Despite the efficacy of tyrosine kinase inhibitors (TKIs) in chronic myeloid leukemia (CML), malignant long-term hematopoietic stem cells (LT-HSC) persist as a source of relapse. However, LT-HSC are heterogenous and the most primitive, drug-resistant LT-HSC subpopulations are not well characterized. In normal hematopoiesis, self-renewal and long-term reconstitution capacity is enriched within LT-HSCs with low c-Kit expression (c-KitLow). Here, using a transgenic CML mouse model, we found that long-term engraftment and leukemogenic capacity were restricted to c-KitLow CML LT-HSC. CML LT-HSC demonstrated enhanced differentiation with expansion of mature progeny following exposure to the c-Kit ligand, stem cell factor (SCF). Conversely, SCF deletion led to depletion of normal LT-HSC but increase in c-KitLow and total CML LT-HSC with reduced generation of mature myeloid cells. CML c-KitLow LT-HSC showed reduced cell cycling, and expressed enhanced quiescence and inflammatory gene signatures. SCF administration led to enhanced depletion of CML primitive progenitors but not LT-HSC after TKI treatment. Human CML LT-HSC with low or absent c-Kit expression were markedly enriched after TKI treatment. We conclude that CML LT-HSC expressing low c-Kit levels are enriched for primitive, quiescent, drug-resistant leukemia initiating cells and represent a critical target for eliminating disease persistence.
Mansi Shah, Harish Kumar, Shaowei Qiu, Hui Li, Mason Harris, Jianbo He, Ajay Abraham, David K. Crossman, Andrew Paterson, Robert S. Welner, Ravi Bhatia
One of the least-investigated areas of brain pathology research is glycosylation, which is a critical regulator of cell surface protein structure and function. β-Galactoside α2,6-sialyltransferase (ST6GAL1) is the primary enzyme that α2,6 sialylates N-glycosylated proteins destined for the plasma membrane or secretion, thereby modulating cell signaling and behavior. We demonstrate a potentially novel, protumorigenic role for α2,6 sialylation and ST6GAL1 in the deadly brain tumor glioblastoma (GBM). GBM cells with high α2,6 sialylation exhibited increased in vitro growth and self-renewal capacity and decreased mouse survival when orthotopically injected. α2,6 Sialylation was regulated by ST6GAL1 in GBM, and ST6GAL1 was elevated in brain tumor-initiating cells (BTICs). Knockdown of ST6GAL1 in BTICs decreased in vitro growth, self-renewal capacity, and tumorigenic potential. ST6GAL1 regulates levels of the known BTIC regulators PDGF Receptor β (PDGFRB), Activated Leukocyte Cell Adhesion Molecule, and Neuropilin, which were confirmed to bind to a lectin-recognizing α2,6 sialic acid. Loss of ST6GAL1 was confirmed to decrease PDGFRB α2,6 sialylation, total protein levels, and the induction of phosphorylation by PDGF-BB. Thus, ST6GAL1-mediated α2,6 sialylation of a select subset of cell surface receptors, including PDGFRB, increases GBM growth.
Sajina GC, Kaysaw Tuy, Lucas Rickenbacker, Robert Jones, Asmi Chakraborty, C. Ryan Miller, Elizabeth A. Beierle, Vidya Sagar Hanumanthu, Anh N. Tran, James A. Mobley, Susan L. Bellis, Anita B. Hjelmeland
Muscle weakness and wasting are defining features of cancer-induced cachexia. Mitochondrial stress occurs before atrophy in certain muscles, but the possibility of heterogeneous responses between muscles and across time remains unclear. Using mice inoculated with Colon-26 (C26) cancer, we demonstrate that specific force production was reduced in quadriceps and diaphragm at 2 weeks in the absence of atrophy. At this time, pyruvate-supported mitochondrial respiration was lower in quadriceps while mitochondrial H2O2 emission was elevated in diaphragm. By 4 weeks, atrophy occurred in both muscles, but specific force production increased to control levels in quadriceps such that reductions in absolute force were due entirely to atrophy. Specific force production remained reduced in diaphragm. Mitochondrial respiration increased and H2O2 emission was unchanged in both muscles vs control while mitochondrial creatine sensitivity was reduced in quadriceps. These findings indicate muscle weakness precedes atrophy and is linked to heterogeneous mitochondrial alterations that could involve adaptive responses to metabolic stress. Eventual muscle-specific restorations in force and bioenergetics highlight how the effects of cancer on one muscle do not predict the response in another muscle. Exploring heterogeneous responses of muscle to cancer may reveal new mechanisms underlying distinct sensitivities, or resistance, to cancer cachexia.
Luca J. Delfinis, Catherine A. Bellissimo, Shivam Gandhi, Sara N. DiBenedetto, Madison C. Garibotti, Arshdeep K. Thuhan, Stavroula Tsitkanou, Megan E. Rosa-Caldwell, Fasih A. Rahman, Arthur J. Cheng, Michael P. Wiggs, Uwe Schlattner, Joe Quadrilatero, Nicholas P. Greene, Christopher G.R. Perry
Oncogenic FOXO1 gene fusions drive a subset of rhabdomyosarcoma (RMS) with poor survival and to date these cancer drivers are therapeutically intractable. To identify new therapies for this disease, we undertook an isogenic CRISPR-interference screen to define PAX3-FOXO1 specific genetic dependencies and identified genes in the GATOR2 complex. GATOR2 loss in RMS abrogated amino acid-induced lysosomal localization of mTORC1 and consequent downstream signaling, slowing G1-S cell cycle transition. In vivo suppression of GATOR2 impaired the growth of tumor xenografts and favored the outgrowth of cells lacking PAX3-FOXO1. Loss of a subset of GATOR2 members can be compensated by direct genetic activation of mTORC1. RAS mutations are also sufficient to decouple mTORC1 activation from GATOR2, and indeed fusion negative RMS harboring such mutations exhibit amino acid-independent mTORC1 activity. A bi-steric, mTORC1-selective small molecule induced tumor regressions in fusion positive patient-derived tumor xenografts. These findings highlight a vulnerability in FOXO1 fusion positive RMS and provide rationale for the clinical evaluation of bi-steric mTORC1 inhibitors, currently in phase 1 testing, to treat this disease. Isogenic genetic screens can thus identify potentially exploitable vulnerabilities in fusion driven pediatric cancers which otherwise remain mostly undruggable.
Jacqueline Morales, David V. Allegakoen, José A. Garcia, Kristen Kwong, Pushpendra K. Sahu, Drew A. Fajardo, Yue Pan, Max A. Horlbeck, Jonathan S. Weissman, W. Clay Gustafson, Trever G. Bivona, Amit J. Sabnis
Peritoneal metastases are associated with a low response rate to immune checkpoint blockade (ICB) therapy. The numbers of peritoneal resident macrophages (PRMs) are reversely correlated with the response rate to ICB therapy. We have previously shown that TLR9 in fibroblastic reticular cells (FRCs) plays a critical role in regulating peritoneal immune cell recruitment. However, the role of TLR9 in FRCs in regulating PRMs is unclear. Here, we demonstrated that the class A TLR9 agonist, ODN1585, markedly enhanced the efficacy of anti–PD-1 therapy in mouse models of colorectal peritoneal metastases. ODN1585 injected i.p. reduced the numbers of Tim4+ PRMs and enhanced CD8+ T cell antitumor immunity. Mechanistically, treatment of ODN1585 suppressed the expression of genes required for retinoid metabolism in FRCs, and this was associated with reduced expression of the PRM lineage–defining transcription factor GATA6. Selective deletion of TLR9 in FRCs diminished the benefit of ODN1585 in anti–PD-1 therapy in reducing peritoneal metastases. The crosstalk between PRMs and FRCs may be utilized to develop new strategies to improve the efficacy of ICB therapy for peritoneal metastases.
Ting Jiang, Hongji Zhang, Yiming Li, Preethi Jayakumar, Hong Liao, Hai Huang, Timothy R. Billiar, Meihong Deng
Docetaxel (DTX) combined with cisplatin and 5-FU has been used as induction chemotherapy for head and neck squamous cell carcinoma (HNSCC). However, the development of acquired resistance remains a major obstacle to treatment response. Tumor-associated macrophages are associated with chemotherapeutic resistance. In the present study, increased infiltration of macrophages into the tumor microenvironment was significantly associated with shorter overall survival and increased resistance to chemotherapeutic drugs, particularly DTX in HNSCC patients. Macrophage co-culture induced expression of intercellular adhesion molecule 1 (ICAM1), which promotes stemness and the formation of polyploid giant cancer cells, thereby reducing the efficacy of DTX. Both genetic silencing and pharmacological inhibition of ICAM1 sensitized HNSCC to DTX. Macrophage secretion of IL-1β was found to induce tumor expression of ICAM1. IL-1β neutralization and IL-1 receptor blockade reversed DTX resistance induced by macrophage co-culture. IL-1β activated superoxide dismutase 2 and inhibited catalase, thereby modulating intracellular levels of reactive oxygen species (ROS) and inducing ICAM1 expression. Arsenic trioxide (ATO) reduced macrophage infiltration into the TME and impaired IL-1β secretion by macrophages. The combinatorial use of ATO enhanced the in vivo efficacy of DTX in a mouse model, which may provide a revolutionary approach to overcoming acquired therapeutic resistance in HNSCC.
Ching-Yun Hsieh, Ching-Chan Lin, Yu-Wen Huang, Jong-Hang Chen, Yung-An Tsou, Ling-Chu Chang, Chi-Chen Fan, Chen-Yuan Lin, Wei-Chao Chang
BACKGROUND. A patient-derived organoid (PDO) platform may serve as a promising tool for translational cancer research. In this study, we evaluated PDO’s ability to predict clinical response to gastrointestinal (GI) cancers. METHODS. We generated PDOs from primary and metastatic lesions of patients with GI cancers, including pancreatic ductal adenocarcinoma, colorectal adenocarcinoma, and cholangiocarcinoma. We compared PDO response with the observed clinical response for donor patients to the same treatments. RESULTS. We reported an approximately 80% concordance rate between PDO and donor tumor response. Importantly, we found a profound influence of culture media on PDO phenotype, where we showed significant difference in response to standard of care chemotherapies, distinct morphologies, and transcriptomes between media within the same PDOs cultures. CONCLUSION. While we demonstrate a high concordance rate between donor tumor and PDO, these studies also showed the important role of culture media when using PDOs to inform treatment selection and predict response across a spectrum of GI cancers. TRIAL REGISTRATION. Not applicable. FUNDING. This work was supported by the Joan F. & Richard A. Abdoo Family Fund in Colorectal Cancer Research, CA265050, GI Cancer program of the Mayo Clinic Cancer Center, Mayo Clinic SPORE in Pancreatic Cancer, Center of Individualized Medicine (Mayo Clinic), Department of Laboratory Medicine and Pathology (Mayo Clinic), Incyte Pharmaceuticals and Mayo Clinic Hepatobiliary SPORE, a University of Minnesota-Mayo Clinic Partnership grant, and the Early Therapeutic program (Department of Oncology, Mayo Clinic).
Tara L. Hogenson, Hao Xie, William J. Phillips, Merih D. Toruner, Jenny J. Li, Isaac P. Horn, Devin J. Kennedy, Luciana L. Almada, David L. Marks, Ryan M. Carr, Murat Toruner, Ashley N. Sigafoos, Amanda N. Koenig-Kappes, Rachel L.O. Olson, Ezequiel J. Tolosa, Cheng Zhang, Hu Li, Jason D. Doles, Jonathan Bleeker, Michael T. Barrett, James H. Boyum, Benjamin R. Kipp, Amit Mahipal, Joleen M. Hubbard, Temperance J. Scheffler Hanson, Gloria M. Petersen, Surendra Dasari, Ann L. Oberg, Mark J. Truty, Rondell P. Graham, Michael J. Levy, Mojun Zhu, Daniel D. Billadeau, Alex A. Adjei, Nelson Dusetti, Juan L. Iovanna, Tanios S. Bekaii-Saab, Wen Wee Ma, Martin E. Fernandez-Zapico
Pancreatic ductal adenocarcinoma (PDA) remains resistant to immune therapies, largely due to robustly fibrotic and immunosuppressive tumor microenvironments. It has been postulated that excessive accumulation of immunosuppressive myeloid cells influences immunotherapy resistance and recent studies targeting macrophages in combination with checkpoint blockade have demonstrated promising preclinical results. Yet, our understanding of tumor-associated macrophage (TAM) function, complexity, and diversity in PDA remains limited. Here, analysis reveals significant macrophage heterogeneity, with bone marrow-derived monocytes serving as the primary source for immunosuppressive TAMs. These cells also serve as a primary source of TNF-α, which suppresses expression of the alarmin IL33 in carcinoma cells. Deletion of Ccr2 in genetically engineered mice decreases monocyte recruitment resulting in profoundly decreased TNF-α and increased IL33 expression, decreased metastasis, and increased survival. Moreover, intervention studies targeting CCR2 with a new orthosteric inhibitor (CCX598) renders PDA susceptible to checkpoint blockade resulting in reduced metastatic burden and increased survival. Our data indicate that this shift in anti-tumor immunity is influenced by increased levels of IL-33, which increases dendritic cell and cytotoxic T cell activity. These data demonstrate that interventions to disrupt infiltration of immunosuppressive macrophages, or their signaling, have the potential to overcome barriers to effective immunotherapeutics for PDA.
Ajay Dixit, Aaron L. Sarver, Jon Zettervall, Huocong Huang, Kexin Zheng, Rolf A. Brekken, Paolo Provenzano
The DNA methyltransferase inhibitor decitabine has classically been used to reactivate silenced genes and as a pre-treatment for anti-cancer therapies. In a new variation of this idea, this study explores the concept of adding low-dose decitabine following administration of chemotherapy to bolster therapeutic efficacy. We find that addition of decitabine following treatment with the chemotherapy gemcitabine improves survival and slows tumor growth in a mouse model of high-grade sarcoma. Unlike prior studies in epithelial tumor models, low-dose decitabine did not induce a robust anti-tumor T cell response in sarcoma. Furthermore, low-dose decitabine synergizes with gemcitabine independently of the immune system. Mechanistic analyses demonstrate that the combination therapy induces bi-phasic cell cycle arrest and apoptosis. Therapeutic efficacy was found to be sequence dependent, with gemcitabine priming cells for treatment with decitabine through inhibition of ribonucleotide reductase. This study identifies a unique application of low-dose decitabine to augment the cytotoxic effects of conventional chemotherapy in an immune-independent manner. The concepts explored in this study represent a promising new paradigm for cancer treatment by augmenting chemotherapy through addition of low-dose decitabine to increase tolerability and improve patient response. These findings have widespread implications for the treatment of sarcomas and other aggressive malignancies.
Wade R. Gutierrez, Amanda Scherer, Jeffrey D. Rytlewski, Emily A. Laverty, Alexa P. Sheehan, Gavin R. McGivney, Qierra R. Brockman, Vickie Knepper-Adrian, Grace A. Roughton, Dawn E. Quelle, David J. Gordon, Varun Monga, Rebecca D. Dodd
Mass cytometry, or cytometry by TOF (CyTOF), provides a robust means of determining protein-level measurements of more than 40 markers simultaneously. While the functional states of immune cells occur along continuous phenotypic transitions, cytometric studies surveying cell phenotypes often rely on static metrics, such as discrete cell-type abundances, based on canonical markers and/or restrictive gating strategies. To overcome this limitation, we applied single-cell trajectory inference and nonnegative matrix factorization methods to CyTOF data to trace the dynamics of T cell states. In the setting of cancer immunotherapy, we showed that patient-specific summaries of continuous phenotypic shifts in T cells could be inferred from peripheral blood–derived CyTOF mass cytometry data. We further illustrated that transfer learning enabled these T cell continuous metrics to be used to estimate patient-specific cell states in new sample cohorts from a reference patient data set. Our work establishes the utility of continuous metrics for CyTOF analysis as tools for translational discovery.
Dimitrios N. Sidiropoulos, Genevieve L. Stein-O’Brien, Ludmila Danilova, Nicole E. Gross, Soren Charmsaz, Stephanie Xavier, James Leatherman, Hao Wang, Mark Yarchoan, Elizabeth M. Jaffee, Elana J. Fertig, Won Jin Ho
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