Proliferation Of Human Osteosarcoma Cells Research Articles

Effect of miconazole on intracellular Ca 2+ levels and proliferation in human osteosarcoma cells

The effect of miconazole, an anti-fungal drug, on cytoplasmic free Ca 2+ concentrations ([Ca 2+] i) in human osteosarcoma cells (MG63) was explored by using the Ca 2+-sensitive dye fura-2. Miconazole acted in a concentration-dependent manner with an EC 50 of 75 μM. The Ca 2+ signal comprised a gradual rise and a sustained elevation. Removal of extracellular Ca 2+ reduced 50% of the signal. In Ca 2+-free medium, the [Ca 2+] i rise induced by 1 μM thapsigargin (an endoplasmic reticulum Ca 2+ pump inhibitor) was completely inhibited by pretreatment with 20 μM miconazole. Pretreatment with thapsigargin partly inhibited miconazole-induced Ca 2+ release. The miconazole-induced Ca 2+ release was not changed by inhibition of phospholipase C with 2 μM U73122. By using tetrazolium as a fluorescent probe, it was shown that 10–100 μM miconazole decreased cell proliferation rate in a concentration-dependent manner. Collectively, this study shows that miconazole induces [Ca 2+] i rises in human osteosarcoma cells via releasing Ca 2+ mainly from the endoplasmic reticulum in a manner independent of phospholipase C activity, and by causing Ca 2+ influx. Furthermore, miconazole may be cytotoxic to the cells at higher concentrations.

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

In human MG63 osteosarcoma cells, the effect of calmidazolium on [Ca(2+)](i) and proliferation was explored using fura-2 and ELISA, respectively. Calmidazolium, at concentrations greater than 0.1 micromol/L, caused a rapid increase in [Ca(2+)](i) in a concentration-dependent manner (EC(50) = 0.5 micromol/L). The calmidazolium-induced [Ca(2+)](i) increase was reduced by 66% by removal of extracellular Ca(2+). In Ca(2+)-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca(2+)-ATPase, caused a monophasic increase in [Ca(2+)](i), after which the effect of calmidazolium to increase [Ca(2+)](i) was completely inhibited. U73122, an inhibitor of phospholipase C (PLC), abolished histamine (but not calmidazolium)-induced increases in [Ca(2+)](i). Pretreatment with phorbol 12-myristate 13-acetate to activate protein kinase C inhibited the calmidazolium-induced increase in [Ca(2+)](i) in Ca(2+)-containing medium by 47%. Separately, it was found that overnight treatment with 2-10 micromol/L calmidazolium inhibited cell proliferation in a concentration-dependent manner. These results suggest that calmidazolium increases [Ca(2+)](i) by stimulating extracellular Ca(2+) influx and also by causing release of intracellular Ca(2+) from the endoplasmic reticulum in a PLC-independent manner. Calmidazolium may be cytotoxic to osteosarcoma cells.

Effect of nortriptyline on intracellular Ca2+ handling and proliferation in human osteosarcoma cells.

The effect of the antidepressant nortriptyline, on bone cells is unknown. In human osteosarcoma MG63 cells, the effect of nortriptyline on intracellular Ca2+ concentration ([Ca2+]i) and proliferation was measured by using fura-2 and tetrazolium, respectively. Nortriptyline (> or = 10 microM) caused a [Ca2+]i rise in a concentration-dependent manner (EC50 = 200 microM). Nortriptyline-induced [Ca2+]i rise was prevented by 60% by removal of extracellular Ca2+ but was not altered by voltage-gated Ca2+ channel blockers. In Ca2+ -free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca2+ -ATPase, caused a monophasic [Ca2+]i rise, after which the increasing effect of nortriptyline on [Ca2+]i was abolished; also, pretreatment with nortriptyline abolished thapsigargin-induced [Ca2+]i increase. U73122, an inhibitor of phospholipase C, did not affect nortriptyline-induced [Ca2+]i rise; however, activation of protein kinase C decrease nortriptyline-induced [Ca2+]i rise by 32%. Overnight incubation with 50 and 100 microM nortriptyline killed 78% and 97% of cells, respectively; while 10 microM nortriptyline had no effect. These data suggest that nortriptyline rapidly increases [Ca2+]i in human osteosarcoma cells by stimulating both extracellular Ca2+ influx and intracellular Ca2+ release, and is cytotoxic at high concentrations.

Effect of the Antidepressant Desipramine on Cytosolic Ca2+ Movement and Proliferation in Human Osteosarcoma Cells

In human osteosarcoma MG63 cells, the effect of desipramine, an antidepressant, on intracellular Ca²⁺ concentration ([Ca²⁺]_i) was measured by using fura-2. Desipramine (>10 µmol/l) caused a rapid and sustained rise of [Ca²⁺]_i in a concentration-dependent manner (EC₅₀ = 200 µmol/l). Desipramine-induced [Ca²⁺]_i rise was prevented by 80% by removal of extracellular Ca²⁺ but was not altered by voltage-gated Ca²⁺ channel blockers. In Ca²⁺-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum (ER) Ca²⁺-ATPase, caused a monophasic [Ca²⁺]_i rise, after which the increasing effect of desipramine on [Ca²⁺]_i was abolished; also, pretreatment with desipramine partly reduced thapsigargin-induced [Ca²⁺]_i increase. U73122, an inhibitor of phospholipase C, did not affect desipramine-induced [Ca²⁺]_i rise. Overnight incubation with 10 µmol/l desipramine did not alter cell proliferation, but killed 32 and 89% of cells at concentrations of 100 and 200 µmol/l, respectively. These findings suggest that desipramine rapidly increases [Ca²⁺]_i in osteoblasts by stimulating both extracellular Ca²⁺ influx and intracellular Ca²⁺ release, and is cytotoxic at high concentrations.

Sex steroids and bone metabolism: comparison of in vitro effects of 17beta-estradiol and testosterone on human osteosarcoma cell lines of various gender and differentiation.

Although numerous clinical studies have demonstrated the beneficial effect of preventing postmenopausal bone loss in elder women by long-term estrogen administration, effects of estrogen at the cellular level still remain unclear. Efforts to determine the precise role of bone cells in estrogen-mediated pathways are often hampered by the lack of suitable cell culture models. Presuming that sex steroids have a direct, stimulating effect on bone cells in vitro, we investigated the influence of 17beta-estradiol, testosterone and 1,25(OH)2D, on cell proliferation and differentiation using four established human osteosarcoma (HOS) cell lines of different gender of the donors (male origin: MG 63, HOS 58; female origin: SaOS 2, TE 85). These cell lines are believed to represent different stages of osteogenic maturation. Thus, the aim of this study was to clarify if possible responses to sex steroids are related to gender or osteogenic commitment of the individual cell culture. HOS cells were cultured in six-well plates and underwent hormone treatment (1 nM and 10 nM 17beta-estradiol. 0.1 nM and I nM testosterone and 1 microM 1,25(OH)2D3) for 48 h hours. Cell proliferation was determined by measuring total cell numbers. Cell function was studied by measuring alkaline phosphatase activity and secreted osteocalcin. In this study, estrogen significantly increased proliferation of both one male (MG 63) and one female (SaOS 2) cell line, but decreased proliferation of the female HOS TE 85 cell line significantly. Testosterone treatment had a positive effect on proliferation of only one female cell line (SaOS 2). A significant increase of alkaline phosphatase activity in SaOS 2 and HOS 58 cells and of osteocalcin levels in SaOS 2 cells was detected following estrogen treatment. Administration of 1.25(OH)2D3 was followed by an increased cell proliferation in HOS 58, MG 63 and SaOS 2. Significant gender-related differences could not be demonstrated. In conclusion, response to hormonal treatment with sex steroids is not related to the gender of the osteosarcoma cell line, but rather depends on its osteoblastic commitment.

The latency-related gene of bovine herpesvirus 1 encodes a product which inhibits cell cycle progression.

Bovine herpesvirus 1 (BHV-1) establishes a latent infection in the sensory ganglionic neurons of cattle. The exclusive viral RNA expressed in a latent infection is the latency-related (LR) RNA, suggesting that it regulates some aspect of a latent infection. During the course of a productive infection, alphaherpesviruses induce certain events which occur during cell cycle progression. Consequently, we hypothesized that a BHV-1 infection might induce events in neurons which occur during cell cycle progression. In agreement with this hypothesis, cyclin A was detected in neurons of trigeminal ganglia when rabbits were infected. Neuronal cell cycle progression or inappropriate expression of cyclin A leads to apoptosis, suggesting that a viral factor inhibits the deleterious effects of cyclin A expression. The BHV-1 LR gene inhibited cell cycle progression and proliferation of human osteosarcoma cells. Antibodies directed against cyclin A or the LR protein coprecipitated the LR protein or cyclin A, respectively, suggesting that the two proteins interact with each other. We conclude that LR gene products inhibit cell cycle progression and hypothesize that this activity enhances the survival of infected neurons.

Oestrogen and Progestogen Synergistically Stimulate Human and Rat Osteoblast Proliferation

Oestrogens play an important role in bone metabolism; they preserve bone mass after the menopause. Their action in bone has recently been shown to be, partly, a direct one, as oestrogen receptors and their effects have been demonstrated in bone cells. The role of progestogens in bone metabolism is less clear. In this study it has been shown that 17 beta-oestradiol exerts only a small, although not significant, stimulatory action with regard to SaOS-2 human osteosarcoma cell proliferation. A pure progestogen (Org 2058) has no effect when added alone. In combination with 17 beta-oestradiol, however, it has a highly synergistic action on SaOS-2 cell proliferation. The same effect was observed in primary rat osteoblasts, showing that this synergism is a general phenomenon in osteoblastic cells. High numbers of oestrogen and progestogen receptors have been demonstrated in SaOS-2 cells, indicating that the effects of these steroids are mediated via the normal route of steroid receptors. These data provide a cellular basis for the clinically recognized positive effect of oestrogen/progestogen combinations on bone formation.

Oestrogen and progestogen synergistically stimulate human and rat osteoblast proliferation.

Oestrogens play an important role in bone metabolism; they preserve bone mass after the menopause. Their action in bone has recently been shown to be, partly, a direct one, as oestrogen receptors and their effects have been demonstrated in bone cells. The role of progestogens in bone metabolism is less clear. In this study it has been shown that 17 beta-oestradiol exerts only a small, although not significant, stimulatory action with regard to SaOS-2 human osteosarcoma cell proliferation. A pure progestogen (Org 2058) has no effect when added alone. In combination with 17 beta-oestradiol, however, it has a highly synergistic action on SaOS-2 cell proliferation. The same effect was observed in primary rat osteoblasts, showing that this synergism is a general phenomenon in osteoblastic cells. High numbers of oestrogen and progestogen receptors have been demonstrated in SaOS-2 cells, indicating that the effects of these steroids are mediated via the normal route of steroid receptors. These data provide a cellular basis for the clinically recognized positive effect of oestrogen/progestogen combinations on bone formation.

Signal transduction via the β1 integrins is a required intermediate in interleukin-1β induction of alkaline phosphatase activity in human osteosarcoma cells

In this report data are presented which demonstrate that the induction of an osteoblastic phenotype by interleukin-1β (IL-1β) requires an intermediate step involving signal transduction via the β 1 family of integrin glycoproteins. Recombinant human IL-1β inhibits human osteosarcoma cell proliferation, stimulates integrin expression, and induces alkaline phosphatase activity, a marker of osteoinductive and osteoblastic phenotype. The approximately 10-fold stimulation of expression of the β 1 integrins occurs rapidly (within 20 to 40 h), whereas the alkaline phosphatase activity is not induced until at least 5 days after the addition of IL-1β. To determine whether the early stimulation of integrin expression is required for the subsequent expression of alkaline phosphatase activity, polyclonal as well as monoclonal antibodies directed against the α 5 and β 1, integrin subunits were added to cultures at the same time as IL-1 β. These antibodies inhibited by 55 to 82% the longer term induction of the osteoblastic differentiation marker, alkaline phosphatase activity, but did not however affect the IL-1β-induced stimulation of integrin expression or the inhibition of cell proliferation. In addition, at the concentrations used, there was no effect of the antibodies on cell attachment. These data suggest that the stimulation of integrin expression by IL-1β, and the resulting enhanced integrin-extracellular matrix interactions, is a required intermediate event in the IL-1β regulation of osteoblastic cell differentiation. The data also suggest that the integrins are capable of signal transduction resulting in altered gene expression, and may also play a crucial role in modulating cytokine-mediated effects on Cell differentiation.

Tumor necrosis factor stimulates proliferation of human osteosarcoma cells and accumulation of c‐myc messenger RNA

The objective of this study was to establish whether human recombinant tumor necrosis factor (TNF) can significantly stimulate the proliferation of some tumor cells. Treatment with TNF had little or no effect on the growth of human tumor cells and murine NIH/3T3 cells cultured in medium with high serum concentration. Two tumor lines, SK-MEL-109 melanoma and HOS osteosarcoma cells, were adapted to grow in medium supplemented with 0.5% serum. The growth of these SK-MEL-109 cells was inhibited by TNF, but that of the HOS cells was greatly stimulated by TNF in a dose-dependent way. Treatment with 10 ng/ml of TNF resulted in a two-fold increase in the rate of cell division. This effect of TNF was also shown by measuring DNA and protein synthesis. The continuous presence of TNF was not required for its mitogenic activity on HOS cells cultured with 0.5% serum, since treatment for only one day with TNF resulted in prolonged growth stimulation. The failure of TNF to promote division of cells cultured in medium with 10% serum may possibly be explained by the presence of saturating amounts of growth factors in serum. Interferons abolished the mitogenic activity of TNF on HOS cells. Furthermore, TNF did not show synergism with insulin or epidermal growth factor in stimulating growth of these cells. The level of c-myc mRNA was increased five-fold after 30 minutes of treatment with TNF. This shows that TNF is a growth factor for HOS cells and that it induces accumulation of c-myc mRNA.