Costunolide increases osteoblast differentiation via ATF4-dependent HO-1 expression in C3H10T1/2 cells

Phytoestrogens as potential anti-osteoporosis nutraceuticals: Major sources and mechanism(s) of action

By 2050, the global aging population is predicted to reach 1.5 billion, highlighting the need to enhance the quality of life of the elderly population. Osteoporotic fractures are projected to affect one in three women and one in five men over age 50. Initial treatments for osteoporosis in postmenopausal women include antiresorptive agents such as bisphosphonates, strontium ranelate, estrogen replacement therapy (ERT) and selective estrogen receptor modulators (SERMs). However, these do not rebuild bone, limiting their effectiveness. Denosumab, an FDA-approved antiresorptive monoclonal antibody, also has drawbacks including high costs, biannual subcutaneous injections, slow healing, impaired bone growth and side effects like eczema, flatulence, cellulitis, osteonecrosis of the jaw (ONJ) and an increased risk of spinal fractures after discontinuation of treatment. Nutraceuticals, particularly phytoestrogens, are gaining attention for their health benefits and safety in osteoporosis prevention, management and treatment. Phytoestrogens are plant metabolites similar to mammalian estrogens and include isoflavones, coumestans, lignans, stilbenes, and flavonoids. They interact with estrogen receptor isoforms ERα and ERβ, acting as agonists or antagonists based on concentration and bioavailability. Their tissue-selective activities are particularly significant: anti-estrogenic effects in reproductive tissues may lower the risk of hormone-related cancers (such as ovarian, uterine, breast and prostate), while estrogenic effects on bone could contribute to the preservation of bone mineral density.Phytoestrogens are, thus, used in managing breast and prostate cancers, cardiovascular diseases, menopause and osteoporosis. The present review focuses on the botanical origin, classification, sources and mechanism(s) of action of major phytoestrogens, their potential in prevention and management of osteoporosis and the requirement for additional clinical trials to achieve more definitive outcomes in order to confirm their efficacy and dosage safety.

Novel insights into the activating transcription factor 4 in Alzheimer's disease and associated aging-related diseases: Mechanisms and therapeutic implications

Ageing is inherent to all human beings, most mechanistic explanations of ageing results from the combined effects of various physiological and pathological processes. Additionally, aging pivotally contributes to several chronic diseases. Activating transcription factor 4 (ATF4), a member of the ATF/cAMP response element-binding protein family, has recently emerged as a pivotal player owing to its indispensable role in the pathophysiological processes of Alzheimer's disease and aging-related diseases. Moreover, ATF4 is integral to numerous biological processes. Therefore, this article aims to comprehensively review relevant research on the role of ATF4 in the onset and progression of aging-related diseases, elucidating its potential mechanisms and therapeutic approaches. Our objective is to furnish scientific evidence for the early identification of risk factors in aging-related diseases and pave the way for new research directions for their treatment. By elucidating the signaling pathway network of ATF4 in aging-related diseases, we aspire to gain a profound understanding of the molecular and cellular mechanisms, offering novel strategies for addressing aging and developing related therapeutics.

Pluronic F127 hydrogel-loaded extracellular vesicles from adipose-derived mesenchymal stem cells promote tracheal cartilage regeneration via SCNN1B delivery

Extracellular vesicles (EVs) derived from adipose-derived mesenchymal stem cells (AMSC-EVs) have been highlighted as a cell-free therapy due to their regenerative capability to enhance tissue and organ regeneration. Herein, we aimed to examine the mechanism of PF127-hydrogel@AMSC-EVs in promoting tracheal cartilage defect repair. Based on bioinformatics methods, SCNN1B was identified as a key gene for the osteogenic differentiation of AMSCs induced by AMSC-EVs. EVs were isolated from rat AMSCs and then loaded onto thermo-sensitive PF-127 hydrogel to develop PF127-hydrogel@AMSC-EVs. It was established that PF127-hydrogel@AMSC-EVs could effectively deliver SCNN1B into AMSCs, where SCNN1B promoted AMSC osteogenic differentiation. The promotive effect was evidenced by enhanced ALP activity, extracellular matrix mineralization, and expression of s-glycosaminoglycan, RUNX2, OCN, collagen II, PERK, and ATF4. Furthermore, the in vivo experiments revealed that PF127-hydrogel@AMSC-SCNN1B-EVs stimulated tracheal cartilage regeneration in rats through PERK/ATF4 signaling axis activation. Therefore, PF127-hydrogel@AMSC-SCNN1B-EVs may be a novel cell-free biomaterial to facilitate tracheal cartilage regeneration and cartilage injury repair.

Advances in the roles of ATF4 in osteoporosis

Osteoporosis (OP) is characterized by reduced bone mass, decreased strength, and enhanced bone fragility fracture risk. Activating transcription factor 4 (ATF4) plays a role in cell differentiation, proliferation, apoptosis, redox balance, amino acid uptake, and glycolipid metabolism. ATF4 induces the differentiation of bone marrow mesenchymal stem cells (BM-MSCs) into osteoblasts, increases osteoblast activity, and inhibits osteoclast formation, promoting bone formation and remodeling. In addition, ATF4 mediates the energy metabolism in osteoblasts and promotes angiogenesis. ATF4 is also involved in the mediation of adipogenesis. ATF4 can selectively accumulate in osteoblasts. ATF4 can directly interact with RUNT-related transcription factor 2 (RUNX2) and up-regulate the expression of osteocalcin (OCN) and osterix (Osx). Several upstream factors, such as Wnt/β-catenin and BMP2/Smad signaling pathways, have been involved in ATF4-mediated osteoblast differentiation. ATF4 promotes osteoclastogenesis by mediating the receptor activator of nuclear factor κ-B (NF-κB) ligand (RANKL) signaling. Several agents, such as parathyroid (PTH), melatonin, and natural compounds, have been reported to regulate ATF4 expression and mediate bone metabolism. In this review, we comprehensively discuss the biological activities of ATF4 in maintaining bone homeostasis and inhibiting OP development. ATF4 has become a therapeutic target for OP treatment.

Advances in the interaction between endoplasmic reticulum stress and osteoporosis

The endoplasmic reticulum (ER) is the main site for protein synthesis, folding, and secretion, and accumulation of the unfolded/misfolded proteins in the ER may induce ER stress. ER stress is an important participant in various intracellular signaling pathways. Prolonged- or high-intensity ER stress may induce cell apoptosis. Osteoporosis, characterized by imbalanced bone remodeling, is a global disease caused by many factors, such as ER stress. ER stress stimulates osteoblast apoptosis, increases bone loss, and promotes osteoporosis development. Many factors, such as the drug's adverse effects, metabolic disorders, calcium ion imbalance, bad habits, and aging, have been reported to activate ER stress, resulting in the pathological development of osteoporosis. Increasing evidence shows that ER stress regulates osteogenic differentiation, osteoblast activity, and osteoclast formation and function. Various therapeutic agents have been developed to counteract ER stress and thereby suppress osteoporosis development. Thus, inhibition of ER stress has become a potential target for the therapeutic management of osteoporosis. However, the in-depth understanding of ER stress in the pathogenesis of osteoporosis still needs more effort.

Zingerone stimulates osteoblast differentiation by increasing Smad1/5/9 mediated HO-1 expression in MC3T3-E1 cells and primary mouse calvarial cells

Zingerone (Zin) is a non-volatile compound found mainly in dried ginger. Zingerone increases the expression of osteogenic markers and has antioxidant effects. A previous study showed that zingerone accelerated osteoblast differentiation by suppressing the expression of Smad7, a member of the inhibitory Smad (I-Smad) family. However, it is not known if zingerone can induce osteoblast differentiation by regulating Smad1/5/9, a member of the receptor-regulated Smad (R-Smad) famlily. In addition, osteoblast differentiation induced by Smad1/5/9 mediated increases in the expression of heme oxygenase 1 (HO-1) has not been reported. This study investigated the effects of zingerone on osteoblast differentiation and confirmed the relationship between Smad1/5/9 and HO-1. Zingerone increased the expression of osteogenic genes including Runx2, Dlx5 and OC, and also promoted Smad1/5/9 phosphorylation. Interestingly, HO-1 expression was also elevated by zingerone, and an inhibitor of HO-1 (Sn(IV) protoporphyrin IX dichloride, SnPP) suppressed the zingerone-induced increase in HO-1 expression and expression of osteogenic marker genes such as Dlx5, Runx2, and OC. Protein phosphatase 2A Cα (PP2A Cα, an inhibitor of Smad1/5/9) suppressed the zingerone-induced increase in HO-1 expression and expression of osteogenic marker genes. The zingerone-induced increase in HO-1 lucifeerase activity was suppressed by PP2A Cα. Taken together, our data demonstrate that zingerone promotes osteoblast differentiation by increasing Smad1/5/9 mediated HO-1 expression.

Anti-Inflammatory and Immunoregulatory Action of Sesquiterpene Lactones

Sesquiterpene lactones (SL), characterized by their high prevalence in the Asteraceae family, are one of the major groups of secondary metabolites found in plants. Researchers from distinct research fields, including pharmacology, medicine, and agriculture, are interested in their biological potential. With new SL discovered in the last years, new biological activities have been tested, different action mechanisms (synergistic and/or antagonistic effects), as well as molecular structure–activity relationships described. The review identifies the main sesquiterpene lactones with interconnections between immune responses and anti-inflammatory actions, within different cellular models as well in in vivo studies. Bioaccessibility and bioavailability, as well as molecular structure–activity relationships are addressed. Additionally, plant metabolic engineering, and the impact of sesquiterpene lactone extraction methodologies are presented, with the perspective of biological activity enhancement. Sesquiterpene lactones derivatives are also addressed. This review summarizes the current knowledge regarding the therapeutic potential of sesquiterpene lactones within immune and inflammatory activities, highlighting trends and opportunities for their pharmaceutical/clinical use.

HO-1 in Bone Biology: Potential Therapeutic Strategies for Osteoporosis

Osteoporosis is a prevalent bone disorder characterized by bone mass reduction and deterioration of bone microarchitecture leading to bone fragility and fracture risk. In recent decades, knowledge regarding the etiological mechanisms emphasizes that inflammation, oxidative stress and senescence of bone cells contribute to the development of osteoporosis. Studies have demonstrated that heme oxygenase 1 (HO-1), an inducible enzyme catalyzing heme degradation, exhibits anti-inflammatory, anti-oxidative stress and anti-apoptosis properties. Emerging evidence has revealed that HO-1 is critical in the maintenance of bone homeostasis, making HO-1 a potential target for osteoporosis treatment. In this Review, we aim to provide an introduction to current knowledge of HO-1 biology and its regulation, focusing specifically on its roles in bone homeostasis and osteoporosis. We also examine the potential of HO-1-based pharmacological therapeutics for osteoporosis and issues faced during clinical translation.

Aucklandiae Radix and Vladimiriae Radix: A systematic review in ethnopharmacology, phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Aucklandiae Radix (AR) and Vladimiriae Radix (VR), as commonly used traditional Chinese herbal medicine, were widely used in the treatment of gastrointestinal diseases. The two herbal medicines were warm, pungent and bitter. They entered the spleen, stomach, large intestine and gallbladder meridians, and had the effect of promoting qi circulation to relieve pain. It is usually used for chest and hypochondrium, abdominal fullness and pain, tenesmus, indigestion, and warming the middle to harmonize the stomach in clinically.

AIM OF THIS REVIEW

To provide a reference for the identification of traditional use, the material basis of efficacy and preclinical research between AR and VR, this review systematically summarized the similarities and differences in ethnopharmacology, phytochemistry and modern pharmacology.

MATERIALS AND METHODS

The literature information was collected systematically from the electronic scientific databases, including PubMed, Science Direct, Google Scholar, Web of Science, Geen Medical, China National Knowledge Infrastructure, as well as other literature sources, such as classic books of herbal medicine, master's thesis, doctoral thesis.

RESULTS

In the plateau areas of Sichuan Province, VR used to be regarded as substitute or local habit for AR, which is regularly used for chest, abdominal fullness and pain, diarrhea, and other related diseases. In Chinese Pharmacopoeia (ChP) 2020 edition, 145 prescription preparations with AR were collected, such as Xianglian Wan, Muxiang Shunqi Wan, Liuwei Muxiang San. However, only one prescription preparation (Jiuxiang Zhitong Wan) contained VR. Additionally, 237 and 254 chemical components were separately isolated and identified from AR and VR, 69 kinds of compounds were common among them, and the significant differences were presented in sesquiterpene lactones, monoterpenoids, triterpenoids and phenylpropanoids. Moreover, Costunolide (COS) and Dehydrocostus lactone (DEH), two main research objects of modern pharmacology, showed multiple pharmacological activities. Not only could they inhibit the activity of some cancer cells (such as breast cancer and leukemia cells), but they regulated the levels of various inflammatory factors (including TNF-α, NF-κB, IL-1β, IL-6) and repressed the growth and reproduction of various microorganisms (like Helicobacter pylori, Staphylococcus aureus).

CONCLUSION

COS and DEH as the common active components, provide a certain basis for local medicine about the substitution of VR for AR in Sichuan province of China in the past. In addition, the sesquiterpenoids are the main common compounds in AR and VR by collecting and collating a large number of literature and various data websites. Furthermore, AR and VR have significant differences in ethnopharmacology and phytochemistry, especially in sesquiterpene lactones, monoterpenoids, triterpenoids and phenylpropanoids, and are probably viewed as reference of a separate list of AR and VR in Chinese Pharmacopoeia.

HO-1: A new potential therapeutic target to combat osteoporosis

Heme oxygenase-1 (HO-1) exerts a protective effect against cell damage and induces the activity of many enzymes involved in the treatment of many human diseases, including osteoporosis. The increasing prevalence of osteoporosis and the limitations of the current treatments available led to a continuous occurrence of bone loss and osteoporotic fractures, highlighting the need of a better understanding of the mechanism and function of HO-1. Many factors cause osteoporosis, including lack of estrogen, aging, and iron overload, and they either cause the increase in inflammatory factors or the increase in reactive oxygen species to break bone reconstruction balance. Therefore, regulating the production of inflammatory factors and reactive oxygen species may become a strategy for the treatment of osteoporosis. Solid evidence showed that the overexpression of HO-1 compensates high oxidation levels by increasing intracellular antioxidant levels and reduces inflammation by suppressing pro-inflammatory factors. Some extracts can target HO-1 and ameliorate osteoporosis. However, no systematic report is available on therapies targeting HO-1 to combat osteoporosis. Therefore, this review summarizes the biological characteristics of HO-1, and the relationship between inflammatory response and reactive oxygen species production regulated by HO-1 and osteoporosis. The understanding of the role of HO-1 in osteoporosis may provide ideas for a potential clinical treatment and new drugs targeting HO-1.

Chrysophanol increases osteoblast differentiation via AMPK/Smad1/5/9 phosphorylation in vitro and in vivo

Chrysophanol (Chrysophanic acid; CA) is a natural anthraquinone found in Senna tora and rhubarb that has various characteristic features, including the ability to suppress adipogenesis. However, its effects on osteoblast differentiation have not been investigated. Herein, this study aimed to demonstrate the mechanism by which CA induces the osteoblast differentiation. CA increased the expression of osteogenic genes. The staining levels Alkaline phosphatase (ALP) and Alizarin Red S (ARS) were increased by chrysophanol. CA induced osteoblast differentiation through AMP-activated protein kinase (AMPK)/Small mothers against decapentaplegic (Smad1/5/9) activation in MC3T3-E1 cells. In addition, compound C, AMPK inhibitor (Comp. C)-induced cells suppressed osteogenic genes expression and AMPK/Smad1/5/9 activation. Interestingly, AMPK in the CA-induced AMPK/Smad1/5/9 signalling pathway was an upstream regulator of Smad1/5/9. In order to further dissect in bone development, we used a zebrafish model to investigate the effect of CA on bone development. These results suggest that CA stimulated bone development via AMPK/Smad1/5/9. Overall, our results demonstrate that CA promotes osteoblast differentiation via AMPK/Smad1/5/9 expression in vitro and in vivo.

Osteopromotive carbon dots promote bone regeneration through the PERK-eIF2α-ATF4 pathway

Bone defects are still an unsolved clinical issue that must be overcome. Carbon dots have shown very promising effects in biological therapy. In the current study, we explored their effects on osteogenesis. Furthermore, we revealed the mechanisms in order to develop novel therapeutic approaches to manage the bone defect. For this study, ascorbic acid carbon dots (CDs) were created by a one-step microwave-assisted method. Results showed that the CDs effectively enhanced matrix mineralization, promoted osteogenic differentiation in vitro, and promoted new bone regeneration in the skull defect model in vivo. Furthermore, our data demonstrated that the ER stress and PERK-eIF2α-ATF4 pathway were activated by the CD-induced increase in intracellular calcium. Taken together, our findings suggest that the PERK pathway plays a critical role in CD-induced osteogenic differentiation, and the CDs created herein have the potential to be used to repair bone defects in clinical practice.

Phytochemicals impact on osteogenic differentiation of mesenchymal stem cells

Medicinal plants have always been utilized for the prevention and treatment of the spread of different diseases all around the world. To name some traditional medicine that has been used over centuries, we can refer to phytochemicals such as naringin, icariin, genistein, and resveratrol gained from plants. Osteogenic differentiation and mineralization of stem cells can be the result of specific bioactive compounds from plants. One of the most appealing choices for therapy can be mesenchymal stem cells (MSCs) because it has a great capability of self-renewal and differentiation into three descendants, namely, endoderm, mesoderm, and ectoderm. Stem cell gives us the glad tidings of great advances in tissue regeneration and transplantation field for treatment of diseases. Using plant bioactive phytochemicals also holds tremendous promises in treating diseases such as osteoporosis. The purpose of the present review article thus is to investigate what are the roles and consequences of phytochemicals on osteogenic differentiation of MSCs.

Carbohydrate responsive element binding protein (ChREBP) negatively regulates osteoblast differentiation via protein phosphatase 2A Cα dependent manner

Carbohydrate responsive element binding protein (ChREBP) is a major transcription factor of lipogenesis regulated by glucose status in the liver. However, the function of ChREBP in osteogenic differentiation is unclear. The present study examined the role of ChREBP in osteoblast differentiation in MC3T3-E1 preosteoblast cell line. The mRNA expression of ChREBP, protein phosphatase 2A catalytic subunit-α (PP2A Cα) and the osteogenic genes such as, DNA-binding protein inhibitor (Id1), runt-related transcription factor-2 (Runx2), and alkaline phosphatase (ALP) was measured by qPCR and RT-PCR. Runx2, ChREBP, and PP2A Cα, protein levels were evaluated by Western blotting. ALP staining experiment was carried out to evaluate ALP enzyme activity, and a luciferase reporter assay was performed to analyze Runx2 transcriptional activity. Expression of ChREBP and PP2A Cα did not change during bone morphogenetic protein-2 (BMP2)-induced osteoblast differentiation. Overexpression of ChREBP reduced the osteogenic genes (Runx2 and ALP) expression and ALP activity, while knockdown of ChREBP had the opposite effects. Overexpression of PP2A Cα increased ChREBP expression, while inhibition of PP2A Cα using okadaic acid not only inhibited the expression of ChREBP, but also restored the mRNA and protein expression of Runx2 and activity of ALP enzyme. These results demonstrate that ChREBP inhibits BMP2-induced osteoblast differentiation in a PP2A Cα- dependent manner.

Effect of gomisin A on osteoblast differentiation in high glucose-mediated oxidative stress

BACKGROUND

Gomisin A is a lignan isolated from the hexane of Schisandra chinensis fruit extract with antioxidant properties. Oxidative stress mediated by high glucose is one of the major complications of diabetes mellitus.

PURPOSE

This study investigates the role of gomisin A in osteoblast differentiation under high glucose-induced oxidative stress in MC3T3 E1 cells and determines its relationship with heme oxygenase-1 (HO-1) and mitochondrial biogenesis.

METHODS

MC3T3 E1 cells were treated by gomisin A following induced by high glucose levels and glucose oxidase to investigate the inhibitory effect of gomisin A against high glucose oxidative stress. Western blot analysis, alizarin red staining, alkaline phosphatase (ALP) activity, analysis of reactive oxygen species (ROS) and confocal microscopy were used to determine mitochondrial biogenesis, oxidative stress, osteoblast differentiation and mineralization. To analyze the role of HO-1, the MC3T3 E1 cells were treated with the HO-1 inhibitor zinc protoporphyrin IX (ZnPP).

RESULTS

Gomisin A enhanced the expression of HO-1, increased mitochondrial biogenesis factors (peroxisome proliferator-activated receptor gamma coactivator 1-alpha, nuclear respiratory factor-1, and mitochondrial transcription factor A), antioxidant enzymes (copper-zinc superoxide dismutases and manganese superoxide dismutase), osteoblast differentiation molecules (bone morphogenic protein-2/7, osteoprotegerin and Runt-related transcription factor-2) and mineralization by upregulation of ALP and alizarin red staining, which were decreased by ZnPP and high glucose oxidative stress. Similarly, gomisin A inhibited ROS which was increased by ZnPP and the high glucose-mediated oxidative stress.

CONCLUSIONS

The findings demonstrated the antioxidative effects of gomisin A, and its role in mitochondrial biogenesis and osteoblast differentiation. It potentially regulated osteoblast differentiation under high glucose-induced oxidative stress via upregulation of HO-1 and maintenance of mitochondrial homeostasis. Thus, gomisin A may represent a potential therapeutic agent for prevention of bone fragility fractures and implant failure triggered by diabetes.

Activating transcription factor 4 is required for high glucose inhibits proliferation and differentiation of MC3T3-E1 cells

Activating transcription factor 4 (ATF4) promotes bone formation in human bone marrow mesenchymal stem cells. However, the underlying mechanisms of ATF4 in high glucose-induced injury of osteoblast still remain unclear. Small interfering RNA and plasmid targeting ATF4 were used to transfect MC3T3-E1 cells to knock down and overexpress ATF4 using Lipofectamin 3000. Cell viability, alkaline phosphatase (ALP) activity and levels were determined by MTT, ALP kit assay, quantitative real-time (qRT)-PCR and Western blot. Osteocalcin (OCN) expression was determined by ELISA, PCR and Western blot. The mRNA and protein levels of ATF4, glucose regulated protein 78 kDa (GRP78) and C/EBP homologous protein (CHOP) were detected by PCR and Western blot. In the current study, viabilities of MC3T3-E1 cells were inhibited by high glucose. Meanwhile, the mRNA and protein levels of ATF4 were effectively up-regulated in high glucose-incubated MC3T3-E1 cells. By conducting functional experiments, silencing ATF4 induced by small interfering RNA partially reversed the inhibitory effects of high glucose on viabilities of MC3T3-E1 cells. We also found that the expressions of ER stress-related proteins (ATF4, GRP78 and CHOP) were higher in high glucose-treated MC3T3-E1 cells but were inhibited by siATF4. However, overexpression of AFT4 had opposite results, and high glucose attenuated the protein levels of osteogenic marker genes ALP and OCN, which were further inhibited by ATF4 knockout gene. Thus, ATF4 was a necessary gene for high glucose to inhibit the proliferation and differentiation of MC3T3-E1 cells.

Effects of various antimicrobial agents on multi-directional differentiation potential of bone marrow-derived mesenchymal stem cells

Antimicrobial drugs of several classes play an important role in the treatment of bone and joint infections. In addition to fighting pathogenic microorganisms, the effects of drugs on local tissues and cells are also related to the course and prognosis of bone and joint infections. The multi-directional differentiation potential of bone marrow-derived mesenchymal stem cells (MSCs) is essential for tissue repair after local injury, which is directly related to the recovery of bone, cartilage, and medullary adipose tissue. Our previous studies and the literature indicate that certain antimicrobial agents can regulate the differentiation potential of bone marrow-derived MSCs. Here, in order to systematically analyze the effects of various antimicrobial drugs on local tissue regeneration, we comprehensively review the studies on the effects of these drugs on MSC differentiation, and classify them according to the three differentiation directions (osteogenesis, chondrogenesis, and adipogenesis). Our review demonstrates the specific effects of different antimicrobial agents on bone marrow-derived MSCs and the range of concentrations at which they work, and provides a basis for drug selection at different sites of infection.

Costunolide-A Bioactive Sesquiterpene Lactone with Diverse Therapeutic Potential

Sesquiterpene lactones constitute a major class of bioactive natural products. One of the naturally occurring sesquiterpene lactones is costunolide, which has been extensively investigated for a wide range of biological activities. Multiple lines of preclinical studies have reported that the compound possesses antioxidative, anti-inflammatory, antiallergic, bone remodeling, neuroprotective, hair growth promoting, anticancer, and antidiabetic properties. Many of these bioactivities are supported by mechanistic details, such as the modulation of various intracellular signaling pathways involved in precipitating tissue inflammation, tumor growth and progression, bone loss, and neurodegeneration. The key molecular targets of costunolide include, but are not limited to, intracellular kinases, such as mitogen-activated protein kinases, Akt kinase, telomerase, cyclins and cyclin-dependent kinases, and redox-regulated transcription factors, such as nuclear factor-kappaB, signal transducer and activator of transcription, activator protein-1. The compound also diminished the production and/expression of proinflammatory mediators, such as cyclooxygenase-2, inducible nitric oxide synthase, nitric oxide, prostaglandins, and cytokines. This review provides an overview of the therapeutic potential of costunolide in the management of various diseases and their underlying mechanisms.

Peroxiredoxin II negatively regulates BMP2-induced osteoblast differentiation and bone formation via PP2A Cα-mediated Smad1/5/9 dephosphorylation

Peroxiredoxin II (Prx II), an antioxidant enzyme in the Prx family, reduces oxidative stress by decreasing the intracellular ROS levels. Osteoblast differentiation is promoted by bone morphogenetic protein 2 (BMP2), which upregulates the expression of osteoblast differentiation marker genes, through Smad1/5/9 phosphorylation. We found that Prx II expression was increased by a high dose of lipopolysaccharide (LPS) but was not increased by a low dose of LPS. Prx II itself caused a decrease in the osteogenic gene expression, alkaline phosphatase (ALP) activity, and Smad1/5/9 phosphorylation induced by BMP2. In addition, BMP2-induced osteogenic gene expression and ALP activity were higher in Prx II knockout (KO) cells than they were in wild-type (WT) cells. These inhibitory effects were mediated by protein phosphatase 2A Cα (PP2A Cα), which was increased and is known to induce the dephosphorylation of Smad1/5/9. The overexpression of Prx II increased the expression of PP2A Cα, and PP2A Cα was not expressed in Prx II KO cells. Moreover, PP2A Cα reduced the level of BMP2-induced osteogenic gene expression and Smad1/5/9 phosphorylation. LPS inhibited BMP2-induced Smad1/5/9 phosphorylation and the suppressed phosphorylation was restored by the PP2A inhibitor okadaic acid (OA). Bone phenotype analyses using microcomputed tomography (μCT) revealed that the Prx II KO mice had higher levels of bone mass than the levels of the WT mice. We hypothesize that Prx II has a negative role in osteoblast differentiation through the PP2A-dependent dephosphorylation of Smad1/5/9.

An antioxidant enzyme actively works to reduce bone synthesis under oxidative stress conditions in order to protect bone cells from damage and cell death. Bone is generated by cells called osteoblasts, which differentiate from stem cells. In osteoporosis and diabetes, excessive reactive oxygen species (ROS) within cells can disrupt osteoblast differentiation. South Korean researchers led by Eun-jung Kim at Kyungpook National University, Daegu, and Won-Gu Jang at Daegu University, Gyeongbuk, have shown that an antioxidant enzyme, peroxiredoxin II (PrxII), helps regulate bone formation under oxidative stress. The team generated PrxII-deficient mice and compared them with healthy normal mice. Under oxidative stress conditions, the mice had higher bone mass and higher expression of genes related to bone formation than the normal mice. PrxII limits osteoblast differentiation during elevated ROS by influencing associated protein activity and signalling pathways.

Salvianolic acid B (Sal B) alleviates the decreased activity induced by prednisolone acetate on osteoblasts by up-regulation of bone formation and differentiation genes

Sal B could promote bone formation and help protect against bone loss caused by prednisolone acetate treatment.

Bone Health and Natural Products- An Insight

Bone metabolism involves a complex balance between matrix deposition, mineralization, and resorption. Numerous evidences have revealed that dietary components and phytoconstituents can influence these processes, through inhibition of bone resorption, thus exhibiting beneficial effects on the skeleton. Various traditional herbal formulae in ayurvedic and Chinese medicine have shown demonstrable benefits in pharmacological models of osteoporosis. The present review discusses normal bone metabolism and disorders caused by bone disruption, with particular reference to osteoporosis and current therapeutic treatment. Furthermore the effects of constituents from natural products on bone tissue are explained, with relevant evidences of efficacy in various experimental models.

Costunolide promotes the proliferation of human hair follicle dermal papilla cells and induces hair growth in C57BL/6 mice

BACKGROUND

Costunolide (COS), a naturally occurring sesquiterpene lactone, is known to exert anti-inflammatory, antioxidant, and anticancer effects. This study was undertaken to investigate the effects of costunolide on the promotion of hair growth.

METHODS

Real-time cell analyzer (RTCA), measurement of 5α-reductase activity, mRNA expression, and Western blotting were adopted to address whether COS can stimulate the proliferation of human hair follicle dermal papilla cells (hHFDPCs). The effect of COS on in vivo hair growth was examined by reconstitution assay and shaven dorsal skin in C57BL/6 mice.

RESULTS

Costunolide significantly promoted the proliferation of hHFDPCs, which is comparable to that of tofacitinib. COS also inhibited the 5α-reductase activity in hHFDPCs. While COS increased the level of β-catenin and Gli1 mRNA and proteins, it suppressed transforming growth factor (TGF)-β1-induced phosphorylation of Smad-1/5 in hHFDPCs. COS increased the number of cultured hHFDPCs to induce hair follicles from mouse epidermal cells in Spheres formation of reconstitution assay. Topical application of COS on the shaven back of C57BL/6 mice significantly improved the hair growth.

CONCLUSIONS

Our results illustrate that COS promotes hair growth in vitro and in vivo by regulating the amount of growth factors and/or the activity of cellular responses through coordination of the WNT-β-catenin, hedgehog-Gli, and TGF-β1-Smad pathways.

Costunolide enhances doxorubicin-induced apoptosis in prostate cancer cells via activated mitogen-activated protein kinases and generation of reactive oxygen species

The management of castration-resistant prostate cancer (CRPC) is challenging, attributable to a lack of efficacious therapies. Chemotherapy is one of the most important treatments for CRPC. Doxorubicin has been extensively used in many different tumors and is often combined with other drugs to enhance effects and reduce toxicity. Costunolide is a natural sesquiterpene lactone with anti-cancer properties. In this study, we first demonstrated that the combination of costunolide and doxorubicin induced apoptosis significantly more than either drug alone in prostate cancer cell lines. Costunolide combined with doxorubicin induced mitochondria-mediated apoptosis through a loss of mitochondrial membrane potential and modulation of Bcl-2 family proteins. We found that this drug combination significantly increased the production of reactive oxygen species (ROS), as well as phosphorylation of c-jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases, which play upstream roles in mitochondria-mediated apoptosis. Further studies showed that N-acetyl cysteine blocked JNK and p38 phosphorylation, suggesting that ROS were upstream activators of JNK and p38. However, a JNK inhibitor, but not a p38 inhibitor, blocked the increase in ROS observed in cells treated with a combination of costunolide and doxorubicin, suggesting that ROS and JNK could activate each other. In vivo, inhibition of tumor growth and induction of apoptosis were greater in mice treated with the costunolide and doxorubicin combination than in mice treated with either drug alone, without an increase in toxicity. Therefore, we suggested that costunolide in combination with doxorubicin was a new potential chemotherapeutic strategy for treating prostate cancer.