Glycosylation of proteins is one of the most important PTMs, with more than half of all human proteins estimated to be glycosylated. It is widely known that aberrant glycosylation has been implicated in many different diseases due to changes associated with biological function and protein folding. In cancer, there is increasing evidence pertaining to the role of glycosylation in tumour formation and metastasis. Alterations in cell surface glycosylation, particularly terminal motifs, can promote invasive behaviour of tumour cells that ultimately lead to the progression of cancer. While a majority of studies have investigated protein glycosylation changes in cancer cell lines and tumour tissue for individual cancers, the review presented here represents a comprehensive, in-depth overview of literature on the structural changes of glycosylation and their associated synthetic enzymes in five different cancer types originating from the breast, colon, liver, skin and ovary. More importantly, this review focuses on key similarities and differences between these cancers that reflect the importance of structural changes of cell surface N- and O-glycans, such as sialylation, fucosylation, degree of branching and the expression of specific glycosyltransferases for each cancer. It is envisioned that the understanding of these biologically relevant glycan alterations on cellular proteins will facilitate the discovery of novel glycan-based biomarkers which could potentially serve as diagnostic and prognostic indicators of cancer.

The causal relationships between insulin levels, insulin resistance, and longevity are not fully elucidated. Genetic downregulation of insulin/insulin-like growth factor 1 (Igf1) signaling components can extend invertebrate and mammalian lifespan, but insulin resistance, a natural form of decreased insulin signaling, is associated with greater risk of age-related disease in mammals. We compared Ins2 mice to Ins2 littermate controls, on a genetically stable Ins1 null background. Proteomic and transcriptomic analyses of livers from 25-week-old mice suggested potential for healthier aging and altered insulin sensitivity in Ins2 mice. Halving Ins2 lowered circulating insulin by 25%-34% in aged female mice, without altering Igf1 or circulating Igf1. Remarkably, decreased insulin led to lower fasting glucose and improved insulin sensitivity in aged mice. Moreover, lowered insulin caused significant lifespan extension, observed across two diverse diets. Our study indicates that elevated insulin contributes to age-dependent insulin resistance and that limiting basal insulin levels can extend lifespan.

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While aberrant protein glycosylation is a recognized characteristic of human cancers, advances in glycoanalytics continue to discover new associations between glycoproteins and tumorigenesis. This glycomics‐centric study investigates a possible link between protein paucimannosylation, an under‐studied class of human N‐glycosylation [Man1‐3GlcNAc2Fuc0‐1], and cancer. The paucimannosidic glycans (PMGs) of 34 cancer cell lines and 133 tissue samples spanning 11 cancer types and matching non‐cancerous specimens are profiled from 467 published and unpublished PGC‐LC‐MS/MS N‐glycome datasets collected over a decade. PMGs, particularly Man2‐3GlcNAc2Fuc1, are prominent features of 29 cancer cell lines, but the PMG level varies dramatically across and within the cancer types (1.0–50.2%). Analyses of paired (tumor/non‐tumor) and stage‐stratified tissues demonstrate that PMGs are significantly enriched in tumor tissues from several cancer types including liver cancer (p = 0.0033) and colorectal cancer (p = 0.0017) and is elevated as a result of prostate cancer and chronic lymphocytic leukaemia progression (p < 0.05). Surface expression of paucimannosidic epitopes is demonstrated on human glioblastoma cells using immunofluorescence while biosynthetic involvement of N‐acetyl‐β‐hexosaminidase is indicated by quantitative proteomics. This intriguing association between protein paucimannosylation and human cancers warrants further exploration to detail the biosynthesis, cellular location(s), protein carriers, and functions of paucimannosylation in tumorigenesis and metastasis.