Extracellular matrices (ECMs) are dynamic structures that provide cells not only with a structural
support but, importantly, exhibit significant functional roles in the control of key cellular events such as
adhesion, migration, proliferation, differentiation, and survival. In tumors, matrix effectors such as
proteoglycans (PGs) and matrix metalloproteinases (MMPs) constitute major regulators of the interactions
between tumor cells and their microenvironment and, therefore, they have been identified as potential
molecular targets that are expected to advance the pharmacological treatment of cancer. ECMs composition is
highly affected by cells through intrinsic regulatory mechanisms, such as the ubiquitin-proteasome system
(UPS). Proteasome is a major cellular protease complex that controls the concentration and turnover of
molecules in ECMs, including certain types of PGs, MMPs and collagens, and consequently, in the tumor
microenvironment. Furthermore, proteasome activity is regulated by PG-derived intracellular glycosaminoglycan
moieties revealing a critical inter-dependence of these compounds. Since ECMs renewal and
degradation can be tightly regulated by proteasome activities, its modulation may be considered as a novel
strategy to control the properties of tumor microenvironment. Currently, there are several proteasome inhibitors
targeting distinct molecular pathways either approved or in clinical trials for the treatment of multiple cancers.
In this review, the novel approach of targeting the proteasome to selectively regulate the synthesis and the
bioactivity of certain matrix PGs and MMPs is presented and discussed.
Keywords: Bortezomib, cancer, decorin, extracellular matrix, fibrosis, heparan sulfate, hyaluronan, matrix
metalloproteinases, pharmacological targeting, proteasome inhibitors, proteasome, proteoglycans, tumor
microenvironment, homeostasis, neurodegenerative disorders.
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