• The Korean Journal of Physiology and Pharmacology
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• v.21 no.6
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• pp.599-607
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• 2017

Most normal cells express L-type amino acid transporter 2 (LAT2). However, L-type amino acid transporter 1 (LAT1) is highly expressed in many tumor cells and presumed to support their increased growth and proliferation. This study examined the effects of JPH203, a selective LAT1 inhibitor, on cell growth and its mechanism for cell death in Saos2 human osteosarcoma cells. FOB human osteoblastic cells and Saos2 cells expressed LAT1 and LAT2 together with their associating protein 4F2 heavy chain, but the expression of LAT2 in the Saos2 cells was especially weak. JPH203 and BCH, a non-selective L-type amino acid transporter inhibitor, potently inhibited L-leucine uptake in Saos2 cells. As expected, the intrinsic ability of JPH203 to inhibit L-leucine uptake was far more efficient than that of BCH in Saos2 cells. Likewise, JPH203 and BCH inhibited Saos2 cell growth with JPH203 being superior to BCH in this regard. Furthermore, JPH203 increased apoptosis rates and formed DNA ladder in Saos2 cells. Moreover, JPH203 activated the mitochondria-dependent apoptotic signaling pathway by upregulating pro-apoptotic factors, such as Bad, Bax, and Bak, and the active form of caspase-9, and downregulating anti-apoptotic factors, such as Bcl-2 and Bcl-xL. These results suggest that the inhibition of LAT1 activity via JPH203, which may act as a potential novel anti-cancer agent, leads to apoptosis mediated by the mitochondria-dependent intrinsic apoptotic signaling pathway by inducing the intracellular depletion of neutral amino acids essential for cell growth in Saos2 human osteosarcoma cells.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.3
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• pp.200-208
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• 2006

Amino acids are required for protein synthesis and energy sources in all living cells. The amino acid transport system L is a major nutrient transport system that is responsible for $Na^+$-independent transport of neutral amino acids including several essential amino acids. In malignant tumors, the L-type amino acid transporter 1 (LAT1), the first isoform of system L, is highly expressed to support tumor cell growth. In the present study, the expression and functional characterization of amino acid transport system L were, therefore, investigated in Saos2 human osteogenic sarcoma cells. RT-PCR and western blot analyses have revealed that the Saos2 cells expressed the LAT1 and the L-type amino acid transporter 2 (LAT2), the second isoform of system L, together with their associating protein heavy chain of 4F2 antigen (4F2hc) in the plasma membrane, but the expression of LAT2 was very weak. The uptakes of [${14}^C$]L-leucine by Saos2 cells were $Na^+$-independent and were completely inhibited by the system L selective inhibitor, 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH). The affinity of [${14}^C$]L-leucine uptake and the inhibition profiles of [${14}^C$]L-leucine uptake by various amino acids in the Saos2 cells were comparable with those for the LAT1 expressed in Xenopus oocytes. The majority of [${14}^C$]L-leucine uptake is, therefore, mediated by LAT1 in the Saos2 cells. These results suggest that the transports of neutral amino acids including several essential amino acids into Saos2 human osteogenic sarcoma cells are for the most part mediated by LAT1. Therefore, the Saos2 human osteogenic sarcoma cells are excellent tools for examine the properties of LAT1. Moreover, the specific inhibition of LAT1 in tumor cells might be a new rationale for anti-tumor therapy.

• Toxicological Research
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• v.18 no.3
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• pp.259-265
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• 2002

Resveratrol, a phytoalexin found in grapes, berries, and peanuts, is one of the most promising agents for cancer prevention. Recent studies show that the antitumor activity of resveratrol occurs through p53-mediated apoptosis. This study demonstrated the mechanism that resveratrol induced apoptosis in human osteosarcoma Saos-2 cells lacking p53. Treatment of osteosarcoma Saos-2 cells with resveratrol resulted in decrease of cell viability, which was revealed as apoptosis characterized by activation of caspase-3 protease as well as cleavage of poly(ADP-ribose) polymerase (PARP) with change of mitochondrial membrane potential transition. These results suggest that resveratrol may be potentially useful to treat osteosarcoma via activation of caspase protease and mitochondrial dysfunction.

• BMB Reports
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• v.46 no.2
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• pp.113-118
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• 2013

TTRAP is a multi-functional protein that is involved in multiple aspects of cellular functions including cell proliferation, apoptosis and the repair of DNA damage. Here, we demonstrated that the lentivirus-mediated overexpression of TTRAP significantly inhibited cell growth and induced apoptosis in osteosarcoma cells. The ectopic TTRAP suppressed the growth and colony formation capacity of two osteosarcoma cell lines, U2OS and Saos-2. Cell apoptosis was induced in U2OS cells and the cell cycle was arrested at G2/M phase in Saos-2 cells. Exogenous expression of TTRAP in serum-starved U2OS and Saos-2 cells induced an increase in caspase-3/-7 activity and a decrease in cyclin B1 expression. In comparison with wild-type TTRAP, mutations in the 5'-tyrosyl-DNA phosphodiesterase activity of TTRAP, in particular $TTRAP^{E152A}$, showed decreased inhibitory activity on cell growth. These results may aid in clarifying the physiological functions of TTRAP, especially its roles in the regulation of cell growth and tumorigenesis.

• Journal of Life Science
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• v.26 no.2
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• pp.147-154
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• 2016

Osteosarcoma (OS) is the most common and malignant bone tumors. Although many types of resection surgery and experimental agents were developed, median survival and clinical prognosis are poorly investigated. Recently, several researches have reported that Eucheuma cottonii has potent as protective effects of coal dust-induced lung damage via inhibition of malondialdehyde (MDA) and oxidative stress in bronchoalveolar lavage fluids (BALF). However, anti-cancer effects and specific molecular mechanism of extract from Eucheuma cottonii (EE) has not been clearly studied yet. This study evaluated that anti-cancer potential of EE in human osteosarcoma Saos-2 cells. EE indicated cytotoxicity on Saos-2 cells in a dose-dependent manner. Morphological degradation and nucleic condensation were also observed under the EE treatment. However, it did not significantly affect on non-cancerous kidney HEK-293 cells under the same concentration which is shown cytotoxicity on Saos-2 cells. The phosphorylation of Fas-Associated Death Domain (FADD) and expression of cleaved caspase-8, -7 and -3 were upregulated in a dose-dependent manner. In immunofluorescence staining, expression level of Fas and cleaved PARP were upregulated by EE treatment. Furthermore, treatment of EE induces upregulation of sub G1 phase by flow cytometry analysis. The results demonstrated that EE has a therapeutic potential against osteosarcoma via FADD mediated caspase cascade apoptosis signal pathway.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.6
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• pp.3681-3684
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• 2013

Deregulated miRNAs participate in osteosarcoma genesis. In this study, the expression of miRNA-218 in human osteosarcomas, adjacent normal tissues and Saos-2 human osteosarcoma cells was first assessed. Then the precise role of miRNA-218 in osteosarcoma cells was investigated. Upon transfection with a miR-218 expression vector, the proliferation of Saos-2 human osteosarcoma cells determined using the ATPlite assay was significantly suppressed, whilw migration of Saos-2 cells detected by wound healing and invasion determined using transwells were dramatically inhibited. Potential target genes of miR-218 were predicted and T-cell lymphoma invasion and metastasis 1 (TIAM1) and matrix metalloproteinase 2 (MMP2) and 9 (MMP9) were identified. This was confirmed by western blotting, which showed that miR-218 expression inhibited TIAM1, MMP2 and MMP9 protein expression. Collectively, these data suggest that miR-218 acts as a tumor suppressor in osteosarcomas by down-regulating TIAM1, MMP2 and MMP9 expression.

• Clinical and Experimental Pediatrics
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• v.52 no.2
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• pp.213-219
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• 2009

Purpose:Iron is a critical nutritional element that is essential for a variety of important biological processes, including cell growth and differentiation, electron transfer reactions, and oxygen transport, activation, and detoxification. Iron is also required for neoplastic cell growth due to its catalytic effects on the formation of hydroxyl radicals, suppression of host defense cell activities, and promotion of cancer cell multiplication. Chronic transfusion-dependent patients receiving chemotherapy may have iron overload, which requires iron-chelating therapy. We performed this study to demonstrate whether the iron chelating agent deferoxamine induces apoptosis in Saos-2 osteosarcoma cells, and to investigate the underlying apoptotic mechanism. Methods:To analyze the apoptotic effects of an iron chelator, cultured Saos-2 cells were treated with deferoxamine. We analyzed cell survival by trypan blue and crystal violet analysis, apoptosis by nuclear condensation, DNA fragmentation, and cell cycle analysis, and the expression of apoptotic related proteins by Western immunoblot analysis. Results:Deferoxamine inhibited the growth of Saos-2 cell in a time- and dose-dependent manner. The major mechanism for growth inhibition with the deferoxamine treatment was by the induction of apoptosis, which was supported by nuclear staining, DNA fragmentation analysis, and flow cytometric analysis. Furthermore, bcl-2 expression decreased, while bax, caspase-3, caspase-9, and PARP expression increased in Saos-2 cells treated with deferoxamine. Conclusion:These results demonstrated that the iron chelating agent deferoxamine induced growth inhibition and mitochondrial-dependent apoptosis in osteosarcoma Saos-2 cells, suggesting that iron chelating agents used in controlling neoplastic cell fate can be potentially developed as an adjuvant agent enhancing the anti-tumor effect for the treatment of osteosarcoma.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.387.1-387.1
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• 2002

Aging and estrogen cleficiency after menopause induce bone loss and result in osteoporosis. This study was investigated effects of n-hexane fraction (Hx) extracted from Astragali Radix on osteoporosis with osteoblast-like cell line (MG-63 and Saos-2) and an ovariectomized (OVX) rat model. Proliferation of osteoblast-like cells. MG-63 and Saos-2. was tested with MTT and alkaline phosphatase (ALP) assays. (omitted)

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.3
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• pp.261-270
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• 2006

The success of an implant is determined by its integration into the tissue surrounding the biomaterial. Surface roughness is considered to influence the behavior of adherent cells. The aim of this in vitro study was to determine the effect of surface roughness on Saos-2 osteoblast-like cells. Titanium disks, blasted with $75{\mu}m$ aluminum oxide particles and anodic oxidized and machined titanium disks were prepared. Saos-2 were plated on the disks at a density of 50,000 cells per well in 48-well dishes. After 1 hour, 1 day, 6 days cell numbers were counted. One day, 6 days after plating, alkaline phosphatase(ALPase) activity was determined. Compared to experimental groups, the number of cells was significantly higher on control group. The stimulatory effect of surface roughness on ALPase was more pronounced on the experimental groups than on control group. These results demonstrate that surface roughness alters proliferation and differentiation of osteoblasts. The results also suggest that implant surface roughness may play a role in determining phenotypic expression of cells.

• Journal of Periodontal and Implant Science
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• v.35 no.4
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• pp.839-850
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• 2005

The success of an implant is determined by its integration into the tissue surrounding the biomaterial. Surface roughness is considered to influence the behavior of adherent cells. The aim of this in vitro study was to determine the effect of surface roughness on Saos-2 osteoblast-like cells. Titanium disks blasted with 75 ${/mu}m$ aluminum oxide particles and machined titanium disks were prepared. Saos-2 were plated on the disks at a density of 50,000 cells per well in 48-well dishes. After 1 hour, 1 day, 6 days cell numbers were counted. One day, 6 days after plating, alkaline phosphatase(ALPase) activity was determined. Compared to experimental group, the number of cells was significantly higher on control group. The stimulatory effect of surface roughness on ALPase was more pronounced on the experimental group than on control group. These results demonstrate that surface roughness alters proliferation and differentiation of osteoblasts. The results also suggest that implant surface roughness may play a role in determining phenotypic expression of cells.