Nanoparticles targeting Sialyl-Tn for efficient tyrosine kinase inhibitor delivery in gastric cancer

Gastric cancer (GC) is the fourth leading cause of cancer-related deaths worldwide and, therefore, it is urgent to develop new and more efficient therapeutic approaches. Foretinib (FRT) is an oral multikinase inhibitor targeting MET (hepatocyte growth factor receptor) and RON (recepteur d'origine nantais) receptor tyrosine kinases (RTKs) that has been used in clinical trials for several solid tumors. Targeted uptake of therapeutic polymeric nanoparticles (NPs) represents a powerful approach in cancer cell drug delivery. Previously, a nanodelivery system composed of polymeric NPs functionalized with B72.3 antibody, which targets the tumor-associated antigen Sialyl-Tn (STn), has been developed. Herein, these NPs were loaded with FRT to evaluate its capacity in delivering the drug to multicellular tumors spheroids (MCTS) and mouse models. The data indicated that B72.3 functionalized FRT-loaded PLGA-PEG-COOH NPs (NFB72.3) specifically target gastric MCTS expressing the STn glycan (MKN45 SimpleCell (SC) cells), leading to a decrease in phospho-RTKs activation and reduced cell viability. In vivo evaluation using MKN45 SC xenograft mice revealed that NFB72.3 were able to decrease tumor growth, reduce cell proliferation and tumor necrosis. NFB72.3-treated tumors also showed inactivation of phospho-MET and phospho-RON. This study demonstrates the value of using NPs targeting STn for FRT delivery, highlighting its potential as a therapeutic application in GC. STATEMENT OF SIGNIFICANCE: Despite the advances in gastric cancer therapeutics, it remains one of the diseases with the highest incidence and mortality in the world. Combining targeted therapies with a controlled drug release is an attractive strategy to reduce drug cytotoxic effects and improve specific drug delivery efficiency to the cancer cells. Thus, we developed nanoparticles loaded with a tyrosine kinase inhibitor and targeting a specific tumor glycan exclusive of cancer cells. In in vivo gastric cancer xenograft mice models, these nanoparticles efficiently reduced tumor growth, cell proliferation and tumor necrosis area and inactivated phosphorylation of targeting receptors. This approach represents an innovative therapeutic strategy with high impact in gastric cancer.

Polymeric nanoparticles targeting Sialyl-Tn in gastric cancer: A live tracking under flow conditions

Drug delivery using nanoparticles (NPs) represents a potential approach for therapy in cancer, such gastric cancer (GC) due to their targeting ability and controlled release properties. The use of advanced nanosystems that deliver anti-cancer drugs specifically to tumor cells may strongly rely on the expression of cancer-associated targets. Glycans aberrantly expressed by cancer cells are attractive targets for such delivery strategy. Sialylated glycans, such as Sialyl-Tn (STn) are aberrantly expressed in several epithelial tumors, including GC, being a potential target for a delivery nanosystem. The aim of this study was the development of NPs surface-functionalized with a specific antibody targeting the STn glycan and further evaluate this nanosystem effectiveness regarding its specificity and recognition capacity. Our results showed that the NPs surface-functionalized with anti-STn antibody efficiently are recognized by cells displaying the cancer-associated STn antigen under static and live cell monitoring flow conditions. This uncovers the potential use of such NPs for drug delivery in cancer. However, flow exposure was disclosed as an important biomechanical parameter to be taken into consideration. Here we presented an innovative and successful methodology to live track the NPs targeting STn antigen under shear stress, simulating the physiological flow. We demonstrate that unspecific binding of NPs agglomerates did not occur under flow conditions, in contrast with static assays. This robust approach can be applied for in vitro drug studies, giving valuable insights for in vivo studies.

Glycosylation of Cancer Extracellular Vesicles: Capture Strategies, Functional Roles and Potential Clinical Applications

Glycans are major constituents of extracellular vesicles (EVs). Alterations in the glycosylation pathway are a common feature of cancer cells, which gives rise to de novo or increased synthesis of particular glycans. Therefore, glycans and glycoproteins have been widely used in the clinic as both stratification and prognosis cancer biomarkers. Interestingly, several of the known tumor-associated glycans have already been identified in cancer EVs, highlighting EV glycosylation as a potential source of circulating cancer biomarkers. These particles are crucial vehicles of cell–cell communication, being able to transfer molecular information and to modulate the recipient cell behavior. The presence of particular glycoconjugates has been described to be important for EV protein sorting, uptake and organ-tropism. Furthermore, specific EV glycans or glycoproteins have been described to be able to distinguish tumor EVs from benign EVs. In this review, the application of EV glycosylation in the development of novel EV detection and capture methodologies is discussed. In addition, we highlight the potential of EV glycosylation in the clinical setting for both cancer biomarker discovery and EV therapeutic delivery strategies.

Different isolation approaches lead to diverse glycosylated extracellular vesicle populations

Extracellular vesicles (EVs) are a heterogeneous group of small secreted particles involved in intercellular communication and mediating a broad spectrum of biological functions. EVs cargo is composed of a large repertoire of molecules, including glycoconjugates. Herein, we report the first study on the impact of the isolation strategy on the EV populations’ glycosylation profile. The use of different state-of-the-art protocols, namely differential ultracentrifugation (UC), total exosome isolation (TEI), OptiPrep^TM density gradient (ODG) and size exclusion chromatography (SEC) resulted in EV populations displaying different sets of glycoconjugates. The EV populations obtained by UC, ODG and SEC methods displayed similar protein and glycan profiles, whereas TEI methodology isolated the most distinct EV population. In addition, ODG and SEC isolation protocols provided an enhanced EV glycoproteins detection. Remarkably, proteins displaying the tumour-associated glycan sialyl-Tn (STn) were identified as packaged cargo into EVs independently of the isolation methodology. STn carrying EV samples isolated by UC, ODG and SEC presented a considerable set of cancer-related proteins that were not detected in EVs isolated by TEI. Our work demonstrates the impact of using different isolation methodologies in the populations of EVs that are obtained, with consequences in the glycosylation profile of the isolated population. Furthermore, our results highlight the importance of selecting adequate EV isolation protocols and cell culture conditions to determine the structural and functional complexity of the EV glycoconjugates.

O-glycans truncation modulates gastric cancer cell signaling and transcription leading to a more aggressive phenotype

BACKGROUND

Changes in glycosylation are known to play critical roles during gastric carcinogenesis. Expression of truncated O-glycans, such as the Sialyl-Tn (STn) antigen, is a common feature shared by many cancers and is associated with cancer aggressiveness and poor-prognosis.

METHODS

Glycoengineered cell lines were used to evaluate the impact of truncated O-glycans in cancer cell biology using in vitro functional assays, transcriptomic analysis and in vivo models. Tumor patients 'samples and datasets were used for clinical translational significance evaluation.

FINDINGS

In the present study, we demonstrated that gastric cancer cells expressing truncated O-glycans display major phenotypic alterations associated with higher cell motility and cell invasion. Noteworthy, the glycoengineered cancer cells overexpressing STn resulted in tumor xenografts with less cohesive features which had a critical impact on mice survival. Furthermore, truncation of O-glycans induced activation of EGFR and ErbB2 receptors and a transcriptomic signature switch of gastric cancer cells. The disclosed top activated genes were further validated in gastric tumors, revealing that SRPX2 and RUNX1 are concomitantly overexpressed in gastric carcinomas and its expression is associated with patients' poor-survival, highlighting their prognosis potential in clinical practice.

INTERPRETATION

This study discloses novel molecular links between O-glycans truncation frequently observed in cancer and key cellular regulators with major impact in tumor progression and patients' clinical outcome.

Mucin-Type O-Glycosylation in Gastric Carcinogenesis

Mucin-type O-glycosylation plays a crucial role in several physiological and pathological processes of the gastric tissue. Modifications in enzymes responsible for key glycosylation steps and the consequent abnormal biosynthesis and expression of their glycan products constitute well-established molecular hallmarks of disease state. This review addresses the major role played by mucins and associated O-glycan structures in Helicobacter pylori adhesion to the gastric mucosa and the subsequent establishment of a chronic infection, with concomitant drastic alterations of the gastric epithelium glycophenotype. Furthermore, alterations of mucin expression pattern and glycan signatures occurring in preneoplastic lesions and in gastric carcinoma are also described, as well as their impact throughout the gastric carcinogenesis cascade and in cancer progression. Altogether, mucin-type O-glycosylation alterations may represent promising biomarkers with potential screening and prognostic applications, as well as predictors of cancer patients' response to therapy.

Unmasking Heavily O-Glycosylated Serum Proteins Using Perchloric Acid: Identification of Serum Proteoglycan 4 and Protease C1 Inhibitor as Molecular Indicators for Screening of Breast Cancer

Heavily glycosylated mucin glycopeptides such as CA 27.29 and CA 15-3 are currently being used as biomarkers for detection and monitoring of breast cancer. However, they are not well detected at the early stages of the cancer. In the present study, perchloric acid (PCA) was used to enhance detection of mucin-type O-glycosylated proteins in the serum in an attempt to identify new biomarkers for early stage breast cancer. Sensitivity and specificity of an earlier developed sandwich enzyme-linked lectin assay were significantly improved with the use of serum PCA isolates. When a pilot case-control study was performed using the serum PCA isolates of normal participants (n = 105) and patients with stage 0 (n = 31) and stage I (n = 48) breast cancer, higher levels of total O-glycosylated proteins in sera of both groups of early stage breast cancer patients compared to the normal control women were demonstrated. Further analysis by gel-based proteomics detected significant inverse altered abundance of proteoglycan 4 and plasma protease C1 inhibitor in both the early stages of breast cancer patients compared to the controls. Our data suggests that the ratio of serum proteoglycan 4 to protease C1 inhibitor may be used for screening of early breast cancer although this requires further validation in clinically representative populations.