High extent of O-GlcNAcylation in breast cancer cells correlates with the levels of HAS enzymes, accumulation of hyaluronan, and poor outcome

Role of glycosylation in breast cancer progression and metastasis: implications for miRNA, EMT and multidrug resistance

Breast cancer (BC) is one of the leading causes of death in women, globally. A variety of biological processes results in metastasis, a poorly understood pathological phenomenon, causing a high relapse rate. Glycosylation, microribonucleic acids (miRNAs) and epithelial to mesenchymal transition (EMT), have been shown to regulate this cascade where tumor cells detach from their primary site, enter the circulatory system and colonize distant sites. Integrated proteomics and glycomics approaches have been developed to probe the molecular mechanism regulating such metastasis. In this review, we describe specific aspects of glycosylation and its interrelation with miRNAs, EMT and multidrug resistance during BC progression and metastasis. We explore various approaches that determine the role of proteomes and glycosylation in BC diagnosis, therapy and drug discovery.

High Levels of Hyaluronic Acid Synthase-2 Mediate NRF2-Driven Chemoresistance in Breast Cancer Cells

Hyaluronic acid (HA), a ligand of CD44, accumulates in some types of tumors and is responsible for tumor progression. The nuclear factor erythroid 2-like 2 (NRF2) regulates cytoprotective genes and drug transporters, which promotes therapy resistance in tumors. Previously, we showed that high levels of CD44 are associated with NRF2 activation in cancer stem like-cells. Herein, we demonstrate that HA production was increased in doxorubicin-resistant breast cancer MCF7 cells (MCF7-DR) via the upregulation of HA synthase-2 (HAS2). HA incubation increased NRF2, aldo-keto reductase 1C1 (AKR1C1), and multidrug resistance gene 1 (MDR1) levels. Silencing of HAS2 or CD44 suppressed NRF2 signaling in MCF7-DR, which was accompanied by increased doxorubicin sensitivity. The treatment with a HAS2 inhibitor, 4-methylumbelliferone (4-MU), decreased NRF2, AKR1C1, and MDR1 levels in MCF7-DR. Subsequently, 4-MU treatment inhibited sphere formation and doxorubicin resistance in MCF7-DR. The Cancer Genome Atlas (TCGA) data analysis across 32 types of tumors indicates the amplification of HAS2 gene is a common genetic alteration and is negatively correlated with the overall survival rate. In addition, high HAS2 mRNA levels are associated with increased NRF2 signaling and poor clinical outcome in breast cancer patients. Collectively, these indicate that HAS2 elevation contributes to chemoresistance and sphere formation capacity of drug-resistant MCF7 cells by activating CD44/NRF2 signaling, suggesting a potential benefit of HAS2 inhibition.

Differential Expression Profiles of Cell-to-Matrix-Related Molecules in Adrenal Cortical Tumors: Diagnostic and Prognostic Implications

The molecular mechanisms of adrenocortical carcinoma development are incompletely defined. De-regulation of cellular-to-extracellular matrix interactions and angiogenesis appear among mechanisms associated to the malignant phenotype. Our aim was to investigate, employing PCR-based array profiling, 157 molecules involved in cell-to-matrix interactions and angiogenesis in a frozen series of 6 benign and 6 malignant adrenocortical neoplasms, to identify novel pathogenetic markers. In 14 genes, a significant dysregulation was detected in adrenocortical carcinomas as compared to adenomas, most of them being downregulated. Three exceptions—hyaluronan synthase 1 (HAS-1), laminin α3 and osteopontin genes—demonstrated an increased expression in adrenocortical carcinomas of 4.46, 4.23 and 20.32-fold, respectively, and were validated by immunohistochemistry on a series of paraffin-embedded tissues, including 20 adenomas and 73 carcinomas. Osteopontin protein, absent in all adenomas, was expressed in a carcinoma subset (25/73) (p = 0.0022). Laminin α3 and HAS-1 were mostly expressed in smooth muscle and endothelial cells of the vascular network of both benign and malignant adrenocortical tumors. HAS-1 was also detected in tumor cells, with a more intense pattern in carcinomas. In this group, strong expression was significantly associated with more favorable clinicopathological features. These data demonstrate that cell-to-matrix interactions are specifically altered in adrenocortical carcinoma and identify osteopontin and HAS-1 as novel potential diagnostic and prognostic biomarkers, respectively, in adrenal cortical tumors.

Fbxl17 is rearranged in breast cancer and loss of its activity leads to increased global O-GlcNAcylation

In cancer, many genes are mutated by genome rearrangement, but our understanding of the functional consequences of this remains rudimentary. Here we report the F-box protein encoded by FBXL17 is disrupted in the region of the gene that encodes its substrate-binding leucine rich repeat (LRR) domain. Truncating Fbxl17 LRRs impaired its association with the other SCF holoenzyme subunits Skp1, Cul1 and Rbx1, and decreased ubiquitination activity. Loss of the LRRs also differentially affected Fbxl17 binding to its targets. Thus, genomic rearrangements in FBXL17 are likely to disrupt SCFFbxl17-regulated networks in cancer cells. To investigate the functional effect of these rearrangements, we performed a yeast two-hybrid screen to identify Fbxl17-interacting proteins. Among the 37 binding partners Uap1, an enzyme involved in O-GlcNAcylation of proteins was identified most frequently. We demonstrate that Fbxl17 binds to UAP1 directly and inhibits its phosphorylation, which we propose regulates UAP1 activity. Knockdown of Fbxl17 expression elevated O-GlcNAcylation in breast cancer cells, arguing for a functional role for Fbxl17 in this metabolic pathway.

Tumor microenvironment and breast cancer survival: combined effects of breast fat, M2 macrophages and hyaluronan create a dismal prognosis

Purpose

Tumor microenvironment, including inflammatory cells, adipocytes and extracellular matrix constituents such as hyaluronan (HA), impacts on cancer progression. Systemic metabolism also influences tumor growth e.g. obesity and type 2 diabetes (T2D) are risk factors for breast cancer. Here, in 262 breast cancer cases, we explored the combined impacts on survival of M2-like tumor associated macrophages (TAMs), the abundance of breast fat visualized as low density in mammograms, and tumor HA, and their associations with T2D.

Methods

Mammographic densities were assessed visually from the diagnostic images and dichotomized into very low density (VLD, density ≤ 10%, “fatty breast”) and mixed density (MID, density > 10%). The amounts of TAMs (CD163+ and CD68+) and tumor HA were determined by immunohistochemistry. The data of T2D was collected from the patient records. Statistical differences between the parameters were calculated with Chi square or Mann–Whitney test and survival analyses with Cox’s model.

Results

A combination of fatty breasts (VLD), abundance of M2-like TAMs (CD163+) and tumor HA associated with poor survival, as survival was 88–89% in the absence of these factors but only 40–47% when all three factors were present (p < 0.001). Also, an association between T2D and fatty breasts was found (p < 0.01). Furthermore, tumors in fatty breasts contained more frequently high levels of M2-like TAMs than tumors in MID breasts (p = 0.01).

Conclusions

Our results demonstrate a dramatic effect of the tumor microenvironment on breast cancer progression. We hypothesize that T2D as well as obesity increase the fat content of the breasts, subsequently enhancing local pro-tumoral inflammation.

Electronic supplementary material

The online version of this article (10.1007/s10549-019-05491-7) contains supplementary material, which is available to authorized users.

Inhibition of the hyaluronan matrix enhances metabolic anticancer therapy by dichloroacetate in vitro and in vivo

Background and Purpose

Aerobic glycolysis is a unique feature of tumour cells that entails several advantages for cancer progression such as resistance to apoptosis. The low MW compound, dichloroacetate, is a pyruvate dehydrogenase kinase inhibitor, which restores oxidative phosphorylation and induces apoptosis in a variety of cancer entities. However, its therapeutic effectiveness is limited by resistance mechanisms. This study aimed to examine the role of the anti‐apoptotic hyaluronan (HA) matrix in this context and to identify a potential add‐on treatment option to overcome this limitation.

Experimental Approach

The metabolic connection between dichloroacetate treatment and HA matrix augmentation was analysed in vitro by quantitative PCR and affinity cytochemistry. Metabolic pathways were analysed using Seahorse, HPLC, fluorophore‐assisted carbohydrate electrophoresis, colourimetry, immunoblots, and immunochemistry. The effects of combining dichloroacetate with the HA synthesis inhibitor 4‐methylumbelliferone was evaluated in 2D and 3D cell cultures and in a nude mouse tumour xenograft regression model by immunoblot, immunochemistry, and FACS analysis.

Key Results

Mitochondrial reactivation induced by dichloroacetate metabolically activated HA synthesis by augmenting precursors as well as O‐GlcNAcylation. This process was blocked by 4‐methylumbelliferone, resulting in enhanced anti‐tumour efficacy in 2D and 3D cell culture and in a nude mouse tumour xenograft regression model.

Conclusions and Implications

The HA rich tumour micro‐environment represents a metabolic factor contributing to chemotherapy resistance. HA synthesis inhibition exhibited pronounced synergistic actions with dichloroacetate treatment on oesophageal tumour cell proliferation and survival in vitro and in vivo suggesting the combination of these two strategies is an effective anticancer therapy.

Knockout of hyaluronan synthase 1, but not 3, impairs formation of the retrocalcaneal bursa

Hyaluronan (HA), a high molecular weight non-sulfated glycosaminoglycan, is an integral component of the extracellular matrix of developing and mature connective tissues including tendon. There are few published reports quantifying HA content during tendon growth and maturation, or detailing its effects on the mechanical properties of the tendon extracellular matrix. Therefore, the goal of the current study was to examine the role of HA synthesis during post-natal skeletal growth and maturation, and its influence on tendon structure and biomechanical function. For this purpose, the morphological, biochemical, and mechanical properties of Achilles tendons from wild type (WT) and hyaluronan synthase 1 and 3 deficient mouse strains (Has1-/- (Has1KO), Has3-/- (Has3KO), and Has1-/- 3-/- (Has1/3KO)) were determined at 4, 8, and 12 weeks of age. Overall, HAS-deficient mice did not show any marked differences from WT mice in Achilles tendon morphology or in the HA and chondroitin/dermatan sulfate (CS/DS) contents. However, HAS1-deficiency (in the single or Has1/3 double KO) impeded post-natal formation of the retrocalcaneal bursa, implicating HAS1 in regulating HA metabolism by cells lining the bursal cavity. Together, these data suggest that HA metabolism via HAS1 and HAS3 does not markedly influence the extracellular matrix structure or function of the tendon body, but plays a role in the formation/maintenance of peritendinous bursa. Additional studies are warranted to elucidate the relationship of HA and CS/DS metabolism to tendon healing and repair in vivo. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2622-2632, 2018.

O-GlcNAc Modification During Pregnancy: Focus on Placental Environment

Successful placentation is a key event for fetal development, which commences following embryo implantation into the uterine wall, eliciting decidualization, placentation, and remodeling of blood vessels to provide physiological exchange between embryo-fetus and mother. Several signaling pathways are recruited to modulate such important processes and specific proteins that regulate placental function are a target for the glycosylation with O-linked β-N-acetylglucosamine (O-GlcNAc), or O-GlcNAcylation. This is a reversible post-translational modification on nuclear and cytoplasmic proteins, mainly controlled by O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). O-GlcNAcylation has been implicated as a modulator of proteins, both in physiological and pathological conditions and, more recently, O-GlcNAc has also been shown to be an important modulator in placental tissue. In this mini-review, the interplay between O-GlcNAcylation of proteins and placental function will be addressed, discussing the possible implications of this post-translational modification through placental development and pregnancy.

Regulation of hyaluronan biosynthesis and clinical impact of excessive hyaluronan production

The tightly regulated biosynthesis and catabolism of the glycosaminoglycan hyaluronan, as well as its role in organizing tissues and cell signaling, is crucial for the homeostasis of tissues. Overexpression of hyaluronan plays pivotal roles in inflammation and cancer, and markedly high serum and tissue levels of hyaluronan are noted under such pathological conditions. This review focuses on the complexity of the regulation at transcriptional and posttranslational level of hyaluronan synthetic enzymes, and the outcome of their aberrant expression and accumulation of hyaluronan in clinical conditions, such as systemic B-cell cancers, aggressive breast carcinomas, metabolic diseases and virus infection.

UDP-sugar accumulation drives hyaluronan synthesis in breast cancer

Increased uptake of glucose, a general hallmark of malignant tumors, leads to an accumulation of intermediate metabolites of glycolysis. We investigated whether the high supply of these intermediates promotes their flow into UDP-sugars, and consequently into hyaluronan, a tumor-promoting matrix molecule. We quantified UDP-N-Acetylglucosamine (UDP-GlcNAc) and UDP-glucuronic acid (UDP-GlcUA) in human breast cancer biopsies, the levels of enzymes contributing to their synthesis, and their association with the hyaluronan accumulation in the tumor. The content of UDP-GlcUA was 4 times, and that of UDP-GlcNAc 12 times higher in the tumors as compared to normal glandular tissue obtained from breast reductions. The surge of UDP-GlcNAc correlated with an elevated mRNA expression of glutamine-fructose-6-phosphate aminotransferase 2 (GFAT2), one of the key enzymes in the biosynthesis of UDP-GlcNAc, and the expression of GFAT1 was also elevated. The contents of both UDP-sugars strongly correlated with tumor hyaluronan levels. Interestingly, hyaluronan content did not correlate with the mRNA levels of the hyaluronan synthases (HAS1-3), thus emphasizing the role of the UDP-sugar substrates of these enzymes. The UDP-sugars showed a trend to higher levels in ductal vs. lobular cancer subtypes. The results reveal for the first time a dramatic increase of UDP-sugars in breast cancer, and suggest that their high supply drives the accumulation of hyaluronan, a known promoter of breast cancer and other malignancies. In general, the study shows how the disturbed glucose metabolism typical for malignant tumors can influence cancer microenvironment through UDP-sugars and hyaluronan.

O-GlcNAcylation in women's cancers: breast, endometrial and ovarian

O-GlcNAcylation is emerging as a critical regulatory post-translational modification, impacting proteins that regulate cell division, apoptosis, metabolism, cell signaling, and transcription. O-GlcNAc also affects biological homeostasis by integrating information coming from the environment, such as nutrient conditions and extracellular stimuli, with cellular response. Aberrant O-GlcNAc modulation has been linked to metabolic and neurodegenerative diseases, as well as cancers. While many studies have highlighted the significance of O-GlcNAc in cancer, a specific function for O-GlcNAc during tumorigenesis remains unclear and seems to differ according to cancer type. Herein, we review the impact of altered O-GlcNAcylation in breast, ovarian and uterine cancers.