Multiple Topoisomerase I (TopoI), Topoisomerase II (TopoII) and Tyrosyl-DNA Phosphodiesterase (TDP) inhibitors in the development of anticancer drugs

DNA Topoisomerases (Topos) are ubiquitous nuclear enzymes involved in regulating the topological state of DNA and, in eukaryotic organisms, Topos can be classified into two structurally and functionally different main classes: TopoI and TopoII. Both these enzymes proved to be excellent targets of clinically significant classes of anticancer drugs. Actually, TopoI or II inhibitors show considerable wide spectrum antitumor activities, an important feature to be included in many chemotherapeutic protocols. Despite their clinical efficacy, the use of inhibitors targeting only one of the two enzymes can increase the levels of the other one, favouring the onset of unwanted phenomena such as drug resistance. Therefore, targeting both TopoI and TopoII can reduce the probability of developing resistance, as well as side effects thanks to the use of lower doses, given the synergistic effect of the dual activity. Moreover, since drug resistance is also due to DNA repair systems such as tyrosyl-DNA phosphodiesterases I and II, inhibiting Topoisomerases concomitantly to Tyrosyl-DNA phosphodiesterase enzymes could allow more efficient and safe drugs. This review represents an update of previous works reporting about dual TopoI and TopoII inhibitors, but also an overview of the new strategy regarding the development of derivatives able to simultaneously inhibit Topo and TDP enzymes, with particular attention to structure-affinity relationship studies. The newly collected de-rivatives are described focusing attention on their chemical structures and their biological profiles. The final aim is to highlight the structural requirements necessary for the development of potent multiple modulators of these targets, thus providing new potential antitumor agents for the clinical usage

Novel positive allosteric modulators of A2B adenosine receptor acting as bone mineralisation promoters

Small-molecules acting as positive allosteric modulators (PAMs) of the A2B adenosine receptor (A2B AR) could potentially represent a novel therapeutic strategy for pathological conditions characterised by altered bone homeostasis, including osteoporosis. We investigated a library of compounds (4-13) exhibiting different degrees of chemical similarity with three indole derivatives (1-3), which have been recently identified by us as PAMs of the A2B AR able to promote mesenchymal stem cell differentiation and bone formation. Evaluation of mineralisation activity of 4-13 in the presence and in the absence of the agonist BAY60-6583 allowed the identification of lead compounds with therapeutic potential as anti-osteoporosis agents. Further biological characterisation of one of the most performing compounds, the benzofurane derivative 9, confirmed that such a molecule behaves as PAM of the A2B AR

Sintesi di nuovi potenziali inibitori duali MET e SMO per la terapia anticancro

I tumori sono la principale causa di morte al mondo dopo le malattie cardiovascolari. Le terapie attualmente utilizzate per il trattamento anticancro sono chirurgia, radioterapia, chemioterapia, scelte in base al tipo di tumore e allo stadio in cui esso si trova. Recentemente sono stati studiati approcci terapeutici alternativi nel tentativo di ridurre gli effetti collaterali: tra questi, le “terapie mirate” costituiscono una delle strategie più innovative. Queste rappresentano uno dei più importanti strumenti della medicina personalizzata; infatti la cura non è più scelta solo in base alla sede di sviluppo del tumore e al suo stato di avanzamento, ma anche in relazione alle sue caratteristiche molecolari, che possono essere diverse da paziente a paziente. L’aspetto peculiare risiede nell’identificazione di specifiche proteine o target molecolari che siano diversamente espressi o alterati nelle cellule tumorali rispetto alle cellule sane, e che quindi possano costituire nuovi bersagli terapeutici per la ricerca in medicinal chemistry. In questo contesto gli inibitori tirosin-chinasici del recettore EGFR (recettore del fattore di crescita epidermico) hanno fornito significativi miglioramenti nelle terapie antitumorali. Tuttavia, la resistenza a questi agenti si manifesta frequentemente e risulta essere correlata sia al pathway Hedgehog che porta all’attivazione del recettore Smoothened (SMO), sia all’attivazione della cascata del recettore tirosinchinasico MET, anche chiamato recettore del fattore di crescita degli epatociti (HGFR). Il progetto di ricerca svolto nel corso di questa tesi sperimentale prevede la sintesi di piccole molecole organiche che siano potenzialmente in grado di inibire entrambi i target MET e SMO, producendo un sinergico effetto antiproliferativo. La progettazione razionale dei nuovi composti è stata effettuata sulla base della struttura di un inibitore duale MET-SMO lead identificato mediante uno studio di virtual screening, con lo scopo finale di ottenere derivati più potenti in termini di effetto antitumorale

Design and synthesis of novel small molecules as anticancer agents.

Cancer is an increasing worldwide emergency, and its incidence and mortality will double in the next twenty years. Thus, it seems to be clear that we need new and more effective pharmacological therapies. This pathology is a set of evolving diseases that differently respond to treatments. It is a multifactorial process characterized by altered function of several proteins, and which involves numerous pathways of various nature. Hence, research is continuously looking for different solutions for fighting tumours. Accordingly, this PhD thesis aims at designing and developing small molecules targeting receptor or enzymes implicated in cancer. Firstly, we focused on the development of molecules capable of selectively inhibiting human Carbonic Anhydrase enzymes IX and XII, also known as the tumour-associated isoforms. Indeed, these enzymes actively support the metastatic spread of tumour cells, and they are highly overexpressed in numerous and different tumours (including renal, breast, ovarian, pancreatic colorectal, and gastrointestinal carcinoma). In addition, this PhD thesis focused on fighting specific forms of cancer, namely glioblastoma (GBM) and multiple myeloma (MM). These are rare forms of cancer, very aggressive and difficult to attack. Although therapies slow down the disease progression and symptoms, to date, the treatment of these tumours is very difficult. Finally, this work focused on immunotherapy; a revolutionary approach able to arm the patient's immune system against cancer cells. Specifically, we concentrated on the PD1-PDL1 interaction, one of the most important immune checkpoints. Indeed, PDL1 is upregulated on the surface of cancer cells, for this reason, interfering with the PD-1/PD-L1 interplay represents an attractive strategy in cancer therapy

The Alpha Keto Amide Moiety as a Privileged Motif in Medicinal Chemistry: Current Insights and Emerging Opportunities

Over the years, researchers in drug discovery have taken advantage of the use of privileged structures to design innovative hit/lead molecules. The α-ketoamide motif is found in many natural products, and it has been widely exploited by medicinal chemists to develop compounds tailored to a vast range of biological targets, thus presenting clinical potential for a plethora of pathological conditions. The purpose of this perspective is to provide insights into the versatility of this chemical moiety as a privileged structure in drug discovery. After a brief analysis of its physical-chemical features and synthetic procedures to obtain it, α-ketoamide-based classes of compounds are reported according to the application of this motif as either a nonreactive or reactive moiety. The goal is to highlight those aspects that may be useful to understanding the perspectives of employing the α-ketoamide moiety in the rational design of compounds able to interact with a specific target

Dual Targeting Topoisomerase/G-Quadruplex Agents in Cancer Therapy—An Overview

Topoisomerase (Topo) inhibitors have long been known as clinically effective drugs, while G-quadruplex (G4)-targeting compounds are emerging as a promising new strategy to target tumor cells and could support personalized treatment approaches in the near future. G-quadruplex (G4) is a secondary four-stranded DNA helical structure constituted of guanine-rich nucleic acids, and its stabilization impairs telomere replication, triggering the activation of several protein factors at telomere levels, including Topos. Thus, the pharmacological intervention through the simultaneous G4 stabilization and Topos inhibition offers a new opportunity to achieve greater antiproliferative activity and circumvent cellular insensitivity and resistance. In this line, dual ligands targeting both Topos and G4 emerge as innovative, efficient agents in cancer therapy. Although the research in this field is still limited, to date, some chemotypes have been identified, showing this dual activity and an interesting pharmacological profile. This paper reviews the available literature on dual Topo inhibitors/G4 stabilizing agents, with particular attention to the structure–activity relationship studies correlating the dual activity with the cytotoxic activity

Indol-3-ylglyoxylamide as Privileged Scaffold in Medicinal Chemistry

In recent years, indolylglyoxylamide-based derivatives have received much attention due to their application in drug design and discovery, leading to the development of a wide array of compounds that have shown a variety of pharmacological activities. Combining the indole nucleus, already validated as a "privileged structure," with the glyoxylamide function allowed for an excellent template to be obtained that is suitable to a great number of structural modifications aimed at permitting interaction with specific molecular targets and producing desirable therapeutic effects. The present review provides insight into how medicinal chemists have elegantly exploited the indolylglyoxylamide moiety to obtain potentially useful drugs, with a particular focus on compounds exhibiting activity in in vivo models or reaching clinical trials. All in all, this information provides exciting new perspectives on existing data that can be useful in further design of indolylglyoxylamide-based molecules with interesting pharmacological profiles. The aim of this report is to present an update of collection data dealing with the employment of this moiety in the rational design of compounds that are able to interact with a specific target, referring to the last 20 years

Tetrahydroquinazole-based secondary sulphonamides as carbonic anhydrase inhibitors: synthesis, biological evaluation against isoforms I, II, IV, and IX, and computational studies

A library of variously decorated N-phenyl secondary sulphonamides featuring the bicyclic tetrahydroquinazole scaffold was synthesised and biologically evaluated for their inhibitory activity against human carbonic anhydrase (hCA) I, II, IV, and IX. Of note, several compounds were identified showing submicromolar potency and excellent selectivity for the tumour-related hCA IX isoform. Structure–activity relationship data attained for various substitutions were rationalised by molecular modelling studies in terms of both inhibitory activity and selectivity

A cyanine-based NIR fluorescent Vemurafenib analog to probe BRAFV600E in cancer cells

: BRAF represents one of the most frequently mutated protein kinase genes and BRAFV600E mutation may be found in many types of cancer, including hairy cell leukemia (HCL), anaplastic thyroid cancer (ATC), colorectal cancer and melanoma. Herein, a fluorescent probe, based on the structure of the highly specific BRAFV600E inhibitor Vemurafenib (Vem, 1) and featuring the NIR fluorophore cyanine-5 (Cy5), was straightforwardly synthesized and characterized (Vem-L-Cy5, 3), showing promising spectroscopic properties. Biological validation in BRAFV600E-mutated cancer cells evidenced the ability of 3 to penetrate inside the cells, specifically binding to its elective target BRAFV600E with high affinity, and inhibiting MEK phosphorylation and cell growth with a potency comparable to that of native Vem 1. Taken together, these data highlight Vem-L-Cy5 3 as a useful tool to probe BRAFV600E mutation in cancer cells, and suitable to acquire precious insights for future developments of more informed BRAF inhibitors-centered therapeutic strategies

A mixed valence diruthenium (II, III) complex endowed with high stability: from experimental evidence to theoretical interpretation

We report here on the synthesis and multi-technique characterization of [Ru2Cl((2-phenylindol-3-yl)glyoxyl-L-leucine-Lphenylalanine) 4] a novel diruthenium (II,III) complex obtained reacting [Ru2(μ-O2CCH3)4Cl] with a dual indolylglyoxylyl dipeptide anticancer agent. We soon realised that the compound is very stable in several different conditions including aqueous buffers or organic solvents. It is also completely unreactive toward proteins. The high stability is also suggested by cellular experiments in a glioblastoma cell line. Indeed, while the parent ligand exerts high cytotoxic effects in the low μM range, the complex is completely non-cytotoxic against the same line, most probably because of the lack of ligand release. To investigate the reasons for such high stability, we carried out DFT calculations that are fully consistent with the experimental findings. Results highlight that the stability of [Ru2Cl((2-phenylindol-3-yl)glyoxyl-L-leucine-L-phenylalanine)4] relies on the nature of the ligand, including its steric hindrance that prevents the reaction of any nucleophilic group with the Ru2 core. The ligand displacement is the key step to allow the reactivity with biological targets of metal-based prodrugs. Accordingly, we discuss the implications of some important aspects that should be considered when active molecules are chosen as ligand for the synthesis of paddle-wheels like complexes with medicinal applications