Abstract
A high-resolution HILIC-MS/MS method was developed to analyze anthranilic acid derivatives of N-glycans released from human serum alpha-1-acid glycoprotein (AGP). The method was applied to samples obtained from 18 patients suffering from high-risk malignant melanoma as well as 19 healthy individuals. It enabled the identification of 102 glycan isomers separating isomers that differ only in sialic acid linkage (α-2,3, α-2,6) or in fucose positions (core, antenna). Comparative assessment of the samples revealed that upregulation of certain fucosylated glycans and downregulation of their nonfucosylated counterparts occurred in cancer patients. An increased ratio of isomers with more α-2,6-linked sialic acids was also observed. Linear discriminant analysis (LDA) combining 10 variables with the highest discriminatory power was employed to categorize the samples based on their glycosylation pattern. The performance of the method was tested by cross-validation, resulting in an overall classification success rate of 96.7%. The approach presented here is significantly superior to serological marker S100B protein in terms of sensitivity and negative predictive power in the population studied. Therefore, it may effectively support the diagnosis of malignant melanoma as a biomarker.
Highlights
Malignant melanoma (MM) is a skin tumor that arises from melanocytes responsible for melanin production and its transfer to keratinocytes
These findings indicate that the separation of glycans in HILIC is primarily affected by the number of sialic acid residues, while the number of antennas, fucose units, and other structural features such as extra
A HILIC-MS/MS method was developed and optimized for characterizing anthranilic acid (AA) labeled N-glycans released from human serum acid glycoprotein (AGP)
Summary
Malignant melanoma (MM) is a skin tumor that arises from melanocytes responsible for melanin production and its transfer to keratinocytes. MM was considered a rare tumor to affect mainly the elderly population, but during the past five decades, its worldwide incidence dramatically increased with a rate greater than that of most malignancies. It represents less than 5% of all cutaneous malignancies, its high mortality rate and severe metastatic potential establish the need to develop specific and sensitive methods to recognize the disease and provide less invasive alternatives to traditional diagnostic procedures including histopathological and immunohistochemical techniques [1,2]. Alpha-1-acid glycoprotein (AGP), known as orosomucoid, is one of the characteristic, highly glycosylated
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