Butyrate reduces liver metastasis of rat colon carcinoma cells in vivo and resistance to oxidative stress in vitro.

Injection of the rat colon carcinoma cell line CC531 into spleen of syngeneic rats results in considerable amounts of liver metastases within 14 days. We investigated whether preincubation of the cells with butyrate reduced their metastatic ability in vivo and whether this was accompanied by reduction in related properties such as secretion of metalloproteinases and their ability to withstand oxidative stress. Butyrate incubation reduced cell growth rate and initiated apoptosis in a dose- and time-related manner, but proliferation was retrieved when cultivation was continued in medium without butyrate. Splenic injection of butyrate treated, proliferating cells resulted in significantly reduced amounts of tumor mass compared to untreated cells. The butyrate treated cells were more susceptible to oxidative stress than control cells, as demonstrated by increased number of apoptotic cells and reduced cell growth after exposure to menadione. A reduction in cellular glutathione was found after prolonged incubation with butyrate. Butyrate appeared not to alter the secretion of active metalloproteinases from the cells although an apparent increase in proforms was demonstrated. Neither did butyrate alter the synthesis of metalloproteinase inhibitors. Lastly, a reduced adhesion of the tumor cells to collagen coated matrix was found after butyrate treatment. Thus, the inhibitory effects of butyrate on tumor malignancy are caused by a diversity of mechanisms.

Interferon-γ Sensitises Human Osteosarcoma Cells to Trail-mediated Apoptosis.

BACKGROUND: Nearly half of all patients with osteosarcoma are still not cured by the currently employed multimodal treatment. New strategies are therefore needed to further improve the outcome. Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL/Apo2) is able to induce programmed cell death in transformed cells, while normal cells remain unaffected. MATERIALS AND METHODS: We have investigated the effect of TRAIL in combination with IFN-γ on four human osteosarcoma cell lines; Saos-2, U2OS, KPDXM and OHS, and on one normal human fibroblast cell line, MRC-5. RESULTS: One of the four osteosarcoma cell lines was TRAIL-resistant, but was sensitised to TRAIL-mediated cell death upon pre-incubation with IFN-γ. In two of the three TRAIL-sensitive cell lines, the effect of TRAIL was enhanced by IFN-γ. The normal human fibroblast cell line MRC-5 was not affected by treatment with TRAIL and IFN-γ. A caspase cascade involving the activation of caspase-8, caspase-7 and PARP was associated with the onset of apoptosis in the osteosarcoma cell lines. Apoptosis was partly inhibited by the addition of caspase inhibitors zVADfmk (general inhibitor) and zIETDfmk (selective caspase-8 inhibitor). These findings further emphasize the important role of the caspases in cell death signalling. CONCLUSION: Our results show that treatment with both IFN-γ and TRAIL efficiently induces cell death in osteosarcoma cell lines and should be further investigated as a potential future therapy.