salicylates and Fibrosarcoma

This study examined possible mechanisms for hypoxia-increased metastasis in a green fluorescent protein-labeled human fibrosarcoma cell line (HT1080). The efficiency of the lung arrest of tumor cells, which can be dependent on the adhesive potential of the tumor cells, was assessed by measuring the level of integrin alpha3beta1 protein and by adhesion assays, whereas the extravasation potential was examined by an invasion assay. These properties were not changed by exposure to hypoxia, indicating that lung arrest and extravasation are unlikely to play a major role in the effect of hypoxia on metastasis in this model. The main effect of hypoxic exposure was found to be increased survival after lung arrest as determined by clonogenic assay of tumor cells recovered from mouse lungs after i.v. injection. Concomitantly, apoptosis was identified as responsible for the death of lung-arrested cells, suggesting the involvement of an altered apoptotic response following hypoxic exposure of these cells. Consistent with this finding, we found that the effect of hypoxia on both increased metastasis and survival of arrested cells was inhibited by treatment with farnesylthiosalicylic acid. However, this effect was not due to down-regulation of hypoxia-inducible factor-1alpha, a mechanism of action of this drug reported by previous studies. Further detailed studies of the mechanisms of action of the drug are needed.

Topics: Animals; Antineoplastic Agents; Cell Adhesion; Cell Hypoxia; Cell Line, Tumor; Cell Survival; Farnesol; Fibrosarcoma; Green Fluorescent Proteins; Humans; Lung Neoplasms; Mice; Mice, SCID; Neoplasm Transplantation; Salicylates; Transplantation, Heterologous

Salicylates are novel biologically active compounds that exhibit multiple therapeutic activities. The anti-cancer effectiveness of calcium salicylate has been investigated on human HT-1080 fibrosarcoma cell lines at relatively low concentrations (predominantly 0.4 mM) compared to those previously reported. Although low calcium salicylate concentrations did not retard tumour growth progression significantly, as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and time-lapse assays, its cytotoxic characteristics were proven to be prominent by various morphological and immunocytological techniques. The results here demonstrate evidence for approximately 25% apoptosis after treatment with calcium salicylate, which up-regulatd the expression of p53, p21 and Bax, and down-regulated Bcl-2 in HT-1080 cells.

Topics: Antineoplastic Agents; Apoptosis; bcl-2-Associated X Protein; Cell Cycle; Cell Line, Tumor; Cell Survival; Fibrosarcoma; Gene Expression Regulation, Neoplastic; Humans; Indicators and Reagents; p21-Activated Kinases; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins c-bcl-2; Salicylates; Tetrazolium Salts; Thiazoles; Tumor Suppressor Protein p53

The mechanism of hyaluronate shedding from eukaryotic cell lines was analysed. All cell lines shed identical sizes of hyaluronate as were retained on the surface. They differed in the amount of hyaluronate synthesized and in the proportions of hyaluronate which were released and retained. A method was developed which could discriminate between shedding due to intramolecular degradation and that due to dissociation as intact macromolecules. This method was applied to B6 and SV3T3 cells in order to study the mechanism of hyaluronate release in more detail. The cells were pulse-labelled to form hyaluronate chains with labelled and unlabelled segments, and the sizes of labelled hyaluronate released into the medium during the pulse extension period were determined by gel filtration. B6 cells released identical sizes of hyaluronate at all labelled segment lengths, indicating that no intramolecular degradation occurred. When chain elongation was blocked by periodate-oxidized UDP-glucuronic acid, hyaluronate release was simultaneously inhibited. These results indicated that B6 cells dissociated hyaluronate as an intact macromolecule. In contrast, SV3T3 cells released hyaluronate of varying molecular mass distributions during extension of the labelled segment, suggesting partial degradation. Exogenous hyaluronate added to SV3T3 cultures was also degraded. This degradation could be prevented by the presence of radical scavengers such as superoxide dismutase and tocopherol. Degradation of endogenous hyaluronate could be inhibited by salicylate. These results led to the conclusion that SV3T3 cells released hyaluronate not only by dissociation, but also by radical-induced degradation.

Topics: Cell Line; Cell Membrane; Cells; Eukaryotic Cells; Fibroblasts; Fibrosarcoma; Free Radicals; Glucosamine; Humans; Hyaluronic Acid; Hyaluronoglucosaminidase; Kinetics; Molecular Weight; Oxidation-Reduction; Periodic Acid; Salicylates; Salicylic Acid; Superoxide Dismutase; Tumor Cells, Cultured; Uridine Diphosphate Glucuronic Acid; Vitamin E

Polyclonal T cell activation, syngeneic tumor cell and alloantigen-induced proliferative responses were studied to determine if the regulation of these responses in normal and tumor-bearing NBR rats is mediated through products of the cyclooxygenase pathway and prostaglandin E2 (PGE2) in particular. Young rats and tumor-bearing rats have previously been shown to produce poor proliferative responses to PHA, Con A and syngeneic methylcholanthrene (MCA)-induced fibrosarcoma cells. The poor responses to PHA and Con A are mediated by PGE2 in unfractionated ( UNF ) and nylon wool adherent (ADH) cells. The same relationship was also established in the mixed leukocyte tumor cell (MLTC) response to MCA tumor cells although it appears to be of only minor significance as the enhancement following indomethacin (IND) treatment is still a relatively poor response. Indomethacin generally had no effect on the proliferative responses of tumor-bearing animals indicating that the suppression was not mediated through the cyclooxygenase pathway. We have also extended a previous observation in which UNF cells were found to be unresponsive to alloantigen stimulation. This suppression does not appear to be mediated through cyclooxygenase products as IND treatment does not enhance the UNF response although it does enhance the ADH response. These data indicate that a complex network of cyclooxygenase dependent and independent regulation exists in normal and tumor-bearing NBR rats.

Topics: Animals; Antigens, Neoplasm; Cyclooxygenase Inhibitors; Dinoprostone; Fibrosarcoma; Immune Tolerance; Indomethacin; Isoantigens; Lymphocyte Activation; Lymphocyte Culture Test, Mixed; Mitogens; Neoplasm Transplantation; Prostaglandins E; Rats; Rats, Inbred Strains; Salicylates; Salicylic Acid; Spleen; T-Lymphocytes

Topics: Anemia; Anemia, Hemolytic; Animals; Antineoplastic Agents; Cortisone; Cricetinae; Fibrosarcoma; Neoplasms; Neoplasms, Experimental; Salicylates; Sodium Salicylate