Nucleolin-Sle A Glycoforms as E-Selectin Ligands and Potentially Targetable Biomarkers at the Cell Surface of Gastric Cancer Cells

Abstract

Background: Gastric cancer (GC) is a major health burden worldwide, with half of patients developing metastases within 5 years after treatment, urging novel biomarkers for diagnosis and efficient therapeutic targeting. Sialyl-Lewis A (SLeA), a terminal glycoepitope of glycoproteins and glycolipids, offers tremendous potential towards this objective. It is rarely expressed in healthy tissues and blood cells, while it is present in highly metastatic cell lines and metastases. SLeA is also involved in E-selectin mediated metastasis, making it an ideal target to control disease dissemination. Methods and Results: To improve cancer specificity, we have explored the SLeA-glycoproteome of six GC cell models, with emphasis on glycoproteins showing affinity for E-selectin. A novel bioinformatics-assisted algorithm identified nucleolin (NCL), a nuclear protein, as a potential targetable biomarker potentially involved in metastasis. Several immunoassays, including Western blot and in situ proximity ligation reinforced the existence of cell surface NCL-SLeA glycoforms in GC. The NCL-SLeA glycophenotype was associated with decreased survival and was not reflected in relevant healthy tissues. Conclusions: NCL-SLeA is a biomarker of poor prognosis in GC holding potential for precise cancer targeting. This is the first report describing SLeA in preferentially nuclear protein, setting a new paradigm for cancer biomarkers discovery and targeted therapies.

Complementary Use of Carbohydrate Antigens Lewis a, Lewis b, and Sialyl-Lewis a (CA19.9 Epitope) in Gastrointestinal Cancers: Biological Rationale towards a Personalized Clinical Application

“…Moreover, activation of other B3GALT genes, as reported in prostatic cancer [89], cannot be excluded. Very recently, an unusual carrier of sLea with potential therapeutic relevance has been detected in gastric cancer cell lines [90], which deserves confirmation in native tissues. We suggest that the future use of Lewis antigens as tumor markers should be based on knowledge of their expression pattern in native cancers and related normal tissues, as well as in nonmalignant diseases of the same organs.…”

NCL Inhibition Exerts Antineoplastic Effects against Prostate Cancer Cells by Modulating Oncogenic MicroRNAs

“…Despite mounting evidence that NCL is a valid therapeutic target in different types of aggressive cancer [ 29 , 32 , 57 , 59 , 60 ], the data for PCa are lacking. In the present study we aimed to demonstrate that targeting surface NCL by the scFv 4LB5 is an effective way to inhibit multiple neoplastic features of PCa cells.…”

“…A protein involved in miRNA regulation, nucleolin (NCL), is expressed predominantly in the nucleolus in normal cells [ 18 ] and is known to participate in a multitude of different cellular processes [ 19 , 20 , 21 ]. In cancer cells, NCL becomes aberrantly overexpressed [ 22 , 23 ], translocated to the cell membrane [ 24 , 25 ], and participates in several cancer-driving activities [ 26 , 27 , 28 , 29 , 30 , 31 ] including biogenesis of oncogenic miRNAs such as miR-21, -103, -221, and -222 [ 32 ]. NCL has been shown to exhibit similar cellular behavior in PCa, and exhibits greater surface expression in CRPC cell lines than in hormone-naïve models [ 33 ].…”

Target Score—A Proteomics Data Selection Tool Applied to Esophageal Cancer Identifies GLUT1-Sialyl Tn Glycoforms as Biomarkers of Cancer Aggressiveness

“…Addressing alterations in the glycosylation of membrane proteins holds a great potential towards this objective [8]. In fact, over the past years, we and other research groups have demonstrated that changes in the structure and distribution of glycans in proteins at the surface of cancer cells may provide the necessary bispecificity towards unique cancer molecular signatures [8,9]. Namely, we have identified MUC16, CD44 and nucleolin glycoforms holding potential for more accurate patient stratification and treatment follow-ups in different types of tumors [9][10][11].…”