Melissa Gray

All Publications

• Upregulation of GALNT7 in prostate cancer modifies O-glycosylation and promotes tumour growth. Oncogene Scott, E., Hodgson, K., Calle, B., Turner, H., Cheung, K., Bermudez, A., Marques, F. J., Pye, H., Yo, E. C., Islam, K., Oo, H. Z., McClurg, U. L., Wilson, L., Thomas, H., Frame, F. M., Orozco-Moreno, M., Bastian, K., Arredondo, H. M., Roustan, C., Gray, M. A., Kelly, L., Tolson, A., Mellor, E., Hysenaj, G., Goode, E. A., Garnham, R., Duxfield, A., Heavey, S., Stopka-Farooqui, U., Haider, A., Freeman, A., Singh, S., Johnston, E. W., Punwani, S., Knight, B., McCullagh, P., McGrath, J., Crundwell, M., Harries, L., Bogdan, D., Westaby, D., Fowler, G., Flohr, P., Yuan, W., Sharp, A., de Bono, J., Maitland, N. J., Wisnovsky, S., Bertozzi, C. R., Heer, R., Guerrero, R. H., Daugaard, M., Leivo, J., Whitaker, H., Pitteri, S., Wang, N., Elliott, D. J., Schumann, B., Munkley, J. 2023

  Abstract

  Prostate cancer is the most common cancer in men and it is estimated that over 350,000 men worldwide die of prostate cancer every year. There remains an unmet clinical need to improve how clinically significant prostate cancer is diagnosed and develop new treatments for advanced disease. Aberrant glycosylation is a hallmark of cancer implicated in tumour growth, metastasis, and immune evasion. One of the key drivers of aberrant glycosylation is the dysregulated expression of glycosylation enzymes within the cancer cell. Here, we demonstrate using multiple independent clinical cohorts that the glycosyltransferase enzyme GALNT7 is upregulated in prostate cancer tissue. We show GALNT7 can identify men with prostate cancer, using urine and blood samples, with improved diagnostic accuracy than serum PSA alone. We also show that GALNT7 levels remain high in progression to castrate-resistant disease, and using in vitro and in vivo models, reveal that GALNT7 promotes prostate tumour growth. Mechanistically, GALNT7 can modify O-glycosylation in prostate cancer cells and correlates with cell cycle and immune signalling pathways. Our study provides a new biomarker to aid the diagnosis of clinically significant disease and cements GALNT7-mediated O-glycosylation as an important driver of prostate cancer progression.

  View details for DOI 10.1038/s41388-023-02604-x

  View details for PubMedID 36725887

• Targeting cancer glycosylation repolarizes tumor-associated macrophages allowing effective immune checkpoint blockade. Science translational medicine Stanczak, M. A., Rodrigues Mantuano, N., Kirchhammer, N., Sanin, D. E., Jacob, F., Coelho, R., Everest-Dass, A. V., Wang, J., Trefny, M. P., Monaco, G., Bärenwaldt, A., Gray, M. A., Petrone, A., Kashyap, A. S., Glatz, K., Kasenda, B., Normington, K., Broderick, J., Peng, L., Pearce, O. M., Pearce, E. L., Bertozzi, C. R., Zippelius, A., Läubli, H. 2022; 14 (669): eabj1270

  Abstract

  Immune checkpoint blockade (ICB) has substantially improved the prognosis of patients with cancer, but the majority experiences limited benefit, supporting the need for new therapeutic approaches. Up-regulation of sialic acid-containing glycans, termed hypersialylation, is a common feature of cancer-associated glycosylation, driving disease progression and immune escape through the engagement of Siglec receptors on tumor-infiltrating immune cells. Here, we show that tumor sialylation correlates with distinct immune states and reduced survival in human cancers. The targeted removal of Siglec ligands in the tumor microenvironment, using an antibody-sialidase conjugate, enhanced antitumor immunity and halted tumor progression in several murine models. Using single-cell RNA sequencing, we revealed that desialylation repolarized tumor-associated macrophages (TAMs). We also identified Siglec-E as the main receptor for hypersialylation on TAMs. Last, we found that genetic and therapeutic desialylation, as well as loss of Siglec-E, enhanced the efficacy of ICB. Thus, therapeutic desialylation represents an immunotherapeutic approach to reshape macrophage phenotypes and augment the adaptive antitumor immune response.

  View details for DOI 10.1126/scitranslmed.abj1270

  View details for PubMedID 36322632

• Genome-Wide CRISPR screens reveal specific ligands for glycan-binding immune checkpoint receptors Wisnovsky, S., Mockl, L., Malaker, S. A., Pedram, K., Hess, G. T., Riley, N. M., Gray, M. A., Smith, B. H., Bassik, M. C., Moerner, W. E., Bertozzi, C. R. OXFORD UNIV PRESS INC. 2021: 1682-1683

  View details for Web of Science ID 000754737200022

• Genome-wide CRISPR screens reveal a specific ligand for the glycan-binding immune checkpoint receptor Siglec-7. Proceedings of the National Academy of Sciences of the United States of America Wisnovsky, S., Mockl, L., Malaker, S. A., Pedram, K., Hess, G. T., Riley, N. M., Gray, M. A., Smith, B. A., Bassik, M. C., Moerner, W. E., Bertozzi, C. R. 2021; 118 (5)

  Abstract

  Glyco-immune checkpoint receptors, molecules that inhibit immune cell activity following binding to glycosylated cell-surface antigens, are emerging as attractive targets for cancer immunotherapy. Defining biologically relevant ligands that bind and activate such receptors, however, has historically been a significant challenge. Here, we present a CRISPRi genomic screening strategy that allowed unbiased identification of the key genes required for cell-surface presentation of glycan ligands on leukemia cells that bind the glyco-immune checkpoint receptors Siglec-7 and Siglec-9. This approach revealed a selective interaction between Siglec-7 and the mucin-type glycoprotein CD43. Further work identified a specific N-terminal glycopeptide region of CD43 containing clusters of disialylated O-glycan tetrasaccharides that form specific Siglec-7 binding motifs. Knockout or blockade of CD43 in leukemia cells relieves Siglec-7-mediated inhibition of immune killing activity. This work identifies a potential target for immune checkpoint blockade therapy and represents a generalizable approach to dissection of glycan-receptor interactions in living cells.

  View details for DOI 10.1073/pnas.2015024118

  View details for PubMedID 33495350

• Targeted glycan degradation potentiates the anticancer immune response in vivo. Nature chemical biology Gray, M. A., Stanczak, M. A., Mantuano, N. R., Xiao, H., Pijnenborg, J. F., Malaker, S. A., Miller, C. L., Weidenbacher, P. A., Tanzo, J. T., Ahn, G., Woods, E. C., Laubli, H., Bertozzi, C. R. 2020

  Abstract

  Currently approved immune checkpoint inhibitor therapies targeting the PD-1 and CTLA-4 receptor pathways are powerful treatment options for certain cancers; however, most patients across cancer types still fail to respond. Consequently, there is interest in discovering and blocking alternative pathways that mediate immune suppression. One such mechanism is an upregulation of sialoglycans in malignancy, which has been recently shown to inhibit immune cell activation through multiple mechanisms and therefore represents a targetable glycoimmune checkpoint. Since these glycans are not canonically druggable, we designed an alphaHER2 antibody-sialidase conjugate that potently and selectively strips diverse sialoglycans from breast cancer cells. In syngeneic breast cancer models, desialylation enhanced immune cell infiltration and activation and prolonged the survival of mice, an effect that was dependent on expression of the Siglec-E checkpoint receptor found on tumor-infiltrating myeloid cells. Thus, antibody-sialidase conjugates represent a promising modality for glycoimmune checkpoint therapy.

  View details for DOI 10.1038/s41589-020-0622-x

  View details for PubMedID 32807964

• DNA origami protection and molecular interfacing through engineered sequence-defined peptoids. Proceedings of the National Academy of Sciences of the United States of America Wang, S., Gray, M. A., Xuan, S., Lin, Y., Byrnes, J., Nguyen, A. I., Todorova, N., Stevens, M. M., Bertozzi, C. R., Zuckermann, R. N., Gang, O. 2020

  Abstract

  DNA nanotechnology has established approaches for designing programmable and precisely controlled nanoscale architectures through specific Watson-Crick base-pairing, molecular plasticity, and intermolecular connectivity. In particular, superior control over DNA origami structures could be beneficial for biomedical applications, including biosensing, in vivo imaging, and drug and gene delivery. However, protecting DNA origami structures in complex biological fluids while preserving their structural characteristics remains a major challenge for enabling these applications. Here, we developed a class of structurally well-defined peptoids to protect DNA origamis in ionic and bioactive conditions and systematically explored the effects of peptoid architecture and sequence dependency on DNA origami stability. The applicability of this approach for drug delivery, bioimaging, and cell targeting was also demonstrated. A series of peptoids (PE1-9) with two types of architectures, termed as "brush" and "block," were built from positively charged monomers and neutral oligo-ethyleneoxy monomers, where certain designs were found to greatly enhance the stability of DNA origami. Through experimental and molecular dynamics studies, we demonstrated the role of sequence-dependent electrostatic interactions of peptoids with the DNA backbone. We showed that octahedral DNA origamis coated with peptoid (PE2) can be used as carriers for anticancer drug and protein, where the peptoid modulated the rate of drug release and prolonged protein stability against proteolytic hydrolysis. Finally, we synthesized two alkyne-modified peptoids (PE8 and PE9), conjugated with fluorophore and antibody, to make stable DNA origamis with imaging and cell-targeting capabilities. Our results demonstrate an approach toward functional and physiologically stable DNA origami for biomedical applications.

  View details for DOI 10.1073/pnas.1919749117

  View details for PubMedID 32165539

• Bump-and-Hole Engineering Identifies Specific Substrates of Glycosyltransferases in Living Cells. Molecular cell Schumann, B. n., Malaker, S. A., Wisnovsky, S. P., Debets, M. F., Agbay, A. J., Fernandez, D. n., Wagner, L. J., Lin, L. n., Li, Z. n., Choi, J. n., Fox, D. M., Peh, J. n., Gray, M. A., Pedram, K. n., Kohler, J. J., Mrksich, M. n., Bertozzi, C. R. 2020

  Abstract

  Studying posttranslational modifications classically relies on experimental strategies that oversimplify the complex biosynthetic machineries of living cells. Protein glycosylation contributes to essential biological processes, but correlating glycan structure, underlying protein, and disease-relevant biosynthetic regulation is currently elusive. Here, we engineer living cells to tag glycans with editable chemical functionalities while providing information on biosynthesis, physiological context, and glycan fine structure. We introduce a non-natural substrate biosynthetic pathway and use engineered glycosyltransferases to incorporate chemically tagged sugars into the cell surface glycome of the living cell. We apply the strategy to a particularly redundant yet disease-relevant human glycosyltransferase family, the polypeptide N-acetylgalactosaminyl transferases. This approach bestows a gain-of-chemical-functionality modification on cells, where the products of individual glycosyltransferases can be selectively characterized or manipulated to understand glycan contribution to major physiological processes.

  View details for DOI 10.1016/j.molcel.2020.03.030

  View details for PubMedID 32325029

• Engineering Orthogonal Polypeptide GalNAc-Transferase and UDP-Sugar Pairs JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Choi, J., Wagner, L. S., Timmermans, S. E., Malaker, S. A., Schumann, B., Gray, M. A., Debets, M. F., Takashima, M., Gehring, J., Bertozzi, C. R. 2019; 141 (34): 13442–53

  Abstract

  O-Linked α-N-acetylgalactosamine (O-GalNAc) glycans constitute a major part of the human glycome. They are difficult to study because of the complex interplay of 20 distinct glycosyltransferase isoenzymes that initiate this form of glycosylation, the polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts). Despite proven disease relevance, correlating the activity of individual GalNAc-Ts with biological function remains challenging due to a lack of tools to probe their substrate specificity in a complex biological environment. Here, we develop a "bump-hole" chemical reporter system for studying GalNAc-T activity in vitro. Individual GalNAc-Ts were rationally engineered to contain an enlarged active site (hole) and probed with a newly synthesized collection of 20 (bumped) uridine diphosphate N-acetylgalactosamine (UDP-GalNAc) analogs to identify enzyme-substrate pairs that retain peptide specificities but are otherwise completely orthogonal to native enzyme-substrate pairs. The approach was applicable to multiple GalNAc-T isoenzymes, including GalNAc-T1 and -T2 that prefer nonglycosylated peptide substrates and GalNAcT-10 that prefers a preglycosylated peptide substrate. A detailed investigation of enzyme kinetics and specificities revealed the robustness of the approach to faithfully report on GalNAc-T activity and paves the way for studying substrate specificities in living systems.

  View details for DOI 10.1021/jacs.9b04695

  View details for Web of Science ID 000484082700023

  View details for PubMedID 31373799

• CRISPR-Cas9 screens identify regulators of antibody-drug conjugate toxicity. Nature chemical biology Tsui, C. K., Barfield, R. M., Fischer, C. R., Morgens, D. W., Li, A., Smith, B. A., Gray, M. A., Bertozzi, C. R., Rabuka, D., Bassik, M. C. 2019

  Abstract

  Antibody-drug conjugates (ADCs) selectively deliver chemotherapeutic agents to target cells and are important cancer therapeutics. However, the mechanisms by which ADCs are internalized and activated remain unclear. Using CRISPR-Cas9 screens, we uncover many known and novel endolysosomal regulators as modulators of ADC toxicity. We identify and characterize C18ORF8/RMC1 as a regulator of ADC toxicity through its role in endosomal maturation. Through comparative analysis of screens with ADCs bearing different linkers, we show that a subset of late endolysosomal regulators selectively influence toxicity of noncleavable linker ADCs. Surprisingly, we find cleavable valine-citrulline linkers can be processed rapidly after internalization without lysosomal delivery. Lastly, we show that sialic acid depletion enhances ADC lysosomal delivery and killing in diverse cancer cell types, including with FDA (US Food and Drug Administration)-approved trastuzumab emtansine (T-DM1) in Her2-positive breast cancer cells. Together, these results reveal new regulators of endolysosomal trafficking, provide important insights for ADC design and identify candidate combination therapy targets.

  View details for DOI 10.1038/s41589-019-0342-2

  View details for PubMedID 31451760

• Inverting family GH156 sialidases define an unusual catalytic motif for glycosidase action. Nature communications Bule, P. n., Chuzel, L. n., Blagova, E. n., Wu, L. n., Gray, M. A., Henrissat, B. n., Rapp, E. n., Bertozzi, C. R., Taron, C. H., Davies, G. J. 2019; 10 (1): 4816

  Abstract

  Sialic acids are a family of related sugars that play essential roles in many biological events intimately linked to cellular recognition in both health and disease. Sialidases are therefore orchestrators of cellular biology and important therapeutic targets for viral infection. Here, we sought to define if uncharacterized sialidases would provide distinct paradigms in sialic acid biochemistry. We show that a recently discovered sialidase family, whose first member EnvSia156 was isolated from hot spring metagenomes, defines an unusual structural fold and active centre constellation, not previously described in sialidases. Consistent with an inverting mechanism, EnvSia156 reveals a His/Asp active center in which the His acts as a Brønsted acid and Asp as a Brønsted base in a single-displacement mechanism. A predominantly hydrophobic aglycone site facilitates accommodation of a variety of 2-linked sialosides; a versatility that offers the potential for glycan hydrolysis across a range of biological and technological platforms.

  View details for DOI 10.1038/s41467-019-12684-7

  View details for PubMedID 31645552

• Glycosyltransferase bump-hole engineering to dissect mucin-type O-glycosylation in the living cell Schumann, B., Debets, M., Wisnovsky, S., Agbay, A., Wagner, L., Choi, J., Gray, M., Bertozzi, C. AMER CHEMICAL SOC. 2018

  View details for Web of Science ID 000447600001778

• Isotype-specific agglutination-PCR (ISAP): Asensitive and multiplex method for measuring allergen-specific IgE. The Journal of allergy and clinical immunology Tsai, C., Mukai, K., Robinson, P. V., Gray, M. A., Waschmann, M. B., Lyu, S., Tsai, M., Chinthrajah, R. S., Nadeau, K. C., Bertozzi, C. R., Galli, S. J. 2018; 141 (5): 1901

  View details for PubMedID 29248495