• BMB Reports
• /
• v.55 no.12
• /
• pp.627-632
• /
• 2022

Dickkopf-1 (DKK1) is a secreted protein that acts as an antagonist of the canonical WNT/β-catenin pathway, which regulates osteoblast differentiation. However, the role of DKK1 on osteoblast differentiation has not yet been fully clarified. Here, we investigate the functional role of DKK1 on osteoblast differentiation. Primary osteoprogenitor cells were isolated from human spinal bone tissues. To examine the role of DKK1 in osteoblast differentiation, we manipulated the expression of DKK1, and the cells were differentiated into mature osteoblasts. DKK1 overexpression in osteoprogenitor cells promoted matrix mineralization of osteoblast differentiation but did not promote matrix maturation. DKK1 increased Ca⁺ influx and activation of the Ca⁺/calmodulin-dependent protein kinase II Alpha (CAMK2A)-cAMP response element-binding protein 1 (CREB1) and increased translocation of p-CREB1 into the nucleus. In contrast, stable DKK1 knockdown in human osteosarcoma cell line SaOS2 exhibited reduced nuclear translocation of p-CREB1 and matrix mineralization. Overall, we suggest that manipulating DKK1 regulates the matrix mineralization of osteoblasts by Ca⁺-CAMK2A-CREB1, and DKK1 is a crucial gene for bone mineralization of osteoblasts.

• Asian Pacific Journal of Cancer Prevention
• /
• v.13 no.7
• /
• pp.3477-3481
• /
• 2012

Purpose: To investigate the killing effect on OS cells of a combination of oxaliplatin and TRAIL and related molecular mechanisms. Methods: TRAIL and oxaliplatin were applied to OS732 cells singly or jointly and survival inhibition rates were measured by MTT assay, changes of cellular shape being assessed with inverted phase contrast and fluorescence microscopy. Apoptotic rates were analyzed by flow cytometry (FCM) and immunocytochemistry was used to examine Mcl1 expression of OS732 cells. Results: The survival inhibition rate of combined application of $100{\mu}g/ml$ TRAIL and $1{\mu}g/ml$ oxaliplatin on OS-732 cells was significantly higher than that of either agent singly (p<0.01). Changes of cellular shape and apoptotic rates also indicated apoptosis-inducing effects of combined application to be much stronger than those of individual application. Oxaliplatin had the effect of down-regulating Mcl1 expression and sensitizing OS cells to TRAIL-induced apoptosis. Conclusion: A combination of TRAIL and oxaliplatin exerts strong killing effects on OS-732 cells which might be related to down-regulation of Mcl1 expression.

• The Journal of Advanced Prosthodontics
• /
• v.1 no.2
• /
• pp.91-96
• /
• 2009

STATEMENT OF PROBLEM. The aim of this study was to study the effects of various surface treatments to a titanium surface on the expression of Runx2 in vitro. MATERIAL AND METHODS. Human Osteosarcoma TE-85 cells were cultured on machined, sandblasted, or anodic oxidized cpTi discs. At various times of incubation, the cells were collected and then processed for the analysis of mRNA expression of Runx2 using reverse transcription-PCR. RESULTS. The expression pattern of Runx2 mRNA was differed according to the types of surface treatment. When the cells were cultured on the untreated control culture plates, the gene expression of Runx2 was not increased during the experiments. In the case of that the cells were cultured on the machined cpTI discs, the expression level was intermediate at the first day, but increased constitutively to day 5. In cells on sandblasted cpTi discs, the expression level was highest in the first day sample and the level was maintained to 5 days. In cells on anodized cpTi discs, the expression level increased rapidly to 3 days, but decreased slightly in the 5-th day sample. CONCLUSION. Different surface treatments may contribute to the regulation of osteoblast function by influencing the level of gene expression of key osteogenic factors.

• Molecules and Cells
• /
• v.41 no.6
• /
• pp.523-531
• /
• 2018

Tumour metastasis is one of the most serious challenges of cancer as it is the major cause of mortality in patients with solid tumours, including osteosarcoma (OS). In this regard, anti-metastatic genes have potential for metastasis inhibition strategies. Recent evidence showed the importance of breast cancer metastasis suppressor 1 (BRMS1) in control of OS invasiveness, but the regulation of BRMS1 in OS remains largely unknown. Here, we used bioinformatics analyses to predict BRMS1-targeting microRNAs (miRNAs), and the functional binding of miRNAs to BRMS1 mRNA was evaluated using a dual luciferase reporter assay. Among all BRMS1-targeting miRNAs, only miR-151b, miR-7-5p and miR-3200-5p showed significant expression in OS specimens. Specifically, we found that only miR-3200-5p significantly inhibited protein translation of BRMS1 via pairing to the 3'-UTR of the BRMS1 mRNA. Moreover, we detected significantly lower BRMS1 and significantly higher miR-3200-5p in the OS specimens compared to the paired adjacent non-tumour bone tissues. Furthermore, BRMS1 and miR-3200-5p levels were inversely correlated to each other. Low BRMS1 was correlated with metastasis and poor patient survival. In vitro, overexpression of miR-3200-5p significantly decreased BRMS1 levels and promoted OS cell invasion and migration, while depletion of miR-3200-5p significantly increased BRMS1 levels and inhibited OS cell invasion and migration. Thus, our study revealed that miR-3200-5p may be a critical regulator of OS cell invasiveness.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.42 no.5
• /
• pp.288-294
• /
• 2016

Chondrosarcoma is a malignant tumor that originates from cartilaginous cells and is characterized by cartilage formation. Only 5% to 10% of chondrosarcoma occurs in the head and neck area, and it is uncommon in the temporomandibular joint area. This report describes an unusual case with a rare, large chondrosarcoma in a 47-year-old woman who presented with painless swelling and trismus. Computed tomography showed a large mass approximately $8.5{\times}6.0$ cm in size arising adjacent to the lateral pterygoid plate and condyle. There were features suggestive of bone resorption. The tumor was resected in a single block with perilesional tissues, and a great auricular nerve graft was performed because of facial nerve sacrifice. Microscopic examination of sections stained with H&E revealed chondrocytes with irregular nuclei and heterogeneous hyper chromatic tumor cells embedded in the chondrocyte lacuna. The diagnosis was a grade I chondrosarcoma. There was no evidence of recurrence at the 8-month follow-up, and a reconstruction surgery with fibular osteocutaneous free flap was performed. We report this unusual entity and a review of the literature.

• International Journal of Oral Biology
• /
• v.45 no.4
• /
• pp.162-168
• /
• 2020

Calcium is the most abundant stored mineral in the human body and is especially vital for bone health; thus, calcium deficiency can cause bone-related diseases, such as osteopenia and osteoporosis. However, a high concentration of serum calcium, which is commonly known as hypercalcemia, can also lead to weakened bones and, in severe cases, osteosarcoma. Therefore, it is necessary to maintain the concentration of calcium that is appropriate for bone biology. In the present study, we aimed to elucidate the effects of high concentration of calcium, approximately 2 folds the normal calcium level, on osteoblast differentiation. The CaCl2 treatment showed dose-dependent suppression of the alkaline phosphatase activity and mineralized nodule formation. Calcium showed cytotoxicity at an extremely high concentration, but a moderately high concentration of calcium that results in inhibitory effects to osteoblast differentiation showed no signs of cytotoxicity. We also confirmed that the CaCl2 treatment repressed the mRNA expression and protein abundance of various osteogenic genes and transcriptional factors. Considered together, these results indicate that a high concentration of calcium negatively regulates the osteoblast differentiation of C2C12 cells.

• Proceedings of the Korean Society of Life Science Conference
• /
• 2005.04a
• /
• pp.220-220
• /
• 2005

• International Journal of Oral Biology
• /
• v.31 no.3
• /
• pp.93-98
• /
• 2006

Biosynthetic processing of fibrillar procollagens is essential for producing mature collagen monomers that polymerize into fibrils by a self-assembly process. The metalloproteinase ADAMTS-2 is the major enzyme that processes the N-propeptide of type I procollagen in the skin and also of type II and type III procollagens. Mutations in the ADAMTS-2 gene cause dermatospraxis in animals and Ehlers-Danlos syndrome VIIC in humans, both of which are characterized by the accumulation of type I pN-collagen and the formation of abnormal collagen fibrils in the skin. Despite its importance in procollagen processing, little is known about the regulation of ADAMTS-2 expression. Here, we demonstrate that ADAMTS-2 can be regulated by 1,25-dihydroxyvitamin D3, an inducer of type I procollagen synthesis. This steroid hormone induced ADAMTS-2 mRNA ${\sim}3-fold$ in MG-63 human osteosarcoma cells and MC3T3-E1 murine osteoblastic cells. This induction was dose- and time-dependent in MG-63 cells. In contrast, secreted ADAMTS-2 protein was increased only 1.4-fold with 1,25-dihydroxyvitamin D3. Finally, 1,25-dihydroxyvitamin D3 in the presence of ascorbate increased levels of secreted ADAMTS-2 1.9-fold over ascorbate treatment alone, which did not appreciably change ADAMTS-2 expression. These data indicate that the regulation of ADAMTS-2 is coupled with the synthesis of type I procollagen through 1,25-dihydroxyvitamin D3 signaling and may involve translational or posttranslational control.

• Molecular & Cellular Toxicology
• /
• v.3 no.1
• /
• pp.36-45
• /
• 2007

Several features of the implant surface, such as topography, roughness, and composition play a relevant role in implant integration with bone. This study was conducted in order to determine the effects of different-coatings on Ti surfaces on the biological responses of a human osteoblast-like cell line (MG63). MG63 cells were cultured on HA (Hydroxyapatite coating on Titanium), Ano (HA coating on anodized surface Titanium), Zr (zirconium-coating on Titanium), and control (non-coating on Titanium). The morphology of these cells was assessed by SEM. The cDNAs prepared from the total RNAs of the MG63 were hybridized into a human cDNA microarray (1,152 elements). The appearances of the surfaces observed by SEM were different on each of the three dental substrate types. MG63 cells cultured on HA, Ano, Zr, and control exhibited cell-matrix interactions. In the expression of several genes were up-, and down-regulated on the different surfaces. The attachment and expression of key osteogenic regulatory genes were enhanced by the surface morphology of the dental materials used.

• Journal of Life Science
• /
• v.15 no.6 s.73
• /
• pp.994-1004
• /
• 2005

The dihydrofolate reductase (dhfr) promoter contains cis-acting element for the transcription factors Spl and E2F. Transcription of dhfr gene shows maximal activity during the Gl/S phase of cell cycle. The member of the Spl transcriptional factor family can act as both negative and positive regulators of gene expression. There was a report that Spl-Rb and E2F4-pl30 complexes cooperate to establish stable repression of dhfr gene expression in CHOC400 cells. Here, we examined the role of HDAC in dhfr, cyclin E, and cyclin A gene regulation using the histone deacetylation inhibitor, trichostatin A (TSA) in U2OS and C33A cells, a Rb-positive human osteosarcoma cell line, and a Rb-negative cervical carcinoma cell line, respectively. When the dhfr promoter constructs were applied in U2OS cells, TSA markedly stimulated over 14-fold of dhfr promoter activity through dhfr-Spl sites by the deletion of an E2F element. In contrast, the deletion of dhfr-Spl binding sites completely abolished promoter stimulation by TSA. The dhfr promoter activity including dhfr-Spl sites increased only 2-fold in C33A cells. Promoter activity containing only dhfr-E2F site did not have much effect by the treatment of TSA in both U2OS and C33A cells. On the other hand, treatment with TSA induced significantly mRNA expression of dhfr and cyclin E, whereas levels of cyclin A decreased in U2OS cells, but had no effect in C33A cells. These results indicate that TSA have contradictory effect, activation of dhfr and cyclin E genes on Gl phase, and down-regulation of cyclin A on G2 phase through transcriptional regulation in U2OS cells.