Truncated O-glycan connection to Cancer: Depletion of O-glycosyltransferase C1GALT1 leads to early PDAC onset and metastasis
Ontology highlight
ABSTRACT: Aberrant expression of truncated O-glycan structures, such as Tn and STn, is frequently observed in pancreatic ductal adenocarcinoma (PDAC). The focus of our study is to investigate the functional role of truncated O-glycans in PDAC progression and metastasis. Our study revealed that kmockout of C1GALT1 leads to increased expression of truncated glycans and accelerates PDAC progression and metastasis.
Project description:Ewing sarcoma (ES) is an aggressive bone cancer driven by the oncogenic fusion-protein EWSR1::FLI1, which is not present in normal cells and is therefore an attractive therapeutic target. However, as a transcription factor, EWSR1::FLI1 is considered undruggable. Factors that promote EWSR1::FLI1 expression, and thus whose inhibition would reduce EWSR1::FLI1 protein levels and function, are potential drug targets. Here, using genome-scale CRISPR/Cas9 knockout screening, we identify C1GALT1, a galactosyltransferase required for the biosynthesis of many O-glycoproteins, as a factor that promotes EWSR1::FLI1 expression. We show that C1GALT1 acts by O-glycosylating the pivotal Hedgehog (Hh) signaling component Smoothened (SMO), thereby stabilizing SMO and stimulating the Hh pathway, which we find directly activates EWSR1::FLI1 transcription. Itraconazole, an FDA-approved anti-fungal agent that is known to inhibit C1GALT1, reduces EWSR1::FLI1 levels in ES cell lines and suppresses growth of ES xenografts in mice. Our study reveals a therapeutically targetable mechanism that promotes EWSR1::FLI1 expression and ES tumor growth.
Project description:Endometrial cancer (EC) is the most common cancer of female reproductive organs. Because some low-grade ECs might also experience tumor recurrence after surgery and a worse prognosis, the study of alterations related to EC pathogenesis of the disease might help to get insights into underlying mechanisms involved in EC development and metastasis and identify novel markers associated to the disease. Here, low C1GALT1 protein expression levels were associated to a more aggressive phenotype of EC. Then, we aimed at investigating the role of C1GALT1 in EC progression by quantitative proteomics. ECC-1 cells were used as endometrioid EC model, and the effect of C1GALT1 depletion was analyzed using C1GALT1 specific short hairpin RNAs (shRNA) in comparison to SCRAMBLE shRNA. SILAC and mass spectrometry analysis were performed to identify and quantify dysregulated proteins associated with C1GALT1 depletion in the cell extract and secretome proteome of shC1GALT1 and SCRAMBLE ECC-1 cells. Out of 5208 proteins identified and quantified by LC-MS/MS, 76 and 143 proteins showed dysregulation (fold-change ≥1.5 or ≤0.67) in shC1GALT1 ECC-1 cells’ extracts and secretome, respectively. Nine dysregulated proteins were selected for validation by orthogonal techniques, confirming their dysregulation upon C1GALT1 depletion. Bioinformatics analyses pointed out to an increase in pathways and dysregulated proteins that associated with more aggressive phenotype. This finding was corroborated by loss-of-function cell-based assays. A higher proliferation, invasion, migration, colony formation and angiogenesis capacity of C1GALT1 depleted cells was observed. Finally, the negative protein expression correlation found by proteomics between C1GALT1 and LGALS3 was confirmed by IHC in actual EC samples, suggesting C1GALT1 stably depleted ECC-1 cells mimic the aggressive phenotype of EC cells and might be useful for the identification and validation of potential markers in aggressive ECs.
Project description:Immunoglobulin A nephropathy (IgAN) is the most common form of primary glomerulonephritis worldwide characterized by aberrant O-glycosylation in the hinge region of IgA1. The basis for the abnormal glycosylation in IgAN is still unknown, but an important involvement of the enzyme core 1, beta 1,3-galactosyltransferase 1 (C1GALT1) is known. However, the role of microRNAs (miRNAs), a new family of key mRNA regulatory molecules, in the IgAN pathogenesis has not yet been reported. In this study, by high-throughput microRNA profiling, we identified 37 miRNAs differentially expressed in peripheral blood mononuclear cells (PBMCs) from IgAN patients compared to healthy subjects. Among them, upregulated miR-148b potentially targeted C1GALT1, INVS and PTEN, three genes notably downregulated in IgAN patients. C1GALT1 expression levels in IgAN patients were reduced and negatively correlated with the upregulated miR-148b expression. We demonstrated the biological relationship between miR-148b and C1GALT1 by transient transfection experiments ex vivo. When we reduced the upregulated miR-148b function in PBMCs of IgAN patients an increase of the C1GALT1 mRNA and protein levels was observed. We validated biologically also the miR-148b targeting of INVS , involved in the altered modulation of the WNT–β-catenin and PI3K/Akt pathways in IgAN patients. All together our data evidence an important role of miR-148b in the pathogenesis of IgAN, which could explain the aberrant glycosylation of IgA1 in the pathogenesis and should light on a potential target for the theraphy of the disease.
Project description:Cosmc is an obligate chaperone for C1GalT1 T transferase necessary for generating mature mucin-type O-glycans. Animals lacking Cosmc in glomerular podocytes develop proteinuria, glomerulosclerosis and progressive renal failure. This study was designed to examine transcriptome differences in 1 month male animals with and without podocyte Cosmc, a time point when proteinuria is established but glomerular architecture is still relatively intact.