Expression of ST3Gal, ST6Gal, ST6GalNAc and ST8Sia in human hepatic carcinoma cell lines, HepG-2 and SMMC-7721 and normal hepatic cell line, L-02

MicroRNA-135b mainly functions as an oncogene during tumor progression

Late diagnosis is considered one of the main reasons of high mortality rate among cancer patients that results in therapeutic failure and tumor relapse. Therefore, it is needed to evaluate the molecular mechanisms associated with tumor progression to introduce efficient markers for the early tumor detection among cancer patients. The remarkable stability of microRNAs (miRNAs) in body fluids makes them potential candidates to use as the non-invasive tumor biomarkers in cancer screening programs. MiR-135b has key roles in prognosis and survival of cancer patients by either stimulating or inhibiting cell proliferation, invasion, and angiogenesis. Therefore, in the present review we assessed the molecular biology of miR-135b during tumor progression to introduce that as a novel tumor marker in cancer patients. It has been reported that miR-135b mainly acts as an oncogene by regulation of transcription factors, signaling pathways, drug response, cellular metabolism, and autophagy. This review paves the way to suggest miR-135b as a tumor marker and therapeutic target in cancer patients following the further clinical trials and animal studies.

Identification and Experimental Validation of the Prognostic Significance and Immunological Correlation of Glycosylation-Related Signature and ST6GALNAC4 in Hepatocellular Carcinoma

Purpose

Glycosylation has been demonstrated to be involved in tumorigenesis, progression, and immunoregulation, and to present specific profiles in different tumors. In this study, we aimed to explore the specific glycosylation-related gene (GRG) signature and its potential immunological roles and prognostic implications in hepatocellular carcinoma (HCC).

Patients and Methods

The GRG expression profile was defined using the transcriptome data from The Cancer Genome Atlas and Gene Expression Omnibus. Univariate and the least absolute shrinkage and selection operator Cox analyses were performed to develop a GRG-based risk score model. A nomogram was subsequently established and validated. Its correlation with cancer immune microenvironment and drug susceptibility was further analyzed. The role and immunological correlation of ST6GALNAC4 were further experimentally validated at the tissue and cellular levels in HCC.

Results

A total of 87 GRGs were identified to be significantly dysregulated in HCC, and a novel risk score model was constructed using eight critical GRGs, which demonstrated superior prognostic discrimination and predictive power in both training and validation groups. High risk scores in HCC patients were associated with lower OS. The model was also identified as an independent risk factor for HCC, and a novel nomogram was subsequently constructed and validated. Notably, significant correlations were found in risk scores with immune cells infiltration, tumor immunophenotyping, immune checkpoint genes' expression, and sensitivities to multiple drugs. Furthermore, we validated in local HCC samples that ST6GALNAC4 was significantly upregulated and its knockdown significantly inhibited the tumor proliferation, migration and invasion ability and affected the expression of immune checkpoints on hepatoma cells.

Conclusion

We identified a novel GRG-based model which showed significant prognostic and immunological correlations in HCC, and the oncogenic role of ST6GALNAC4 has been validated and may serve as a potential drug target.

Sialyltransferase Inhibitors for the Treatment of Cancer Metastasis: Current Challenges and Future Perspectives

Potent, cell-permeable, and subtype-selective sialyltransferase inhibitors represent an attractive family of substances that can potentially be used for the clinical treatment of cancer metastasis. These substances operate by specifically inhibiting sialyltransferase-mediated hypersialylation of cell surface glycoproteins or glycolipids, which then blocks the sialic acid recognition pathway and leads to deterioration of cell motility and invasion. A vast amount of evidence for the in vitro and in vivo effects of sialyltransferase inhibition or knockdown on tumor progression and tumor cell metastasis or colonization has been accumulated over the past decades. In this regard, this review comprehensively discusses the results of studies that have led to the recent discovery and development of sialyltransferase inhibitors, their potential biomedical applications in the treatment of cancer metastasis, and their current limitations and future opportunities.

Comprehensive quali-quantitative profiling of neutral and sialylated O-glycome by mass spectrometry based on oligosaccharide metabolic engineering and isotopic labeling

An isotopic precursor based metabolic amplification and labeling (IPMAL) strategy using the Ac₃GalNAc-α-Bn precursor to simultaneously quantify neutral and sialylated O-glycans.

Upregulation of microRNA-135b and microRNA-182 promotes chemoresistance of colorectal cancer by targeting ST6GALNAC2 via PI3K/AKT pathway

MicroRNAs (miRNAs) are increasingly involved in the development of drug resistance, including 5-fluorouracil (5-FU) resistance in colorectal cancer (CRC). Aberrant sialylation is correlated with human CRC. The study was to explore whether miR-135b and miR-182 modulated 5-FU chemoresistance of CRC by targeting ST6GALNAC2 via PI3K/AKT pathway. MiR-135b and miR-182 were found to be up-regulated in CRC tissues and 5-FU resistant CRC cell lines. Forced miR-135b and miR-182 expression also affected ST6GALNAC2 levels. Using reporter-gene assay, ST6GALNAC2 was identified as direct target of miR-135b and miR-182, while ST6GALNAC2 expression exhibited patterns opposite to that of miR-135b and miR-182 in CRC samples and cell lines. Interestingly, up-regulation of miR-135b or miR-182 increased drug resistance and proliferation, but decreased apoptosis in 5-FU resistant CRC cell lines. Suppression of these miRNAs implicated an inverse function, while altered expression of ST6GALNAC2 mediated CRC progression upon transfection with miR-135b/-182 mimic or inhibitor. Furthermore, miR-135b and miR-182 were clarified to regulate the activity of phosphoinositide-3 kinase (PI3K)/AKT pathway. Inhibition of the PI3K/AKT pathway enhanced the chemosensitivity to 5-FU in HCT-8/5-FU and LoVo/5-FU. Taken together, miR-135b and miR-182 may reverse the resistance to 5-FU in CRC cells by targeting ST6GALNAC2 via PI3K/AKT pathway, which render potential chemotherapy targets for the treatment of CRC.

Enhanced expression of α2,3-linked sialic acids promotes gastric cancer cell metastasis and correlates with poor prognosis

Gastric cancer (GC) is a highly metastatic disease and one of the leading causes of cancer death in the world. Aberrant glycosylation is one of many molecular changes that accompany malignant transformation. This study was aimed at identification of glycan profiling changes in GC progression and its potential mechanisms. We employed a microarray with 91 lectins to compare the differential glycans in the three human GC cell lines, SGC-7901, BGC-823 and MGC-803. According to glycan-binding specificities of lectins, all GC cell lines expressed common sugar structures, such as mannose, galactose and fucose. Importantly, we found that the binding of Maackia amurensis lectin-I (MAL-I) to GC cells was proportional to their metastatic capacity. Further analysis revealed that the level of α2,3-linked sialic acids (α2-3Sia), which can be recognized by MAL-I, was significantly overexpressed in MGC-803 cells, while low expression was detected in SGC-7901 cells. In addition, the mRNA and protein expression levels of β-galactoside α2,3-sialyltransferase IV (ST3Gal-IV), which was related to the synthesis of α2-3Sia, were substantially increased in MGC-803 cells. Knockdown of ST3Gal-IV in MGC-803 cells led to a decreased level of α2-3Sia and decreased ability of invasion and migration. Exogenous expression of ST3Gal-IV in SGC-7901 cells enhanced cell migration, invasion and the content of α2-3Sia. Furthermore, the staining of MAL-I in GC tissues showed that high expression of α2-3Sia was closely correlated with lymph node metastasis, TNM stage and poor overall survival. These findings lead to better understanding of the function of α2-3Sia in the progression and metastasis of GC. This property may be important for developing new therapeutic approaches for GC.

Overexpression of ST3Gal-I promotes migration and invasion of HCCLM3 in vitro and poor prognosis in human hepatocellular carcinoma

PURPOSE

Excessive ST3Gal-I levels predict a poor outcome for patients with several types of tumors. This study aims to investigate the role of ST3Gal-I in determining the invasive and metastatic potential of human hepatocellular carcinoma (HCC) and clinical prognosis for patients with HCC.

METHODS

We compared the expression of ST3Gal-I in various HCC cell lines and in 20 pairs of tumor and peritumor tissue samples using Western blot analysis. Changes in the degree of invasiveness and migration were determined before and after small interfering RNA-induced knockdown of ST3Gal-I using a Transwell matrigel invasion assay and scratch wound assay. The correlation between ST3Gal-I expression and prognosis was determined in a large HCC patient cohort (n=273).

RESULTS

ST3Gal-I expression was higher in metastatic HCCLM3 cells and tumor tissue compared with normal adjacent tissue. Following the ST3Gal-I knockdown, the invasiveness and migration of HCCLM3 cells were markedly reduced. ST3Gal-I expression in HCC correlated closely with tumor thrombus (P<0.001), tumor size (>5.0 cm, P=0.032), tumor node metastasis stages II-III (P=0.002), and Barcelona Clinic Liver Cancer stages B-C (P<0.001). Cox regression analysis demonstrated that ST3Gal-I is an independent predictor of prognosis in patients with HCC, and related to disease-free survival (hazard ratio =1.464, P=0.037) and overall survival (hazard ratio =1.662, P=0.012).

CONCLUSION

ST3Gal-I might contribute to the invasiveness and metastatic nature of HCC and, thus, could be an independent predictor of recurrence and a suitable pharmaceutical target in patients with HCC.