Bong-Soo Park

Melatonin promotes osteoblast differentiation and mineralization of MC3T3-E1 cells under hypoxic conditions through activation of PKD/p38 pathways.

Osteoblastic differentiation and bone‐forming capacity are known to be suppressed under hypoxic conditions. Melatonin has been shown to influence cell differentiation. A number of in vitro and in vivo studies have suggested that melatonin also has an anabolic effect on bone, by promoting osteoblastic differentiation. However, the precise mechanisms and the signaling pathways involved in this process, particularly under hypoxic conditions, are unknown. This study investigated whether melatonin could promote osteoblastic differentiation and mineralization of preosteoblastic MC3T3‐E1 cells under hypoxic conditions. Additionally, we examined the molecular signaling pathways by which melatonin mediates this process. We found that melatonin is capable of promoting differentiation and mineralization of MC3T3‐E1 cells cultured under hypoxic conditions. Melatonin upregulated ALP activity and mRNA levels of Alp, Osx, Col1, and Ocn in a time‐ and concentration‐dependent manner. Alizarin red S staining showed that the mineralized matrix in hypoxic MC3T3‐E1 cells formed in a manner that was dependent on melatonin concentration. Moreover, melatonin stimulated phosphorylation of p38 Mapk and Prkd1 in these MC3T3‐E1 cells. We concluded that melatonin promotes osteoblastic differentiation of MC3T3‐E1 cells under hypoxic conditions via the p38 Mapk and Prkd1 signaling pathways.

The bacterial protein azurin enhances sensitivity of oral squamous carcinoma cells to anticancer drugs.

Purpose Surgical therapy is the primary treatment for oral cancer, but it can cause facial distortion. Therefore, if anticancer drugs are effective against oral cancer, they may be used preferentially. However, oral squamous carcinoma cells (OSCCs) are resistant to these drugs, so finding a way to enhance the sensitivity of these cells to anticancer drugs is important. The bacterial protein azurin is known to selectively enter cancer cells and induce apoptosis. In this study, we show the anticancer effect of azurin in OSCC. Materials and Methods OSCC cell line (YD-9) was subjected to azurin treatment. Cell viability, morphology and protein expression levels were monitored after treatment of azurin. Cells were also subjected to combination treatment of azurin with either 5-fluorouracil or etopside. Results Azurin-treated cells showed decreased cell viability accompanied by apoptotic phenotypes including morphological change, DNA breakage, and increases in p53 and cyclin B1 protein levels. Combination treatment of azurin with other anti-tumor agents caused an increase in sensitivity to anticancer drugs in azurin-treated YD-9 cells. Conclusion Azurin has a strong synergistic anticancer effect on oral cancer cells when it is used along with anticancer drugs.

Combined effect of bisphosphonate and recombinant human bone morphogenetic protein 2 on bone healing of rat calvarial defects

BackgroundThis study aimed to investigate new bone formation using recombinant human bone morphogenetic protein 2 (rhBMP-2) and locally applied bisphosphonate in rat calvarial defects.MethodsThirty-six rats were studied. Two circular 5 mm diameter bony defect were formed in the calvaria using a trephine bur. The bony defect were grafted with Bio-Oss® only (group 1, n = 9), Bio-Oss® wetted with rhBMP-2 (group 2, n = 9), Bio-Oss® wetted with rhBMP-2 and 1 mM alendronate (group 3, n = 9) and Bio-Oss® wetted with rhBMP-2 and 10 mM alendronate (group 4, n = 9). In each group, three animals were euthanized at 2, 4 and 8 weeks after surgery, respectively. The specimens were then analyzed by histology, histomorphometry and immunohistochemistry analysis.ResultsThere were significant decrease of bone formation area (p < 0.05) between group 4 and group 2, 3. Group 3 showed increase of new bone formation compared to group 2. In immunohistochemistry, collagen type I and osteoprotegerin (OPG) didn’t show any difference. However, receptor activator of nuclear factor κB ligand (RANKL) decreased with time dependent except group 4.ConclusionLow concentration bisphosphonate and rhBMP-2 have synergic effect on bone regeneration and this is result from the decreased activity of RANKL of osteoblast.

α-Mangostin Induces Apoptosis and Cell Cycle Arrest in Oral Squamous Cell Carcinoma Cell

Mangosteen has long been used as a traditional medicine and is known to have antibacterial, antioxidant, and anticancer effects. Although the effects of α-mangostin, a natural compound extracted from the pericarp of mangosteen, have been investigated in many studies, there is limited data on the effects of the compound in human oral squamous cell carcinoma (OSCC). In this study, α-mangostin was assessed as a potential anticancer agent against human OSCC cells. α-Mangostin inhibited cell proliferation and induced cell death in OSCC cells in a dose- and time-dependent manner with little to no effect on normal human PDLF cells. α-Mangostin treatment clearly showed apoptotic evidences such as nuclear fragmentation and accumulation of annexin V and PI-positive cells on OSCC cells. α-Mangostin treatment also caused the collapse of mitochondrial membrane potential and the translocation of cytochrome c from the mitochondria into the cytosol. The expressions of the mitochondria-related proteins were activated by α-mangostin. Treatment with α-mangostin also induced G1 phase arrest and downregulated cell cycle-related proteins (CDK/cyclin). Hence, α-mangostin specifically induces cell death and inhibits proliferation in OSCC cells via the intrinsic apoptosis pathway and cell cycle arrest at the G1 phase, suggesting that α-mangostin may be an effective agent for the treatment of OSCC.

Low-level laser therapy affects osseointegration in titanium implants: resonance frequency, removal torque, and histomorphometric analysis in rabbits.

Objectives The purpose of this study was to investigate the effects of low-level laser therapy (LLLT) with a diode gallium-aluminum-arsenide (Ga-Al-As) low-level laser device on the healing and attachment of titanium implants in bone. Materials and Methods Thirteen New Zealand white male rabbits weighing 3.0±0.5 kg were used for this study. Dental titanium implants (3.75 mm in diameter and 8.5 mm in length, US II RBM plus fixture; Osstem, Seoul, Korea) were implanted into both femurs of each rabbit. The rabbits were randomly divided into a LLLT group and a control group. The LLLT was initiated immediately after surgery and then repeated daily for 7 consecutive days in the LLLT group. Six weeks and 12 weeks after implantation, we evaluated and compared the osseointegration of the LLLT group and control group, using histomorphometric analysis, removal torque testing, and resonance frequency analysis (RFA). The results were statistically significant when the level of probability was 0.05 or less based on a non-parametric Mann-Whitney U-test. Results The implant survival rate was about 96%. Histologically and histomorphometrically, we observed that the titanium implants were more strongly attached in LLLT group than in control group. However, there was no significant difference between the LLLT group and control group in removal torque or RFA. Conclusion Histologically, LLLT might promote cell-level osseointegration of titanium implants, but there was no statistically significant effects.

Remifentanil Protects Human Keratinocytes against Hypoxia–Reoxygenation Injury through Activation of Autophagy

The proliferation, differentiation, and migration of keratinocytes are essential in the early stages of wound healing. Hypoxia-Reoxygenation (H/R) injury to keratinocytes can occur in various stressful environments such as surgery, trauma, and various forms of ulcers. The effects of remifentanil on human keratinocytes under hypoxia-reoxygenation have not been fully studied. Therefore, we investigated the effects of remifentanil on the proliferation, apoptosis, and autophagic activation of human keratinocytes during hypoxic-reoxygenation. Human keratinocytes were cultured under 1% oxygen tension for 24 h. The cells were then treated with various concentrations of remifentanil (0.01, 0.1, 0.5, and 1 ng/mL) for 2 h. Thereafter, the cells were reoxygenated for 12 h at 37°C. We measured cell viability via MTT assay. Using quantitative real-time PCR and western blot analysis, we measured the expression levels of proteins associated with apoptosis and autophagy. Quantification of apoptotic cells was performed using flow cytometer analysis and autophagic vacuoles were observed under a fluorescence microscope. Remifentanil treatment brought about an increase in the proliferation of human keratinocytes damaged by hypoxia-reoxygenation and decreased the apoptotic cell death, enhancing autophagic activity. However, the autophagy pathway inhibitor 3-MA inhibited the protective effect of remifentanil in hypoxia-reoxygenation injury. In conclusion, the current study demonstrated that remifentanil treatment stimulated autophagy and reduced apoptotic cell death in a hypoxia-reoxygenation model of human keratinocytes. Our results provide additional insights into the relationship between apoptosis and autophagy.

Effects of Remifentanil Preconditioning on Osteoblasts under Hypoxia-Reoxygenation Condition

Background: Ischemia-reperfusion of bone occurs in a variety of clinical conditions, such as orthopedic arthroplasty, plastic gnathoplasty, spinal surgery, and amputation. Usually, cellular models of hypoxia-reoxygenation reflect in vivo models of ischemia-reperfusion. With respect to hypoxia-reoxygenation conditions, the effects of remifentanil on osteogenesis have received little attention. Therefore, we investigated the effects of remifentanil on the proliferation and differentiation of osteoblasts during hypoxic-reoxygenation. Methods: After remifentanil (0.1, 1 ng/mL) preconditioning for 2 hours, human osteoblasts were cultured under 1% oxygen tension for 24 hours. Thereafter, the cells were reoxygenated for 12 hours at 37 °C. The naloxone groups were treated with naloxone for 30 minutes before remifentanil treatment. We measured cell viability via MTT assay. Osteoblast maturation was determined by assay of bone nodular mineralization. Quantitative PCR and western blot methods were used to determine BMP-2, osteocalcin, Akt, type I collagen, osterix, TGF-β1, HIF-1α, and RUNX2 expression levels. Results: Osteoblast viability and bone nodular mineralization by osteoblasts is recovered by remifentanil preconditioning from hypoxia-reoxygenation insult. During hypoxic-reoxygenation condition, remifentanil preconditioning induced the expression of BMP-2, osteocalcin, Akt, type I collagen, osterix, TGF-β1, HIF-1α, and RUNX2 in osteoblasts. Conclusions: Under hypoxia-reoxygenation conditions, remifentanil preconditioning enhanced the cell viability and maturation of osteoblasts, and stimulated the expression of proteins associated with osteoblast proliferation and differentiation of the osteoblast. Our results suggest that remifentanil may help in the treatment of bone stress injuries.

Clinical implications of the topography of the arteries supplying the medial pterygoid muscle.

The literature contains numerous accounts of the muscular anatomy of the medial pterygoid muscle, but little is known about the detailed vascular supply of the muscle. Numerous surgical procedures, such as mandibular ramus osteotomy, angle reduction, and/or parotidectomy, are performed around the muscle in the absence of this information. This study aimed to clarify the arterial supplies to the medial pterygoid muscle to provide critical information for use during various surgical procedures. Detailed dissections were performed on 20 sides of adult cadaveric head and neck specimens after injecting the carotid artery with red liquid neoprene latex. The medial pterygoid muscle was supplied by the following 5 branches of the external carotid artery: (1) the pterygoid artery of the maxillary artery, (2) a direct muscular branch of the facial artery, (3) the ascending palatine artery, (4) an anterior muscular branch of the facial artery, and (5) a previously undescribed muscular branch of the external carotid artery. This analysis of vascular anatomy has revealed new anatomic information on the blood supplies to the medial pterygoid muscle and will be useful to the development of guidelines for preventing hemorrhage during surgical procedures.

Resveratrol Induces Mitochondrial Apoptosis and Inhibits Epithelial-Mesenchymal Transition in Oral Squamous Cell Carcinoma Cells

ABSTRACT OSCC is the most common malignant cancer of the head and neck. EMT is an essential cellular process critical to the morphogenesis and homeostasis of solid tissues. It is also involved in the initial stage of cancer metastasis and invasion in which cells lose epithelial characteristics. While cancer therapy protocols such as surgery, radiation, and chemotherapy are effective and useful, the drug tolerance and toxicity of OSCC patients remain a problem. Resveratrol is mainly produced in red grape skin and exhibits anti-oxidative, anti-inflammatory, anti-proliferative, and anti-cancer properties. This study was undertaken to investigate the underlying mechanisms giving rise to the induction of apoptosis by resveratrol in the human tongue squamous cell carcinoma cell line. Resveratrol treatment resulted in a time- and dose-dependent decrease in cell viability and increased the apoptotic cell ratio in CAL-27, SCC15, and SCC25 cells. Resveratrol treatment of CAL-27 cells showed that several lines of apoptotic manifestation and decreased cell migration, invasion, and EMT-inducing transcription factor. Taken together, our findings demonstrate the inhibitory effect of resveratrol in human OSCC cells via the mitochondrial pathway and that resveratrol is able to inhibit cell invasion and migration by inhibiting the EMT-inducing transcription factors.

Delphinidin induces apoptosis and inhibits epithelial‐to‐mesenchymal transition via the ERK/p38 MAPK‐signaling pathway in human osteosarcoma cell lines

Delphinidin is major anthocyanidin that is extracted from many pigmented fruits and vegetables. This substance has anti‐oxidant, anti‐inflammatory, anti‐angiogenic, and anti‐cancer properties. In addition, delphinidin strongly suppresses the migration and invasion of various cancer cells during tumorigenesis. Although delphinidin has anti‐cancer effects, little is known about its functional roles in osteosarcoma (OS). For these reasons, we have demonstrated the effects of delphinidin on OS cell lines. The effects of delphinidin on cell viability and growth of OS cells were assessed using the MTT assay and colony formation assays. Hoechst staining indicated that the delphinidin‐treated OS cells were undergoing apoptosis. Flow cytometry, confocal microscopy, and a western blot analysis also indicated evidence of apoptosis. Inhibition of cell migration and invasion was found to be associated with epithelial‐to‐mesenchymal transition (EMT), observed by using a wound healing assay, an invasion assay, and a western blot analysis. Furthermore, delphinidin treatment resulted in a profound reduction of phosphorylated forms of ERK and p38. These findings demonstrate that delphinidin treatment suppressed EMT through the mitogen‐activated protein kinase (MAPK) signaling pathway in OS cell lines. Taken together, our results suggest that delphinidin strongly inhibits cell proliferation and induces apoptosis. Delphinidin treatment also suppresses cell migration and prevents EMT via the MAPK‐signaling pathway in OS cell lines. For these reasons, delphinidin has anti‐cancer effects and can suppress metastasis in OS cell lines, and it might be worth using as an OS therapeutic agent.