi , Gong Zhengran , Liu Zixuan , Zheng Haodong , Chen Xinjie , Zhong Chen
Published: March 2024

Stimulation in response to nanoparticles responding to endogenous stimuli in the tumor microenvironment has been extensively studied for the release of chemotherapeutic drug. Therefore, we aimed to develop a biocompatible delivery of taxol (TAX) delivery vector system for the treatment of hepatocellular carcinoma (HCC). A basic backbone, TAX loaded poly (3-hydroxybutyrate-co-3-hydroxyvalerate) PHBV nanoparticle (PHBV-TAX-NPs), were designed and prepared via sonochemical method. The pH-responsive shell of PHBV-TAX-NPs was formed by oxidative self-polymerization of dopamine (PDA) in an alkaline environment. The HCC-targeted peptide SP94 binds to PDA-coated nanoparticles (NPs) through the Michael reaction. Moreover, the nanoparticle surface-grafted SP94 peptide serve as a specific ligand for targeting HCC. The chemical structures and properties of these nanoparticles were characterized by transmission electron microscope, dynamic light scattering-autosizer, differential scanning calorimetry, fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetry. As expected, excellent targeting of these SP94-PDA-PHBV-TAX-NPs was demonstrated by cellular uptake and cytotoxicity experiments in HCC cells. Compared with that of free TAX, the SP94-PDA-PHBV-TAX-NPs showed more superior antitumor efficacy in the xenograft mouse model. Notably, the SP94-PDA-PHBV-TAX-NPs were except for their potent anticancer activity, it was less toxic in vitro and in vivo compared to TAX in mice. These studies suggest the potential beneficial use of SP94-PDA-PHBV-TAX-NPs in future HCC-targeted therapy with drug-loaded nanocarriers.

Citation Format: Mingfang Wu, Qi Wang, Zhengran Gong, Zixuan Liu, Haodong Zheng, Xinjie Chen, Chen Zhong. Sonochemical preparation of SP94 peptide-decorated pH-responsive biodegradable biopolyester nanoparticles for targeted therapy in hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5736.
Abstract 5738: Repurposing disulfiram for cancer: A drug delivery and population-based approach
Authors: Heroux Devon , Leung Ada W. , Gilabert-Oriol Roger , Bally Marcel B.
Published: March 2024

Purpose: Disulfiram was approved by the FDA for treatment of alcohol abuse in 1951, although for over 40 years there has been evidence supporting disulfiram’s use as an anti-cancer drug. Upon administration, disulfiram is hydrolyzed to form two molecules of DDC, which upon binding Cu forms Cu(DDC)2, the proposed active form against cancer. It was our goal to formulate the water-insoluble Cu(DDC)2 in liposomes to facilitate its repurposing for breast and colon cancers. In addition, we also initiated an ongoing population-based study assessing the protective and treatment effects of disulfiram with cancer.

Methods: Cu(DDC)2 liposomes were generated by the thin-film hydration method followed by extrusion, using DSPC and cholesterol (55:45 molar ratio). DDC and CuSO4 were added to the liposomes forming Cu(DDC)2, which was transported inside the liposomes. Anti-tumor activity was evaluated in tumor-bearing mice with or without competent immune systems, and immune system activation was assessed via a cancer vaccination model and the expression of markers of immunogenic cell death (ICD). A study was also initiated for cancer cases and controls in British Columbia (BC Cancer) with at least one prescription of disulfiram from 1996-2022 (PharmaNET), patients treated with immune-modulating therapies (BC Cancer), and outcome of death (Vital Statistics).

Results: Liposomes encapsulating Cu(DDC)2 had a size of 100 nm and polydispersity of 0.1, and caused a 40% reduction in tumor burden in a MDA-MB-231 xenograft model. In a syngeneic tumor model of breast cancer the response with immune-competent mice was greater than mice lacking immune function, and a cancer vaccination model and the presence of ATP, HMBG1 and surface-exposed calreticulin indicated the presence of ICD.

Conclusions: Cu(DDC)2 was formulated in liposomes facilitating its parenteral administration, and its anti-cancer activity was found to be due in part to activation of the adaptive immune system through ICD. A case-control study is currently being employed to examine the clinical potential of disulfiram, as a protectant and as an adjuvant with immune-activating therapies such as checkpoint inhibitors and anthracyclines to potentially improve efficacy through induction of ICD.

Citation Format: Devon Heroux, Ada W. Leung, Roger Gilabert-Oriol, Marcel B. Bally. Repurposing disulfiram for cancer: A drug delivery and population-based approach [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5738.
Abstract 5758: Gold nanoparticles with graphene quantum dots as drug delivery platforms for anticancer applications
Authors: Suárez Fabiola M. Rosa , Morell Gerardo , Weiner Brad , Medina Nataniel , Pantoja Wenndy
Published: March 2024

Cancer is a global health challenge that has a profound impact on the lives of people worldwide, either directly affecting individuals or their loved ones. Among the various types of cancer, prostate cancer stands out as one of the most prevalent in men. Prostate cancer is primarily identified by symptoms related to urinary health. Conventional medical approaches often rely on drug-based treatments to address this form of cancer. However, like many treatments, drug therapy comes with its own set of challenges. In our research project, we propose an alternative approach for managing prostate cancer. Our innovative idea centers around utilizing nanoparticles as a means of drug delivery. Specifically, we are investigating the use of Taxol, also known as Paclitaxel, as the drug of interest. Taxol possesses a significant challenge due to its hydrophobic nature, which hinders its circulation within the bloodstream. Its solubility is extremely low, at 0.00025 mg per milliliter. To overcome this limitation, we have undertaken the synthesis and integration of AuNPs (gold nanoparticles) with GQDs (graphene quantum dots). This combination enhances the drug's hydrophilic properties, making it more effective in transportation. Our research has led us to conduct experiments on prostate cancer cells (specifically the PC3 cell line). We aim to compare the IC50 value, which represents the drug concentration required to kill 50% of the cancer cells, when using the drug alone versus when using the drug in conjunction with the nanoparticles. Taxol's IC50 value is determined to be 5.73nM. In addition to assessing the impact on cancer cells, we have also examined how the nanoparticles interact with blood, and how this interaction influences the morphology of red blood cells. Furthermore, we have characterized the system using various analytical techniques, including FTIR, NMR, Fluorescence, and UV-Vis spectroscopy. To pinpoint the accumulation sites of the drug and delivery agents, we have employed confocal microscopy on the cancer cells. Our ultimate objective is to equip the drug with the necessary components to facilitate its entry into prostate cancer cells effectively.

Citation Format: Fabiola M. Rosa Suárez, Gerardo Morell, Brad Weiner, Nataniel Medina, Wenndy Pantoja. Gold nanoparticles with graphene quantum dots as drug delivery platforms for anticancer applications [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5758.