Murine Osteosarcoma Cells Research Articles

Zoledronic acid inhibits vasculogenic mimicry in murine osteosarcoma cell line in vitro

BackgroundTo study the effects of zoledronic acid (ZA) on the vasculogenic mimicry of osteosarcoma cells in vitro.MethodsA Three-dimensional culture of LM8 osteosarcoma cells on a type I collagen matrix was used to investigate whether osteosarcoma cells can develop vasculogenic mimicry, and to determine the effects of ZA on this process. In addition, the cellular ultrastructural changes were observed using scanning electron microscopy and laser confocal microscopy. The effects of ZA on the translocation of RhoA protein from the cytosol to the membrane in LM8 cells were measured via immunoblotting.ResultsZA inhibited the development of vasculogenic mimicry by the LM8 osteosarcoma cells, decreased microvilli formation on the cell surface, and disrupted the F-actin cytoskeleton. ZA prevented translocation of RhoA protein from the cytosol to the membrane in LM8 cells.ConclusionsZA can impair RhoA membrane localization in LM8 cells, causing obvious changes in the ultrastructure of osteosarcoma cells and induce cell apoptosis, which may be one of the underlying mechanisms by which the agent inhibits the development of vasculogenic mimicry by the LM8 cells.

Dynamic Metabolic Transformation in Tumor Invasion and Metastasis in Mice with LM-8 Osteosarcoma Cell Transplantation

While extensive evidence indicates that tumor cells shift their global metabolic programs, the molecular details of the metabolic transformation in tumor invasion, progression, and metastasis remain largely unknown. Characterization of the time-dependent metabolic shift during the tumor invasion, development, and metastasis will describe an important aspect of tumor phenotypes and potentially allow us to design therapies that inhibit tumor cell movement. In this study, a metabonomic study was performed to characterize the global metabolic changes during the process of tumor invasion and metastasis to lung in a mouse model with subcutaneous transplantation of murine osteosarcoma cell line (LM8). The serum metabolic profiling revealed that many key metabolites in glycolysis and tricarboxylic acid (TCA) cycle, as well as most of the amino acids were elevated at rapidly growing stage of tumor, presumably resulting from a high energy demand and turnover of anabolic metabolism during the tumor cell proliferation. Serum levels of succinic acid and proline significantly increased (with fold change FC = 10.75 and 4.43, relative to controls) among all the metabolites in the third week. The serum metabolic profile of lung metastasis at week 4 was different from that at week 3, in that most of previously increased serum metabolites were found decreased, except for cholesterol and several free fatty acids, suggesting lowered carbohydrate and amino acids metabolism, but an elevated lipid metabolism associated with tumor metastasis.

Ganglioside GD1a negatively regulates hepatocyte growth factor expression through caveolin-1 at the transcriptional level in murine osteosarcoma cells

Background Hepatocyte growth factor (HGF) is a mesenchyme-derived, multifunctional protein that is implicated in tumor growth and invasive behavior. Some tumor cells express both HGF and its receptor MET, forming an autocrine loop that permanently activates it. Ganglioside GD1a suppresses metastatic capacity in murine FBJ osteosarcoma cells and MET phosphorylation activated by HGF binding, but the signaling pathway controlling HGF production has not been fully explored. Methods Expression of HGF, caveolins, or MET of the cells that had been transfected with siRNA or cDNA directed to GM2/GD2 synthase, caveolin-1 or HGF was determined by semi-quantitative RT-PCR and Western blots. Results HGF expression in highly metastatic, GD1a-deficient FBJ-LL cells was higher than that in the poorly metastatic, GD1a-rich FBJ-S1 cells. Transfection with GM2/GD2 synthase cDNA increased GD1a levels in FBJ-LL cells and suppressed HGF expression. Treatment with siRNAs directed toward GM2/GD2 synthase in FBJ-S1 cells reduced gangliosides and augmented HGF expression. GD1a was found to be the only ganglioside species suppressing HGF expression upon addition to FBJ-LL cells. HGF expression was decreased by GD1a addition to FBJ-LL cells after 48 h, enough to induce caveolin-1 expression. Silencing caveolin-1 up-regulated HGF, and the re-introduction of caveolin-1 cDNA decreased HGF expression. Caveolin-1 suppressed MET phosphorylation. We also found GD1a regulation of HGF in Lewis lung carcinoma cells. Conclusions HGF expression was negatively regulated by GD1a through caveolin-1 at the transcriptional level via the suppression of MET phosphorylation. General significance This is the first report that ganglioside GD1a negatively regulates HGF expression through caveolin-1.

Radio-sensitization of the murine osteosarcoma cell line LM8 with parthenolide, a natural inhibitor of NF-κB

Nuclear factor (NF)-κB has been shown to be associated with cancer resistance to radiotherapy (RT), and is constitutively active in the murine osteosarcoma cell line, LM8. Parthenolide has been reported to show antitumor activity through inhibition of the NF-κB pathway. In this study, we investigated the radio-sensitizing activity of parthenolide. We established Luc-LM8, a stable transfectant reporter construct of NF-κB transcriptional activity into LM8. Luc-LM8 maintained the malignancy observed with LM8. In vitro, Luc-LM8 cells were cultured with or without parthenolide treatment, irradiated, and subjected to cell viability and apoptosis assays. In vivo, to investigate whether parthenolide enhances radio-sensitivity of tumors, a tumor growth assay was conducted. Parthenolide enhanced the growth inhibitory effect of RT and induced the apoptosis of Luc-LM8 cells with RT in vitro. The in vivo tumor growth was significantly suppressed in the mice treated with parthenolide and RT. The present study suggests that parthenolide sensitizes Luc-LM8 cells to irradiation. Thus, parthenolide is a potential candidate for use as a potent radio-sensitizing drug for use in cancer RT.

CYR61 downregulation reduces osteosarcoma cell invasion, migration, and metastasis

Osteosarcoma is the most common primary tumor of bone. The rapid development of metastatic lesions and resistance to chemotherapy remain major mechanisms responsible for the failure of treatments and the poor survival rate for patients. We showed previously that the HMGCoA (3-hydroxy-3-methylglutaryl-coenzyme A) reductase inhibitor statin exhibits antitumoral effects on osteosarcoma cells. Here, using microarray analysis, we identify Cyr61 as a new target of statins. Transcriptome and molecular analyses revealed that statins downregulate Cyr61 expression in human and murine osteosarcoma cells. Cyr61 silencing in osteosarcoma cell lines enhanced cell death and reduced cell migration and cell invasion compared with parental cells, whereas Cyr61 overexpression had opposite effects. Cyr61 expression was evaluated in 231 tissue cores from osteosarcoma patients. Tissue microarray analysis revealed that Cyr61 protein expression was higher in human osteosarcoma than in normal bone tissue and was further increased in metastatic tissues. Finally, tumor behavior and metastasis occurrence were analyzed by intramuscular injection of modified osteosarcoma cells into BALB/c mice. Cyr61 overexpression enhanced lung metastasis development, whereas cyr61 silencing strongly reduced lung metastases in mice. The results reveal that cyr61 expression increases with tumor grade in human osteosarcoma and demonstrate that cyr61 silencing inhibits in vitro osteosarcoma cell invasion and migration as well as in vivo lung metastases in mice. These data provide a novel molecular target for therapeutic intervention in metastatic osteosarcoma.

Transfection of NF-κB decoy oligodeoxynucleotide suppresses pulmonary metastasis by murine osteosarcoma

Nuclear factor-kappa B (NF-κB) has a pivotal role in the progression and distant metastasis of cancers, including malignant bone tumors. To inhibit NF-κB activation, a new molecular therapy using synthetic double-stranded oligodeoxynucleotide (ODN) as a 'decoy' cis element against NF-κB has been developed. To determine whether pulmonary metastasis of osteosarcoma is reduced by inhibiting the action of NF-κB, NF-κB decoy ODN was transfected into the nuclei of murine osteosarcoma cells with high pulmonary metastatic potential, the LM8 cell line, using a three-dimensional alginate spheroid culture model. An in vitro study demonstrated the successful transfection of LM8 cells cultured in alginate beads by 'naked' NF-κB decoy ODN and that the activation of NF-κB signaling was significantly suppressed. Tumor growth was not affected by transfection of NF-κB decoy ODN, however, the expression of vascular endothelial growth factor (VEGF) and intercellular adhesion molecule 1 (ICAM-1) mRNA was markedly decreased. Furthermore, the transfection of 'naked' NF-κB decoy ODN effectively suppressed pulmonary metastasis in an in vivo alginate bead transplantation model. Our results suggest that NF-κB has a central and specific role in the regulation of tumor metastasis and could be a molecular target for development of anti-metastatic treatments for osteosarcoma.

A small oxazine compound as an anti-tumor agent: A novel pyranoside mimetic that binds to VEGF, HB-EGF, and TNF-α

A novel pyranoside mimetic compound, DMBO (2-(2,6-difluorophenyl)-5-(4-methoxyphenyl)-1-oxa-3-azaspiro[5.5]undecane), was designed and synthesized. The sugar mimicking behavior of DMBO was addressed by its ability to bind several growth factors/cytokines such as vascular endothelial growth factor (VEGF), heparin-binding epidermal growth factor-like growth factor (HB-EGF), and tumor necrosis factor (TNF)-α as demonstrated by the recently developed surface plasmon resonance assay. DMBO exhibited strong anti-proliferation activity in vitro against tumor cells including a highly metastatic murine osteosarcoma cell line LM8G7 that secretes VEGF as well as two human ovarian cell lines, OVSAHO and SKOV-3, which secrete TNF-α and HB-EGF respectively. Furthermore, DMBO inhibited the metastatic activity to the mouse liver of LM8G7 cells injected from a lateral tail vein, and affected the heparan-degrading activity of LM8G7 cells. Here, we report that DMBO acts as a human heparanase inhibitor in vitro possibly as a substrate mimetic. DMBO also inhibited the migration and invasion of LM8G7 cells and angiogenic events such as endothelial cell proliferation, migration and capillary tube-like formation in vitro. More prominently, the administration of DMBO with heparin resulted in synergistic anti-tumor effects in mouse modelofosteosarcoma. These preclinical data shows the potential anti-cancer effects of DMBO.

Acanthamoeba spp.: In vitro effects of clinical isolates on murine macrophages, osteosarcoma and HeLa cells

Three different cell lines (murine macrophages, HeLa and osteosarcoma cells) were assayed in order to check for the manifestation of the cytopathic effects of three strains of Acanthamoeba recently isolated in our laboratory from contact lens cases: CLC-16, CLC-41.r and CLC-51-l. Adhesion and cytotoxicity assays were carried out with these strains and the type strain Acanthamoeba castellanii Neff as a control. Briefly, the ability of these amoebae to bind to the three cell lines was calculated and supernatants were examined for cytotoxicity by measuring lactate dehydrogenase released as an estimate of cytotoxicity using a commercial detection kit. The three strains showed high adhesion and cytotoxicity levels when tested in the three cell lines. This study demonstrates the ability of these amoebae to degrade any of the tested cell lines. To the best of our knowledge, this is the first report of the in vitro effects of acanthamoebae on osteosarcoma cells.

Synthesis, characterization and in vitro anti-tumor activities of novel 9-ethyl-9H-purine derivatives

Newer series of 9-ethyl-9H-purine derivatives (EPD) were synthesized and screened for their efficacy in inhibiting the proliferation of various tumor cells in vitro. We evaluated the effects of EPD against HeLa, SiHa, CaSki (human cervical cancer cells), LM8, LM8G7 (murine osteosarcoma cells), OVSAHO and SKOV-3 (human ovarian cancer cells). The chemical structures of the EPD were confirmed by (1)H NMR and LCMS analyses. The inhibitory effects of EPD were studied by using trypan blue exclusion, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and TetraColor One reagents. Furthermore, SAR studies revealed that the presence of trifluoromethoxy and trifluromethyl group in 4b and 4g, respectively are responsible for the significant activity of the EPD against cervical cancer cells and the presence of isopropoxy group in 4f has influence in inhibiting the proliferation of osteosarcoma and ovarian cancer cell types.

Three-dimensional alginate spheroid culture system of murine osteosarcoma

Osteosarcoma (OS) is the most common primary malignant tumor of the bone and often forms pulmonary metastases, which are the most important prognostic factor. For further elucidation of the mechanism underlying the progression and metastasis of human OS, a culture system mimicking the microenvironment of the tumor in vivo is needed. We report a novel three-dimensional (3D) alginate spheroid culture system of murine osteosarcoma. Two different metastatic clones, the parental Dunn and its derivative line LM8, which has a higher metastatic potential to the lungs, were encapsulated in alginate beads to develop the 3D culture system. The beads containing murine OS cells were also transplanted into mice to determine their metastatic potential in vivo. In this culture system, murine OS cells encapsulated in alginate beads were able to grow in a 3D structure with cells detaching from the alginate environment. The number of detaching cells was higher in the LM8 cell line than the Dunn cell line. In the in vivo alginate bead transplantation model, the rate of pulmonary metastasis was higher with LM8 cells compared with that of Dunn cells. The cell characteristics and kinetics in this culture system closely reflect the original malignant potential of the cells in vivo.

Hyperbaric oxygen as a chemotherapy adjuvant in the treatment of osteosarcoma

Although hyperbaric oxygen has been shown to enhance the efficacy of radiotherapy and chemotherapy for the treatment of several malignant tumors, the impact of hyperbaric oxygen on osteosarcoma has not yet been demonstrated. In this study, we investigated the efficacy of hyperbaric oxygen alone and in combination with an anti-cancer drug as an adjuvant to chemotherapy. In vitro, highly metastatic murine osteosarcoma cell lines were exposed to hyperbaric oxygen and cell viability was examined. Hyperbaric oxygen alone significantly suppressed cell proliferation, and hyperbaric oxygen plus carboplatin exhibited significant synergism in suppression of cell proliferation. In vivo, C3H mice were subcutaneously inoculated with osteosarcoma cells and divided into four groups: control, hyperbaric oxygen, carboplatin, and carboplatin plus hyperbaric oxygen. After 5 weeks, increase in both tumor volume and number of lung metastases was significantly suppressed in the hyperbaric oxygen group. Concomitant hyperbaric oxygen clearly enhanced the chemotherapeutic effects of carboplatin on both tumor growth and lung metastasis in osteosarcoma-bearing mice. Moreover, mortality in the carboplatin plus hyperbaric oxygen group was significantly lower than in the other three groups. These findings suggest that hyperbaric oxygen plus carboplatin combination therapy could be an appropriate therapeutic regimen for the treatment of patients with osteosarcoma.

Immunotherapy with Interleukin-18 in Combination with Preoperative Chemotherapy with Ifosfamide Effectively Inhibits Postoperative Progression of Pulmonary Metastases in a Mouse Osteosarcoma Model

The effect of immunotherapy with interleukin-18 (IL-18) in combination with preoperative chemotherapy on the postoperative progression of pulmonary metastasis was examined using a spontaneous pulmonary metastasis model of mouse osteosarcoma. Mice were inoculated subcutaneously with highly metastatic murine osteosarcoma cells (LM8) and then underwent chemotherapy with ifosfamide (30 or 60 mg/kg body weight, days 14–16), immunotherapy with IL-18 (2 μg/mouse, days 18–24) or combined immunotherapy and chemotherapy. Tumors developed in mice were excised 21 days after cell inoculation when microscopic but not macroscopic pulmonary metastasis was observed in mice. Three weeks after the excision of the tumors, macroscopic pulmonary metastasis was observed on the surface of the lung. Administration of ifosfamide or IL-18 alone decreased the number of macroscopic pulmonary metastases, and combined administration of ifosfamide and IL-18 resulted in much greater inhibition of pulmonary metastasis. These results suggest that immunotherapy in combination with preoperative chemotherapy is highly effective in suppressing postoperative progression of pulmonary metastasis.

Anti-tumor and anti-angiogenic activity of novel hydantoin derivatives: Inhibition of VEGF secretion in liver metastatic osteosarcoma cells

A series of new azaspiro bicyclic hydantoin derivatives has been designed and synthesized. Initially, the anti-proliferative effect of the hydantoin derivatives was evaluated against human ovarian cancer cells (SKOV-3 and OVSAHO) and murine osteosarcoma cells (LM8 and LM8G7). Among the tested compounds, 8-(3-fluorobenzyl)-1′-(4-(methylsulfonyl)benzyl)-8-azaspiro[bicyclo[3.2.1]octane-3,4′-imidazolidine]-2′,5′-dione ( 7h) and 8-(3,4-difluorobenzyl)-1′-(4-(methylsulfonyl)benzyl)-8-azaspiro[bicyclo[3.2.1]octane-3,4′-imidazolidine]-2′,5′-dione ( 7i) showed a significant anti-proliferative activity against the OVSAHO and LM8G7 cells. The real-time monitoring of the effect of the compounds 7h and 7i against the proliferation of LM8G7 was revealed that resulting IC 50 values were 102 μM and 13 μM, respectively. We reasoned that the presence of fluorine atom at the 3rd position of the phenyl ring of the hydantoin side chain may determine the potency of the molecule. Furthermore, the compound 7i inhibited the tube formation of the mouse endothelial cells. Finally, the treatment of the compound 7i against the proliferation of LM8G7 cells demonstrated the down regulation of the secretion of VEGF, indicate the potential angioinhibitory effects. In conclusion, our findings demonstrate the suppression of the secretion of VEGF by LM8G7 cells by the compound 7i might contribute at least in part to the antitumor action.

Elevated expression of CTRP3/cartducin contributes to promotion of osteosarcoma cell proliferation

CTRP3/cartducin, a novel secretory protein, is a member of the C1q and tumor necrosis factor (TNF)-related protein (CTRP) superfamily, and plays important roles in regulating both embryonic cartilage development and postnatal longitudinal bone growth. CTRP3/cartducin is expressed in human osteosarcomas. We hypothesized that CTRP3/cartducin might have a role in osteosarcoma tumor growth and metastasis. Murine osteosarcoma cell lines, NHOS and LM8, were used as a model. RT-PCR analysis showed that the mRNA level of CTRP3/cartducin was increased in these two murine osteosarcoma cell lines compared with its level in normal murine osteoblast MC3T3-E1 cells. Western blot analysis showed that the protein level of CTRP3/cartducin was also increased in these two osteosarcoma cell lines. Stimulation of NHOS and LM8 cells by CTRP3/cartducin promoted tumor cell growth but not migration in vitro. Further, CTRP3/cartducin stimulation led to the activation of extracellular signal-regulated kinase 1/2 (ERK1/2) in these two osteosarcoma cell lines. MAPK/ERK kinase 1/2 (MEK1/2) inhibitor, U0126, blocked CTRP3/cartducin-induced cell proliferation. These results suggest that CTRP3/cartducin expression may play a role in osteosarcoma tumor growth associated with activation of the ERK1/2 signaling pathway.

Involvement of chondroitin sulfate E in the liver tumor focal formation of murine osteosarcoma cells

Cell surface heparan sulfate plays a critical role in regulating the metastatic behavior of tumor cells, whereas the role of chondroitin sulfate/dermatan sulfate (CS/DS) has been little understood in this context. Here, we characterized CS/DS chains from the murine osteosarcoma cell line LM8G7, which forms tumor nodules in liver. Structural analysis of the CS/DS chains showed a higher proportion of GlcUA beta 1-3GalNAc(4,6-O-disulfate) (E-units) in LM8G7 (12%) than in its parental cell line LM8 (6%), which rarely forms tumors in the liver. Immunostaining with GD3G7, an antibody specific to E-units, confirmed the higher expression of the epitope in LM8G7 than LM8 cells. The tumor focal formation of LM8G7 cells in the liver in mice was effectively inhibited by the preadministration of CS-E (rich in E-unit) or the preincubation of the antibody GD3G7 with the tumor cells. CS-E or GD3G7 inhibited the adhesion of LM8G7 cells to a laminin-coated plate in vitro. In addition, the invasive ability of LM8G7 cells in vitro was also reduced by the addition of CS-E or the antibody. Further, CS-E or the antibody inhibited the proliferation of LM8G7 cells dose dependently. The binding of LM8G7 cells to VEGF in vitro was also significantly reduced by CS-E and GD3G7. Thus, the present study reveals the significance of highly sulfated CS/DS structures in the liver colonization of osteosarcoma cells and also provides a framework for the development of GAG-based anticancer molecules.

Inhibition of AP-1 Transcriptional Activity Blocks the Migration, Invasion, and Experimental Metastasis of Murine Osteosarcoma

A well-characterized murine osteosarcoma model for metastasis and invasion was used in this study to determine the role of AP-1 in the progression of this disease. We analyzed K12 and K7M2 cells, two clonally related murine osteosarcoma cell lines that have been characterized as low metastatic or high metastatic, respectively, for AP-1 components and activity. AP-1 DNA binding was similar between the two cell lines; however AP-1 transcriptional activity was enhanced by 3- to 5-fold in K7M2 cells relative to that in K12 cells. The AP-1 complexes in K12 and K7M2 cells was composed primarily of cJun, JunD, FosB, Fra1, and Fra2, with the contribution of individual components in the complex varying between the two cell lines. In addition, an increase in phosphorylated cJun, JNK activity, and phosphorylated ERK1/2 was associated with the more metastatic osteosarcoma phenotype. The significance of AP-1 activation was confirmed by conditional expression of TAM67, a dominant negative mutant of cJun. Under conditions where TAM67 inhibited AP-1 activity in K7M2 cells, migration and invasion potential was significantly blocked. Tam67 expression in aggressive osteosarcoma cells decreased long-term in vivo experimental metastasis and increased survival of mice. This study shows that differences in metastatic activity can be due to AP-1 activation. The inhibition of AP-1 activity may serve as a therapeutic tool in the management of osteosarcoma.

Murine osteosarcoma primary tumour growth and metastatic progression is maintained after marked suppression of serum insulin-like growth factor I

The insulin-like growth factor I (IGF-I) signaling pathway has been shown to play an important role in several aspects of cancer biology, including metastasis. The aim of this study was to define the contribution of serum (endocrine) and local (tumour microenvironment) IGF-I on osteosarcoma tumour growth and metastasis, a cancer that is known to be dependent on the IGF-I axis. To test this hypothesis, we evaluated the primary tumour growth and metastatic progression of K7M2 murine osteosarcoma cells injected to a genetically engineered mouse [liver-specific IGF-I deficient (LID)] in which serum IGF-I levels are reduced by 75%, while maintaining expression of IGF-I in normal tissues. We first demonstrated that IGF-I in the tumour and the tumour-microenvironment were maintained in the LID mice. Within this designed model, there was no difference in primary tumour growth or in pulmonary metastasis in LID mice compared to control mice. Furthermore, there was no difference in the number or localization of single metastatic cells immediately after their arrival in the lungs of LID mice and control mice, as analysed by single cell video microscopy. Collectively, these data suggest that marked reduction in serum IGF-I is not sufficient to slow the progression of either primary or metastatic models of osteosarcoma.

Blockade of the RhoA-JNK-c-Jun-MMP2 Cascade by Atorvastatin Reduces Osteosarcoma Cell Invasion

Osteosarcoma is characterized by a high malignant and metastatic potential, which points to the need for new therapeutic strategies to prevent cell metastasis. In this study, we show that statin-induced HMG-CoA reductase inhibition reduces cell migration and invasion in human and murine osteosarcoma cells, independently of the genotype. The statin-induced reduction of cell migration and invasion was independent of induction of apoptosis and was geranylgeranylpyrophosphate-dependent. The statin reduced matrix metalloproteinase (MMP) 2, 9, and 14 and TIMP2 expression or activity in invading cells. Forced expression of MMP2 and MMP14 overcame the inhibitory effect of the statin on cell invasion, suggesting a role for these MMPs in invasive potential. We also investigated the mechanisms involved in the reduced MMP2 activity and cell invasion. Inhibition of JNK, but not ERK1/2 signaling, reduced MMP2 activity. Pharmacological or constitutive activation of JNK overcame the reduced MMP2 activity and cell invasion induced by the statin. The statin decreased JNK phosphorylation and c-Jun nuclear translocation, suggesting that HMG-CoA reductase inhibition targets the JNK-c-Jun signaling pathway. We showed that mevalonate or geranylgeranylpyrophosphate treatment prevented the statin-induced reduction in JNK phosphorylation, MMP2 activity, and cell invasion. Forced expression of a constitutively active form of RhoA increased JNK phosphorylation and overcame the inhibitory effect of atorvastatin on MMP2 activity and cell invasion. The data establish a link between RhoA, JNK, c-Jun, and MMP2 activity that is functionally involved in the reduction in osteosarcoma cell invasion by the statin. This suggests a novel strategy targeting RhoA-JNK-c-Jun signaling to reduce osteosarcoma cell tumorigenesis.

Re-implantation of tumour tissue treated by cryotreatment with liquid nitrogen induces anti-tumour activity against murine osteosarcoma

We evaluated the possible induction of a systemic immune response to increase anti-tumour activity by the re-implantation of destructive tumour tissue treated by liquid nitrogen in a murine osteosarcoma (LM8) model. The tumours were randomised to treatment by excision alone or by cryotreatment after excision. Tissue from the tumour was frozen in liquid nitrogen, thawed in distilled water and then re-implanted in the same animal. In addition, some mice received an immunological response modifier of OK-432 after treatment. We measured the levels of interferon-gamma and interleukin-12 cytokines and the cytotoxicity activity of splenocytes against murine LM8 osteosarcoma cells. The number of lung and the size of abdominal metastases were also measured. Re-implantation of tumour tissue after cryotreatment activated immune responses and inhibited metastatic tumour growth. OK-432 synergistically enhanced the anti-tumour effect. Our results suggest that the treatment of malignant bone tumours by reconstruction using autografts containing tumours which have been treated by liquid nitrogen may be of clinical value.

Decorin suppresses lung metastases of murine osteosarcoma

Lung metastasis is the most crucial event affecting the therapeutic outcome of osteosarcoma. The prevention of lung metastasis is therefore important in improving the prognosis of patients with osteosarcoma. Decorin is a major extracellular matrix protein which has become the focus of various cancer studies. The biological role of decorin in osteosarcoma has yet to be clarified. The aim of this study was to examine the potential of decorin as a novel biological target for the treatment of osteosarcoma. In this study, the LM8 murine osteosarcoma cell line (LM8) with high metastatic potential to the lung was used. The two cell lines established were LM8-DCN which stably expressed human decorin (hDCN) and LM8-mock, established as a control. The LM8-DCN cell line was subcutaneously injected into the backs of mice. Significantly fewer pulmonary metastases were observed in mice with LM8-DCN compared to mice inoculated with LM8 and LM8-mock (P<0.001). In addition, the mice in the LM8-DCN inoculated group survived significantly longer than those in the LM8 and LM8-mock inoculated group, based on the Kaplan-Meier survival analysis and log-rank tests (P<0.005). The effect of decorin on the growth rates, motility and invasion ability of LM8 was investigated in vitro. There was no difference in the morphology and growth rates, but the motility and invasion of LM8 were inhibited by decorin. These results suggest that decorin has the therapeutic potential to prevent lung metastasis in osteosarcoma.