A Novel Rhein Derivative Modulates Bone Formation and Resorption and Ameliorates Estrogen-Dependent Bone Loss

Abstract

Osteoporosis, an osteolytic disease that affects millions of people worldwide, features a bone remodeling imbalance between bone resorption by osteoclasts and bone formation by osteoblasts. Identifying dual target-directed agents that inhibit excessive bone resorption and increase bone formation is considered an efficient strategy for developing new osteoporosis treatments. Rhein, a natural anthraquinone, can be isolated from various Asian herbal medicines. Rhein and its derivatives have been reported to have various beneficial pharmacological effects, especially their bone-targeting ability and anti-osteoclastogenesis activity. Moreover, hydrogen sulfide (H 2 S) was reported to prevent ovariectomy-(OVX-) induced bone loss by enhancing bone formation, and sulfur replacement therapy has been considered a novel and plausible therapeutic option. Based on this information, we synthesized a rheinderived thioamide (RT) and investigated its effects on bone resorption and bone formation in vitro and in vivo. It has been found that the RT-inhibited receptor activator of the nuclear factor-kB (NF-kB) ligand-(RANKL-) induced osteoclastogenesis and bone resorption in a dose-dependent manner. The expression of osteoclast marker genes was also suppressed by RT treatment. Furthermore, exploration of signal transduction pathways indicated that RT markedly blocked RANKL-induced osteoclastogenesis by attenuating MAPK pathways. However, RT treatment in an osteoblastic cell line, MC3TE-E1, indicated that RT led to an increase in the deposition of minerals and the expression of osteoblast marker genes, as demonstrated by Alizarin Red staining and alkaline phosphatase activity. Importantly, an OVX mouse model showed that RT could attenuate the bone loss in estrogen deficiency-induced osteoporosis in vivo with a smart H 2 S-releasing property and that there was a considerable improvement in the biomechanical properties of bone. Accordingly, our current work highlights the dual regulation of bone remodeling by the rhein-derived molecule RT. This may be a highly promising approach for a new type of anti-osteoporosis agent.Journal of Bone and Mineral Research 50 ng/mL RANKL for 3 days. Cell lysates were then subjected to Western blotting analysis for cathepsin K. (H) The ratio of the density of cathepsin K. bands relative to b-actin bands was then determined using Image J. n ¼ 3. Ã p < 0.5 and ÃÃ p < 0.01 versus control. 366 JIANG ET AL. Journal of Bone and Mineral ResearchFig 3. Rhein-derived thioamide (RT) suppresses the mRNA expressions of osteoclast marker genes and phosphorylations of p38 and ERK cascade. (A-D)Bone marrow monocytes/macrophages (BMMs) were stimulated with M-CSF and RANKL in the presence of different doses of RT for 3 days. Osteoclasts marker gene levels of NFATc1, c-fos, TRAP, V-ATPase2 were determined by quantitative RT-PCR analysis of RT at indicated concentrations in combination with M-CSF and RANKL in BMMs. The results were normalized to b-actin expression and expressed as fold change relative to gene expression i...

A Synthetic Peptide, CK2.3, Inhibits RANKL-Induced Osteoclastogenesis through BMPRIa and ERK Signaling Pathway

“…Targeting the ERK MAPK signaling pathway has been employed as a therapeutic strategy to treat cancer and neurological diseases, highlighting its importance in the regulation of these diseases [ 76 , 77 ]. Similarly, although there has yet to be an available therapeutic strategy that is designed to specifically target the ERK MAPK signaling pathway to treat osteoporosis, various other strategies such as estrogen, rhein-derived thioamide (RT), prostaglandin E2 (PGE2), and Src inhibitors, to name a few, have mechanisms involved in the regulation of the ERK MAPK signaling pathway [ 74 , 78 , 79 , 80 , 81 , 82 ]. Estrogen and PGE2 activate ERK to promote osteoblast differentiation, but estrogen also activates ERK to inhibit osteoclast differentiation, as mentioned above [ 74 , 81 ].…”

BMP9 Reduces Bone Loss in Ovariectomized Mice by Dual Regulation of Bone Remodeling

“…However, because of the coupling and synchronization of bone resorption and new bone formation, anti‐bone resorption drugs can inhibit both bone resorption and bone formation, while anabolic drugs, such as parathyroid hormone (PTH) or parathyroid hormone–related protein (PTHrP), mainly enhance bone formation and meanwhile stimulate bone resorption . Researchers are constantly striving to explore dual‐action agents that modulate bone remodeling for the treatment of osteoporosis, such as an anti‐sclerostin antibody that is now available on the market and several others that are under investigation …”

Protective Effects of Punicalagin on Osteoporosis by Inhibiting Osteoclastogenesis and Inflammation via the NF-κB and MAPK Pathways

“…Osteoclasts originate from bone marrow monocytes/macrophages (Chen et al, 2019). Estrogen deficiency induces the activation of receptor activator of nuclear factor kB (NF-kB) ligand (RANKL), the key molecule required for osteoclast differentiation, which can bind with receptor activator of NF-kB (RANK) on preosteoclast membranes and stimulate the NF-kB and mitogen-activated protein kinase (MAPK) pathways for osteoclast differentiation and formation (Chen et al, 2018;Jiang et al, 2019;Shang and Wu, 2019). Then, nuclear factor of activated T cells cytoplasmic 1 (NFATc1), the main transcription factor that regulates osteoclast differentiation, will be triggered to stimulate preosteoclast maturation (Jiang et al, 2019;Zhao K. et al, 2019).…”

“…Estrogen deficiency induces the activation of receptor activator of nuclear factor kB (NF-kB) ligand (RANKL), the key molecule required for osteoclast differentiation, which can bind with receptor activator of NF-kB (RANK) on preosteoclast membranes and stimulate the NF-kB and mitogen-activated protein kinase (MAPK) pathways for osteoclast differentiation and formation (Chen et al, 2018;Jiang et al, 2019;Shang and Wu, 2019). Then, nuclear factor of activated T cells cytoplasmic 1 (NFATc1), the main transcription factor that regulates osteoclast differentiation, will be triggered to stimulate preosteoclast maturation (Jiang et al, 2019;Zhao K. et al, 2019). Maturational osteoclasts, which are characterized by tartrate-resistant acid phosphatase (TRAP) expression, can generate actin-bound sealing zones for attaching to the surface of bone, and osteoclasts then release proteolytic enzymes, such as cathepsin K (CTSK), which promote resorption pit formation (Lee et al, 2019;Zhao X. et al, 2019).…”