br Table Primers for Real
Table 1. Primers for Real-Time RT-PCR
Inventoried primer list of RT-PCR reactions.
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Advanced Drug Delivery Reviews xxx (2019) xxx
Contents lists available at ScienceDirect
Advanced Drug Delivery Reviews
Cathepsin-sensitive nanoscale drug delivery systems for cancer therapy and other diseases
Divya Dheer a,b,c, Julien Nicolas a, , Ravi Shankar b,c,
a Institut Galien Paris-Sud, Univ Paris-Sud, UMR CNRS 8612, Faculté de Pharmacie, 5 rue Jean-Baptiste Clément, F-92296 Châtenay-Malabry Cedex, France
b Bio-organic Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Jammu 180001, India
c Academy of Scientific and Innovative Research (AcSIR), CSIR-IIIM, Jammu Campus, Jammu 180001, India
Available online xxxx
Cathepsins are an important category of enzymes that have attracted great attention for the delivery of drugs to improve the therapeutic outcome of a broad range of nanoscale drug delivery systems. These proteases can be utilized for instance through actuation of polymer-drug conjugates (e.g., triggering the drug release) to bypass limitations of many drug candidates. A substantial amount of work has been witnessed in the design and the evaluation of Cathepsin-sensitive drug delivery systems, especially based on the tetra-peptide sequence (Gly-Phe-Leu-Gly, GFLG) which has been extensively used as a spacer that can be cleaved in the presence of Ca-thepsin B. This Review Article will give an in-depth overview of the design and the biological evaluation of Cathepsin-sensitive drug delivery systems and their application in different pathologies including cancer before discussing Cathepsin B-cleavable prodrugs under clinical trials.
Cathepsins are widely known proteolytic enzymes whose main function is to degrade proteins or peptides . Nevertheless, this per-ception has changed over the past many years as they are being consid-ered as important signaling molecules playing different crucial roles [2,3]. There are dozens of Cathepsins which are classified according to their structure, catalytic mechanism and substrate. Based on the human genome draft sequence, the main Cathepsin categories are ser-ine (Cathepsin A and G), aspartic (Cathepsin D and E) and lysosomal cysteine proteases (Cathepsin B,C,F,H,K,L1,L2/V,O,S,W,X/Z) [4,5]. They have multiple functions, as one finds digestive proteases (present in sa-liva, stomach and intestines) for food processing inside the gastrointes-tinal tract (GIT), lysosomal proteases for intracellular housekeeping or caspases for transduction of one-way signal in apoptosis [6–8]. Interest-ingly, lysosomal Cathepsins (i.e., intracellular enzymes) have been widely involved in drug targeting as they require a slightly acidic envi-ronment to exhibit optimal enzymatic activity [9–11]. Given the fea-tures of disease-associated proteolysis (i.e., cleavage of amide bond), different types of prodrugs, nanocarriers, biomaterials or probes, have been designed and synthesized to exert their activity in endosomal/
Corresponding author at: Bio-organic Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Jammu 180001, India E-mail addresses: [email protected] (J. Nicolas), [email protected] (R. Shankar).
lysosomal compartments [12–14]. For instance, Cathepsins can induce the release of active ingredients from nanocarriers, chemically or phys-ically, leading to enhanced therapeutic activity or in situ imaging sensi-tivity . Kopecek, Duncan and others have shown the importance of protease-cleavable linkers, especially those sensitive to Cathepsin B, in polymer-based, nanoscale drug delivery constructs for enhancing the in vivo delivery of drugs to tumor tissues [16–18].
Cysteine cathepsins and their substrate interaction have been well-identified on the basis of papain (Carica papaya) used as a model of ly-sosomal proteases, as first introduced by Schechter and Berger . In this model, the substrate residues (P) as well as the subsites (S) were given nomenclature based on their position bonded to the protease sur-face. Later, this model was revisited by Turk et al.  who showed that the subsites were positioned on the left-hand side (i.e., S2’, S1 and S3) along with right-hand side of the active site (i.e., S1’ and S2), and further composed of two L-domain loops consisting of Gln-19–Cys-25 as well as Arg-59–Tyr-67 residues and two R-domain loops consisting of Leu-134–His-159 as well as Asn-175–Ser-205 residues (Fig. 1) .