Osteoblast-specific inactivation of p53 results in locally increased bone formation

Advances of Osteosarcoma Models for Drug Discovery and Precision Medicine

The management of osteosarcoma (OS) patients presents a significant clinical challenge. Despite progress in conventional and targeted therapies, the survival rate of OS patients remains limited largely due to therapy resistance and the high metastatic potential of the disease. OS models that accurately reflect the fundamental characteristics are vital to the innovation and validation of effective therapies. This review provides an insight into the advances and challenges in OS drug development, focusing on various preclinical models, including cell lines, 3D culture models, murine models, and canine models. The relevance, strengths, and limitations of each model in OS research are explored. In particular, we highlight a range of potential therapeutics identified through these models. These instances of successful drug development represent promising pathways for personalized OS treatment.

Jintiange proteins promote osteogenesis and inhibit apoptosis of osteoblasts by enhancing autophagy via PI3K/AKT and ER stress pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Tiger bone, which had long been used in traditional Chinese medicine, had the action of removing wind and alleviating pain, strengthening the sinews and bones, and often used to treat bone impediment, and atrophic debility of bones in TCM clinical practice. As a substitute of natural bone tiger, artificial tiger bone Jintiange (JTG), has been approved by the State Food and Drug Administration of China for relief the symptom of osteoporosis, such as lumbago and back pain, lassitude in loin and legs, flaccidity and weakness legs, and walk with difficulty based on TCM theory. JTG has similar chemical profile to natural tiger bone, and contains mineral substance, peptides and proteins, and has been shown to protect bone loss in ovariectomized mice and exert the regulatory effects on osteoblast and osteoclast activities. But how the peptides and proteins in JTG modulate bone formation remains unclear.

AIM

To investigate the stimulating effects of JTG proteins on osteogenesis and explore the possible underlying mechanisms.

MATERIALS AND METHODS

JTG proteins were prepared from JTG Capsules by extracting calcium, phosphorus and other inorganic elements using SEP-PaktC18 desalting column. MC3T3-E1 cells were treated with JTG proteins to evaluate their effects and explore the underlying mechanisms. Osteoblast proliferation was detected by CCK-8 method. ALP activity was detected using a relevant assay kit, and bone mineralized nodules were stained with alizarin red-Tris-HCl solution. Cell apoptosis was analyzed by flow cytometry. Autophagy was observed by MDC staining, and autophagosomes were observed by TEM. Nuclear translocations of LC3 and CHOP were detected by immunofluorescence and observed under a laser confocal microscope. The expression of key proteins related to osteogenesis, apoptosis, autophagy and PI3K/AKT and ER stress pathways was analyzed by Western Blot analysis.

RESULTS

JTG proteins improved osteogenesis as evidenced by the alteration of proliferation, differentiation and mineralization of MC3T3-E1 osteoblasts, inhibited their apoptosis, and enhanced autophagosome formation and autophagy. They also regulated the expression of key proteins of PI3K/AKT and ER stress pathways. In addition, PI3K/AKT and ER stress pathway inhibitors could reverse the regulatory effects of JTG proteins on osteogenesis, apoptosis, autophagy and PI3K/AKT and ER stress pathways.

CONCLUSION

JTG proteins increased the osteogenesis and inhibited osteoblast apoptosis by enhancing autophagy via PI3K/AKT and ER stress signaling pathways.

CK1α/RUNX2 Axis in the Bone Marrow Microenvironment: A Novel Therapeutic Target in Multiple Myeloma

Simple Summary

Multiple myeloma (MM) is an incurable disease for which novel therapeutic approaches targeting the malignant cells and the associated bone disease are urgently needed. CK1α is a protein kinase that plays a crucial role in the signaling network that sustains plasma cell (PC) survival and bone disease. This protein regulates Wnt/β-catenin signaling, which is fundamental for both MM cell survival and mesenchymal stromal cell (MSC) osteogenic differentiation. In this study, we investigated its involvement in MM–MSC cross-talk. We found that, by lowering CK1α expression levels in co-cultures of MM and MSC cells, expression of RUNX2—the master regulator of osteogenic differentiation—was regulated differently in the two cell types. Our data suggest the possibility of using a specific CK1α inhibitor as part of a novel therapeutic approach to selectively kill malignant PCs and overcome the blocking of osteogenic differentiation induced by MM cells in MSCs.

Abstract

Multiple myeloma (MM) is a malignant plasma cell (PC) neoplasm, which also displays pathological bone involvement. Clonal expansion of MM cells in the bone marrow causes a perturbation of bone homeostasis that culminates in MM-associated bone disease (MMABD). We previously demonstrated that the S/T kinase CK1α sustains MM cell survival through the activation of AKT and β-catenin signaling. CK1α is a negative regulator of the Wnt/β-catenin cascade, the activation of which promotes osteogenesis by directly stimulating the expression of RUNX2, the master gene regulator of osteoblastogenesis. In this study, we investigated the role of CK1α in the osteoblastogenic potential of mesenchymal stromal cells (MSCs) and its involvement in MM–MSC cross-talk. We found that CK1α silencing in in vitro co-cultures of MMs and MSCs modulated RUNX2 expression differently in PCs and in MSCs, mainly through the regulation of Wnt/β-catenin signaling. Our findings suggest that the CK1α/RUNX2 axis could be a potential therapeutic target for constraining malignant PC expansion and supporting the osteoblastic transcriptional program of MSCs, with potential for ameliorating MMABD. Moreover, considering that Lenalidomide treatment leads to MM cell death through Ikaros, Aiolos and CK1α proteasomal degradation, we examined its effects on the osteoblastogenic potential of MSC compartments.