Si113-prodrugs selectively activated by plasmin against hepatocellular and ovarian carcinoma

Unraveling the Potential of SGK1 in Osteoporosis: From Molecular Mechanisms to Therapeutic Targets

Osteoporosis (OP) is a prevalent metabolic bone disease, with several million cases of fractures resulting from osteoporosis worldwide each year. This phenomenon contributes to a substantial increase in direct medical expenditures and poses a considerable socioeconomic burden. Despite its prevalence, our understanding of the underlying mechanisms remains limited. Recent studies have demonstrated the involvement of serum glucocorticoid-regulated protein kinase 1 (SGK1) in multiple signaling pathways that regulate bone metabolism and its significant role in the development of osteoporosis. Therefore, it is of great significance to deeply explore the mechanism of SGK1 in osteoporosis and its therapeutic potential. In this paper, we present a comprehensive review of the structure and activation mechanism of SGK1, its biological function, the role of SGK1 in different types of osteoporosis, and the inhibitors of SGK1. The aim is to comprehensively assess the latest research progress with regards to SGK1's role in osteoporosis, clarify its role in the regulation of bone metabolism and its potential as a therapeutic target, and lay the foundation for the development of novel therapeutic strategies and personalized treatment in the future. Furthermore, by thoroughly examining the interactions between SGK1 and other molecules or signaling pathways, potential biomarkers may be identified, thereby enhancing the efficacy of early screening and intervention for osteoporosis.

Hit to lead optimization of the 4-trifluoromethylquinoline derivatives as novel SGK1 inhibitors with potent anti-prostate cancer activity

Prostate cancer (PCa) remains a significant health concern for males, and serum/glucocorticoid-regulated kinase-1 (SGK1) plays a crucial role in its pathogenesis. This provides a promising target for the development of novel therapies against PCa. Herein, we reported the structural optimization of the hit compound H1, which was discovered in our previous work as an SGK1 inhibitor. Based on docking research for the active binding conformation of compound H1, a series of novel 4-trifluoromethyl quinoline derivatives were developed by replacing the 6-methoxy group in the quinoline skeleton of compound H1 with a larger aryl ring to occupy the hinge region of SGK1. Among them, compound 12f showed the strongest SGK1 inhibitory potency, with an IC50 value of 0.39 μM, representing a 7.8-fold improvement over compound H1. Molecular docking studies revealed that the 6-methoxyphenylamine moiety of compound 12f effectively extends into the hinge region of SGK1, establishing a crucial hydrogen bonding interaction with Glu183 that enhances its biological potency. In vivo, compound 12f effectively suppressed tumor growth in the PC3 xenograft model in BALB/c nude mice without inducing any observable toxicity. Moreover, mechanistic studies showed that compound 12f hindered PC3 cell migration and invasion, improved the thermal stability of SGK1 protein in PC3 cells, decreased SGK1 protein levels in tumor tissues, and effectively inhibited the phosphorylation of SGK1 and its substrates in PC3 cells in a dose- and time-dependent manner. In summary, the results of this study highlight the potential of 12f as a lead compound for further optimization in the development of new therapies against PCa targeting SGK1.

Current scenario of fused pyrimidines with in vivo anticancer therapeutic potential

Cancer, characterized by uncontrolled cell growth and metastasis, is responsible for nearly one in six deaths and represents a severe threat to public health worldwide. Chemotherapy can substantially improve the quality of life and survival of patients with cancer, but anticancer chemotherapeutics are associated with a range of adverse effects. Moreover, almost all currently available anticancer chemotherapeutics could develop drug resistance over a period of time of application in cancer patients and ultimately lead to cancer relapse and death in 90% of patients, creating an urgent need to develop new anticancer agents. Fused pyrimidines trait the inextricable part of DNA and RNA and are vital in numerous biological processes. Fused pyrimidines can act on various biological cancer targets and have the potential to address drug resistance. In addition, more than 20 fused pyrimidines have already been approved for clinical treatment of different cancers and occupy a prominent place in the current therapeutic arsenal, revealing that fused pyrimidines are privileged scaffolds for the development of novel anticancer chemotherapeutics. The purpose of this review is to summarize the current scenario of fused pyrimidines with in vivo anticancer therapeutic potential along with their acute toxicity, metabolic profiles as well as pharmacokinetic properties, toxicity and mechanisms of action developed from 2020 to the present to facilitate further rational exploitation of more effective candidates.

Strategies for the development of stimuli-responsive small molecule prodrugs for cancer treatment

Approved anticancer drugs typically face challenges due to their narrow therapeutic window, primarily because of high systemic toxicity and limited selectivity for tumors. Prodrugs are initially inactive drug molecules designed to undergo specific chemical modifications. These modifications render the drugs inactive until they encounter specific conditions or biomarkers in vivo, at which point they are converted into active drug molecules. This thoughtful design significantly improves the efficacy of anticancer drug delivery by enhancing tumor specificity and minimizing off-target effects. Recent advancements in prodrug design have focused on integrating these strategies with delivery systems like liposomes, micelles, and polymerosomes to further improve targeting and reduce side effects. This review outlines strategies for designing stimuli-responsive small molecule prodrugs focused on cancer treatment, emphasizing their chemical structures and the mechanisms controlling drug release. By providing a comprehensive overview, we aim to highlight the potential of these innovative approaches to revolutionize cancer therapy.

Identification of Novel Non-Nucleoside Inhibitors of Zika Virus NS5 Protein Targeting MTase Activity

Zika virus (ZIKV) is a positive-sense single-stranded virus member of the Flaviviridae family. Among other arboviruses, ZIKV can cause neurological disorders such as Guillain Barré syndrome, and it can have congenital neurological manifestations and affect fertility. ZIKV nonstructural protein 5 (NS5) is essential for viral replication and limiting host immune detection. Herein, we performed virtual screening to identify novel small-molecule inhibitors of the ZIKV NS5 methyltransferase (MTase) domain. Compounds were tested against the MTases of both ZIKV and DENV, demonstrating good inhibitory activities against ZIKV MTase. Extensive molecular dynamic studies conducted on the series led us to identify other derivatives with improved activity against the MTase and limiting ZIKV infection with an increased selectivity index. Preliminary pharmacokinetic parameters have been determined, revealing excellent stability over time. Preliminary in vivo toxicity studies demonstrated that the hit compound 17 is well tolerated after acute administration. Our results provide the basis for further optimization studies on novel non-nucleoside MTase inhibitors.

Inhibition of serum- and glucocorticoid-induced kinase 1 ameliorates hydrocephalus in preclinical models

BACKGROUND

Hydrocephalus is a pathological accumulation of cerebrospinal fluid (CSF), leading to ventriculomegaly. Hydrocephalus may be primary or secondary to traumatic brain injury, infection, or intracranial hemorrhage. Regardless of cause, current treatment involves surgery to drain the excess CSF. Importantly, there are no long-term, effective pharmaceutical treatments and this represents a clinically unmet need. Many forms of hydrocephalus involve dysregulation in water and electrolyte homeostasis, making this an attractive, druggable target.

METHODS

In vitro, a combination of electrophysiological and fluid flux assays was used to elucidate secretory transepithelial electrolyte and fluid flux in a human cell culture model of the choroid plexus epithelium and to determine the involvement of serum-, glucocorticoid-induced kinase 1 (SGK1). In vivo, MRI studies were performed in a genetic rat model of hydrocephalus to determine effects of inhibition of SGK1 with a novel inhibitor, SI113.

RESULTS

In the cultured cell line, SI113 reduced secretory transepithelial electrolyte and fluid flux. In vivo, SI113 blocks the development of hydrocephalus with no effect on ventricular size of wild-type animals and no overt toxic effects. Mechanistically, the development of hydrocephalus in the rat model involves an increase in activated, phosphorylated SGK1 with no change in the total amount of SGK1. SI113 inhibits phosphorylation with no changes in total SGK1 levels in the choroid plexus epithelium.

CONCLUSION

These data provide a strong preclinical basis for the use of SGK1 inhibitors in the treatment of hydrocephalus.

The Pyrazolo[3,4-d]Pyrimidine Derivative Si306 Encapsulated into Anti-GD2-Immunoliposomes as Therapeutic Treatment of Neuroblastoma

Si306, a pyrazolo[3,4-d]pyrimidine derivative recently identified as promising anticancer agent, has shown favorable in vitro and in vivo activity profile against neuroblastoma (NB) models by acting as a competitive inhibitor of c-Src tyrosine kinase. Nevertheless, Si306 antitumor activity is associated with sub-optimal aqueous solubility, which might hinder its further development. Drug delivery systems were here developed with the aim to overcome this limitation, obtaining suitable formulations for more efficacious in vivo use. Si306 was encapsulated in pegylated stealth liposomes, undecorated or decorated with a monoclonal antibody able to specifically recognize and bind to the disialoganglioside GD2 expressed by NB cells (LP[Si306] and GD2-LP[Si306], respectively). Both liposomes possessed excellent morphological and physio-chemical properties, maintained over a period of two weeks. Compared to LP[Si306], GD2-LP[Si306] showed in vitro specific cellular targeting and increased cytotoxic activity against NB cell lines. After intravenous injection in healthy mice, pharmacokinetic profiles showed increased plasma exposure of Si306 when delivered by both liposomal formulations, compared to that obtained when Si306 was administered as free form. In vivo tumor homing and cytotoxic effectiveness of both liposomal formulations were finally tested in an orthotopic animal model of NB. Si306 tumor uptake resulted significantly higher when encapsulated in GD2-LP, compared to Si306, either free or encapsulated into untargeted LP. This, in turn, led to a significant increase in survival of mice treated with GD2-LP[Si306]. These results demonstrate a promising antitumor efficacy of Si306 encapsulated into GD2-targeted liposomes, supporting further therapeutic developments in pre-clinical trials and in the clinic for NB.

Focused library of phenyl-fused macrocyclic amidinoureas as antifungal agents

The rise of antimicrobial-resistant phenotypes and the spread of the global pandemic of COVID-19 are worsening the outcomes of hospitalized patients for invasive fungal infections. Among them, candidiases are seriously worrying, especially since the currently available drug armamentarium is extremely limited. We recently reported a new class of macrocyclic amidinoureas bearing a guanidino tail as promising antifungal agents. Herein, we present the design and synthesis of a focused library of seven derivatives of macrocyclic amidinoureas, bearing a second phenyl ring fused with the core. Biological activity evaluation shows an interesting antifungal profile for some compounds, resulting to be active on a large panel of Candida spp. and C. neoformans. PAMPA experiments for representative compounds of the series revealed a low passive diffusion, suggesting a membrane-based mechanism of action or the involvement of active transport systems. Also, compounds were found not toxic at high concentrations, as assessed through MTT assays.