4-Methylumbelliferone Treatment and Hyaluronan Inhibition as a Therapeutic Strategy in Inflammation, Autoimmunity, and Cancer

Askew

Journal of Biological Chemistry

et al. 2016

Depletion of the cartilage proteoglycan aggrecan is one of the earliest events that occurs in association with osteoarthritis. This loss is often accompanied by a coordinate loss in another glycosaminoglycan, hyaluronan. Chondrocytes experimentally depleted of cell-associated hyaluronan respond by switching to a pro-catabolic metabolism that includes enhanced production of endogenous inflammatory mediators and increased synthesis of matrix metalloproteinases. Hyaluronan turnover is also increased. Together, such a response provides for possible establishment of a self-perpetuating spiral of events that maintains or prolongs the pro-catabolic state. Chondrocytes or cartilage can also be activated by treatment with pro-inflammatory cytokines and mediators such as IL-1␤, TNF␣, LPS, fibronectin fragments, and hyaluronan oligosaccharides. To determine the mechanism of chondrocyte activation due to hyaluronan loss, a depletion method was required that did not include degrading the hyaluronan. In recent years, several laboratories have used the coumarin derivative, 4-methylumbelliferone, as a potent inhibitor of hyaluronan biosynthesis, due in part to its ability to sequester intracellular UDP-glucuronic acid and inhibition of hyaluronan synthase transcription. However, contrary to our expectation, although 4-methylumbelliferone was indeed an inhibitor of hyaluronan biosynthesis, this depletion did not give rise to an activation of chondrocytes or cartilage. Rather, 4-methylumbelliferone directly and selectively blocked gene products associated with the pro-catabolic metabolic state of chondrocytes and did so through a mechanism preceding and independent of hyaluronan inhibition. These data suggest that 4-methylumbelliferone has additional useful applications to block pro-inflammatory cell activation events but complicates how it is used for defining functions related to hyaluronan.The pronounced loss of aggrecan from articular cartilage is an early critical event associated with osteoarthritis (OA) 2 (1, 2). Aggrecan turnover within the extracellular matrix occurs due to the enhanced activity of endoproteinases such as a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) 4 (3, 4) and 5 (5, 6) as well as other matrix metalloproteinases (MMPs) (7)(8)(9)(10)(11). In addition to aggrecan, a significant loss of hyaluronan (HA) is also observed in human OA cartilage as compared with normal human cartilage (12,13). A marked depletion of HA was also observed in articular cartilage damaged experimentally, such as in the anterior cruciate ligament transection model of OA (14) and a reduced-loading, splint immobilization model (15) in dogs. In our studies, cultured explants of human articular cartilage treated with IL-1␣ displayed a loss of HA within the superficial and upper middle layers of cartilage, the same layers in which aggrecan loss occurred (16). Other studies on cytokine-stimulated cartilage explants suggested that HA is lost from the cartilage (17,18), and other studies revealed that the HA is lost...

Section: Resultsmentioning

confidence: 69%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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4-Methylumbelliferone Diminishes Catabolically Activated Articular Chondrocytes and Cartilage Explants via a Mechanism Independent of Hyaluronan Inhibition

Askew

Journal of Biological Chemistry

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

“…The coumarin derivative 4-methylumbelliferone (4-MU, Hymecromone) in particular has been shown to inhibit HA production in vitro and in vivo (reviewed in ref. 19). 4-MU functions as a competitive substrate for UDP-glucuronyltransferase, an enzyme involved in HA synthesis (Fig.…”

mentioning

confidence: 99%

Hyaluronan synthesis is necessary for autoreactive T-cell trafficking, activation, and Th1 polarization

Kuipers

Rieck

Gurevich

et al. 2016

Self Cite

The extracellular matrix polysaccharide hyaluronan (HA) accumulates at sites of autoimmune inflammation, including white matter lesions in multiple sclerosis (MS), but its functional importance in pathogenesis is unclear. We have evaluated the impact of 4-methylumbelliferone (4-MU), an oral inhibitor of HA synthesis, on disease progression in the experimental autoimmune encephalomyelitis (EAE) mouse model of MS. Treatment with 4-MU decreases the incidence of EAE, delays its onset, and reduces the severity of established disease. 4-MU inhibits the activation of autoreactive T cells and prevents their polarization toward a Th1 phenotype. Instead, 4-MU promotes polarization toward a Th2 phenotpye and induction of Foxp3+ regulatory T cells. Further, 4-MU hastens trafficking of T cells through secondary lymphoid organs, impairs the infiltration of T cells into the CNS parenchyma, and limits astrogliosis. Together, these data suggest that HA synthesis is necessary for disease progression in EAE and that treatment with 4-MU may be a potential therapeutic strategy in CNS autoimmunity. Considering that 4-MU is already a therapeutic, called hymecromone, that is approved to treat biliary spasm in humans, we propose that it could be repurposed to treat MS.

“…In concordance with increased expression of HAS2, bladder cancer cells with AGL loss presented increased levels of HA synthesis (15). To further validate the significance of HAS2-driven HA synthesis in AGL low bladder cancer, genetic knockdown of the HAS2 gene and treatment with HA synthesis inhibitor, 4-methylumbelliferone (4MU) (20), was carried out in bladder cancer cells with and without AGL followed by in vitro and in vivo growth assays. Knockdown of HAS2 resulted in loss of anchorage-independent growth, reduced proliferation and xenograft tumor growth of bladder cancer cells without AGL expression (15).…”

Section: Agl and Hyaluronic Acid Synthesismentioning

confidence: 99%

Involvement of glycogen debranching enzyme in bladder cancer

Weinhaus

Guin

2017

Biomedical Reports

Abstract. Bladder cancer is the most common malignancy of the urinary system, however the molecular pathways underlying this disease are incompletely understood. To understand new regulators of bladder cancer progression, the authors carried out a functional genomic screen which identified glycogen debranching enzyme (AGL) as a novel regulator of bladder cancer growth. Glycogen debranching enzyme is involved in glycogen breakdown and germline loss of function mutation of this gene leads to glycogen storage disease type III. To the best of the authors' knowledge, the present study is the first to demonstrate that loss of AGL leads to aggressive bladder tumor growth. AGL mRNA and protein expression in bladder tumors serve as a prognostic marker for patients. Interestingly, AGL's participation in regulating tumor growth is independent of its enzymatic function and involvement with glycogen metabolism in general. Detailed metabolomics and transcriptomic analysis indicated that increases in glucose metabolism, glycine synthesis driven by serine hydroxymethyltransferase 2 and increases in hyaluronic acid synthase 2-driven HA synthesis are major contributors of aggressive bladder tumor growth with loss of AGL. However, the detailed mechanism of how AGL regulates the above mentioned metabolic and genetic pathways is unknown and is being investigated. The present review focuses on AGL's involvement in bladder cancer.