Human Osteosarcoma Cells (human + osteosarcoma_cell)

Distribution by Scientific Domains

Terms modified by Human Osteosarcoma Cells

  • human osteosarcoma cell line

  • Selected Abstracts


    The Aberrant Expressions of Nuclear Matrix Proteins During the Apoptosis of Human Osteosarcoma Cells

    THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 5 2010
    Zhen-Li Zhao
    Abstract The objective of this study was to investigate altered expressions of nuclear matrix proteins (NMPs) of human osteosarcoma (OS) MG-63 cells during curcumin-induced apoptosis of human OS MG-63 cells. MG-63 cells were cultured with curcumin (7.5 mg/L) for 72 hr. Morphological alterations of cells were captured using light microscopy and transmission electron microscopy, and cell cycle distribution was estimated by flow cytometry. NMPs were selectively extracted and subjected to two-dimensional gel electrophoresis (2-DE) analysis. Western blots were performed to determine changes in the expression levels of specific NMPs. The results demonstrated that typical characteristics of apoptosis were observed. Cellular chromatin agglutinated, cell nuclei condensed, and apoptotic bodies were formed after treatment with curcumin. The 2-DE results displayed 27 NMPs, 21 of which were identified to have change in expression levels significantly during apoptosis. The altered expressions of three of these NMPs (nucleophosmin, prohibitin, and vimentin) were further confirmed by immunoblotting. These findings indicated that the apoptosis of MG-63 cells was accompanied by the expression alteration of NMPs. Our results might help to reveal the relationship between NMPs and the regulation of gene expression in the process of apoptosis, as well as provide the basic concepts for future studies on the mechanisms of apoptosis and the therapy for bone diseases. Anat Rec, 2010. © 2010 Wiley-Liss, Inc. [source]


    Effects of Antrodia camphorata on viability, apoptosis, [Ca2+]i, and MAPKs phosphorylation in MG63 human osteosarcoma cells

    DRUG DEVELOPMENT RESEARCH, Issue 2 2007
    Yih-Chau Lu
    Abstract The present study explored the effect of Antrodia camphorata (AC) on viability, apoptosis, mitogen-activated protein kinases (MAPKs) phosphorylation, and Ca2+ regulation in MG63 human osteosarcoma cells. AC (25,50,µg/ml) did not affect cell viability, but at 100,200,µg/ml decreased viability and induced apoptosis in a concentration-dependent manner. AC at concentrations of 25,200,µg/ml did not alter basal [Ca2+]i, but at 25,µg/ml decreased [Ca2+]i increases induced by ATP, bradykinin, histamine, and thapsigargin. ATP, bradykinin, and histamine increased cell viability while thapsigargin decreased it. AC (25,µg/ml) pretreatment failed to alter bradykinin- and thapsigargin-induced effects on viability, but potentiated ATP- and histamine-induced increases in viability. Immunoblotting showed that MG63 cells did not have background phospho-JNK and phospho-p38 mitogen-activated protein kinases (MAPKs); and AC did not induce the phosphorylation of these two MAPKs. Conversely, the cells had significant background phospho-ERK MAPK that was inhibited by 200,µg/ml AC. The ERK-specific inhibitor PD98059 also induced cell death. Collectively, in MG63 cells, AC exerted multiple effects on viability and [Ca2+]i, caused apoptosis probably via inhibition of ERK MAPK phosphorylation. Drug Dev Res 68:71,78, 2007. © 2007 Wiley-Liss, Inc. [source]


    Arsenite induces delayed mutagenesis and transformation in human osteosarcoma cells at extremely low concentrations

    ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 5 2003
    Kanae Mure
    Abstract Arsenite is a human multisite carcinogen, but its mechanism of action is not known. We recently found that extremely low concentrations (,0.1 ,M) of arsenite transform human osteosarcoma TE85 (HOS) cells to anchorage-independence. In contrast to other carcinogens which transform these cells within days of exposure, almost 8 weeks of arsenite exposure are required for transformation. We decided to reexamine the question of arsenite mutagenicity using chronic exposure in a spontaneous mutagenesis assay we previously developed. Arsenite was able to cause a delayed increase in mutagenesis at extremely low concentrations (,0.1 ,M) in a dose-dependent manner. The increase in mutant frequency occurred after almost 20 generations of growth in arsenite. Transformation required more than 30 generations of continuous exposure. We also found that arsenite induced gene amplification of the dihydrofolate reductase (DHFR) gene in a dose-dependent manner. Since HOS cells are able to methylate arsenite at a very low rate, it was possible that active metabolites such as monomethylarsonous acid (MMAIII) contributed to the delayed mutagenesis and transformation in these cells. However, when the assay was repeated with MMAIII, we found no significant increase in mutagenesis or transformation, suggesting that arsenite-induced delayed mutagenesis and transformation are not caused by arsenite's metabolites, but by arsenite itself. Our results suggest that long-term exposure to low concentrations of arsenite may affect signaling pathways that result in a progressive genomic instability. Environ. Mol. Mutagen. 41:322,331, 2003. © 2003 Wiley-Liss, Inc. [source]


    Ascochlorin activates p53 in a manner distinct from DNA damaging agents

    INTERNATIONAL JOURNAL OF CANCER, Issue 12 2009
    Ji-Hak Jeong
    Abstract Ascochlorin, a prenylphenol antitumor antibiotic, profoundly increases the expression of endogenous p53 by increasing protein stability in the human osteosarcoma cells and human colon cancer cells. Ascochlorin also increases DNA binding activity to the p53 consensus sequence in nuclear extract and enhances transcription of p53 downstream targets. Ascochlorin specifically induces p53 phosphorylation at ser 392 without affecting ser 15 or 20, whereas DNA damaging agents typically phosphorylate these serines. Moreover, ascochlorin does not induce phosphorylation of ATM and CHK1, an established substrate of ATR that is activated by genotoxins, nor does it increase DNA strand break, as confirmed by comet assay. The structure-activity relationship suggests that p53 activation by ascochlorin is related to inhibition of mitochondrial respiration, which is further supported by the observation that respiratory inhibitors activate p53 in a manner similar to ascochlorin. These results suggest that ascochlorin, through the inhibition of mitochondrial respiration, activates p53 through a mechanism distinct from genotoxins. © 2009 UICC [source]


    Silencing of hSlo potassium channels in human osteosarcoma cells promotes tumorigenesis

    INTERNATIONAL JOURNAL OF CANCER, Issue 2 2008
    Béatrice Cambien
    Abstract Potassium channels, the most diverse superfamily of ion channels, have recently emerged as regulators of carcinogenesis, thus introducing possible new therapeutic strategies in the fight against cancer. In particular, the large conductance Ca2+ -activated K+ channels, often referred to as BK channels, are at the crossroads of several tumor-associated processes such as cell proliferation, survival, secretion and migration. Despite the high BK channel expression in osteosarcoma (OS), their function has not yet been investigated in this malignant bone pathology. Here, using stable RNA interference to reduce the expression of hSlo, the human pore-forming ,-subunit of the BK channel, in human Cal72 OS cells, we show that BK channels play a functional role in carcinogenesis. Our results reveal for the first time that BK channels exhibit antitumoral properties in OS in vivo and affect the tumor microenvironment through the modulation of both chemokine expression and leukocyte infiltration. © 2008 Wiley-Liss, Inc. [source]


    Preparation and properties of ,-chitin-whisker-reinforced hyaluronan,gelatin nanocomposite scaffolds

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010
    Parintorn Hariraksapitak
    Abstract Tissue scaffolds made of naturally derived polymers present poor mechanical properties, which may limit their actual utilization in certain areas where high strength is a key criterion. This study was aimed at developing tissue scaffolds from a 50 : 50 w/w blend of hyaluronan (HA) and gelatin (Gel) that contained different amounts of acid-hydrolyzed ,-chitin whiskers (CWs) by a freeze-drying method. The weight ratios of the CWs to the blend were 0,30%. These scaffolds were characterized for their physical, physicochemical, mechanical, and biological properties. Regardless of the CW content, the average pore size of the scaffolds ranged between 139 and 166 ,m. The incorporation of 2% CWs in the HA,Gel scaffolds increased their tensile strength by about two times compared to those of the other groups of the scaffolds. Although the addition of 20,30% CWs in the scaffolds improved their thermal stability and resistance to biodegradation, the scaffolds with 10% CWs were the best for supporting the proliferation of cultured human osteosarcoma cells (SaOS-2). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]


    Focal Adhesion Kinase pp125FAK Interacts With the Large Conductance Calcium-Activated hSlo Potassium Channel in Human Osteoblasts: Potential Role in Mechanotransduction,

    JOURNAL OF BONE AND MINERAL RESEARCH, Issue 10 2003
    Roger Rezzonico
    Abstract Molecular events of mechanotransduction in osteoblasts are poorly defined. We show that the mechanosensitive BK channels open and recruit the focal adhesion kinase FAK in osteoblasts on hypotonic shock. This could convert mechanical signals in biochemical events, leading to osteoblast activation. Introduction: Mechanical strains applied to the skeleton influence bone remodeling and architecture mainly through the osteoblast lineage. The molecular mechanisms involved in osteoblastic mechanotransduction include opening of mechanosensitive cation channels and the activation of protein tyrosine kinases, notably FAK, but their interplay remains poorly characterized. The large conductance K+ channel (BK) seems likely as a bone mechanoreceptor candidate because of its high expression in osteoblasts and its ability to open in response to membrane stretch or hypotonic shock. Propagation of the signals issued from the mechanosensitivity of BK channels inside the cell likely implies complex interactions with molecular partners involved in mechanotransduction, notably FAK. Methods: Interaction of FAK with the C terminus of the hSlo ,-subunit of BK was investigated using the yeast two-hybrid system as well as immunofluorescence microscopy and coimmunoprecipitation experiments with a rabbit anti-hslo antibody on MG63 and CAL72 human osteosarcoma cell lines and on normal human osteoblasts. Mapping of the FAK region interacting with hSlo was approached by testing the ability of hSlo to recruit mutated ot truncated FAK proteins. Results: To the best of our knowledge, we provide the first evidence of the physical association of FAK with the intracellular part of hslo. We show that FAK/hSlo interaction likely takes place through the Pro-1-rich domain situated in the C-terminal region of the kinase. FAK/hSlo association occurs constitutively at a low, but appreciable, level in human osteosarcoma cells and normal human osteoblasts that express endogenous FAK and hSlo. In addition, we found that application of an hypo-osmotic shock to these cells induced a sustained activation of BK channels associated to a marked increase in the recruitment of FAK on hSlo. Conclusions: Based on these data, we propose that BK channels might play a triggering role in the signaling cascade induced by mechanical strains in osteoblasts. [source]


    2-methoxyestradiol-mediated anti-tumor effect increases osteoprotegrin expression in osteosarcoma cells

    JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 5 2010
    Michaela B. Benedikt
    Abstract Osteosarcoma is a bone tumor that frequently develops during adolescence. 2-Methoxyestradiol (2-ME), a naturally occurring metabolite of 17,-estradiol, induces cell cycle arrest and cell death in human osteosarcoma cells. To investigate whether the osteoprotegrin (OPG) protein plays a role in 2-ME actions, we studied the effect of 2-ME treatment on OPG gene expression in human osteosarcoma cells. 2-ME treatment induced OPG gene promoter activity and mRNA levels. Also, Western blot analysis showed that 2-ME treatment increased OPG protein levels in MG63, KHOS, 143B and LM7 osteosarcoma cells by 3-, 1.9-, 2.8-, and 2.5-fold, respectively, but did not affect OPG expression in normal bone cells. In addition, increases in OPG protein levels were observed in osteosarcoma cell culture media after 3 days of 2-ME treatment. The effect of 2-ME on osteosarcoma cells was ligand-specific as parent estrogen, 17,-estradiol and a tumorigenic estrogen metabolite, 16,-hydroxyestradiol, which do not affect osteosarcoma cell cycle and cell death, had no effect on OPG protein expression. Furthermore, co-treating osteosarcoma cells with OPG protein did not further enhance 2-ME-mediated anti-tumor effects. OPG-released in 2-ME-treated cultures led to an increase in osteoblastic activity and a decrease in osteoclast number, respectively. These findings suggest that OPG is not directly involved in 2-ME-mediated anti-proliferative effects in osteosarcoma cells, but rather participates in anti-resorptive functions of 2-ME in bone tumor environment. J. Cell. Biochem. 109: 950,956, 2010. © 2010 Wiley-Liss, Inc. [source]


    9-Cis-retinoic acid reduces ischemic brain injury in rodents via bone morphogenetic protein

    JOURNAL OF NEUROSCIENCE RESEARCH, Issue 2 2009
    Hui Shen
    Abstract Retinoic acid (RA), a biologically active derivative of vitamin A, has protective effects against damage caused by H2O2 or oxygen-glucose deprivation in mesangial and PC12 cells. In cultured human osteosarcoma cells, RA enhances the expression of bone morphogenetic protein-7 (BMP7), a trophic factor that reduces ischemia- or neurotoxin-mediated neurodegeneration in vivo. The purpose of this study is to examine whether RA reduces ischemic brain injury through a BMP7 mechanism. We found that intracerebroventricular administration of 9-cis-retinoic acid (9cRA) enhanced BMP7 mRNA expression, detected by RT-PCR, in rat cerebral cortex at 24 hr after injection. Rats were also subjected to transient focal ischemia induced by ligation of the middle cerebral artery (MCA) at 1 day after 9cRA injection. Pretreatment with 9cRA increased locomotor activity and attenuated neurological deficits 2 days after MCA ligation. 9cRA also reduced cerebral infarction and TUNEL labeling. These protective responses were antagonized by the BMP antagonist noggin given 1 day after 9cRA injection. Taken together, our data suggest that 9cRA has protective effects against ischemia-induced injury, and these effects involve BMPs. © 2008 Wiley-Liss, Inc. [source]


    Anticancer effects of zoledronic acid against human osteosarcoma cells

    JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 6 2006
    B. Kubista
    Abstract Based on neoadjuvant chemotherapy, the prognosis of osteosarcoma patients has improved dramatically. However, due to therapy resistance in patient subgroups, the development of new treatment strategies is still of utmost importance. The aim of our study was to test the effects of the nitrogen-containing bisphosphonate zoledronic acid (ZOL) on osteosarcoma cell lines (N,=,9). Exposure to ZOL at low micromolar concentrations induced a dose- and time-dependent block of DNA synthesis and cell cycle progression followed by microfilament breakdown and apoptosis induction. The ZOL-induced cell cycle accumulation in S phase was accompanied by significant changes in the expression of cyclins and cyclin-dependent kinase inhibitors with a prominent loss of cyclin E and D1. ZOL not only inhibited growth but also migration of osteosarcoma cells. The mevalonate pathway intermediary geranyl-geraniol (GGOH) but not farnesol (FOH) significantly inhibited the anticancer effects of ZOL against osteosarcoma cells. Correspondingly, ZOL sensitivity correlated with the blockade of protein geranylgeranylation indicated by unprenylated Rap1. Overexpression of even high levels of P-glycoprotein, as frequently present in therapy-resistant osteosarcomas, did not impair the anticancer activity of ZOL. Summarizing, our data suggest that ZOL, which selectively accumulates in the bone, represents a promising agent to improve osteosarcoma therapy. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res [source]


    Rapid quantitative bioassay of osteoinduction

    JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2000
    Huston Davis Adkisson
    We developed a reproducible, relatively rapid bioassay that quantitatively correlates with the osteoinductive capacity of demineralized bone matrix obtained from human long bones. We have found that Saos human osteosarcoma cells proliferate in response to incubation with demineralized bone matrix and that an index of this proliferative activity correlates with demineralized bone matrix-induced osteogenesis in vivo. The bioassay (Saos cell proliferation) had an interassay coefficient of variation of 23 ± 2% and an intra-assay cocfficient of 11 ± 1%. Cell proliferation was normalized to a standard sample of demineralized bone matrix with a clinically high osteoinductive capacity, which was assigned a value of one. The Saos cell proliferation for each sample was related to the standard and assigned a value placing it into thc low (0.00-0.39), intermediate (0.40-0.69). or high (0.70-1.49) osteoinductivc index group. Osteoinduction of human demineralized bone matrix was quantitated by expressing new bone formation as a function of the total bone volume (new bone plus the demineralized bone powder). The demineralized bone matrix was placed in pouches formed in the rectus abdominis muscles of athymic rats, and endochondral bone formation was assessed at 35 days following implantation, when marrow spaces in the ossicles were formed by new bone bridging the spaces between demineralized bone matrix particles. The proliferative index correlated with the area of new bone formation in histological sections ol the newly formed ossicles. When the proliferative index (the osteoinductive index) was divided into low, intermediate. and high groups, the correlation between it and new bone formation (osteoinduction) was 0.850 (p < 0.0005) in 25 samples of demineralized bone matrix. There was no overlap in the osteoinduction stimulated between the samples with low and high osteoinductive indices. We conclude that the proliferation assay is useful for the routine screening of bone allograft donors for osteoinductivc potential. Furthermore, the two-dimensional area of new bone formation. as it relates to total new bone area, is a quantitative measure of osteoinduction. [source]


    Signal transduction pathways involved in the stimulation of tissue type plasminogen activator by interleukin-1, and Porphyromonas gingivalis in human osteosarcoma cells

    JOURNAL OF PERIODONTAL RESEARCH, Issue 5 2006
    Yu-Chao Chang
    Background:, Recently, evidences have shown that tissue type plasminogen activator (t-PA) may play an important role in the pathogenesis of periodontal diseases. However, the mechanisms and signal transduction pathways involved in the production of t-PA in human osteosarcoma cells are not fully understood. Objectives:, The purpose of this study was to investigate the caseinolytic activity in human osteosarcoma cell line U2OS cells stimulated with interleukin-1, (IL-1,) or Porphyromonas gingivalis in the absence or presence of p38 inhibitor SB203580, mitogen-activated protein kinase kinase (MEK) inhibitor U0126, and phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002. Methods:, IL-1, and the supernatants of P. gingivalis were used to evaluate the caseinolytic activity in U2OS cells by using casein zymography and enzyme-linked immunosorbent assay (ELISA). Furthermore, to search possible signal transduction pathways, SB203580, U0126, and LY294002 were added to test how they modulated the caseinolytic activity. Results:, Casein zymography exhibited a caseinolytic band with a molecular weight of approximately 70 kDa, suggestive of the presence of t-PA. Secretion of t-PA was found to be stimulated with IL-1, and P. gingivalis during a 2-day culture period (p < 0.05). From the results of casein zymography and ELISA, SB203580, U0126, and LY294002 significantly reduced the IL-1, or P. gingivalis -stimulated t-PA production, respectively (p < 0.05). Conclusions:, Our findings demonstrated that IL-1, and P. gingivalis enhance t-PA production in human osteosarcoma cells, and that the signal transduction pathways p38, MEK, and PI3K are involved in the inhibition of t-PA. SB203580, U0126, and LY294002 suppress t-PA production and/or activity and may therefore be valuable therapeutics in t-PA-mediated periodontal destruction, and might be proved clinically useful agents, in combination with standard treatment modalities, in the treatment of periodontitis. [source]


    Characterisation of ligand binding to the parathyroid hormone/parathyroid hormone-related peptide receptor in MCF7 breast cancer cells and SaOS-2 osteosarcoma cells

    CELL BIOCHEMISTRY AND FUNCTION, Issue 2 2007
    Majed S. Alokail
    Abstract Parathyroid hormone-related peptide (PTHrP) and parathyroid hormone (PTH)/PTHrP-receptor, PTH/PTHrP-R, are frequently expressed in mammary carcinomas as well as in bone cells. In this study we compared the ligand binding characteristics of the PTH/PTHrP,R in SaOS-2 human osteosarcoma cells with those in MCF7 breast cancer cells. We used both Scatchard analysis of saturation kinetics for iodinated ligand and the level of expressed receptor protein by visualising the single radio-labelled receptor-ligand complex from isolated membrane preparations from the two cell lines. In MCF7 cells, ligand binding, (receptor number) was increased by prior exposure of the cultured cells to epidermal growth factor (EGF), estradiol (E2), or dexamethasone (DEX), and decreased following calcitriol (1,25 DHCC). In contrast in the SaOS-2 cells, PTH/PTHrP-R number was increased by exposure to E2 and 1,25DHCC and decreased by DEX while EGF had no effect. These data were confirmed when the PTH/PTHrP-R was cross linked with 125I-PTHrP-1-34Tyr, and extended by visualising the intensity of the isolated radiolabelled receptor complex by autoradiography following SDS-PAGE at several time points during the treatment. Copyright © 2005 John Wiley & Sons, Ltd. [source]


    Synthesis and Characterization of a C(6) Nucleoside Analogue for the in vivo Imaging of the Gene Expression of Herpes Simplex Virus Type-1 Thymidine Kinase (HSV1 TK)

    CHEMISTRY & BIODIVERSITY, Issue 3 2006
    Anass Johayem
    Abstract The synthesis and biological evaluation of ,6-(1,3-dihydroxyisobutyl)thymine' (DHBT; 1), which corresponds to 6-[3-hydroxy-2-(hydroxymethyl)propyl]-5-methylpyrimidine-2,4(1H,3H)-dione, is reported. DHBT (1) was designed as a new substrate for herpes simplex virus type-1 thymidine kinase (HSV1 TK). The compound was found to be exclusively phosphorylated by HSV1 TK, and to exhibit good binding affinity (Ki,=,35.3±1.3,,M). Cell-proliferation assays with HSV1-TK-transduced human osteosarcoma cells (143B-TK+-HSV1-WT) and with both human-thymidine-kinase-1-negative (143B-TK,) and non-transduced parental (MG-63) cells indicate that 1 is less cytotoxic than the standard drug Ganciclovir. Thus, DHBT (1) represents a promising precursor of a nontoxic reporter probe for the monitoring of HSV1 TK gene expression by means of positron-emission tomography (PET). [source]


    Laser Microbeams and Optical Tweezers in Ageing Research

    CHEMPHYSCHEM, Issue 1 2009
    Paulius Grigaravi
    Abstract We show how a technique developed within the framework of physics and physical chemistry,in a true interdisciplinary approach,can answer questions in life sciences that are not solvable by using other techniques. Herein, we focus on blood-pressure regulation and DNA repair in ageing studies. Laser microbeams and optical tweezers are now established tools in many fields of science, particularly in the life sciences. A short glimpse is given on the wide field of non-age-research applications in life sciences. Then, optical tweezers are used to show that exerting a vertical pressure on cells representing the inner lining of blood vessels results in bursts of NO liberation concomitant with large changes in cell morphology. Repeated treatment of such human umbilical vein endothelial cells (HUVEC) results in stiffening, a hallmark of manifest high blood pressure, a disease primarily of the elderly. As a second application in ageing research, a laser microbeam is used to induce, with high spatial and temporal resolution, DNA damages in the nuclei of U2OS human osteosarcoma cells. A pairwise study of the recruitment kinetics of different DNA repair proteins reveals that DNA repair starts with non-homologous end joining (NHEJ), a repair pathway, and may only after several minutes switch to the error-free homologous recombination repair (HRR) pathway. Since DNA damages,when incorrectly repaired,accumulate with time, laser microbeams are becoming well-used tools in ageing research. [source]


    Effect of calmidazolium on Ca2+ movement and proliferation in human osteosarcoma cells

    CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 10 2004
    Li-Lin Tseng
    Summary 1.,In human MG63 osteosarcoma cells, the effect of calmidazolium on [Ca2+]i and proliferation was explored using fura-2 and ELISA, respectively. 2.,Calmidazolium, at concentrations greater than 0.1 µmol/L, caused a rapid increase in [Ca2+]i in a concentration-dependent manner (EC50 = 0.5 µmol/L). The calmidazolium-induced [Ca2+]i increase was reduced by 66% by removal of extracellular Ca2+. In Ca2+ -free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca2+ -ATPase, caused a monophasic increase in [Ca2+]i, after which the effect of calmidazolium to increase [Ca2+]i was completely inhibited. U73122, an inhibitor of phospholipase C (PLC), abolished histamine (but not calmidazolium)-induced increases in [Ca2+]i. Pretreatment with phorbol 12-myristate 13-acetate to activate protein kinase C inhibited the calmidazolium-induced increase in [Ca2+]i in Ca2+ -containing medium by 47%. 3.,Separately, it was found that overnight treatment with 2,10 µmol/L calmidazolium inhibited cell proliferation in a concentration-dependent manner. 4.,These results suggest that calmidazolium increases [Ca2+]i by stimulating extracellular Ca2+ influx and also by causing release of intracellular Ca2+ from the endoplasmic reticulum in a PLC-independent manner. Calmidazolium may be cytotoxic to osteosarcoma cells. [source]