Regulation of pancreatic cancer TRAIL resistance by protein O-GlcNAcylation

Stem cell-based targeted therapy in pancreatic cancer: Current approaches and future prospects

Despite recent improvements in oncology, diagnosis, and therapy, pancreatic cancer remains extremely difficult to cure due to its aggressive growth pattern with early invasion and distant metastases, chemoresistance, and a lack of effective screening modalities for early detection. Here, novel therapeutic approaches for treating pancreatic cancer are urgently needed. Recently, stem cells have drawn a lot of interest as a possible treatment for pancreatic cancer due to their ability to locate tumors. Though research over the last few decades has revealed some very exciting and promising new treatment approaches, the clinical success of these stem-cell based anti-cancer medicines has been quite limited. The most effective stem cell-mediated therapeutic options will only be available with a deeper understanding of the intricate molecular biology underlying pancreatic cancer and the subsequent identification of cancer stem cells as a novel target that promotes the growth of the cancer and resistance to chemotherapy. This review will highlight the stem cell based anti-cancer therapy targeting pancreatic cancer stem cells and different molecular signaling pathways. A particular focus will be on the therapeutic potential of naïve Stem cells, anti-cancer drug loaded stem cells, genetically engineered stem cells and exosomal miRNA released by stem cells in pancreatic cancer treatment. Similarly, the role of nanotechnology in stem cell based anticancer therapy will be further discussed to better implementation of these cell-based cancer therapy.

E3 ubiquitin ligase UBR5 promotes gemcitabine resistance in pancreatic cancer by inducing O-GlcNAcylation-mediated EMT via destabilization of OGA

Pancreatic cancer (PC) is among the deadliest malignancies, with an extremely poor diagnosis and prognosis. Gemcitabine (GEM) remains the first-line drug for treating PC; however, only a small percentage of patients benefit from current immunotherapies or targeted therapies. Resistance to GEM is prevalent and affects long-term survival. We found that ubiquitin-protein ligase E3 module N-recognition 5 (UBR5) is a therapeutic target against GEM resistance. UBR5 was markedly upregulated in clinical GEM-resistant PC samples and GEM-resistant PC cells. UBR5 knockdown markedly increased GEM sensitivity in GEM-resistant PC cell lines. UBR5-mediated GEM resistance was accompanied by activation of epithelial-mesenchymal transition (EMT) and could be mitigated by inhibiting EMT. Further analysis revealed that UBR5 promoted GEM resistance in PC cells by enhancing O-GlcNAcylation-mediated EMT. In addition, UBR5 knockdown resulted in increased O-GlcNAase (OGA) levels, an essential negatively regulated enzyme in the O-GlcNAcylation process. We identified a negative association between OGA and UBR5 levels, which further supported the hypothesis that O-GlcNAcylation-mediated GEM resistance induced by UBR5 is OGA-dependent in PC cells. Mechanistic studies revealed that UBR5 acts as an E3 ubiquitin ligase of OGA and regulates O-GlcNAcylation by binding and modulating OGA, facilitating its degradation and ubiquitination. Additionally, high-throughput compound library screening using three-dimensional protein structure analysis and drug screening identified a Food and Drug Administration drug, Y-39983 dihydrochloride, as a potent GEM sensitiser and UBR5 inhibitor. The combination of Y-39983 dihydrochloride and GEM attenuated tumour growth in a mouse xenograft tumour model. Collectively, these data demonstrated that UBR5 plays a pivotal role in the sensitisation of PC to GEM and provides a potential therapeutic strategy to overcome GEM resistance.

Targeting O-GlcNAcylation in cancer therapeutic resistance: The sugar Saga continues

O-linked-N-acetylglucosaminylation (O-GlcNAcylation), a dynamic post-translational modification (PTM), holds profound implications in controlling various cellular processes such as cell signaling, metabolism, and epigenetic regulation that influence cancer progression and therapeutic resistance. From the therapeutic perspective, O-GlcNAc modulates drug efflux, targeting and metabolism. By integrating signals from glucose, lipid, amino acid, and nucleotide metabolic pathways, O-GlcNAc acts as a nutrient sensor and transmits signals to exerts its function on genome stability, epithelial-mesenchymal transition (EMT), cell stemness, cell apoptosis, autophagy, cell cycle. O-GlcNAc also attends to tumor microenvironment (TME) and the immune response. At present, several strategies aiming at targeting O-GlcNAcylation are under mostly preclinical evaluation, where the newly developed O-GlcNAcylation inhibitors markedly enhance therapeutic efficacy. Here we systematically outline the mechanisms through which O-GlcNAcylation influences therapy resistance and deliberate on the prospects and challenges associated with targeting O-GlcNAcylation in future cancer treatments.

TNF-Related Apoptosis-Inducing Ligand: Non-Apoptotic Signalling

TNF-related apoptosis-inducing ligand (TRAIL or Apo2 or TNFSF10) belongs to the TNF superfamily. When bound to its agonistic receptors, TRAIL can induce apoptosis in tumour cells, while sparing healthy cells. Over the last three decades, this tumour selectivity has prompted many studies aiming at evaluating the anti-tumoral potential of TRAIL or its derivatives. Although most of these attempts have failed, so far, novel formulations are still being evaluated. However, emerging evidence indicates that TRAIL can also trigger a non-canonical signal transduction pathway that is likely to be detrimental for its use in oncology. Likewise, an increasing number of studies suggest that in some circumstances TRAIL can induce, via Death receptor 5 (DR5), tumour cell motility, potentially leading to and contributing to tumour metastasis. While the pro-apoptotic signal transduction machinery of TRAIL is well known from a mechanistic point of view, that of the non-canonical pathway is less understood. In this study, we the current state of knowledge of TRAIL non-canonical signalling.

Reciprocal regulation of TWIST1 and OGT determines the decitabine efficacy in MDS/AML

Chemoresistance poses a significant impediment to effective treatment strategies for myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). Our previous study unveiled that oncogene TWIST1 interacted with DNA methyltransferase 3a (DNMT3a) to regulate the decitabine (DAC) resistance in MDS/AML. However, the underlying mechanism of TWIST1 dysregulation in DAC resistance remained enigmatic. Here, we found that O-GlcNAc modification was upregulated in CD34+ cells from MDS/AML patients who do not respond to DAC treatment. Functional study revealed that O-GlcNAcylation could stabilize TWIST1 by impeding its interaction with ubiquitin E3 ligase CBLC. In addition, as one typical transcription factor, TWIST1 could bind to the promoter of O-GlcNAc transferase (OGT) gene and activate its transcription. Collectively, we highlighted the crucial role of the O-GlcNAcylated TWIST1 in the chemoresistance capacity of MDS/AML clonal cells, which may pave the way for the development of a new therapeutic strategy targeting O-GlcNAcylated proteins and reducing the ratio of MDS/AML relapse. Video Abstract.

O-GlcNAcylation in cancer development and immunotherapy

O-linked β-D-N-acetylglucosamine (O-GlcNAc), as a posttranslational modification (PTM), is a reversible reaction that attaches β-N-GlcNAc to Ser/Thr residues on specific proteins by O-GlcNAc transferase (OGT). O-GlcNAcase (OGA) removes the O-GlcNAc from O-GlcNAcylated proteins. O-GlcNAcylation regulates numerous cellular processes, including signal transduction, the cell cycle, metabolism, and energy homeostasis. Dysregulation of O-GlcNAcylation contributes to the development of various diseases, including cancers. Accumulating evidence has revealed that higher expression levels of OGT and hyper-O-GlcNAcylation are detected in many cancer types and governs glucose metabolism, proliferation, metastasis, invasion, angiogenesis, migration and drug resistance. In this review, we describe the biological functions and molecular mechanisms of OGT- or O-GlcNAcylation-mediated tumorigenesis. Moreover, we discuss the potential role of O-GlcNAcylation in tumor immunotherapy. Furthermore, we highlight that compounds can target O-GlcNAcylation by regulating OGT to suppress oncogenesis. Taken together, targeting protein O-GlcNAcylation might be a promising strategy for the treatment of human malignancies.

O-GlcNAcylation enhances Reticulon 2 protein stability and its promotive effects on gastric cancer progression

Our previous study indicated that Reticulon 2 (RTN2) was upregulated and facilitated the progression of gastric cancer. Protein O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) is a general feature during tumorigenesis, and regulates protein activity and stability through post-translational modification on serine/threonine. However, the relationship between RTN2 and O-GlcNAcylation have never been determined. In this study, we explored the influence of O-GlcNAcylation on RTN2 expression and its promotive role in gastric cancer. We found that RTN2 interacted with O-GlcNAc transferase (OGT) and was modified by O-GlcNAc. O-GlcNAcylation enhanced RTN2 protein stability via attenuating its lysosomal degradation in gastric cancer cells. Furthermore, our results demonstrated that RTN2-induced activation of ERK signalling was dependent on O-GlcNAcylation. Consistently, the stimulative effects of RTN2 on cellular proliferation and migration were abrogated by OGT inhibition. Tissue microarray with immumohistochemical staining also confirmed that the expression of RTN2 was positively correlated with the level of total O-GlcNAcylation as well as the phosphorylation level of ERK. Besides, combined RTN2 and O-GlcNAc staining intensity could improve predictive accuracy for gastric cancer patients' survival compared with each alone. Altogether, these findings suggest that O-GlcNAcylation on RTN2 was pivotal for its oncogenic functions in gastric cancer. Targeting RTN2 O-GlcNAcylation might provide new ideas for gastric cancer therapies.

Targeting O-GlcNAcylation to overcome resistance to anti-cancer therapies

In cancer cells, metabolic reprogramming is associated with an alteration of the O-GlcNAcylation homeostasis. This post-translational modification (PTM) that attaches O-GlcNAc moiety to intracellular proteins is dynamically and finely regulated by the O-GlcNAc Transferase (OGT) and the O-GlcNAcase (OGA). It is now established that O-GlcNAcylation participates in many features of cancer cells including a high rate of cell growth, invasion, and metastasis but little is known about its impact on the response to therapies. The purpose of this review is to highlight the role of O-GlcNAc protein modification in cancer resistance to therapies. We summarize the current knowledge about the crosstalk between O-GlcNAcylation and molecular mechanisms underlying tumor sensitivity/resistance to targeted therapies, chemotherapies, immunotherapy, and radiotherapy. We also discuss potential benefits and strategies of targeting O-GlcNAcylation to overcome cancer resistance.

Ogt Demonstrated Conspicuous Clinical Significance in Cancers, from Pan-Cancer to Small-Cell Lung Cancer

The clinical progression of small-cell lung cancer (SCLC) remains pessimistic. The aim of the present study was to promote the understanding of the clinical significance and mechanism of O-linked N-acetylglucosamine (GlcNAc) transferase (OGT) in SCLC. Wilcoxon tests, standardized mean difference (SMD), and Kruskal–Wallis tests were utilized to compare OGT level differences among the experimental and control groups. The univariate Cox regression analysis, Kaplan–Meier curves, and receiver operating characteristic curves were applied to determine OGT's clinical relevance in cancers. The Spearman correlation analysis and enrichment analysis were utilized to explore the underlying mechanisms of OGT in cancers. For the first time in the field, we provide an overview of OGT in 32 cancers using a large number of samples (n = 21,196), determining distinct OGT expression in 25 cancers and its prognosis effects in 12 cancers. Furthermore, using 950 samples from multiple sources, upregulated OGT was found in both mRNA and protein levels in SCLC (SMD = 0.93, 95% CI [0.24, 1.63]). Higher OGT levels represented a more unfavorable disease-free interval for SCLC patients (p < 0.001). The research also identified OGT expression as a potential marker for SCLC prediction (sensitivity = 0.79, specificity = 0.86, and AUC = 0.88). The high expression of OGT in SCLC may result from the positive regulation of two transcription factors—DEK and XRN2. We primarily investigated the underlying mechanisms of OGT in SCLC. Herein, based on the analyses from pan-cancer to SCLC, OGT demonstrated conspicuous clinical significance. OGT may be an underlying biomarker for the treatment and identification of some cancers, including SCLC.

O-GlcNAcylation regulation of cellular signaling in cancer

O-GlcNAcylation is a post-translational modification occurring on serine/threonine residues of nuclear and cytoplasmic proteins, mediated by the enzymes OGT and OGA which catalyze the addition or removal of the UDP-GlcNAc moieties, respectively. Structural changes brought by this modification lead to alternations of protein stability, protein-protein interactions, and phosphorylation. Importantly, O-GlcNAcylation is a nutrient sensor by coupling nutrient sensing with cellular signaling. Elevated levels of OGT and O-GlcNAc have been reported in a variety of cancers and has been linked to regulation of multiple cancer signaling pathways. In this review, we discuss the most recent findings on the role of O-GlcNAcylation as a metabolic sensor in signaling pathways and immune response in cancer.

Thymidylate synthase O-GlcNAcylation: a molecular mechanism of 5-FU sensitization in colorectal cancer

Alteration of O-GlcNAcylation, a dynamic posttranslational modification, is associated with tumorigenesis and tumor progression. Its role in chemotherapy response is poorly investigated. Standard treatment for colorectal cancer (CRC), 5-fluorouracil (5-FU), mainly targets Thymidylate Synthase (TS). TS O-GlcNAcylation was reported but not investigated yet. We hypothesize that O-GlcNAcylation interferes with 5-FU CRC sensitivity by regulating TS. In vivo, we observed that combined 5-FU with Thiamet-G (O-GlcNAcase (OGA) inhibitor) treatment had a synergistic inhibitory effect on grade and tumor progression. 5-FU decreased O-GlcNAcylation and, reciprocally, elevation of O-GlcNAcylation was associated with TS increase. In vitro in non-cancerous and cancerous colon cells, we showed that 5-FU impacts O-GlcNAcylation by decreasing O-GlcNAc Transferase (OGT) expression both at mRNA and protein levels. Reciprocally, OGT knockdown decreased 5-FU-induced cancer cell apoptosis by reducing TS protein level and activity. Mass spectrometry, mutagenesis and structural studies mapped O-GlcNAcylated sites on T251 and T306 residues and deciphered their role in TS proteasomal degradation. We reveal a crosstalk between O-GlcNAcylation and 5-FU metabolism in vitro and in vivo that converges to 5-FU CRC sensitization by stabilizing TS. Overall, our data propose that combining 5-FU-based chemotherapy with Thiamet-G could be a new way to enhance CRC response to 5-FU.

O-GlcNAcylation in Chronic Lymphocytic Leukemia and Other Blood Cancers

In the past decade, aberrant O-GlcNAcylation has emerged as a new hallmark of cancer. O-GlcNAcylation is a post-translational modification that results when the amino-sugar β-D-N-acetylglucosamine (GlcNAc) is made in the hexosamine biosynthesis pathway (HBP) and covalently attached to serine and threonine residues in intracellular proteins by the glycosyltransferase O-GlcNAc transferase (OGT). O-GlcNAc moieties reflect the metabolic state of a cell and are removed by O-GlcNAcase (OGA). O-GlcNAcylation affects signaling pathways and protein expression by cross-talk with kinases and proteasomes and changes gene expression by altering protein interactions, localization, and complex formation. The HBP and O-GlcNAcylation are also recognized to mediate survival of cells in harsh conditions. Consequently, O-GlcNAcylation can affect many of the cellular processes that are relevant for cancer and is generally thought to promote tumor growth, disease progression, and immune escape. However, recent studies suggest a more nuanced view with O-GlcNAcylation acting as a tumor promoter or suppressor depending on the stage of disease or the genetic abnormalities, proliferative status, and state of the p53 axis in the cancer cell. Clinically relevant HBP and OGA inhibitors are already available and OGT inhibitors are in development to modulate O-GlcNAcylation as a potentially novel cancer treatment. Here recent studies that implicate O-GlcNAcylation in oncogenic properties of blood cancers are reviewed, focusing on chronic lymphocytic leukemia and effects on signal transduction and stress resistance in the cancer microenvironment. Therapeutic strategies for targeting the HBP and O-GlcNAcylation are also discussed.

Chemo-Sensitization of CD133+ Cancer Stem Cell Enhances the Effect of Mesenchymal Stem Cell Expressing TRAIL in Non-Small Cell Lung Cancer Cell Lines

Simple Summary

The anti-tumor properties of mesenchymal stem cell (MSCs) expressing TNF-related apoptosis inducing ligand (TRAIL) or MSC-TRAIL have been well documented by several reports. However, some tumors are resistant to TRAIL due to the existence of cancer stem cells (CSCs). Chemo-sensitization of tumors and their CSCs has been reported to enhance TRAIL-mediated inhibition. In this study, we examined the effect of pre-treatment using first-line chemotherapies on MSC-TRAIL-induced inhibition in non-small cell lung cancers (NSCLCs)–derived CSCs. We found that these chemotherapies were able to induce a chemo-sensitization effect to the CSC, thus improving the MSC-TRAIL-induced inhibition. We also noticed that the effect of chemo-sensitization was cell type specific and selecting chemotherapies for the right NSCLC subtypes might help in inducing a more meaningful combinatory effect. As such, this study has proven that chemo-sensitization of the CSCs was able to enhance the MSC-TRAIL-induced inhibition in NSCLC cell lines.

Abstract

Pre-clinical studies have demonstrated the efficacy of mesenchymal stem cells (MSCs) expressing tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) or MSC-TRAIL against several tumors. However, due to the existence of cancer stem cells (CSCs), some tumors, including non-small cell lung cancer (NSCLC), exhibit TRAIL resistance. This study was designed to evaluate the capacity of using first-line chemotherapies including cisplatin, 5-fluorouracil (5-FU) and vinorelbine to act as a chemo-sensitizer on CD133+ (prominin-1 positive) CSCs derived from NSCLC cell lines (A549, H460 and H2170) for the purpose of MSC-TRAIL-induced inhibition. We showed that MSC-TRAIL was resistant to all three chemotherapies compared to the NSCLC cell lines, suggesting that the chemotherapies had little effect on MSC-TRAIL viability. Pre-treatment using either cisplatin or 5-FU, but not with vinorelbine, was able to increase the efficacy of MSC-TRAIL to kill the TRAIL-resistant A549-derived CSCs. The study also demonstrated that both 5-FU and vinorelbine were an effective chemo-sensitizer, used to increase the anti-tumor effect of MSC-TRAIL against H460- and H2170-derived CSCs. Furthermore, pre-treatment using cisplatin was noted to enhance the effect of MSC-TRAIL in H460-derived CSCs; however, this effect was not detected in the H2170-derived CSCs. These findings suggest that a pre-treatment using certain chemotherapies in NSCLC could enhance the anti-tumor effect of MSC-TRAIL to target the CSCs, and therefore the combination of chemotherapies and MSC-TRAIL may serve as a novel approach for the treatment of NSCLC.

Recent Developments and Applications of Quantitative Proteomics Strategies for High-Throughput Biomolecular Analyses in Cancer Research

Innovations in medical technology and dedicated focus from the scientific community have inspired numerous treatment strategies for benign and invasive cancers. While these improvements often lend themselves to more positive prognoses and greater patient longevity, means for early detection and severity stratification have failed to keep pace. Detection and validation of cancer-specific biomarkers hinges on the ability to identify subtype-specific phenotypic and proteomic alterations and the systematic screening of diverse patient groups. For this reason, clinical and scientific research settings rely on high throughput and high sensitivity mass spectrometry methods to discover and quantify unique molecular perturbations in cancer patients. Discussed within is an overview of quantitative proteomics strategies and a summary of recent applications that enable revealing potential biomarkers and treatment targets in prostate, ovarian, breast, and pancreatic cancer in a high throughput manner.

O-GlcNAc Transferase - An Auxiliary Factor or a Full-blown Oncogene?

The β-linked N-acetyl-d-glucosamine (GlcNAc) is a posttranslational modification of serine and threonine residues catalyzed by the enzyme O-GlcNAc transferase (OGT). Increased OGT expression is a feature of most human cancers and inhibition of OGT decreases cancer cell proliferation. Antiproliferative effects are attributed to posttranslational modifications of known regulators of cancer cell proliferation, such as MYC, FOXM1, and EZH2. In general, OGT amplifies cell-specific phenotype, for example, OGT overexpression enhances reprogramming efficiency of mouse embryonic fibroblasts into stem cells. Genome-wide screens suggest that certain cancers are particularly dependent on OGT, and understanding these addictions is important when considering OGT as a target for cancer therapy. The O-GlcNAc modification is involved in most cellular processes, which raises concerns of on-target undesirable effects of OGT-targeting therapy. Yet, emerging evidence suggest that, much like proteasome inhibitors, specific compounds targeting OGT elicit selective antiproliferative effects in cancer cells, and can prime malignant cells to other treatments. It is, therefore, essential to gain mechanistic insights on substrate specificity for OGT, develop reagents to more specifically enrich for O-GlcNAc-modified proteins, identify O-GlcNAc "readers," and develop OGT small-molecule inhibitors. Here, we review the relevance of OGT in cancer progression and the potential targeting of this metabolic enzyme as a putative oncogene.