Plasmin-Binding Tripeptide-Decorated Liposomes Loading Pyrazolo[3,4‑<i>d</i>]pyrimidines for Targeting Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most fatal cancer types worldwide. HCC cells were proved to overexpress c-Src and Sgk1, a tyrosine and a serine-threonine kinase, respectively, whose role is crucial for the development and progression of the tumor. Pyrazolo­[3,4-<i>d</i>]­pyrimidine derivatives are a class of tyrosine kinase inhibitors that have shown good activity against HepG2. HCC cells were also proved to overexpress plasmin, which is localized on the cell surface bound to its receptors. In this study, a tripeptide with sequence d-Ala-Phe-Lys, which binds a specific reactive site of plasmin, was synthesized and characterized. This tripeptide was used to decorate liposomes encapsulating three selected pyrazolo­[3,4-<i>d</i>]­pyrimidines. Liposomes bearing tripeptide have been characterized, not showing remarkable differences with respect to the corresponding tripeptide-free liposomes. <i>In vitro</i> HepG2 cell uptake profiles and cytotoxicities showed that the presence of the tripeptide on the liposomal membrane surface improves the cell-penetrating ability of liposomes and increases the activity of two of the three tested compounds

Identification of New Fyn Kinase Inhibitors Using a FLAP-Based Approach

The abnormal activity of Fyn tyrosine kinase has been shown to be related to various human cancers. Furthermore, its involvement in signaling pathways that lead to severe pathologies, such as Alzheimer’s and Parkinson’s diseases, has also been demonstrated, thus making Fyn an attractive target for the discovery of potential novel therapeutics for brain pathologies and tumors. In this study we evaluated the reliability of various screening approaches based on the FLAP software. By the application of the best procedure, the virtual screening workflow was used to filter the Gold and Platinum database from Asinex to identify new Fyn inhibitors. Enzymatic assays revealed that among the eight top-scoring compounds five proved to efficiently inhibit Fyn activity with IC₅₀ values in the micromolar range. These results demonstrate the validity of the methodologies we followed. Furthermore, the five active compounds herein described may be considered as interesting leads for the development of new and more efficient Fyn inhibitors

In Silico Identification and Biological Evaluation of Novel Selective Serum/Glucocorticoid-Inducible Kinase 1 Inhibitors Based on the Pyrazolo-Pyrimidine Scaffold

The serum/glucocorticoid-inducible kinase 1 (Sgk1) has demonstrated antiapoptotic function and the capability to regulate cell survival, proliferation, and differentiation. A pivotal role of Sgk1 in carcinogenesis and in resistance to anticancer therapy has been suggested. With the aim of identifying new Sgk1 modulators, 322 pyrazolo-pyrimidine derivatives have been virtually screened with respect to a crystallographic model of Sgk1. The top five ranked compounds have been evaluated demonstrating Sgk1 inhibition in vitro and selectivity compared to RAC-alpha serine/threonine-protein kinase (Akt1)

Design, Synthesis, and Biological Evaluation of Pyrazolo[3,4‑<i>d</i>]pyrimidines Active in Vivo on the Bcr-Abl T315I Mutant

Starting from our in-house library of pyrazolo­[3,4-<i>d</i>]­pyrimidines, a cross-docking simulation was conducted on Bcr-Abl T315I mutant. Among the selected compounds (<b>2a</b>–<b>e</b>), the 4-bromo derivative <b>2b</b> showed the best activity against the Bcr-Abl T315I mutant. Deeper computational studies highlighted the importance of the bromine atom in the para position of the N1 side chain phenyl ring for the interaction with the T315I mutant. A series of 4-bromo derivatives was thus synthesized and biologically evaluated. Compound <b>2j</b> showed a good balance of different ADME properties, high activity in cell-free assays, and a submicromolar potency against T315I Bcr-Abl expressing cells. In addition, it was converted into a water-soluble formulation by liposome encapsulation, preserving a good activity on leukemic T315I cells and avoiding the use of DMSO as solubilizing agent. In vivo studies on mice inoculated with 32D-T315I cells and treated with <b>2j</b> showed a more than 50% reduction in tumor volumes

Combining X‑ray Crystallography and Molecular Modeling toward the Optimization of Pyrazolo[3,4‑<i>d</i>]pyrimidines as Potent c‑Src Inhibitors Active in Vivo against Neuroblastoma

c-Src is a tyrosine kinase belonging to the Src-family kinases. It is overexpressed and/or hyperactivated in a variety of cancer cells, thus its inhibition has been predicted to have therapeutic effects in solid tumors. Recently, the pyrazolo­[3,4-<i>d</i>]­pyrimidine <b>3</b> was reported as a dual c-Src/Abl inhibitor. Herein we describe a multidisciplinary drug discovery approach for the optimization of the lead <b>3</b> against c-Src. Starting from the X-ray crystal structure of c-Src in complex with <b>3</b>, Monte Carlo free energy perturbation calculations were applied to guide the design of c-Src inhibitors with improved activities. As a result, the introduction of a <i>meta</i> hydroxyl group on the C4 anilino ring was computed to be particularly favorable. The potency of the synthesized inhibitors was increased with respect to the starting lead <b>3</b>. The best identified compounds were also found active in the inhibition of neuroblastoma cell proliferation. Furthermore, compound <b>29</b> also showed in vivo activity in xenograft model using SH-SY5Y cells

Prodrugs of Pyrazolo[3,4‑<i>d</i>]pyrimidines: From Library Synthesis to Evaluation as Potential Anticancer Agents in an Orthotopic Glioblastoma Model

Pyrazolo­[3,4-<i>d</i>]­pyrimidines are potent protein kinase inhibitors with promising antitumor activity but suboptimal aqueous solubility, consequently worth being further optimized. Herein, we present the one-pot two-step procedure for the synthesis of a set of pyrazolo­[3,4-<i>d</i>]­pyrimidine prodrugs (<b>1a</b>−<b>8a</b> and <b>9a</b>−<b>e</b>) with higher aqueous solubility and enhanced pharmacokinetic and therapeutic properties. ADME studies demonstrated for the most promising prodrugs a better aqueous solubility, a favorable hydrolysis in human and murine serum, and an increased ability to cross cell membranes with respect to the parental drugs, explaining their better 24 h <i>in vitro</i> cytotoxicity against human glioblastoma U87 cell line. Finally, the <b>4–4a</b> couple of drug/prodrug was also evaluated <i>in vivo</i>, revealing a profitable pharmacokinetic profile of the prodrug associated with a good efficacy. The application of the prodrug approach demonstrated to be a successful strategy for improving aqueous solubility of the parental drugs, determining a positive impact also in their biological efficacy