Ixazomib enhances parathyroid hormone-induced β-catenin/T-cell factor signaling by dissociating β-catenin from the parathyroid hormone receptor

Abaloparatide Maintains Normal Rat Blood Calcium Level in Part Via 1,25-Dihydroxyvitamin D/osteocalcin Signaling Pathway

The PTH-related peptide(1-34) analog, abaloparatide (ABL), is the second anabolic drug available for the treatment of osteoporosis. Previous research demonstrated that ABL had a potent anabolic effect but caused hypercalcemia at a significantly lower rate. However, the mechanism by which ABL maintains the stability of blood calcium levels remains poorly understood. Our in vivo data showed that ABL treatment (40 µg/kg/day for 7 days) significantly increased rat blood level of 1,25-dihydroxyvitamin D [1,25-(OH)2D] without raising the blood calcium value. ABL also significantly augmented the carboxylated osteocalcin (Gla-Ocn) in the blood and bone that is synthesized by osteoblasts, and increased noncarboxylated Ocn, which is released from the bone matrix to the circulation because of osteoclast activation. The in vitro data showed that ABL (10 nM for 24 hours) had little direct effects on 1,25-(OH)2D synthesis and Gla-Ocn formation in nonrenal cells (rat osteoblast-like cells). However, ABL significantly promoted both 1,25-(OH)2D and Gla-Ocn formation when 25-hydroxyvitamin D, the substrate of 1α-hydroxylase, was added to the cells. Thus, the increased 1,25-(OH)2D levels in rats treated by ABL result in high levels of Gla-Ocn and transient calcium increase in the circulation. Gla-Ocn then mediates calcium ions in the extracellular fluid at bone sites to bind to hydroxyapatite at bone surfaces. This regulation by Gla-Ocn at least, in part, maintains the stability of blood calcium levels during ABL treatment. We conclude that the signaling pathway of ABL/1,25-(OH)2D/Gla-Ocn contributes to calcium homeostasis and may help understand the mechanism of ABL for osteoporosis therapy.

LINC00461 Knockdown Enhances the Effect of Ixazomib in Multiple Myeloma Cells

BACKGROUND

LINC00461 has been implicated to be involved in several types of cancer while its roles in multiple myeloma remain unclear. Our study aims to investigate the roles of LINC00461 in multiple myeloma and explore its effects on ixazomib therapy.

METHODS

LINC00461 and small nuclear ribonucleoprotein polypeptide (SNRP) B2 knockdown stable cell lines were constructed. Cell viability assays including MTT, cell number counting, and colony formation were performed. RNA-pull down and immunoblotting assays were conducted to determine the intramolecular interactions. qRT-PCR and western blotting were conducted to determine the levels of target genes. Kaplan-Meier analysis was used to evaluate overall survival rates.

RESULTS

Knockdown of LINC00461 or SNRPB2 enhanced ixazomib's cytotoxicity, as well as affected its regulatory effects on cell apoptosis and cell cycle distribution. Further results showed that LINC00461 knockdown reduced the expression levels of SNRPB2 by their interactions. Additionally, a positive correlation between LINC00461 and SNRPB2 was found in patients with multiple myeloma. Low expression of SNRPB2 was associated with a high survival rate in patients with multiple myeloma.

CONCLUSION

Knockdown of LINC00461 enhanced the therapeutic effects of ixazomib against multiple myeloma in part by the regulation of SNRPB2.

High-Throughput Screening of FDA-Approved Drug Library Reveals Ixazomib Is a Broad-Spectrum Antiviral Agent against Arboviruses

The emergence of significant arboviruses and their spillover transmission to humans represent a major threat to global public health. No approved drugs are available for the treatment of significant arboviruses in circulation today. The repurposing of clinically approved drugs is one of the most rapid and promising strategies in the identification of effective treatments for diseases caused by arboviruses. Here, we screened small-molecule compounds with anti-tick-borne encephalitis virus, West Nile virus, yellow fever virus and chikungunya virus activity from 2580 FDA-approved drugs. In total, 60 compounds showed antiviral efficacy against all four of the arboviruses in Huh7 cells. Among these compounds, ixazomib and ixazomib citrate (inhibitors of 20S proteasome β5) exerted antiviral effects at a low-micromolar concentration. The time-of-drug-addition assay suggested that ixazomib and ixazomib citrate disturbed multiple processes in viruses’ life cycles. Furthermore, ixazomib and ixazomib citrate potently inhibited chikungunya virus replication and relieved virus-induced footpad swelling in a mouse model. These results offer critical information which supports the role of ixazomib as a broad-spectrum agent against arboviruses.

Mutation of Methionine to Asparagine but Not Leucine in Parathyroid Hormone Mimics the Loss of Biological Function upon Oxidation

Human parathyroid hormone (PTH) is an 84-amino acid peptide that contains two methionine (Met) residues located at positions 8 and 18. It has long been recognized that Met residues in PTH are subject to oxidation to become Met sulfoxide, resulting in a decreased biological function of the peptide. However, the mechanism of the lost biological function of PTH oxidation remains elusive. To characterize whether the shift from the hydrophobic nature of the native Met residue to the hydrophilic nature of Met sulfoxide plays a role in the reduction of biological activity upon PTH oxidation, we conducted in silico and in vitro site-directed mutagenesis of Met-8 and Met-18 to the hydrophilic residue asparagine (Asn) or to the hydrophobic residue leucine (Leu) and compared the behavior of these mutated peptides with that of PTH oxidized at Met-8 and/or Met-18. Our results showed that the biological activity of the Asn-8 and Asn-8/Asn-18 mutants was significantly reduced, similar to Met-8 sulfoxide and Met-8/Met-18 sulfoxide analogues, while the functions of Asn-18, Leu-8, Leu-8/Leu-18 mutants, or Met-18 sulfoxide analogues were similar to wild-type PTH. This is rationalized from molecular modeling and immunoprecipitation assay, demonstrating disruption of hydrophobic interactions between Met-8 and Met-18 of PTH and type-1 PTH receptor (PTHR1) upon mutation or oxidation. Thus, these novel findings support the notion that the loss of biological function of PTH upon oxidation of Met-8 is due, at least in part, to the conversion from a hydrophobic to a hydrophilic residue that disrupts direct hydrophobic interaction between PTH and PTHR1.

Recent Research Progress of Chiral Small Molecular Antitumor-Targeted Drugs Approved by the FDA From 2011 to 2019

Chiral drugs usually contain chiral centers, which are present as single enantiomers or racemates. Compared with achiral drugs, they have significant advantages in safety and efficacy with high stereoselectivity. Of these drugs, chirality not only exerts influence on the solubility and pharmacokinetic characteristics but also has specific mechanistic characteristics on their targets. We noted that small molecules with unique chiral properties have emerged as novel components of antitumor drugs approved by the FDA in decade. Since approved, these drugs have been continuously explored for new indications, new mechanisms, and novel combinations. In this mini review, recent research progress of twenty-two FDA-approved chiral small molecular-targeted antitumor drugs from 2011 to 2019 is summarized with highlighting the potential and advantages of their applications. We believe that these updated achievements may provide theoretical foundation and stimulate research interests for optimizing drug efficacy, expanding clinical application, overcoming drug resistance, and advancing safety in future clinical administrations of these chiral targeted drugs.

The role of Wnt/β-catenin signaling pathway in the pathogenesis and treatment of multiple myeloma (review)

Multiple myeloma (MM) is a refractory hematological malignancy characterized by aberrant accumulation of plasma cells. Patients with MM are susceptible to becoming resistant to chemotherapy, eventually leading to relapse. Progression of MM is largely dependent on the bone marrow microenvironment. Stromal cells in the bone marrow microenvironment secrete Wnt ligands to activate Wnt signaling in MM, which is mediated through the transcription regulator β-catenin. In addition, Wnt/β-catenin pathway encourages osteoblast differentiation and bone formation, dysregulation of which is responsible for proliferation and drug resistance of MM cells. As a result, direct inhibition or silencing of β-catenin or associated genes in the Wnt/β-catenin pathway has been proposed to be an effective therapeutic anti-MM strategy. However, the underlying regulatory mechanism of the Wnt/β-catenin pathway in MM remains to be fully elucidated. Herein, we summarized research advances on the specific genes and molecular biology process of Wnt/β-catenin pathway involved in tumorigenesis of MM, as well as the interaction with bone marrow microenvironment. Additionally, comprehensive summaries of drugs or small molecule inhibitors acting on Wnt/β-catenin pathway and targeting MM were introduced. This review intends to provide an overview of theoretical supports for novel Wnt/β-catenin pathway based treatment strategies in MM.

Bone remineralization of lytic lesions in multiple myeloma - The Arkansas experience

Multiple myeloma (MM) patients frequently present with extensive osteolytic bone lesions. However, the impact of myeloma treatment on focal lytic lesion remineralization has not been extensively studied. In this study, the effect of anti-myeloma treatment on the extent of bone remineralization was examined and potential mediators identified. Newly diagnosed MM patients enrolled in the Total Therapy 4 and 5 (TT4; n = 231, TT5; n = 64) protocols were longitudinally evaluated for changes in radiological parameters for a median of 6.1 years. Bone remineralization was defined as a sclerotic CT change within the lytic lesion and quantified as a percentage of remineralization, using the initial lesion size as a reference. Such changes were correlated to clinical and biochemical parameters, and the gene expression profile of bone marrow biopsy. Overall, remineralization occurred in 72% of patients (213/295). Of those patients that experienced remineralization, 36% (107/295) achieved at least 25% of bone remineralization. Patients with high-risk disease defined by gene expression profile signature (GEP70 ≥ 0.66) experienced significant remineralization compared to low-risk MM. Female patients were also more likely to experience bone remineralization and in a shorter median time (2.0 vs. 3.3 y). Factors such as serum alkaline phosphatase along with high levels of RUNX2 and SOX4 gene expression correlated with increasing extent of bone remineralization. This analysis demonstrated significant remineralization of lytic lesions in MM patients treated on TT clinical trials. While the underlying mechanism remains elusive these findings support the hypothesis that patient baseline bone-related factors play a fundamental role in the skeletal repair of bone lesions in MM that provide new opportunities for improving patient outcomes.

Therapeutic status and the prospect of CRISPR/Cas9 gene editing in multiple myeloma

In recent years, CRISPR/Cas9, a novel gene-editing technology, has shown considerable potential in the design of novel research methods and future options for treating multiple myeloma (MM). The use of CRISPR/Cas9 promises faster and more accurate identification and validation of target genes. In this review, we summarize the current research status of the application of CRISPR technology in MM, especially in detecting the expression of MM gene, exploring the mechanism of drug action, screening for drug-resistant genes, developing immunotherapy and screening for new drug targets. Given the tremendous progress that has been made, we believe that CRISPR/Cas9 possesses great potential in MM-related clinical practice.

Ixazomib Improves Bone Remodeling and Counteracts sonic Hedgehog signaling Inhibition Mediated by Myeloma Cells

Multiple myeloma (MM) is a clonal B-cell malignancy characterized by an accumulation of plasma cells (PC) in the bone marrow (BM), leading to bone loss and BM failure. Osteolytic bone disease is a common manifestation observed in MM patients and represents the most severe cause of morbidity, leading to progressive skeletal damage and disabilities. Pathogenetic mechanisms of MM bone disease are closely linked to PCs and osteoclast (OCs) hyperactivity, coupled with defective osteoblasts (OBs) function that is unable to counteract bone resorption. The aim of the present study was to investigate the effects of Ixazomib, a third-generation proteasome inhibitor, on osteoclastogenesis and osteogenic differentiation. We found that Ixazomib was able to reduce differentiation of human monocytes into OCs and to inhibit the expression of OC markers when added to the OC medium. Concurrently, Ixazomib was able to stimulate osteogenic differentiation of human mesenchymal stromal cells (MSCs), increasing osteogenic markers, either alone or in combination with the osteogenic medium. Given the key role of Sonic Hedgehog (SHH) signaling in bone homeostasis, we further investigated Ixazomib-induced SHH pathway activation. This set of experiments showed that Ixazomib, but not Bortezomib, was able to bind the Smoothened (SMO) receptor leading to nuclear translocation of GLI1 in human MSCs. Moreover, we demonstrated that PCs act as GLI1 suppressors on MSCs, thus reducing the potential of MSCs to differentiate in OBs. In conclusion, our data demonstrated that Ixazomib regulates bone remodeling by decreasing osteoclastogenesis and prompting osteoblast differentiation via the canonical SHH signaling pathway activation, thus, representing a promising therapeutic option to improve the complex pathological condition of MM patients.

Nek2B activates the wnt pathway and promotes triple-negative breast cancer chemothezrapy-resistance by stabilizing β-catenin

Background

The chemotherapy-resistance of triple-negative breast cancer (TNBC) remains a major challenge. The Nek2B kinase and β-catenin serve as crucial regulators of mitotic processes. The aim of this study was to test the correlation between Nek2B and TNBC chemotherapy sensitivity, and to determine the regulation of Nek2B on β-catenin and wnt/β-catenin signal pathway.

Methods

Gene Expression Omnibus(GEO) databases were used to gather gene exprsssion data of TNBC patients who undergoing chemotherapy. The co-expression of Nek2B and β-catenin in TNBC surgical sections and cells were analysed by immunohistochemistry, Q-RT-PCR, Western-blot and immunofluorescent staining. The impact of the expression of Nek2B and β-catenin in prognosis was also assessed using the Kaplan-Meier curves. CCK8 assay was used to detect the IC50 value of TNBC cell line. The endogenous binding capacity of Nek2B and β-catenin and phosphorylation of β-catenin by Nek2B were detected using co-immunoprecipitation (CO-IP). Chromatin immune-precipitation (ChIP) analysis and Luciferase Assays were used to evaluate the binding ability of the Nek2B, β-catenin and TCF4 complex with LEF-1 promoter. Nek2B-siRNA and Nek2B plasmid were injected into nude mice, and tumorigenesis was monitored.

Results

We found that overexpression of Nek2B and β-catenin in TNBC samples, was associated with patients poor prognosis. Patients with positive Nek2B expression were less sensitive to paclitaxel-containing neoadjuvant chemotherapy. Interestingly, in a panel of established TNBC cell line, Nek2B and β-catenin were highly expressed in cells exhibiting paclitaxel resistance. Our data also suggest that β-catenin binded to and was phosphorylated by Nek2B, and was in a complex with TCF4. Nek2B mainly regulates the expression of β-catenin in TNBC nucleus. Nek2B, β-catenin and TCF4 can be binded with the WRE functional area of LEF-1 promoter. Nek2B can activite wnt signaling pathway and wnt downstream target genes. The tumors treated by Nek2B siRNA associated with paclitaxel were the smallest in nude mouse, and Nek2B can regulate the expression of β-catenin and wnt downstream target genes in vivo.

Conclusion

Our study suggested that Nek2B can bind to β-catenin and the co-expression correlated with TNBC patients poor prognosis. It appears that Nek2B and β-catenin might synergize to promote chemotherapy resistance.

Parathyroid hormone and premature thymus ageing in patients with chronic kidney disease

Premature immune ageing, including thymic atrophy, is observed in patients with chronic kidney disease (CKD). Parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23), which are mineral and bone disorder (MBD)-related factors, affect immune cells and possibly cause thymic atrophy. We examined the cross-sectional association between thymic atrophy, evaluated as the number of CD3⁺CD4⁺CD45RA⁺CD31⁺ cells [recent thymic emigrants (RTE)/μL], and MBD-related factors [(serum PTH, FGF23, and alkaline phosphatase (ALP) level] in 125 patients with non-dialysis dependent CKD. Median estimated glomerular filtration rate (eGFR) was 17 mL/min/1.73 m². Older age (r = −0.46), male sex (r = −0.34), lower eGFR (r = 0.27), lower serum-corrected calcium (r = 0.27), higher PTH (r = −0.36), and higher ALP level (r = −0.20) were identified as determinants of lower number of RTE. In contrast, serum concentrations of FGF23 and phosphorus were not correlated with RTE. Multivariate non-linear regression analysis indicated a negative association between serum PTH and log-transformed RTE (P = 0.030, P for non-linearity = 0.124). However, the serum levels of FGF23 and ALP were not associated with RTE. In patients with CKD, serum PTH concentrations were related to thymic atrophy which contributes to immune abnormality.

Effect of the PTHrP(1-34) analog abaloparatide on inducing chondrogenesis involves inhibition of intracellular reactive oxygen species production

Osteoarthritis (OA) is a degenerative joint disease characterized by a progressive loss of articular cartilage. Mesenchymal stem cells transplanted to damaged tissues are promising for OA cartilage repair. However, these cells are poor survival after transplantation and acquire hypertrophic properties during chondrogenic induction. Parathyroid hormone-related protein (PTHrP) promotes chondrogenesis and suppresses chondrocyte hypertrophic differentiation. Additionally, PTHrP was reported to have anti-oxidant effects. The synthetic PTHrP(1-34) analog abaloparatide (ABL) is a newly approved drug for osteoporosis therapy. It is unknown whether ABL stimulates chondrogenesis and affects intracellular reactive oxygen species (ROS) production. By using mouse embryonic limb bud mesenchymal stem cells in micromass culture as an in vitro model of chondrogenic differentiation, we found that mesenchymal stem cells in micromass cultures spontaneously produced ROS, and N-acetyl-l-cysteine, a potent antioxidant, enhanced chondrogenesis. The effect of ABL on stimulation of chondrogenesis is involved in its inhibition of intracellular ROS generation. These novel findings support the use of ABL for the damaged cartilage regeneration.

Biased signaling of the proton-sensing receptor OGR1 by benzodiazepines

GPCRs have diverse signaling capabilities, based on their ability to assume various conformations. Moreover, it is now appreciated that certain ligands can promote distinct receptor conformations and thereby bias signaling toward a specific pathway to differentially affect cell function. The recently deorphanized G protein-coupled receptor OGR1 [ovarian cancer G protein-coupled receptor 1 ( GPR68)] exhibits diverse signaling events when stimulated by reductions in extracellular pH. We recently demonstrated airway smooth muscle cells transduce multiple signaling events, reflecting a diverse capacity to couple to multiple G proteins. Moreover, we recently discovered that the benzodiazepine lorazepam, more commonly recognized as an agonist of the γ-aminobutyric acid A (GABAA) receptor, can function as an allosteric modulator of OGR1 and, similarly, can promote multiple signaling events. In this study, we demonstrated that different benzodiazepines exhibit a range of biases for OGR1, with sulazepam selectively activating the canonical Gs of the G protein signaling pathway, in heterologous expression systems, as well as in several primary cell types. These findings highlight the potential power of biased ligand pharmacology for manipulating receptor signaling qualitatively, to preferentially activate pathways that are therapeutically beneficial.-Pera, T., Deshpande, D. A., Ippolito, M., Wang, B., Gavrila, A., Michael, J. V., Nayak, A. P., Tompkins, E., Farrell, E., Kroeze, W. K., Roth, B. L., Panettieri, R. A. Jr Benovic, J. L., An, S. S., Dulin, N. O., Penn, R. B. Biased signaling of the proton-sensing receptor OGR1 by benzodiazepines.

PTH1R-CaSR Cross Talk: New Treatment Options for Breast Cancer Osteolytic Bone Metastases

Metastatic breast cancer (BrCa) is currently incurable despite great improvements in treatment of primary BrCa. The incidence of skeletal metastases in advanced BrCa occurs up to 70%. Recent findings have established that the distribution of BrCa metastases to the skeleton is not a random process but due to the favorable microenvironment for tumor invasion and growth. The complex interplay among BrCa cells, stromal/osteoblastic cells, and osteoclasts in the osseous microenvironment creates a bone-tumor vicious cycle (a feed-forward loop) that results in excessive bone destruction and progressive tumor growth. Both the type 1 PTH receptor (PTH1R) and extracellular calcium-sensing receptor (CaSR) participate in the vicious cycle and influence the skeletal metastatic niche. Thus, this review focuses on how the PTH1R and CaSR signaling pathways interact and contribute to the pathogenesis of BrCa bone metastases. The effects of intermittent PTH and allosteric modulators of CaSR for the use of bone-anabolic agents and prevention of BrCa bone metastases constitute a proof of principle for therapeutic consideration. Understanding the interplay between PTH1R and CaSR signaling in the development of BrCa bone metastases could lead to a novel therapeutic approach to control both osteolysis and tumor burden in the bone.