The molecular mechanism of nitrogen-containing bisphosphonates as antiosteoporosis drugs

Structures of Mycobacterium tuberculosis isoprenyl diphosphate synthase Rv2173 in substrate-bound forms

We report structures of the Mycobacterium tuberculosis isoprenyl diphosphate synthase Rv2173 in three forms: apo and two substrate-bound forms [isoprenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP)]. The protein possesses a canonical all-α-helical trans-isoprenyl diphosphate synthase fold that is dimeric in each form. There are some differences between the structures: the IPP-bound form shows IPP bound in the DMAPP/allylic substrate-binding site with three divalent metal ions bound around the IPP and the complete C-terminus closing around the active site, while the apo and DMAPP-bound forms are more open, with some of the C-terminal region disordered, supporting suggestions that the C-terminus is important in substrate entry/product exit. In the DMAPP form DMAPP occupies the expected allylic substrate site, but only two metal ions are associated with the binding, with the DMAPP diphosphates adopting a slightly different binding pose compared with IPP in the same site, and the third metal-binding site is unoccupied. In no case is the IPP binding site occupied by IPP. There has been some uncertainty regarding product length for Rv2173, with variable lengths being reported. In the structures reported here, the `capping' residue at the bottom of the binding cavity is tryptophan and comparison with other IPP synthases suggests that the structure of Rv2173 is most consistent with a C10-C15 final product size.

Sequential and Long-term Therapy for Osteoporosis

PURPOSE OF THE REVIEW

Osteoporosis requires life-long management. This involves the use of different drugs in various sequences followed by long-term maintenance therapy. This review highlights the important transitions among osteoporosis therapies and outlines a strategy of intermittent bisphosphonate therapy for long-term maintenance.

RECENT FINDINGS

Over the past few years, the effects and limitations of long-term treatment with bisphosphonates and denosumab have become apparent as have several key factors in the sequential use of anti-remodeling drugs and osteoanabolic agents. Strategies for transitions from estrogen, bisphosphonates, denosumab and the bone-forming drugs will be discussed, based on extant evidence, clinical experience and expert opinion. By appropriate selection of both the initial and subsequent drugs for the prevention and treatment of osteoporosis, therapeutic benefits can be optimized and safety issues minimized. Developing a strategy for long-term maintenance of the benefits of the initial therapies can provide a life plan for managing patients with osteoporosis.

Local delivery of pamidronate with collagen matrix mitigates buccal bone resorption following immediate implant placement - An experimental in vivo study

AIMS

The aim of this experimental in vivo pilot study was to evaluate the effect of the local delivery of pamidronate within a collagen membrane on the changes in the buccal soft and hard tissue dimensions at the time of immediate implant placement and whether this effect was influenced by the placement of bone substitutes.

METHODS

In six beagle dogs, the distal roots of the third and fourth premolars were extracted, and immediate implants were placed. Treatment groups were randomly allocated to each socket: (i) covering the buccal bone with pamidronate-soaked collagen membrane (BP group), (ii) filling the gap defect with synthetic bone substitute (BS group), (iii) filling the gap defect with synthetic bone substitute and covering the buccal bone with pamidronate soaked collagen membrane (BP/BS group), (iv) no treatment (control group). Intraoral scanning was performed immediately after the surgery and at 20 weeks. Histomorphometric and micro-computed tomography (CT) outcomes were evaluated at 20 weeks.

RESULTS

The micro CT analysis demonstrated that the BP group showed no apparent difference in vertical bone level with residual mesial root area, while control group showed significant buccal bone resorption at the implant site. The histomorphometric analysis demonstrated that the vertical bone level of buccal plate was significantly differed between the BP and control group (0.34 ± 0.93 and 1.27 ± 0.56 mm, respectively; p = .041). There was no statistically significant difference in the horizontal ridge width (HRW 1, 2, 3) among the groups. Also, the thickness, height and buccal contours of the soft tissue did not reveal significant changes among the groups.

CONCLUSION

The local delivery of pamidronate to the outer surface of the buccal wall at the time of immediate implant placement effectively limits buccal bone resorption. The results from the present investigation should be interpreted with caution, as well as its clinical translatability. Further investigation is needed to understand the pamidronate binding and releasing kinetic, as well as the ideal carrier of this drug for its topical application.

Rapid assessment of the osteogenic capacity of hydroxyapatite/aragonite using a murine tibial periosteal ossification model

Biomaterials are widely used as orthopaedic implants and bone graft substitutes. We aimed to develop a rapid osteogenic assessment method using a murine tibial periosteal ossification model to evaluate the bone formation/remodelling potential of a biomaterial within 2-4 weeks. A novel hydroxyapatite/aragonite (HAA) biomaterial was implanted into C57BL/6 mice juxtaskeletally between the tibia and tibialis anterior muscle. Rapid intramembranous bone formation was observed at 14 days, with 4- to 8-fold increases in bone thickness and callus volume in comparison with sham-operated animals (p < 0.0001), followed by bone remodelling and a new layer of cortical bone formation by 28 days after implantation. The addition of zoledronate, a clinically-utilised bisphosphonate, to HAA, promoted significantly more new bone formation than HAA alone over 28 days (p < 0.01). The osteogenic potential of HAA was further confirmed by implanting into a 3.5 mm diameter femoral cancellous bone defect in rats and a 5 mm diameter femoral cortical bone defect in minipigs. To understand the biodegradation and the cellular activity at the cell/biomaterial interfaces, non-decalcified specimens were resin embedded and sections subjected to combined scanning electron microscopy (SEM)/electron backscatter diffraction (EBSD)/energy dispersive X-ray spectrometry (EDS) analysis. We conclude that murine tibial periosteal ossification is a novel method for rapid assessment of the interaction of bioactive materials with osteogenic tissues. This study also highlights that combining calcium carbonate with hydroxyapatite enhances biodegradation and osteogenesis.

Unveiling the Potential of Tetrahedral DNA Frameworks in Clinical Medicine: Mechanisms, Advances, and Future Perspectives

As deoxyribonucleic acis (DNA) nanotechnology advances, DNA, a fundamental biological macromolecule, has been employed to treat various clinical diseases. Among the advancements in this field, tetrahedral frameworks nucleic acids (tFNAs) have gained significant attention due to their straightforward design, structural simplicity, low cost, and high yield since their introduction by Turberfield in the early 2000s. Due to its stable spatial structure, tFNAs can resist the impact of innate immune responses on DNA and nuclease activity. Meanwhile, structural programmability of tFNAs allows for the development of static tFNA-based nanomaterials through the engineering of functional oligonucleotides or therapeutic molecules and dynamic tFNAs through the attachment of stimuli-responsive DNA apparatuses. This review first summarizes the key merits of tFNAs, including natural biocompatibility, biodegradability, structural stability, unparalleled programmability, functional diversity, and efficient cellular internalization. Based on these strengths, this review comprehensively analyzes applications of tFNAs in different clinical settings, including orthopedics, stomatology, urinary system diseases, liver-related diseases, tumors, infection, neural system diseases, ophthalmic diseases, and immunoprophylaxis. We also discuss the limitations of tFNAs and the challenges encountered in preclinical studies. This review provides new perspectives for future research and valuable guidance for researchers working in this field.

Engineering dimer mutants of human geranylgeranyl pyrophosphate synthase

Geranylgeranyl pyrophosphate synthase (GGPPS), a key enzyme in protein prenylation, plays a critical role in cellular signal transduction and is a promising target for cancer therapy. However, the enzyme's native hexameric quaternary structure presents challenges for crystallographic studies. The primary objective of this study was to engineer dimeric forms of human GGPPS to facilitate high-resolution crystallographic analysis of its ligand binding interactions. Through site-directed mutagenesis, we disrupted the inter-dimer interactions required for hexamer assembly, generating three stable double-site mutants: Y246D/C247L, Y246D/C205A, and Y246K/C247L. Enzyme assays confirmed that all mutants retained wild-type catalytic activity under both saturating and subsaturating substrate conditions. Differential scanning fluorimetry showed that the mutant proteins had a ~10°C lower melting temperature than the wild-type enzyme but exhibited similar shifts in melting temperature in the presence of the known inhibitors risedronate and zoledronate. Crystallographic analysis of the Y246D/C247L mutant yielded a 2.1 Å resolution structure, providing detailed insights into the binding of isopentenyl pyrophosphate. Closer inspection also revealed the unexpected formation of intermolecular disulfide bonds connecting neighboring dimers, which may explain the enhanced crystallizability of the Y246D/C247L mutant compared to the wild-type and other mutants. These findings highlight the potential of the dimeric mutants as substitutes for wild-type GGPPS in future studies. Optimized dimeric mutants could serve as valuable molecular tools to further our understanding of the enzyme's structural and functional properties and aid in the rational design of novel therapeutic agents targeting GGPPS.

Geranylgeranyl diphosphate synthase inhibition impairs osteoclast differentiation, morphology, and resorptive activity

Nitrogen bisphosphonates, such as zoledronic acid, target the enzyme farnesyl diphosphate synthase (FDPS) in the isoprenoid biosynthetic pathway (IBP), and are the frontline treatment for osteolytic bone diseases. A strong affinity of these agents for bone limits their distribution out of the skeleton. Geranylgeranyl diphosphate synthase (GGDPS) is directly downstream to FDPS in the IBP and novel GGDPS inhibitors such as RAM2061 have been shown to have key drug-like features including prolonged half-life, metabolic stability, and systemic distribution. Furthermore, RAM2061 exerts anti-neoplastic benefits in mouse models of multiple myeloma and Ewing sarcoma. Therefore, we are interested in determining the potential impact of RAM2061 on osteoclast biology and bone remodeling. Studies utilizing undifferentiated RAW264.7 cells demonstrated that treatment with RAM2061 depletes cells of geranylgeranyl diphosphate, impairs protein geranylgeranylation, and induces markers of the unfolded protein response pathway and apoptosis. Differentiation of RAW264.7 cells to mature osteoclasts is disrupted by RAM2061, resulting in decreased numbers of mature osteoclasts, altered morphology, and decreased tartrate-resistant acid phosphatase activity. Treatment of fully differentiated RAW264.7 cells with RAM2061 led to decreased resorptive activity. Confocal microscopy studies revealed that RAM2061 disrupts Cdc42 localization, inhibiting proper actin ring formation in osteoclasts. No significant impact on bone turnover markers or bone histomorphology was observed following a 3-week treatment of CD-1 mice with RAM2061, although decreased numbers of osteoclasts were observed. Liquid chromatography-tandem mass spectrometry studies confirmed accumulation of RAM2061 in bone from the in vivo studies as well as hydroxyapatite binding in vitro. In conclusion, these studies are the first to demonstrate the anti-osteoclastic activity of GGDPS inhibitor treatment and support future studies exploring the therapeutic benefit of this novel therapy in the setting of pathological bone remodeling.

Peptides as modulators of FPPS enzyme: A multifaceted evaluation from the design to the mechanism of action

Bone diseases are medical conditions caused by the loss of bone homeostasis consecutive to increased osteoclast activity and diminished osteoblast activity. The mevalonate pathway (MVA) is crucial for maintaining this balance since it drives the post-translational prenylation of small guanosine triphosphatases (GTPases) proteins. Farnesyl pyrophosphate synthase (FPPS) plays a crucial role in the MVA pathway. Consequently, in the treatment of bone-related diseases, FPPS is the target of FDA-approved nitrogen-containing bisphosphonates (N-BPs), which have tropism mainly for bone tissue due to their poor penetration in soft tissues. The development of inhibitors targeting the FPPS enzyme has garnered significant interest in recent decades due to FPPS's role in the biosynthesis of cholesterol and other isoprenoids, which are implicated in cancer, bone diseases, and other conditions. In this study, we describe a multidisciplinary approach to designing novel FPPS inhibitors, combining computational modeling, biochemical assays, and biophysical techniques. A series of peptides and phosphopeptides were designed, synthesized, and evaluated for their ability to inhibit FPPS activity. Molecular docking was employed to predict the binding modes of these compounds to FPPS, while Surface Plasmon Resonance (SPR) and Nuclear Magnetic Resonance (NMR) spectroscopy experiments - based on Saturation Transfer Difference (STD) and an enzymatic NMR assay - were used to measure their binding affinities and kinetics. The biological activity of the most promising compounds was further assessed in cellular assays using murine colorectal cancer (CRC) cells. Additionally, genomics and metabolomics profiling allowed to unravel the possible mechanisms underlying the activity of the peptides, confirming their involvement in the modulation of the MVA pathway. Our findings demonstrate that the designed peptides and phosphopeptides exhibit significant inhibitory activity against FPPS and possess antiproliferative effects on CRC cells, suggesting their potential as therapeutic agents for cancer.

Comparison of the Effects of Four Laser Wavelengths on Medication-Related Osteonecrosis of the Jaw (MRONJ) in a Murine Model: An In Vivo Photobiomodulation Study

Background: This study aims to investigate the effectiveness of lasers at various wavelengths in treating medication-related osteonecrosis of the jaw (MRONJ) using biochemical, clinical scoring, micro CT analysis, and histopathological methods. The study follows the ARRIVE guidelines to ensure robust and transparent research. Methods: In our study, there were 6 groups, including one SHAM group, one CONTROL group, and four experimental groups, with 8 rats in each individual group. Each rat received antiresorptive drug intraperitoneally for 4 weeks and then had the left second molar in the mandible extracted. All animals were sacrificed at the end of the 12th week. In the experimental groups, lasers at wavelengths of 405nm, 445nm, 660nm, and 808nm were applied to the animals. Parameters such as serum vitamin D levels, bone density and bone volume at the extraction site, new bone formation, dead bone count, inflammatory cell count, and epithelial regeneration were examined. Additionally, clinical scoring was conducted after sacrifice. The laser parameters included power density, area, time, fluence, and mode (continuous wave), and the light was administered using a fiber with a Gaussian profile. Statistical analyses were performed with the NCSS (Number Cruncher Statistical System) 2007 Statistical Software (Utah, USA) package program. The results were evaluated at the p<0.05 significance level. Results: According to the results obtained from our study, new bone formation in all experimental groups was significantly higher than in the SHAM and CONTROL groups. Furthermore, the 660nm and 808nm wavelengths increased serum vitamin D levels significantly. The most successful outcomes were observed in clinical scoring, dead bone count, epithelial cell regeneration, and bone density in the 660nm and 808nm wavelength groups. Conclusions: The combined use of lasers at 660nm and 808nm wavelengths may yield successful results in treating MRONJ.

Kinetic and structural characterization of NUDT15 and NUDT18 as catalysts of isoprene pyrophosphate hydrolysis

Isoprene pyrophosphates play a crucial role in the synthesis of a diverse array of essential nonsterol and sterol biomolecules and serve as substrates for posttranslational isoprenylation of proteins, enabling specific anchoring to cellular membranes. Hydrolysis of isoprene pyrophosphates would be a means to modulate their levels, downstream products, and protein isoprenylation. While NUDIX hydrolases from plants have been described to catalyze the hydrolysis of isoprene pyrophosphates, homologous enzymes with this function in animals have not yet been reported. In this study, we screened an extensive panel of human NUDIX hydrolases for activity in hydrolyzing isoprene pyrophosphates. We found that human nucleotide triphosphate diphosphatase NUDT15 and 8-oxo-dGDP phosphatase NUDT18 efficiently catalyze the hydrolysis of several physiologically relevant isoprene pyrophosphates. Notably, we demonstrate that geranyl pyrophosphate is an excellent substrate for NUDT18, with a catalytic efficiency of 2.1 × 105 m-1·s-1, thus making it the best substrate identified for NUDT18 to date. Similarly, geranyl pyrophosphate proved to be the best isoprene pyrophosphate substrate for NUDT15, with a catalytic efficiency of 4.0 × 104 M-1·s-1. LC-MS analysis of NUDT15 and NUDT18 catalyzed isoprene pyrophosphate hydrolysis revealed the generation of the corresponding monophosphates and inorganic phosphate. Furthermore, we solved the crystal structure of NUDT15 in complex with the hydrolysis product geranyl phosphate at a resolution of 1.70 Å. This structure revealed that the active site nicely accommodates the hydrophobic isoprenoid moiety and helped identify key binding residues. Our findings imply that isoprene pyrophosphates are endogenous substrates of NUDT15 and NUDT18, suggesting they are involved in animal isoprene pyrophosphate metabolism.

Comparative evaluation of the clinical and radiographic efficacy of 0.05% zoledronate gel as local drug delivery system in treating intrabony defects in stage III grade B periodontitis patients with and without type-2 diabetes mellitus-A randomized split-mouth clinical trial

BACKGROUND

This 6-month randomized split-mouth and placebo-controlled clinical trial aimed to evaluate the clinical and radiographic efficacy of adjunctive use of 0.05% zoledronate (ZLN) gel as local drug delivery to scaling and root planing (SRP) in stage III, grade B periodontitis patients with and without controlled type-2 diabetes mellitus (DM).

METHODS

A total of 120 infrabony sites were divided into two groups: Group-1 (non-diabetic periodontitis) and Group-2 (periodontitis + DM). A total of 60 sites in each group were randomized to receive treatment with SRP + placebo gel (control) or SRP + 0.05% ZLN gel (test). Plaque index (PI), modified sulcus bleeding index (mSBI), pocket probing depth (PPD), and relative attachment levels (RAL) were assessed at baseline, 3 and 6 months, and digital intraoral periapical and cone-beam computed tomography imaging were used to measure the linear and percentage reduction of intrabony defect depth (DD, DDR%) after 6 months.

RESULTS

Group-1 showed significant reduction in PI (0.56 ± 0.15 and 0.52 ± 0.19 from 0.67 ± 0.17), mSBI (0.7 ± 0.60 and 0.47 ± 0.57 from 0.9 ± 0.48), PPD (4.6 ± 0.85 and 3.43 ± 0.63 from 6.5 ± 1.04) and gain in RAL (7.03 ± 0.85 and 5.93 ± 0.69 from 8.9 ± 1.09) in the ZLN-treated sites than the placebo sites and also from Group-2 sites after 3 and 6 months, respectively. A significant reduction in DD of 28.79% in Group-1 and 22.20% in Group-2 at ZLN sites was seen compared to placebo sites of both groups.

CONCLUSION

ZLN gel applied subgingivally in infrabony pockets resulted in significant clinical improvements evident by probing depth reduction and gain in attachment levels along with radiographic evidence of more bone fill seen in non-diabetic patients compared to diabetic periodontitis patients.

Proteomic Biomarkers Associated with Low Bone Mineral Density: A Systematic Review

Osteoporosis is a globally relevant public health issue. Our study aimed to summarize the knowledge on the proteomic biomarkers for low bone mineral density over the last years. We conducted a systematic review following the PRISMA guidelines; the scoured databases were PubMed, Web of Sciences, Scopus, and EBSCO, from inception to 2 June 2023. A total of 610 relevant studies were identified and 33 were assessed for eligibility. Finally, 29 studies met the criteria for this systematic review. The risk of bias was evaluated using the Joanna Briggs Institute Critical Appraisal Checklist tool. From the studies selected, 154 proteins were associated with changes of bone mineral density, from which only 10 were reported in at least two articles. The protein-protein network analysis indicated potential biomarkers involved in the skeletal system, immune system process, regulation of protein metabolic process, regulation of signaling, transport, cellular component assembly, cell differentiation, hemostasis, and extracellular matrix organization. Mass spectrometry-based proteomic profiling has allowed the discovery of new biomarkers with diagnostic potential. However, it is necessary to compare and validate the potential biomarkers in different populations to determine their association with bone metabolism and evaluate their translation to the clinical management of osteoporosis.

Updates on protein-prenylation and associated inherited retinopathies

Membrane-anchored proteins play critical roles in cell signaling, cellular architecture, and membrane biology. Hydrophilic proteins are post-translationally modified by a diverse range of lipid molecules such as phospholipids, glycosylphosphatidylinositol, and isoprenes, which allows their partition and anchorage to the cell membrane. In this review article, we discuss the biochemical basis of isoprenoid synthesis, the mechanisms of isoprene conjugation to proteins, and the functions of prenylated proteins in the neural retina. Recent discovery of novel prenyltransferases, prenylated protein chaperones, non-canonical prenylation-target motifs, and reversible prenylation is expected to increase the number of inherited systemic and blinding diseases with aberrant protein prenylation. Recent important investigations have also demonstrated the role of several unexpected regulators (such as protein charge, sequence/protein-chaperone interaction, light exposure history) in the photoreceptor trafficking of prenylated proteins. Technical advances in the investigation of the prenylated proteome and its application in vision research are discussed. Clinical updates and technical insights into known and putative prenylation-associated retinopathies are provided herein. Characterization of non-canonical prenylation mechanisms in the retina and retina-specific prenylated proteome is fundamental to the understanding of the pathogenesis of protein prenylation-associated inherited blinding disorders.

A review on potential therapeutic targets for the treatment of leishmaniasis

Leishmania, a protozoan parasite, is responsible for the occurrence of leishmaniasis, a disease that is prevalent in tropical regions. Visceral Leishmaniasis (VL), also known as kala-azar in Asian countries, is one of the most significant forms of VL, along with Cutaneous Leishmaniasis (CL) and Mucocutaneous Leishmaniasis (ML). Management of this condition typically entails the use of chemotherapy as the sole therapeutic option. The current treatments for leishmaniasis present several drawbacks, including a multitude of side effects, prolonged treatment duration, disparate efficacy across different regions, and the emergence of resistance. To address this urgent need, it is imperative to identify alternative treatments that are both safer and more effective. The identification of appropriate pharmacological targets in conjunction with biological pathways constitutes the initial stage of drug discovery. In this review, we have addressed the key metabolic pathways that represent potential pharmacological targets as well as prominent treatment options for leishmaniasis.

Bone equilibria and disruptions

Osteoporosis is considered a disease of adulthood, but there is increasing recognition that poor bone density during childhood can have effects decades later. To understand the pathogenesis of osteoporosis, it is important to understand normal bone maintenance and remodeling, since disruptions of these processes lead to pathologic bone. Bone maintenance is a complex and highly regulated system, consisting of several homeostatic equilibria. This article highlights three homeostatic systems. The first, the interplay between the differentiation of osteoblasts from mesenchymal stem cells and osteoclasts from hematopoietic stem cells, is the most important. Estrogen has a direct effect on the system, and its absence is pivotal. The second is a lesser-known homeostasis that functions between bone and bone marrow adipose tissue, which can insidiously drive osteoporosis. Bone marrow adipose tissue acts as a regulator of bone metabolism, negatively affecting bone formation. The third homeostatic system covered is the microbiota-gut-bone axis, where the make-up of the gut microbiome can influence a balance between osteoblastic and osteoclastic T-cells. Understanding these systems has provided avenues of study for existing and future treatments.

Key Concepts

(1)The balance between bone formation and bone resorption is driven by factors that initiate the differentiation of mesenchymal stem cells to osteoblasts and hematopoietic stem cells to osteoclasts.(2)Bone marrow adipose tissue is formed by adipocytes that are the result of diversion of mesenchymal stem cells from the osteoblastic differentiation pathway.(3)The health of the gut microbiome has direct effects on the bone homeostatic processes.

Engineering small-molecule and protein drugs for targeting bone tumors

Bone cancer is common and severe. Both primary (e.g., osteosarcoma, Ewing sarcoma) and secondary (e.g., metastatic) bone cancers lead to significant health problems and death. Currently, treatments such as chemotherapy, hormone therapy, and radiation therapy are used to treat bone cancer, but they often only shrink or slow tumor growth and do not eliminate cancer completely. The bone microenvironment contributes unique signals that influence cancer growth, immunogenicity, and metastasis. Traditional cancer therapies have limited effectiveness due to off-target effects and poor distribution on bones. As a result, therapies with improved specificity and efficacy for treating bone tumors are highly needed. One of the most promising strategies involves the targeted delivery of pharmaceutical agents to the site of bone cancer by introduction of bone-targeting moieties, such as bisphosphonates or oligopeptides. These moieties have high affinities to the bone hydroxyapatite matrix, a structure found exclusively in skeletal tissue, and can enhance the targeting ability and efficacy of anticancer drugs when combating bone tumors. This review focuses on the engineering of small molecules and proteins with bone-targeting moieties for the treatment of bone tumors.

The effect of black cohosh extract and risedronate coadministration on bone health in an ovariectomized rat model

Preparations of black cohosh extract are sold as dietary supplements marketed to relieve the vasomotor symptoms of menopause, and some studies suggest it may protect against postmenopausal bone loss. Postmenopausal women are also frequently prescribed bisphosphonates, such as risedronate, to prevent osteoporotic bone loss. However, the pharmacodynamic interactions between these compounds when taken together is not known. To investigate possible interactions, 6-month-old, female Sprague-Dawley rats underwent bilateral ovariectomy or sham surgery and were treated for 24 weeks with either vehicle, ethinyl estradiol, risedronate, black cohosh extract or coadministration of risedronate and black cohosh extract, at low or high doses. Bone mineral density (BMD) of the femur, tibia, and lumbar vertebrae was then measured by dual-energy X-ray absorptiometry (DEXA) at weeks 0, 8, 16, and 24. A high dose of risedronate significantly increased BMD of the femur and vertebrae, while black cohosh extract had no significant effect on BMD individually and minimal effects upon coadministration with risedronate. Under these experimental conditions, black cohosh extract alone had no effect on BMD, nor did it negatively impact the BMD-enhancing properties of risedronate.

Synthesis and preliminary anticancer evaluation of photo-responsive prodrugs of hydroxymethylene bisphosphonate alendronate

The antitumoral activity of hydroxymethylene bisphosphonates (HMBP) such as alendronate or zoledronate is hampered by their exceptional bone-binding properties and their short plasmatic half-life which preclude their accumulation in non-skeletal tumors. In this context, the use of lipophilic prodrugs represents a simple and straightforward strategy to enhance the biodistribution of bisphosphonates in these tissues. We describe in this article the synthesis of light-responsive prodrugs of HMBP alendronate. These prodrugs include lipophilic photo-removable nitroveratryl groups which partially mask the highly polar alendronate HMBP scaffold. Photo-responsive prodrugs of alendronate are stable in physiological conditions and display reduced toxicity compared to alendronate against MDA-MB-231 cancer cells. However, the antiproliferative effect of these prodrugs is efficiently restored after cleavage of their nitroveratryl groups upon exposure to UV light. In addition, substitution of alendronate with such photo-responsive substituents drastically reduces its bone-binding properties, thereby potentially improving its biodistribution in soft tissues after i.v. administration. The development of such lipophilic photo-responsive prodrugs is a promising approach to fully exploit the anticancer effect of HMBPs on non-skeletal tumors.

Giant cell arteritis associated with intravenous zoledronic acid administration

Bisphosphonates frequently provoke a cytokine-driven acute clinical response (ACR) characterized by fever, chills, arthralgias, and myalgias. More rarely, an association between aminobisphosphonates, such as alendronate and zoledronic acid, and rheumatologic and/or immune-mediated syndromes (RIMS) has been described. Herein we report 2 patients, one with a prior history of rheumatic disease and one without, who developed giant cell arteritis meeting the American College of Rheumatology 2022 criteria following zoledronic acid infusion. We subsequently review existing mechanistic and clinical literature supporting this link. The duration of symptoms and elevation of inflammatory markers may serve as indicators for differentiating between the more common ACR and less frequent but potentially morbid RIMS. Although the benefit of bisphosphonates will outweigh the risk of RIMS for most patients with high fracture risk, clinicians should be aware of this phenomenon to assist earlier diagnosis and treatment in affected individuals.

Lactobacillus plantarum attenuates glucocorticoid-induced osteoporosis by altering the composition of rat gut microbiota and serum metabolic profile

Introduction

Osteoporosis, one of the most common non-communicable human diseases worldwide, is one of the most prevalent disease of the adult skeleton. Glucocorticoid-induced osteoporosis(GIOP) is the foremost form of secondary osteoporosis, extensively researched due to its prevalence.Probiotics constitute a primary bioactive component within numerous foods, offering promise as a potential biological intervention for preventing and treating osteoporosis. This study aimed to evaluate the beneficial effects of the probiotic Lactobacillus plantarum on bone health and its underlying mechanisms in a rat model of glucocorticoid dexamethasone-induced osteoporosis, using the osteoporosis treatment drug alendronate as a reference.

Methods

We examined the bone microstructure (Micro-CT and HE staining) and analyzed the gut microbiome and serum metabolome in rats.

Results and discussion

The results revealed that L. plantarum treatment significantly restored parameters of bone microstructure, with elevated bone density, increased number and thickness of trabeculae, and decreased Tb.Sp. Gut microbiota sequencing results showed that probiotic treatment increased gut microbial diversity and the ratio of Firmicutes to Bacteroidota decreased. Beneficial bacteria abundance was significantly increased (Lachnospiraceae_NK4A136_group, Ruminococcus, UCG_005, Romboutsia, and Christensenellaceae_R_7_group), and harmful bacteria abundance was significantly decreased (Desulfovibrionaceae). According to the results of serum metabolomics, significant changes in serum metabolites occurred in different groups. These differential metabolites were predominantly enriched within the pathways of Pentose and Glucuronate Interconversions, as well as Propanoate Metabolism. Furthermore, treatment of L. plantarum significantly increased serum levels of Pyrazine and gamma-Glutamylcysteine, which were associated with inhibition of osteoclast formation and promoting osteoblast formation. Lactobacillus plantarum can protect rats from DEX-induced GIOP by mediating the "gut microbial-bone axis" promoting the production of beneficial bacteria and metabolites. Therefore L. plantarum is a potential candidate for the treatment of GIOP.

Structural Insight into Geranylgeranyl Diphosphate Synthase (GGDPS) for Cancer Therapy

Geranylgeranyl diphosphate synthase (GGDPS), the source of the isoprenoid donor in protein geranylgeranylation reactions, has become an attractive target for anticancer therapy due to the reliance of cancers on geranylgeranylated proteins. Current GGDPS inhibitor development focuses on optimizing the drug-target enzyme interactions of nitrogen-containing bisphosphonate-based drugs. To advance GGDPS inhibitor development, understanding the enzyme structure, active site, and ligand/product interactions is essential. Here we provide a comprehensive structure-focused review of GGDPS. We reviewed available yeast and human GGDPS structures and then used AlphaFold modeling to complete unsolved structural aspects of these models. We delineate the elements of higher-order structure formation, product-substrate binding, the electrostatic surface, and small-molecule inhibitor binding. With the rise of structure-based drug design, the information provided here will serve as a valuable tool for rationally optimizing inhibitor selectivity and effectiveness.

Green Approach Toward Triazole Forming Reactions for Developing Anticancer Drugs

Compounds containing triazole have many significant applications in the dye and ink industry, corrosion inhibitors, polymers, and pharmaceutical industries. These compounds possess many antimicrobial, antioxidant, anticancer, antiviral, anti-HIV, antitubercular, and anticancer activities. Several synthetic methods have been reported for reducing time, minimizing synthetic steps, and utilizing less hazardous and toxic solvents and reagents to improve the yield of triazoles and their analogues synthesis. Among the improvement in methods, green approaches towards triazole forming biologically active compounds, especially anticancer compounds, would be very important for pharmaceutical industries as well as global research community. In this article, we have reviewed the last five years of green chemistry approaches on click reaction between alkyl azide and alkynes to install 1,2,3-triazole moiety in natural products and synthetic drug-like molecules, such as in colchicine, flavanone cardanol, bisphosphonates, thiabendazoles, piperazine, prostanoid, flavonoid, quinoxalines, C-azanucleoside, dibenzylamine, and aryl-azotriazole. The cytotoxicity of triazole hybrid analogues was evaluated against a panel of cancer cell lines, including multidrug-resistant cell lines.

Bisphosphonates as Radiopharmaceuticals: Spotlight on the Development and Clinical Use of DOTAZOL in Diagnostics and Palliative Radionuclide Therapy

Bisphosphonates are therapeutic agents that have been used for almost five decades in the treatment of various bone diseases, such as osteoporosis, Paget disease and prevention of osseous complications in cancer patients. In nuclear medicine, simple bisphosphonates such as 99mTc-radiolabelled oxidronate and medronate remain first-line bone scintigraphic imaging agents for both oncology and non-oncology indications. In line with the growing interest in theranostic molecules, bifunctional bisphosphonates bearing a chelating moiety capable of complexing a variety of radiometals were designed. Among them, DOTA-conjugated zoledronate (DOTAZOL) emerged as an ideal derivative for both PET imaging (when radiolabeled with 68Ga) and management of bone metastases from various types of cancer (when radiolabeled with 177Lu). In this context, this report provides an overview of the main medicinal chemistry aspects concerning bisphosphonates, discussing their roles in molecular oncology imaging and targeted radionuclide therapy with a particular focus on bifunctional bisphosphonates. Particular attention is also paid to the development of DOTAZOL, with emphasis on the radiochemistry and quality control aspects of its preparation, before outlining the preclinical and clinical data obtained so far with this radiopharmaceutical candidate.

Insights into the underlying pathogenesis and therapeutic potential of endoplasmic reticulum stress in degenerative musculoskeletal diseases

Degenerative musculoskeletal diseases are structural and functional failures of the musculoskeletal system, including osteoarthritis, osteoporosis, intervertebral disc degeneration (IVDD), and sarcopenia. As the global population ages, degenerative musculoskeletal diseases are becoming more prevalent. However, the pathogenesis of degenerative musculoskeletal diseases is not fully understood. Previous studies have revealed that endoplasmic reticulum (ER) stress is a stress response that occurs when impairment of the protein folding capacity of the ER leads to the accumulation of misfolded or unfolded proteins in the ER, contributing to degenerative musculoskeletal diseases. By affecting cartilage degeneration, synovitis, meniscal lesion, subchondral bone remodeling of osteoarthritis, bone remodeling and angiogenesis of osteoporosis, nucleus pulposus degeneration, annulus fibrosus rupture, cartilaginous endplate degeneration of IVDD, and sarcopenia, ER stress is involved in the pathogenesis of degenerative musculoskeletal diseases. Preclinical studies have found that regulation of ER stress can delay the progression of multiple degenerative musculoskeletal diseases. These pilot studies provide foundations for further evaluation of the feasibility, efficacy, and safety of ER stress modulators in the treatment of musculoskeletal degenerative diseases in clinical trials. In this review, we have integrated up-to-date research findings of ER stress into the pathogenesis of degenerative musculoskeletal diseases. In a future perspective, we have also discussed possible directions of ER stress in the investigation of degenerative musculoskeletal disease, potential therapeutic strategies for degenerative musculoskeletal diseases using ER stress modulators, as well as underlying challenges and obstacles in bench-to-beside research.

Bisphosphonates and Atypical Femur Fractures: Is the Relationship Causal or Casual?

Bisphosphonates (BPs) are a time-tested drug class with multivariate use cases. They are used in pathologies ranging from osteoporosis to Paget's disease, and also help in accelerated fracture healing. They have been used to treat both benign and malignant lesions of the skeletal system since a long time. However, there have been reports of increased incidences of atypical femoral fractures (AFFs) in patients exhibiting chronic use of bisphosphonates in the past years. This has led to the widespread dissuasion of physicians and practitioners from using the drug class. By means of this review of the literature, the authors aim to investigate the relationship between BP use and its association with AFFs. The review focuses on and elucidates the basic pharmacology of BPs and goes on to illustrate the indications of BPs in various pathologies of the musculoskeletal system, further exploring the effects of BPs on the healing of various bony fractures. The authors also explore the incidences of other pathologies, such as osteonecrosis of the jaw and nephropathies associated with BP use, and elaborate on their features. Through this review, the authors have tried to educate and induce critical thinking on the part of clinicians and medical professionals in regard to prescribing BPs to patients that need them, by keeping in mind the risk-reward relationship that accompanies their use.

Molecular and Cellular Mechanisms of Osteoporosis

Osteoporosis is a widespread systemic disease characterized by a decrease in bone mass and an imbalance of the microarchitecture of bone tissue. Experimental and clinical studies devoted to investigating the main pathogenetic mechanisms of osteoporosis revealed the important role of estrogen deficiency, inflammation, oxidative stress, cellular senescence, and epigenetic factors in the development of bone resorption due to osteoclastogenesis, and decreased mineralization of bone tissue and bone formation due to reduced function of osteoblasts caused by apoptosis and age-depended differentiation of osteoblast precursors into adipocytes. The current review was conducted to describe the basic mechanisms of the development of osteoporosis at molecular and cellular levels and to elucidate the most promising therapeutic strategies of pathogenetic therapy of osteoporosis based on articles cited in PubMed up to September 2023.

Aminobisphosphonates reactivate the latent reservoir in people living with HIV-1

Antiretroviral therapy (ART) is not curative due to the existence of cellular reservoirs of latent HIV-1 that persist during therapy. Current research efforts to cure HIV-1 infection include "shock and kill" strategies to disrupt latency using small molecules or latency-reversing agents (LRAs) to induce expression of HIV-1 enabling cytotoxic immune cells to eliminate infected cells. The modest success of current LRAs urges the field to identify novel drugs with increased clinical efficacy. Aminobisphosphonates (N-BPs) that include pamidronate, zoledronate, or alendronate, are the first-line treatment of bone-related diseases including osteoporosis and bone malignancies. Here, we show the use of N-BPs as a novel class of LRA: we found in ex vivo assays using primary cells from ART-suppressed people living with HIV-1 that N-BPs induce HIV-1 from latency to levels that are comparable to the T cell activator phytohemagglutinin (PHA). RNA sequencing and mechanistic data suggested that reactivation may occur through activation of the activator protein 1 signaling pathway. Stored samples from a prior clinical trial aimed at analyzing the effect of alendronate on bone mineral density, provided further evidence of alendronate-mediated latency reversal and activation of immune effector cells. Decay of the reservoir measured by IPDA was however not detected. Our results demonstrate the novel use of N-BPs to reverse HIV-1 latency while inducing immune effector functions. This preliminary evidence merits further investigation in a controlled clinical setting possibly in combination with therapeutic vaccination.

Regulation of VKORC1L1 is critical for p53-mediated tumor suppression through vitamin K metabolism

Here, we identified vitamin K epoxide reductase complex subunit 1 like 1 (VKORC1L1) as a potent ferroptosis repressor. VKORC1L1 protects cells from ferroptosis by generating the reduced form of vitamin K, a potent radical-trapping antioxidant, to counteract phospholipid peroxides independent of the canonical GSH/GPX4 mechanism. Notably, we found that VKORC1L1 is also a direct transcriptional target of p53. Activation of p53 induces downregulation of VKORC1L1 expression, thus sensitizing cells to ferroptosis for tumor suppression. Interestingly, a small molecular inhibitor of VKORC1L1, warfarin, is widely prescribed as an FDA-approved anticoagulant drug. Moreover, warfarin represses tumor growth by promoting ferroptosis in both immunodeficient and immunocompetent mouse models. Thus, by downregulating VKORC1L1, p53 executes the tumor suppression function by activating an important ferroptosis pathway involved in vitamin K metabolism. Our study also reveals that warfarin is a potential repurposing drug in cancer therapy, particularly for tumors with high levels of VKORC1L1 expression.

Association between bisphosphonate use and COVID-19 related outcomes

Background

Although there are several efficacious vaccines against COVID-19, vaccination rates in many regions around the world remain insufficient to prevent continued high disease burden and emergence of viral variants. Repurposing of existing therapeutics that prevent or mitigate severe COVID-19 could help to address these challenges. The objective of this study was to determine whether prior use of bisphosphonates is associated with reduced incidence and/or severity of COVID-19.

Methods

A retrospective cohort study utilizing payer-complete health insurance claims data from 8,239,790 patients with continuous medical and prescription insurance January 1, 2019 to June 30, 2020 was performed. The primary exposure of interest was use of any bisphosphonate from January 1, 2019 to February 29, 2020. Bisphosphonate users were identified as patients having at least one bisphosphonate claim during this period, who were then 1:1 propensity score-matched to bisphosphonate non-users by age, gender, insurance type, primary-care-provider visit in 2019, and comorbidity burden. Main outcomes of interest included: (a) any testing for SARS-CoV-2 infection; (b) COVID-19 diagnosis; and (c) hospitalization with a COVID-19 diagnosis between March 1, 2020 and June 30, 2020. Multiple sensitivity analyses were also performed to assess core study outcomes amongst more restrictive matches between BP users/non-users, as well as assessing the relationship between BP-use and other respiratory infections (pneumonia, acute bronchitis) both during the same study period as well as before the COVID outbreak.

Results

A total of 7,906,603 patients for whom continuous medical and prescription insurance information was available were selected. A total of 450,366 bisphosphonate users were identified and 1:1 propensity score-matched to bisphosphonate non-users. Bisphosphonate users had lower odds ratios (OR) of testing for SARS-CoV-2 infection (OR = 0.22; 95%CI:0.21-0.23; p<0.001), COVID-19 diagnosis (OR = 0.23; 95%CI:0.22-0.24; p<0.001), and COVID-19-related hospitalization (OR = 0.26; 95%CI:0.24-0.29; p<0.001). Sensitivity analyses yielded results consistent with the primary analysis. Bisphosphonate-use was also associated with decreased odds of acute bronchitis (OR = 0.23; 95%CI:0.22-0.23; p<0.001) or pneumonia (OR = 0.32; 95%CI:0.31-0.34; p<0.001) in 2019, suggesting that bisphosphonates may protect against respiratory infections by a variety of pathogens, including but not limited to SARS-CoV-2.

Conclusions

Prior bisphosphonate-use was associated with dramatically reduced odds of SARS-CoV-2 testing, COVID-19 diagnosis, and COVID-19-related hospitalizations. Prospective clinical trials will be required to establish a causal role for bisphosphonate-use in COVID-19-related outcomes.

Funding

This study was supported by NIH grants, AR068383 and AI155865, a grant from MassCPR (to UHvA) and a CRI Irvington postdoctoral fellowship, CRI2453 (to PH).

Pharmacological options in the treatment of osteogenesis imperfecta: A comprehensive review of clinical and potential alternatives

Osteogenesis imperfecta (OI) is a genetically heterogeneous connective tissue disorder characterized by bone fragility and different extra-skeletal manifestations. The severity of these manifestations makes it possible to classify OI into different subtypes based on the main clinical features. This review aims to outline and describe the current pharmacological alternatives for treating OI, grounded on clinical and preclinical reports, such as antiresorptive agents, anabolic agents, growth hormone, and anti-TGFβ antibody, among other less used agents. The different options and their pharmacokinetic and pharmacodynamic properties will be reviewed and discussed, focusing on the variability of their response and the molecular mechanisms involved to attain the main clinical goals, which include decreasing fracture incidence, improving pain, and promoting growth, mobility, and functional independence.

Farnesyl diphosphate synthase promotes cell proliferation by regulating gene expression and alternative splicing profiles in HeLa cells

Farnesyl diphosphate synthase (FDPS), an essential enzyme involved in the mevalonate pathway, is implicated in various diseases, including multiple types of cancer. As an RNA-binding protein (RBP), FDPS is also involved in transcriptional and post-transcriptional regulation. However, to the best of our knowledge, transcriptome-wide targets of FDPS still remain unknown. In the present study, FDPS expression patterns in pan-cancer were analyzed. In addition, it was investigated how FDPS overexpression (FDPS-OE) regulates the transcriptome in HeLa cells. FDPS-OE increased the proliferation rate in HeLa cells by MTT assay. Using transcriptome-wide high throughput sequencing and bioinformatics analysis, it was found that FDPS upregulated the expression levels of genes enriched in cell proliferation and extracellular matrix organization, including the laminin subunit γ2, interferon-induced proteins with tetratricopeptide repeats 2 and matrix metallopeptidase 19 genes. According to alternative splicing (AS) analysis, FDPS modulated the splicing patterns of the bone morphogenic protein 1, semaphorin 4D, annexin A2 and sirtuin 2 genes, which are enriched in the cell cycle and DNA repair, and are related to cell proliferation. To corroborate the FDPS-regulated transcriptome findings, FDPS was overexpressed in human osteosarcoma cells. Differentially expressed genes and regulated AS genes in the cells were both validated by reverse transcription-quantitative PCR. The results suggested that, as an emerging RBP, FDPS may serve an important role in transcriptome profiles by altering gene expression and regulating AS. FDPS also affected the cell proliferation rate. These findings broaden the understanding of the molecular functions of FDPS, and the potential of FDPS as a target in therapy should be investigated.

Synthesis of Pyrazolo[1,5-a]pyridinyl, Pyrazolo[1,5-a]quinolinyl, and Pyrazolo[5,1-a]isoquinolinyl Sulfonyl Fluorides via a [3 + 2] Annulation

A [3 + 2] cycloaddition reaction of N-aminopyridines, N-aminoquinolines, and N-aminoisoquinolines with 1-bromoethene-1-sulfonyl fluoride (BESF) was performed to obtain optimum yields of various useful pyrazolo[1,5-a]pyridinyl, pyrazolo[1,5-a]quinolinyl, and pyrazolo[5,1-a]isoquinolinyl sulfonyl fluorides (43-90% yield). The transformation process showed broad substrate specificity, mild reaction conditions, and operational simplicity. Therefore, the reaction has great applicable value in the field of medicinal chemistry and other disciplines.

Vulnerable Plaque Imaging

Atherosclerotic plaques progress as a result of inflammation. Both invasive and noninvasive imaging techniques have been developed to identify and characterize plaque as vulnerable (more likely to rupture and cause a clinical event). Imaging techniques to identify vulnerable include identifying vessels with focal subendothelial collections of I) inflammatory cells; II) lipid/ fatty acid; III) local regions of hypoxia; IV) local expression of angiogenesis factors; V) local expression of protease; VI) intravascular foci of thrombus; hemorrhage (most often seen in the aftermath of a clinical event); VII) apoptosis and VIII) microcalcification. This review provides an overview of atherosclerotic plaque progression and tracers which can visualize specific molecules associated with vulnerability.

Aminobisphosphonates reactivate the latent reservoir in people living with HIV-1

Antiretroviral therapy (ART) is not curative due to the existence of cellular reservoirs of latent HIV-1 that persist during therapy. Current research efforts to cure HIV-1 infection include "shock and kill" strategies to disrupt latency using small molecules or latency-reversing agents (LRAs) to induce expression of HIV-1 enabling cytotoxic immune cells to eliminate infected cells. The modest success of current LRAs urges the field to identify novel drugs with increased clinical efficacy. Aminobisphosphonates (N-BPs) that include pamidronate, zoledronate, or alendronate, are the first-line treatment of bone-related diseases including osteoporosis and bone malignancies. Here, we show the use of N-BPs as a novel class of LRA: we found in ex vivo assays using primary cells from ART-suppressed people living with HIV-1 that N-BPs induce HIV-1 from latency to levels that are comparable to the T cell activator phytohemagglutinin (PHA). RNA sequencing and mechanistic data suggested that reactivation may occur through activation of the activator protein 1 signaling pathway. Stored samples from a prior clinical trial aimed at analyzing the effect of alendronate on bone mineral density, provided further evidence of alendronate-mediated latency reversal and activation of immune effector cells. Decay of the reservoir measured by IPDA was however not detected. Our results demonstrate the novel use of N-BPs to reverse HIV-1 latency while inducing immune effector functions. This preliminary evidence merits further investigation in a controlled clinical setting possibly in combination with therapeutic vaccination.

Therapeutics of Charcot neuroarthropathy and pharmacological mechanisms: A bone metabolism perspective

Charcot neuroarthropathy (CN) is a chronic, destructive, and painless damage of the skeletal system that affects the life quality of patients. CN, with an unclear mechanism, is characterized with invasive destruction of bones and a serious abnormality of bone metabolism. Unfortunately, development of an effective prevention and treatment strategy for CN is still a great challenge. Of note, recent studies providing an insight into the molecular mechanisms of bone metabolism and homeostasis have propelled development of novel CN therapeutic strategies. Therefore, this review aims to shed light on the pathogenesis, diagnosis, and treatment of CN. In particular, we highlight the eminent role of the osteoprotegerin (OPG)-receptor activator of nuclear factor-κB (RANK)-RANK ligand (RANKL) system in the development of CN. Furthermore, we summarize and discuss the diagnostic biomarkers of CN as well as the potential pharmacological mechanisms of current treatment regimens from the perspective of bone metabolism. We believe that this review will enhance the current state of knowledge on the diagnosis, prevention, and therapeutic efficacy of CN.

Design, Synthesis, Molecular Docking, Dynamics and in vitro Evaluation of Novel 2-substituted-1-hydroxyethane-1, 1-bis(phosphonic acid) Derivatives as Human Farnesyl Pyrophosphate Synthase Inhibitors with Expected Anticancer Activity

BACKGROUND

Nitrogenous bisphosphonates (NBPs) are the major class of drugs that are used to treat osteoporosis. Recently, bisphosphonates (BPs) were reported to have an anticancer effect. These agents feature a high affinity that enables them to bind strongly to the human farnesyl pyrophosphate synthase enzyme. The correlation between this affinity and their anticancer effect was confirmed.

OBJECTIVE

To date, the use of an oxygen atom as an isosteric replacement for the electronegative nitrogen atom in NBPs has not been reported, and its ability to retain the linker length and bisphosphonate pharmacophore remains unknown. The main aim of this work was to design some isosteric bisphosphonate analogs with oxygen atoms and evaluation of their binding affinity and anticancer activity.

METHODS

The binding mode and stability of the designed compounds were achieved using human farnesyl pyrophosphate synthase (HFPPS) by docking and dynamic simulations. The compounds were synthesized, characterized, and screened for their anticancer activity against the breast cancer MCF-7 cell line and lung cancer A-549 cell line. The inhibitory activity of the tested compounds against HFPPS was evaluated.

RESULTS

The compounds under investigation showed potential anticancer activity against the lung cell line with IC50 values of 41.7, 47.4, and 34.8 μg/ml in comparison to that of Risedronic acid (115 μg/ml). However, they do not exhibit potential activity against the breast cancer cell line.

CONCLUSION

Compounds VII and VIII showed in vitro inhibition of human farnesyl pyrophosphate synthase with IC50 values of 82.2 and 98.8 μg/ml, respectively. Further optimization may be required in the future.

Cancer-related hypercalcemia and potential treatments

Cancer-related hypercalcemia is a common finding typically seen in patients with advanced cancer and occurs in about 20 to 30 percent of cases. The most common cause of hypercalcemia in hospitalized patients is hypercalcemia due to malignancy.This clinical problem is seen in patients with both solid tumors and patients with hematologic malignancies. Hypercalcemia is associated with a poor prognosis in oncology patients. This pathologic condition can occur due to many different mechanisms but is usually caused by abnormal calcium use resulting from bone resorption, intestinal absorption, or renal excretion. Hypercalcemia may present with a wide range of symptoms ranging from gastrointestinal system symptoms to neurologic symptoms. Timely diagnosis and initiation of treatment by the physician significantly reduce the risk of complications. Treatment aims to decrease serum calcium by increasing calciuresis, decreasing bone resorption, and decreasing intestinal calcium absorption. The mainstays of treatment are IV hydration, bisphosphonates and calcitonin, denosumab, and in some patients, prednisone, and cinacalcet. Patients with underlying advanced kidney disease and refractory severe hypercalcemia should be evaluated for hemodialysis. Every physician dealing with oncology patients should know the fastest and most effective management of hypercalcemia. We aimed to contribute in this sense.

The Role of the Innate Immune System in Wear Debris-Induced Inflammatory Peri-Implant Osteolysis in Total Joint Arthroplasty

Periprosthetic osteolysis remains a leading complication of total hip and knee arthroplasty, often resulting in aseptic loosening of the implant and necessitating revision surgery. Wear-induced particulate debris is the main cause initiating this destructive process. The purpose of this article is to review recent advances in understanding of how wear debris causes osteolysis, and emergent strategies for the avoidance and treatment of this disease. A strong activator of the peri-implant innate immune this debris-induced inflammatory cascade is dictated by macrophage secretion of TNF-α, IL-1, IL-6, and IL-8, and PGE2, leading to peri-implant bone resorption through activation of osteoclasts and inhibition of osteoblasts through several mechanisms, including the RANK/RANKL/OPG pathway. Therapeutic agents against proinflammatory mediators, such as those targeting tumor necrosis factor (TNF), osteoclasts, and sclerostin, have shown promise in reducing peri-implant osteolysis in vitro and in vivo; however, radiographic changes and clinical diagnosis often lag considerably behind the initiation of osteolysis, making timely treatment difficult. Considerable efforts are underway to develop such diagnostic tools, therapies, and identify novel targets for therapeutic intervention.

Reducing farnesyl diphosphate synthase levels activates Vγ9Vδ2 T cells and improves tumor suppression in murine xenograft cancer models

Human Vγ9Vδ2 T cells are attractive candidates for cancer immunotherapy due to their potent capacity for tumor recognition and cytolysis of many tumor cell types. However, efforts to deploy clinical strategies for Vγ9Vδ2 T cell cancer therapy are hampered by insufficient potency. We are pursuing an alternate strategy of modifying tumors to increase the capacity for Vγ9Vδ2 T cell activation, as a means for strengthening the anti-tumor response by resident or ex vivo manufactured Vγ9Vδ2 T cells. Vγ9Vδ2 T cells are activated in vitro by non-peptidic antigens including isopentenyl pyrophosphate (IPP), a substrate of farnesyl diphosphate synthase (FDPS) in the pathway for biosynthesis of isoprenoids. In an effort to improve in vivo potency of Vγ9Vδ2 T cells, we reduced FDPS expression in tumor cells using a lentivirus vector encoding a short-hairpin RNA that targets FDPS mRNA (LV-shFDPS). Prostate (PC3) or hepatocellular carcinoma (Huh-7) cells transduced with LV-shFDPS induced Vγ9Vδ2 T cell stimulation in vitro, resulting in increased cytokine expression and tumor cell cytotoxicity. Immune deficient mice implanted with LV-shFDPS transduced tumor cells showed dramatic responses to intraperitoneal injection of Vγ9Vδ2 T cells with strong suppression of tumor growth. In vivo potency was increased by transducing tumor cells with a vector expressing both shFDPS and human IL-2. Tumor suppression by Vγ9Vδ2 T cells was dose-dependent with greater effects observed in mice injected with 100% LV-shFDPS transduced cells compared to mice injected with a mixture of 50% LV-shFDPS transduced cells and 50% control (no vector) tumor cells. Delivery of LV-shFDPS by intratumoral injection was insufficient to knockdown FDPS in the majority of tumor cells, resulting in insignificant tumor suppression by Vγ9Vδ2 T cells. Thus, Vγ9Vδ2 T cells efficiently targeted and suppressed tumors expressing shFDPS in mouse xenotransplant models. This proof-of-concept study demonstrates the potential for suppression of genetically modified tumors by human Vγ9Vδ2 T cells and indicates that co-expression of cytokines may boost the anti-tumor effect.

Bone Health Management in the Continuum of Prostate Cancer Disease

Prostate cancer (PCa) is the second-leading cause of cancer-related deaths in men. PCa cells require androgen receptor (AR) signaling for their growth and survival. Androgen deprivation therapy (ADT) is the preferred treatment for patients with locally advanced and metastatic PCa disease. Despite their initial response to androgen blockade, most patients eventually will develop metastatic castration-resistant prostate cancer (mCRPC). Bone metastases are common in men with mCRPC, occurring in 30% of patients within 2 years of castration resistance and in >90% of patients over the course of the disease. Patients with mCRPC-induced bone metastasis develop lesions throughout their skeleton; the 5-year survival rate for these patients is 47%. Bone-metastasis-induced early changes in the bone that proceed the osteoblastic response in the bone matrix are monitored and detected via modern magnetic resonance and PET/CT imaging technologies. Various treatment options, such as targeting osteolytic metastasis with bisphosphonates, prednisone, dexamethasone, denosumab, immunotherapy, external beam radiation therapy, radiopharmaceuticals, surgery, and pain medications are employed to treat prostate-cancer-induced bone metastasis and manage bone health. However, these diagnostics and treatment options are not very accurate nor efficient enough to treat bone metastases and manage bone health. In this review, we present the pathogenesis of PCa-induced bone metastasis, its deleterious impacts on vital organs, the impact of metastatic PCa on bone health, treatment interventions for bone metastasis and management of bone- and skeletal-related events, and possible current and future therapeutic options for bone management in the continuum of prostate cancer disease.

Osteoporosis and Fragility Fractures: currently available pharmacological options and future directions

Osteoporosis is a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture. The average lifetime risk of a 50-year-old woman to suffer a fracture of the spine, hip, proximal humerus, or distal forearm has been estimated at close to 50%. In general, pharmacological treatment is recommended in patients who suffered a fragility fracture because their risk of suffering a subsequent fracture is increased dramatically. Therefore, many guidelines recommend pharmacological treatment in patients without a prevalent fracture if their fracture probability is comparable to or higher than that of a person of the same age with a prevalent fracture. The present review aims to highlight currently available pharmacological treatment options and their antifracture efficacy including safety aspects. Drug classes discussed comprise bisphosphonates, selective estrogen receptor modulators, parathyroid hormone peptides and derivatives, humanized monoclonal antibodies, and estrogens and gestagens and their combinations. Furthermore, a brief glimpse is provided into a potentially promising treatment option that involves mesenchymal stem cells.

The Rationale for Using Neridronate in Musculoskeletal Disorders: From Metabolic Bone Diseases to Musculoskeletal Pain

Neridronate or ((6-amino-1-hydroxy-1-phosphonohexyl) phosphonic acid) is an amino-bisphosphonate (BP) synthetized in Italy in 1986. Bisphosphonates are molecules with a P-C-P bond in their structure that allows strong and selectively binding to hydroxyapatite (HAP) as well as osteoclasts inhibition through different mechanisms of action. Neridronate was initially used to treat Paget disease of the bone, demonstrating effectiveness in reducing bone turnover markers as well as pain. The interesting molecular properties of neridronate foster its wide use in several other conditions, such as osteogenesis imperfecta, and osteoporosis. Thanks to the unique safety and efficacy profile, neridronate has been used in secondary osteoporosis due to genetic, rheumatic, and oncological diseases, including in pediatric patients. In the last decade, this drug has also been studied in chronic musculoskeletal pain conditions, such as algodystrophy, demonstrating effectiveness in improving extraskeletal outcomes. This review highlights historical and clinical insights about the use of neridronate for metabolic bone disorders and musculoskeletal pain conditions.

Advances in Our Understanding of the Mechanism of Action of Drugs (including Traditional Chinese Medicines) for the Intervention and Treatment of Osteoporosis

Osteoporosis (OP) is known as a silent disease in which the loss of bone mass and bone density does not cause obvious symptoms, resulting in insufficient treatment and preventive measures. The losses of bone mass and bone density become more severe over time and an only small percentage of patients are diagnosed when OP-related fractures occur. The high disability and mortality rates of OP-related fractures cause great psychological and physical damage and impose a heavy economic burden on individuals and society. Therefore, early intervention and treatment must be emphasized to achieve the overall goal of reducing the fracture risk. Anti-OP drugs are currently divided into three classes: antiresorptive agents, anabolic agents, and drugs with other mechanisms. In this review, research progress related to common anti-OP drugs in these three classes as well as targeted therapies is summarized to help researchers and clinicians understand their mechanisms of action and to promote pharmacological research and novel drug development.

[68Ga]Ga-NODAGAZOL uptake in atherosclerotic plaques correlates with the cardiovascular risk profile of patients

OBJECTIVES

This study aimed to determine the correlation of [⁶⁸Ga]Ga-NODAGA^ZOL uptake in atherosclerotic plaques and the cardiovascular risk profile of patients imaged with positron emission tomography (PET), wherein quantification of uptake was determined by atherosclerotic plaque maximum target-to-background ratio (TBRmax). We also correlated uptake with a history of cardiovascular events.

METHODS

We included patients who underwent PET/CT imaging post-injection of [⁶⁸Ga] Ga-NODAGA^ZOL. We documented the number of atherosclerotic plaques found in the major arteries on CT and the cardiovascular risks in each patient. We quantified the intensity of tracer uptake in atherosclerotic plaque in the major arteries using the maximum standardized uptake value (SUVmax). The SUVmax of the most tracer-avid plaque was documented as representative of the individual arterial bed. We determined background vascular tracer activity using the mean standardized uptake value (SUVmean) obtained from the lumen of the superior vena cava. The maximum target-to-background ratio (TBRmax) was calculated as a ratio of the SUVmax to the SUVmean. The TBRmax was correlated to the number of atherogenic risk factors and history of cardiovascular events.

RESULTS

Thirty-four patients (M: F 31:3; mean age ± SD: 63 ± 10.01 years) with ≥ 2 cardiovascular risk factors were included. Statistically significant correlation between TBRmax and the number of cardiovascular risk factors was noted in the right carotid (r = 0.50; p < 0.05); left carotid (r = 0. 649; p < 0.05); ascending aorta (r = 0.375; p < 0.05); aortic arch (r = 0.483; p < 0.05); thoracic aorta (r = 0.644; p < 0.05); left femoral (r = 0.552; p < 0.05) and right femoral arteries (r = 0.533; p < 0.05). TBRmax also demonstrated a positive correlation to history of cardiovascular event in the right carotid (U = 26.00; p < 0.05); left carotid (U = 11.00; p < 0.05); ascending aorta (U = 49.00; p < 0.05); aortic arch (U = 37.00; p < 0.05); thoracic aorta (U = 16.00; p < 0.05); left common iliac (U = 49.500; p < 0.05), right common iliac (U = 43.00; p < 0.05), left femoral (U = 40.500; p < 0.05) and right femoral (U = 37.500; p < 0.05).

CONCLUSION

In this cohort of patients, a positive correlation was noted between atherosclerotic plaque uptake of [⁶⁸Ga]Ga-NODAGA^ZOL and the number of atherogenic risk factors which translates to the risk of atherosclerosis and cardiovascular risk factors.

Bone Health in Children with Rheumatic Disorders: Focus on Molecular Mechanisms, Diagnosis, and Management

Bone is an extremely dynamic and adaptive tissue, whose metabolism and homeostasis is influenced by many different hormonal, mechanical, nutritional, immunological and pharmacological stimuli. Genetic factors significantly affect bone health, through their influence on bone cells function, cartilage quality, calcium and vitamin D homeostasis, sex hormone metabolism and pubertal timing. In addition, optimal nutrition and physical activity contribute to bone mass acquisition in the growing age. All these factors influence the attainment of peak bone mass, a critical determinant of bone health and fracture risk in adulthood. Secondary osteoporosis is an important issue of clinical care in children with acute and chronic diseases. Systemic autoimmune disorders, like juvenile idiopathic arthritis, can affect the skeletal system, causing reduced bone mineral density and high risk of fragility fractures during childhood. In these patients, multiple factors contribute to reduce bone strength, including systemic inflammation with elevated cytokines, reduced physical activity, malabsorption and nutritional deficiency, inadequate daily calcium and vitamin D intake, use of glucocorticoids, poor growth and pubertal delay. In juvenile arthritis, osteoporosis is more prominent at the femoral neck and radius compared to the lumbar spine. Nevertheless, vertebral fractures are an important, often asymptomatic manifestation, especially in glucocorticoid-treated patients. A standardized diagnostic approach to the musculoskeletal system, including prophylaxis, therapy and follow up, is therefore mandatory in at risk children. Here we discuss the molecular mechanisms involved in skeletal homeostasis and the influence of inflammation and chronic disease on bone metabolism.

Pathway Engineering, Re-targeting, and Synthetic Scaffolding Improve the Production of Squalene in Plants

Plants are increasingly becoming an option for sustainable bioproduction of chemicals and complex molecules like terpenoids. The triterpene squalene has a variety of biotechnological uses and is the precursor to a diverse array of triterpenoids, but we currently lack a sustainable strategy to produce large quantities for industrial applications. Here, we further establish engineered plants as a platform for production of squalene through pathway re-targeting and membrane scaffolding. The squalene biosynthetic pathway, which natively resides in the cytosol and endoplasmic reticulum, was re-targeted to plastids, where screening of diverse variants of enzymes at key steps improved squalene yields. The highest yielding enzymes were used to create biosynthetic scaffolds on co-engineered, cytosolic lipid droplets, resulting in squalene yields up to 0.58 mg/gFW or 318% higher than a cytosolic pathway without scaffolding during transient expression. These scaffolds were also re-targeted to plastids where they associated with membranes throughout, including the formation of plastoglobules or plastidial lipid droplets. Plastid scaffolding ameliorated the negative effects of squalene biosynthesis and showed up to 345% higher rates of photosynthesis than without scaffolding. This study establishes a platform for engineering the production of squalene in plants, providing the opportunity to expand future work into production of higher-value triterpenoids.

Current Treatments and New Possible Complementary Therapies for Epithelial Ovarian Cancer

Epithelial ovarian cancer (EOC) is one of the deadliest gynaecological malignancies. The late diagnosis is frequent due to the absence of specific symptomatology and the molecular complexity of the disease, which includes a high angiogenesis potential. The first-line treatment is based on optimal debulking surgery following chemotherapy with platinum/gemcitabine and taxane compounds. During the last years, anti-angiogenic therapy and poly adenosine diphosphate-ribose polymerases (PARP)-inhibitors were introduced in therapeutic schemes. Several studies have shown that these drugs increase the progression-free survival and overall survival of patients with ovarian cancer, but the identification of patients who have the greatest benefits is still under investigation. In the present review, we discuss about the molecular characteristics of the disease, the recent evidence of approved treatments and the new possible complementary approaches, focusing on drug repurposing, non-coding RNAs, and nanomedicine as a new method for drug delivery.

Hajdu Cheney syndrome; A novel NOTCH2 mutation in a Syrian child, and treatment with zolidronic acid: A case report and a literature review of treatments

INTRODUCTION

Hajdu Cheney Syndrome (HCS) is a rare genetic disorder characterized by skeletal deformities such as acroosteolysis, osteoporosis, unique craniofacial features, and other systemic abnormalities. This syndrome is caused by NOTCH2 gene mutations, which cause an increase of osteoclast and osteoblast activity that leads to the increased bone resorption. Because of how rare the syndrome is and the vague onset of the symptoms, it can be challenging to make an early diagnosis.

CASE PRESENTATION

We report a case of a female child with HCS who has a new NOTCH2 mutation sequence; (NM_024408.3:c.6463G > T) protein change (Glu2155*), and to our knowledge this is the first reported and diagnosed case in Syria. She presents with short stature, unique craniofacial features, scoliosis, kyphosis, and signs of osteoporosis, in addition to Patent Ductus Arteriosus. The patient was diagnosed with Hajdu Cheney Syndrome, and administered zolidronic acid, and she responded well to the treatment; showing signs of improved bone density and improvement in height, where her bone density improved from 0.23 to 0.31, and she gained 11 cm in height after the treatment.

CONCLUSION

Due to the rarity of the syndrome, there is no established guideline for treatment yet. Based on the pathophysiology of the syndrome that causes increased bone resorption, treatment with the Bisphosphonates group has yielded positive outcomes. Furthermore, we compare different treatments in the literature with their results.

Synthesis, predictions of drug-likeness, and pharmacokinetic properties of some chiral thioureas as potent enzyme inhibition agents

A series of chiral thioureas (1 - 17) were synthesized from and tested for their anticholinesterase, tyrosinase, and urease enzyme inhibitor activities. Various phenylisothiocyanates were added to solution of l-cysteine in methanol: water (1 : 1 v/v) at room temperature and stirred for 24 h. The precipitated solid was recrystallized from n-butanol. Pure compounds were characterized by NMR (1H and 13C), FTIR, and CHNS. Tertiary amine containing N-(4-(diethylamino)phenyl)-N'-(2-mercapto-carboxyethanyl)thiourea 17, N-(4-(dimethylamino)phenyl)-N'-(2-mercapto-carboxyethanyl)thiourea 16 and trimethoxy containing N-(3,4,5-trimethoxyphenyl)-N'-(2-mercapto-carboxyethanyl)thiourea 14 were more active than galantamine against AChE and BChE enzymes. In tyrosinase enzyme inhibition activity, compound 14, 10, 12, 6, 13, and 11 exhibited higher tyrosinase inhibitory activity showing IC50 values of 1.1 ± 0.1, 1.5 ± 0.3, 1.6 ± 0.6, 1.9 ± 0.5, 2.2 ± 0.9 and 2.9 ± 0.2 mM, respectively. In urease enzyme inhibition activity assay, 17 showed higher activity. This work demonstrates the pharmacological significance of chiral thiourea derivatives synthesized from l-cysteine and shows their potential. There is a need to perform more in vitro and in vivo biological activities followed by clinical trials to bring such thiourea to the market.