Molecular Cancer Therapeutics最新文献

{"title":"Abstract A008: Pre-diabetic D-glucose exposure promotes EOC progression and cisplatin resistance: Role of BAD associated pathway and potential therapeutic strategy","authors":"Jing Huang, Xi Zhang, Peng Huang, Basappa Basappa, Tao Zhu, P. Lobie, Vijay Pandey","doi":"10.1158/1538-8514.synthleth24-a008","DOIUrl":"https://doi.org/10.1158/1538-8514.synthleth24-a008","url":null,"abstract":"\u0000 Prediabetes denotes a condition when blood sugar levels exceed normal thresholds (>7mmol) but have not reached the diagnostic criteria for type 2 diabetes (<11mmol). It positively correlates with diminished progression-free survival and overall survival among women with epithelial ovarian cancer (EOC). This suggests a potential metabolic state associated with prediabetes that may facilitate tumor survival and progression. Moreover, prediabetes is also associated with an increased risk of recurrence and poorer survival outcomes of EOC patients, possibly promoting tumor aggressiveness and resistance to treatment, although the precise mechanisms remain unclear and warrant additional investigation. In this study, we aimed to explore whether prediabetic D-glucose levels accelerate EOC progression and elucidate underlying mechanisms. We also aimed to propose a viable and effective therapy strategy for EOC progression. Various in vitro and ex vivo oncogenic assays were used to assess the effects of prediabetic levels of D-glucose in EOC cells. It was found to stimulate oncogenic phenotypes in EOC cells in a dose-dependent manner. EOC cells exposed to prediabetic levels of D-glucose (8mM) exhibited increased cell survival, enhanced foci formation on monolayer, growth in soft agar, spheroid formation capacity in 3D Matrigel (ex-vivo culture), increased migration and invasion, and resistance to cisplatin compared to those exposed to lower D-glucose doses (4mM). Exposure to 8mM D-glucose led to metabolic alterations associated with cisplatin resistance, including increased D-glucose consumption, elevated ATP production, increased thermogenesis, enhanced glycolytic capacity, and augmented mitochondrial activity. RNA sequencing analysis showed the BCL-2-associated death promoter (BAD) pathway positively correlates with metabolic alterations of EOC cells in 8mM. Prediabetic levels of D-glucose upregulated phosphorylation of BAD at serine (S) 99 residue along with key metabolic enzymes such as ALDH1A1, HK2, PFKP, G6PD, and LDHA. Inhibition of glycolysis with 2-deoxy-D-glucose (2-DG) attenuated 8mM D-glucose effects. Furthermore, forced expression of phosphorylated BADS99 increased oncogenic phenotypes of EOC. The elevated activities of metabolic enzymes associated with BADS99 phosphorylation were observed in EOCs, while this effect was diminished with dephosphorylated BADS99. High-throughput screening identified a combination therapy involving a BADS99 phosphorylation inhibitor and HDAC inhibitors demonstrated higher synergy to stimulate apoptosis in EOC cells. The combined BADS99-HDAC inhibition synergistically enhanced the efficacy of HDAC inhibitors, significantly reducing their IC50 values. It impaired cell survival, viability, anchorage-independent growth, mitochondrial activity, energy production, growth in 3D Matrigel and successfully overcome cisplatin resistance of EOC cell lines and a patient-derived cell line (AFC). This synergistic therapeutic app","PeriodicalId":18791,"journal":{"name":"Molecular Cancer Therapeutics","volume":null,"pages":null},"PeriodicalIF":5.7,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141365313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abstract IA021: Environmental challenge rewires functional connections among human genes","authors":"Luke Gilbert, Ben Herken","doi":"10.1158/1538-8514.synthleth24-ia021","DOIUrl":"https://doi.org/10.1158/1538-8514.synthleth24-ia021","url":null,"abstract":"\u0000 A fundamental question in biology is how a limited number of genes combinatorially govern cellular responses to environmental changes. While the prevailing hypothesis is that relationships between genes, processes, and ontologies could be plastic to achieve this adaptability, quantitatively comparing human gene functional connections between specific environmental conditions at scale is very challenging. Therefore, it remains unclear whether and how human genetic interaction networks are rewired in response to changing environmental conditions. Here, we developed a framework for mapping context-specific genetic interactions, enabling us to measure the plasticity of human genetic architecture upon environmental challenge for ∼250,000 interactions, using cell cycle interruption, genotoxic perturbation, and nutrient deprivation as archetypes. We discover large-scale rewiring of human gene relationships across conditions, highlighted by dramatic shifts in the functional connections of epigenetic regulators (TIP60), cell cycle regulators (PP2A), and glycolysis metabolism. Our study demonstrates that upon environmental perturbation, intra-complex genetic rewiring is rare while inter-complex rewiring is common, suggesting a modular and flexible evolutionary genetic strategy that allows a limited number of human genes to enable adaptation to a large number of environmental conditions.\u0000 Citation Format: Luke Gilbert, Ben Herken. Environmental challenge rewires functional connections among human genes [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Expanding and Translating Cancer Synthetic Vulnerabilities; 2024 Jun 10-13; Montreal, Quebec, Canada. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(6 Suppl):Abstract nr IA021.","PeriodicalId":18791,"journal":{"name":"Molecular Cancer Therapeutics","volume":null,"pages":null},"PeriodicalIF":5.7,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141363338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MYTX-011: A pH-Dependent Anti-c-MET Antibody-Drug Conjugate Designed for Enhanced Payload Delivery to c-MET-Expressing Tumor Cells.","authors":"Nimish Gera, Kyle M Fitzgerald, Vijay Ramesh, Purvi Patel, Deepak Kanojia, Federico Colombo, Lena Kien, Simon Aoyama, Lihui Xu, Jussekia Jean, Amit M Deshpande, William C Comb, Thomas Chittenden, Brian P Fiske","doi":"10.1158/1535-7163.MCT-23-0784","DOIUrl":"https://doi.org/10.1158/1535-7163.MCT-23-0784","url":null,"abstract":"<p><p>Advances in linker payload technology and target selection have been at the forefront of recent improvements in antibody-drug conjugate (ADC) design, leading to several approvals over the last decade. In contrast, the potential of novel ADC technologies to enhance payload delivery to tumors is relatively underexplored. We demonstrate that incorporation of pH-dependent binding in the antibody component of a c-mesenchymal-epithelial transition (MET)-targeting ADC (MYTX-011) can overcome the requirement for high c-MET expression on tumors, an innovation that has the potential to benefit a broader population of patients with lower c-MET levels. MYTX-011 drove fourfold higher net internalization than a non-pH-engineered parent ADC in non-small cell lung cancer (NSCLC) cells and showed increased cytotoxicity against a panel of cell lines from various solid tumors. A single dose of MYTX-011 showed at least threefold higher efficacy than a benchmark ADC in mouse xenograft models of NSCLC ranging from low to high c-MET expression. Moreover, MYTX-011 showed improved pharmacokinetics over parent and benchmark ADCs. In a repeat dose toxicology study, MYTX-011 exhibited a toxicity profile similar to other monomethyl auristatin E-based ADCs. These results highlight the potential of MYTX-011 for treating a broader range of patients with NSCLC with c-MET expression than other c-MET-targeting ADCs. A first-in-human study is ongoing to determine the safety, tolerability, and preliminary efficacy of MYTX-011 in patients with NSCLC (NCT05652868).</p>","PeriodicalId":18791,"journal":{"name":"Molecular Cancer Therapeutics","volume":null,"pages":null},"PeriodicalIF":5.7,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141296413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abstract IA002: Overcoming the K-Ras inhibitor resistant cell state in PDAC with molecular glues.","authors":"F. Ferguson","doi":"10.1158/1538-8514.synthleth24-ia002","DOIUrl":"https://doi.org/10.1158/1538-8514.synthleth24-ia002","url":null,"abstract":"\u0000 K-Ras inhibitor resistance in PDAC is associated with metabolic reprogramming towards a high OXPHOS state. Existing inhibitors of components of the electron transport chain have on-target toxicities that limit their use in the clinic, highlighting an opportunity to develop mechanistically orthogonal approaches. In this talk, I discuss our development of molecular glue degraders that target metabolic vulnerabilities in K-Ras inhibitor resistant PDAC.\u0000 Citation Format: Fleur M. Ferguson. Overcoming the K-Ras inhibitor resistant cell state in PDAC with molecular glues [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Expanding and Translating Cancer Synthetic Vulnerabilities; 2024 Jun 10-13; Montreal, Quebec, Canada. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(6 Suppl):Abstract nr IA002.","PeriodicalId":18791,"journal":{"name":"Molecular Cancer Therapeutics","volume":null,"pages":null},"PeriodicalIF":5.7,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141362795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abstract A014: Inhibiting eIF4E phosphorylation sensitizes triple-negative breast cancer to CDK4/6 inhibition","authors":"Qiyun Deng, Mehdi Amiri, Anastasija Ana Piric, Yasaman Bagherian, Zilan Li, Sidong Huang, Michael Pollak, Nahum Sonenberg","doi":"10.1158/1538-8514.synthleth24-a014","DOIUrl":"https://doi.org/10.1158/1538-8514.synthleth24-a014","url":null,"abstract":"\u0000 This abstract is being presented as a short talk in the scientific program. A full abstract is printed in the Proffered Abstracts section (PR011) of the Conference Program/Proceedings.\u0000 Citation Format: Qiyun Deng, Mehdi Amiri, Anastasija Ana Piric, Yasaman Bagherian, Zilan Li, Sidong Huang, Michael Pollak, Nahum Sonenberg. Inhibiting eIF4E phosphorylation sensitizes triple-negative breast cancer to CDK4/6 inhibition [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Expanding and Translating Cancer Synthetic Vulnerabilities; 2024 Jun 10-13; Montreal, Quebec, Canada. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(6 Suppl):Abstract nr A014.","PeriodicalId":18791,"journal":{"name":"Molecular Cancer Therapeutics","volume":null,"pages":null},"PeriodicalIF":5.7,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141365525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abstract PR005: CX-5461 sensitizes DNA damage repair-proficient castrate-resistant prostate cancer to PARP inhibition","authors":"M. Lawrence, L. Porter, Nicholas K Choo, E. Sanij, R. Taylor, Richard B. Pearson, Kaylene Simpson, Ross D. Hannan, S. Sandhu, Luc Furic","doi":"10.1158/1538-8514.synthleth24-pr005","DOIUrl":"https://doi.org/10.1158/1538-8514.synthleth24-pr005","url":null,"abstract":"\u0000 Monotherapy with PARP inhibitors is effective for the subset of castrate-resistant prostate cancer (CRPC) with defects in homologous recombination (HR) DNA repair. New treatments are required for the remaining tumors, and an emerging strategy is to combine PARP inhibitors with other therapies that induce DNA damage. Here we tested whether PARP inhibitors are effective for HR-proficient CRPC, including androgen receptor (AR)-null tumors, when used in combination with CX-5461, a small molecule that inhibits RNA polymerase I transcription and activates the DNA damage response, and has antitumor activity in early phase I trials. The combination of CX-5461 and talazoparib significantly decreased in vivo growth of patient-derived xenografts of HR-proficient CRPC, including AR-positive, AR-null, and neuroendocrine tumors. CX-5461 and talazoparib synergistically inhibited the growth of organoids and cell lines, and significantly increased the levels of DNA damage. Decreased tumor growth after combination therapy was maintained for 2 weeks without treatment, significantly increasing host survival. Therefore, combination treatment with CX-5461 and talazoparib is effective for HR-proficient tumors that are not suitable for monotherapy with PARP inhibitors, including AR-null CRPC. This expands the spectrum of CRPC that is sensitive to PARP inhibition. We have recently initiated a clinical trial combining CX-5461 with talazoparib in mCRPC patients (REPAIR trial, NCT05425862) to explore this combination in both HR proficient and deficient settings.\u0000 Citation Format: Mitchell G. Lawrence, Laura H. Porter, Nicholas Choo, Elaine Sanij, Renea Taylor, Richard Pearson, Kaylene J. Simpson, Ross D. Hannan, Shahneen Sandhu, Luc Furic. CX-5461 sensitizes DNA damage repair-proficient castrate-resistant prostate cancer to PARP inhibition [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Expanding and Translating Cancer Synthetic Vulnerabilities; 2024 Jun 10-13; Montreal, Quebec, Canada. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(6 Suppl):Abstract nr PR005.","PeriodicalId":18791,"journal":{"name":"Molecular Cancer Therapeutics","volume":null,"pages":null},"PeriodicalIF":5.7,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141366317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abstract IA009: Single strand DNA GAP accumulation as a functional biomarker for DNA Repair Inhibitors","authors":"Alan D. D'Andrea","doi":"10.1158/1538-8514.synthleth24-ia009","DOIUrl":"https://doi.org/10.1158/1538-8514.synthleth24-ia009","url":null,"abstract":"\u0000 Deficiency of homologous recombination (HR)-mediated DNA repair occurs through genetic or epigenetic inactivation of the BRCA1 and BRCA2 (BRCA1/2) genes. HR-deficiency also provides unique opportunities for targeted therapy, through the mechanism of synthetic lethality, as exemplified by the hypersensitivity of BRCA1/2-mutated tumors to PARP inhibitors (PARPi). To date, several PARP inhibitors have been approved for clinical use. The promising clinical response of patients with germline BRCA1/2-mutations prompted the use of PARPi for patients with somatic BRCA1/2 mutations as well. In addition, these results extended the use of PARPi for various types of ovarian, breast, pancreatic, and prostate tumors with HR defects. PARPi resistance is emerging as the major obstacle to clinical effectiveness in patients with HR-deficient tumors. PARPi resistance results from several independent mechanisms, leading to the restoration of Homologous Recombination and/or Replication Fork stabilization. The absence of alternative options for patients with tumors with innate or acquired resistance underlines the urgency to develop additional therapeutics. More recent studies have identified new synthetic lethal opportunities for BRCA1/2 deficient tumors. Knockout of the genes for POLQ (DNA polymerase theta) or for USP1 (Ubiquitin Specific Protease 1) results in killing of these tumors, and inhibitors of these enzymes are emerging as promising agents for HR-deficient tumors. POLQ and USP1 expression is particularly high in subtypes of breast and ovarian tumors with defects in HR. As a result, POLQi or USP1i in HR-deficient tumors induces cell death. POLQi or USP1i can synergize with PARPi in killing HR-deficient tumors or PARPi-resistant tumors. BRCA1/2 deficient tumors have an increase in single strand DNA gaps (ssGAPs) near replication forks. Treatment with PARPi results in an increase in the size and number for these ssGAPs, ultimately leading to DSBs and cell death. Interestingly, PARPi resistance results, at least in part, from the ability of resistant cells to close the ssGAPs through enhanced POLQ and USP1 activity, thereby providing a rationale for the combination of PARP1, POLQi, and USP1 in HR-deficient cancers. USP1 inhibition was synergistic with PARP and POLQ inhibition in BRCA1-mutant cells, with enhanced ssDNA gap accumulation. Moreover, this synergy was observed in a set of patient-derived ovarian cancer organoids (PDOs), thus confirming the sensitivity of BRCA1-deficient cells to inhibition by these agents. The accumulation of ssDNA gaps after treatment with a USP1i, PARP, or POLQi correlated with the sensitivity to these drugs in all models tested. Ovarian cancer PDOs provide a powerful tool for detecting drug synergy and for rapid in vitro sensitivity testing. The detection of ssDNA gap accumulation may be a useful predictive biomarker for response to DNA Repair inhibitors as monotherapy or in combination in ongoing clinical trials.\u0000 Citation For","PeriodicalId":18791,"journal":{"name":"Molecular Cancer Therapeutics","volume":null,"pages":null},"PeriodicalIF":5.7,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141365523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abstract A015: Exploiting endogenous replication stress with a novel targeted therapy in Ewing sarcoma","authors":"E. Isenhart, Ajay Gupta, Bryan M. Gillard, Kristopher Attwood, Joyce Ohm","doi":"10.1158/1538-8514.synthleth24-a015","DOIUrl":"https://doi.org/10.1158/1538-8514.synthleth24-a015","url":null,"abstract":"\u0000 Ewing sarcoma (EwS) is a rare and aggressive disease that typically affects the bone of children and young adults. Although there are moderate 5-year survival rates for primary disease, there is a high rate of recurrence and a lack of targeted therapies in this setting. Furthermore, pediatric exposure to chemotherapies leads to an increased risk of long-term complications, including secondary cancers, cardiomyopathy, and infertility. Therefore, there is a desperate need for targeted therapies which improve therapeutic outcomes and reduce exposure to chemotherapy in these patients. Like many pediatric cancers, EwS has a low mutational burden. Instead, it is driven by chromosomal translocation between a FET family member, EWSR1, and an ETS family member, usually FLI1. The EWSR1-FLI1 fusion protein acts as an aberrant and oncogenic transcription factor, disrupting cell cycle control, cell migration, and proliferation. ETS family members in these fusions retain their ability to bind to the SWI/SNF chromatin remodeling complex, further dysregulating DNA methylation and gene expression. Although targeting of the EWSR1 fusion has not yet been successful, these elevated levels of replication stress (RS) present a unique element of vulnerability within the cell. To this end, our lab has previously identified replication stress response (RSR) inhibitors, DDKi and WEE1i, which can be utilized to exploit the characteristic ability of EwS to maintain high levels of replication stress (RS) and push EwS cells into mitotic catastrophe in vitro. Here, we evaluate the efficacy of the replication stress response inhibitors (RSRi) TAK931 (DDKi) and MK1775 (WEE1i) with chemotherapy regimens commonly utilized in the relapsed/refractory setting in vivo. Using cell line derived xenografts in NSG mice, we show that DDKi and WEE1i with irinotecan limits tumor growth significantly more than existing therapy (temozolomide + irinotecan). Dosing schedules are optimized through dosing de-escalation and alternative-day dosing strategies. We further demonstrate the ability of our RSRi combination to effectively limit tumor growth over time in vivo even when irinotecan dosage is decreased. We go on to investigate the RSRi combination in the presence of ultra-low dose irinotecan. Finally, we utilize reduced representation bisulfite sequencing to examine the epigenetic effects of these treatment regimens. Overall, the exploitation of high endogenous replication stress in EwS by targeted RSRi presents a promising potential therapeutic option for this pediatric patient population.\u0000 Citation Format: Emily Isenhart, Ajay Gupta, Bryan Gillard, Kristopher Attwood, Joyce Ohm. Exploiting endogenous replication stress with a novel targeted therapy in Ewing sarcoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Expanding and Translating Cancer Synthetic Vulnerabilities; 2024 Jun 10-13; Montreal, Quebec, Canada. Philadelphia (PA): AACR; Mol Cancer Ther 2024;2","PeriodicalId":18791,"journal":{"name":"Molecular Cancer Therapeutics","volume":null,"pages":null},"PeriodicalIF":5.7,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141365335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abstract IA001: Exploiting pathway activation as a new form of synthetic lethality","authors":"William R. Sellers","doi":"10.1158/1538-8514.synthleth24-ia001","DOIUrl":"https://doi.org/10.1158/1538-8514.synthleth24-ia001","url":null,"abstract":"\u0000 Targeting activated oncogenes is an effective treatment strategy across many cancers now including therapeutics targeting KRAS. Genetic events including DNA damage deficiencies and tumor suppressor mutations require alternative strategies and the concept of synthetic lethality has been applied to these alterations. PARPi inhibitors were a founding member of this class of therapeutics demonstrating enhanced activity in the setting of BRCA-deficiency. By applying large-scale loss-of-function approaches1 we and other discovered the vulnerability to PRMT5 and WRN inhibition imposed by co-deletions of MTAP and CDKN2A, and the MSI+ genotype respectively2,3. Such inhibitors are now in clinical trials. To explore the potential for paralogous genes to act as synthetic lethal gene pairs we enacted dual knockout screens. These early efforts led to the discovery of DUSP4/6 paralog dependence in the setting of BRAF and NRAS mutations in melanoma4. Intriguingly the loss of DUSP4/6 impaired cancer cell viability through the increased activation of ERK highlighting the susceptibility of cancers to pathway activation in addition to the more common sensitivity to pathway inhibition. This inappropriate activation of the ERK signaling pathway, the conflict between EGFR and KRAS activation, the synthetic lethality enacted by TRIM8 knockouts, and the effects of AR agonists on prostate cancer viability, points to a wider than expected vulnerability of cancer to inappropriate gene activation. To systematically identify context-specific gene activation induced lethalities in cancer, we developed methods for enacting gain-of-function perturbations across ∼500 barcoded cancer cell lines. With this approach, we queried the pan-cancer vulnerability landscape upon activating 10 key cancer pathway revealing activation dependencies in MAPK and PI3K pathways. Notably, we discovered novel pathway hyperactivation dependencies in subsets of APC-mutant colorectal cancers where further activation of the WNT pathway by APC knockdown or direct β-catenin overexpression led to robust antitumor effects in xenograft and patient-derived organoid models. These latter discoveries paradoxically point to the residual activity of the APC ubiquitin-ligase complex as a target in APC-mutant CRC5. 1. McDonald, E. R., 3rd et al. Project DRIVE: A Compendium of Cancer Dependencies and Synthetic Lethal Relationships Uncovered by Large-Scale, Deep RNAi Screening. Cell 170, 577-592.e10 (2017). 2. Mavrakis, K. J. et al. Disordered methionine metabolism in MTAP/CDKN2A-deleted cancers leads to dependence on PRMT5. Science 351, 1208–1213 (2016). 3. Chan, E. M. et al. WRN helicase is a synthetic lethal target in microsatellite unstable cancers. Nature 568, 551–556 (2019). 4. Ito, T. et al. Paralog knockout profiling identifies DUSP4 and DUSP6 as a digenic dependence in MAPK pathway-driven cancers. Nat. Genet. 53, 1664–1672 (2021). 5. Chang, L. et al. Systematic profiling of conditional pathway activation ide","PeriodicalId":18791,"journal":{"name":"Molecular Cancer Therapeutics","volume":null,"pages":null},"PeriodicalIF":5.7,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141366276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abstract PR007: Delineating functional drivers of esophageal adenocarcinoma to identify synthetic lethal interactions","authors":"Julia V. Milne, Ebtihal Mustafa, Kenji Fujihara, Eric P. Kusnadi, A. Trigos, N. Thio, Maree Pechlivanis, C. Cabalag, Twishi Gulati, Kaylene Simpson, C. Duong, Luc Furic, Wayne Phillips, Nicholas Clemons","doi":"10.1158/1538-8514.synthleth24-pr007","DOIUrl":"https://doi.org/10.1158/1538-8514.synthleth24-pr007","url":null,"abstract":"\u0000 Application of molecular targeted therapies for esophageal adenocarcinoma (EAC) has been limited by a lack of druggable oncogenic drivers. We propose that synthetic lethal interactions may provide new opportunities for targeted therapies in EAC. We have taken an integrated multi-omics approach incorporating Perturb-Seq (CRISPR editing combined with single cell RNA sequencing) and in vivo tumorigenesis assays to perform high-throughput characterisation of >70 high-confidence EAC driver genes, and genome-wide CRISPR-Cas9 knockout screens in isogenic models of EAC tumorigenesis to identify disease relevant synthetic lethal genetic interactions. MS-based proteomics, reverse phase protein arrays, polysome profiling and bulk RNA-sequencing of isogenic models were utilised to interrogate the biology of bona fide EAC drivers and associated driver specific gene dependencies. The overall goals were to (i) enhance our understanding of EAC tumorigenesis, (ii) identify potential opportunities for therapeutic interventions targeting EAC drivers via synthetic lethal-like approaches, and (iii) reduce the complexity of genetic heterogeneity by categorising EAC drivers with similar phenotypic outcomes. Through our approach we have identified complex crosstalk between the tumor suppressor SMAD4 and regulation of mTOR signaling, with specific downstream effects on translational reprogramming in EAC. Mutation or loss of SMAD4 occurs in up to 20% of EAC, but not pre-malignant tissue (Barrett’s esophagus), and is sufficient to promote transformation of pre-malignant cells in our in vivo tumorigenesis model. In this model, xenotransplanted SMAD4-deficient (via CRISPR-Cas9 knockout or shRNA knockdown) Barrett’s metaplasia cells formed invasive, metastatic tumors after a period of latency. SMAD4 deficient cells had downregulated expression of 4E-BP1, which inhibits EIF4E, the cap-dependent translation initiation factor. This was accompanied by increased mTOR activity, including phosphorylation and inactivation of 4EBP1. Moreover, we found that SMAD4-deficient cells preferentially upregulate cap-dependent translation at the expense of IRES mediated translation. Furthermore, perturbation of additional negative regulators of mTOR signaling in combination with SMAD4 knockout exacerbated these effects and accelerated tumorigenesis in vivo. We have extended these findings to a model of Barrett’s esophagus patient-derived organoids (PDOs) and observed increased proliferative potential of our genetically modified PDOs. Finally, analysing gene ontologies for differentially expressed genes from Perturb-seq revealed that driver-dependent transcriptional changes can be categorized into a smaller number of functional pathways allowing us to potentially consider groups of drivers as functional units. This work advances our understanding of EAC tumorigenesis, provides new mechanistic insights into SMAD4-driven transformation as well as novel potential therapeutic avenues for SMAD4-def","PeriodicalId":18791,"journal":{"name":"Molecular Cancer Therapeutics","volume":null,"pages":null},"PeriodicalIF":5.7,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141362673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}