# Status Quo of Glycoslation in Cancer: What Is, What Is Not and What Is to Be
###### Abstract  
Glycobiology is gaining paramount importance for its influence on diseases as a consequence of a fundamental understanding of the underlying processes involved in them. Cancer is still posing threats to human health and welfare and therapies are perpetually being sought. Glycans are selectively attached to proteins and lipids during glycosylation, and these hold anchorage positions in many important biological processes involved in cancer through their altered expression or activity upon malignant transformation. Aberrant glycosylation is well established as a hallmark of cancer, linked to tumor development and metastasis. The analytical inputs and milestones achieved and the characterization and detection of glycosylation in cancer have been summarized in this review. The milestones achieved in cancer research through inputs from glycosylation have been highlighted. With almost 70% of biopharmaceuticals being glycoproteins and almost 80% of cancer biomarkers being glycan in origin, glycosylation has a lot of say in cancer prognosis and diagnosis. The future of glycosylation in cancer and the lacunae in the smooth channelization of state-of-the-art technologies for taking this research knowledge from bench top to bedside (actual clinical settings) is speculated upon. The incorporation of cross-disciplinary integrated approaches and nano-instrumentation sophistications are proposed for achieving scaling up. cancer; glycopology; biomarkers; aberrant glycosylation; analytical instrumentation +
Footnote †: journal: Medical  
they are attached to. Glycosylation is an essential co- and post-translational modification (PTM) occurring in cells. Glycans, carbohydrate molecules, are selectively attached to proteins and lipids during glycosylation, exhibiting control over protein folding and clearance rates, inflammation and metastasis, while functioning as biomarkers of diseases [8]. Glycosylation is involved in cell signaling, immune recognition and cell-cell interaction and plays a key role in cancer-related aspects such as cell adhesion, cell signaling, migration, interactions with the cell matrix, immune surveillance and cellular metabolism. Glycan modifications in cells or tissues take place through the synchronized action of numerous glycosylation enzymes inside the Golgi and the endoplasmic reticulum. Glycans are linked to lipids and proteins through two mechanisms namely O- and N-linked glycosylation [9; 10; 11]. The synthesis of aberrant glycan chains is now an established hallmark of cancer. This is a consequence of distinct alterations in the microenvironment-metabolism and in glycoproteins enzymes [12]. These aberrations become more apparent as the tumor becomes more aggressive and translate to function as biomarkers of the disease. In this way, aberrant protein glycosylation has now become a promising source of glycopomarkers for diagnosis and prognosis. Glycoprotein enter the circulatory system through leakage, rendering serum as a biomarker pool from a diagnostic perspective. A lot more prospective developments leading to cancer vaccines is also anticipated as a challenging perspective. The existence of complex truncated or novel glycan structures influences ligand-receptor interactions. This further interferes with the regulation of various biological processes in the cell. Aberrant glycosylation, thus reflects cancer-inflicted alterations in glycan biosynthesis. This is rendered possible through altered expression of glycosyltransferases, glycosylases, fucosylation and sialylation. Being able to distinguish differences in the glycosylation of proteins within cancer and controls, glycopiology is established as a potential biomarker identifier [13]. This review highlights the achievements of glycosylation in cancer, diagnosis, prognosis and therapy. The analytical inputs for cancer diagnosis in the area of glycosylation and the progress from glycan-based cancer biomarkers have been summarized.