The melanoma tumor glyco-code impacts human dendritic cells’ functionality and dictates clinical outcomes

Abstract

Subversion of immunity is a hallmark of cancer development. Dendritic cells (DCs) are strategic immune cells triggering anti-tumor immune responses, but tumor cells exploit their versatility to subvert their functions. Tumor cells harbor unusual glycosylation patterns, which can be sensed through glycan-binding receptors (lectins) expressed by immune cells that are crucial for DCs to shape and orientate antitumor immunity. Yet, the global tumor glyco-code and its impact on immunity has not been explored in melanoma. To decrypt the potential link between aberrant glycosylation patterns and immune evasion in melanoma, we investigated the melanoma tumor glyco-code through the GLYcoPROFILE™ methodology (lectin arrays), and depicted its impact on patients’ clinical outcome and DC subsets’ functionality. Specific glycan patterns correlated with clinical outcome of melanoma patients, GlcNAc, NeuAc, TF-Ag and Fuc motifs being associated with poor outcome, whereas Man and Glc residues elicited better survival. Strikingly, tumor cells differentially impacting cytokine production by DCs harbored distinct glyco-profiles. GlcNAc exhibited a negative influence on cDC2s, whereas Fuc and Gal displayed inhibitory impacts on cDC1s and pDCs. We further identified potential booster glycans for cDC1s and pDCs. Targeting specific glycans on melanoma tumor cells restored DCs’ functionality. The tumor glyco-code was also linked to the nature of the immune infiltrate. This study unveils the impact of melanoma glycan patterns on immunity, and paves the way for innovative therapeutic options. Glycans/lectins interactions arise as promising immune checkpoints to rescue DCs from tumor’ hijacking to reshape antitumor immunity and inhibit immunosuppressive circuits triggered by aberrant tumor glycosylation.

Melanoma tumour‐derived glycans hijack dendritic cell subsets through C‐type lectin receptor binding

“…Thus, s-Tn/ CLEC2 could influence features of cDC1s. Sialyl motifs were demonstrated to be of importance in melanoma progression, as higher levels of NeuAc motifs on tumour cells were associated with poor outcome of patients [33], and an increased α2,3-sialylation was associated with a more aggressive phenotype in melanoma [49]. CLEC-2 (CLEC1B) belongs to the Dectin-1 cluster, displays a broad range of ligands, is involved in DC migration and mediates cytokine secretion [50].…”

“…The production of cytokines and chemokines by DC subsets was then measured in supernatants by Luminex. function [33]. Glycan/CLR interactions were disrupted either by pre-incubating PanDCs with a mix of anti-CLR antibodies preventing interactions of DCs with the identified adverse glycan motifs (anti-CLEC2, -Dectin-2, -Dectin-1, -NKp44, -Mincle, -MGL, -Langerin), or by blocking tumour cell glycans with a mixture of rhCLRs (rh-MGL, -Langerin, -DC-SIGN) masking the major glycan motifs involved in DC subversion (GalNAc, Gal and Fuc).…”

“…Intracellular cytokine production by DC subsets was then assessed by flow cytometry (Figure S15C). We beforehand established by lectin array the glycoprofile of tumour cell lines derived from melanoma patients using the GLYcoPROFILE™ technology [33] (Figure S16). It revealed a major expression of Man, GalNAc, Fuc, GlcNAc and sialyl motifs.…”

“…In melanoma, perturbations of enzymes involved in glycosylation/deglycosylation processes (e.g., glycosyl-transferases, glycosidases) lead to dysregulation of glycan biosynthesis [30][31][32]. By depicting the 'glyco-code' of primary melanoma tumour cell lines, we recently identified aberrant glycans exposed on their surface including Gal, Man, GalNAc, s-Tn, fucose (Fuc) and GlcNAc motifs [33]. Altered glycan profiles play a critical role in tumour progression through promotion of tumour cell proliferation, adhesion, migration, invasion and angiogenesis in many cancer types [34], including melanoma [32].…”

Dendritic Cell Subsets in Melanoma: Pathophysiology, Clinical Prognosis and Therapeutic Exploitation

“…In melanoma patients, we recently highlighted that the CLR profiles in circulating and tumor-infiltrating DC subsets display strong perturbations, correlated with unique DCs’ features, and dictated clinical outcomes [ 101 ]. Furthermore, the melanoma tumor glycocode directly affects the DC subsets’ functionality [ 102 ], revealing the glycan/CLR axis as a potential DC subversion pathway in melanoma.…”