Transplantable mouse methylcholanthrene- induced fibrosarcoma (CMC4 tumour growing in CBA/HZgr mice), characterized by lung metastases developing shortly after local tumour cell transplantation, was used as an experimental model to investigate the problem of tumour metastases after local tumour treatment. Surgery and/or irradiation were performed on locally growing tumour of particular size. Further, heavily irradiated, viable but not dividing tumour cells, imitating the situation in treated tumour-bearing organism, were injected intraperitoneally in a parallel group of treated tumour-bearing mice. The animals were killed 35 days after tumour transplantation and the number and volume of lung metastases were determined. Depending on the treatment performed, when the tumour mass was reduced or even eliminated, the number of lung metastases and their volume were significantly lower than in control mice, but the addition of tumour mass (injection of heavily irradiated tumour cells) resulted in a significant increase in lung metastases parameters, pointing to a possible role of the host's immune reaction against the tumour. Further, the release of a simple molecule, such as nitric oxide, from tumour mass seems to be detrimental for the survival of tumour cells and subsequently their metastases through the induction of angiogenesis and possible suppression of immune reaction. Thus, complex mechanisms could be involved when a locally growing tumour is exposed to a particular therapeutic approach.

Fumagillin is an antibiotic derived from the fungus Aspergillus fumigatus. It has been used successfully for the treatment of intestinal microsporidiosis in HIV-positive humans, as well as in those suffering from intestinal amebiasis and microsporidial keratoconjunctivitis. In veterinary medicine it is approved for the treatment of microsporidiosis in bees and fish. In this research fumagillin was tested for the ability to provoke chromosomal aberrations in mouse bone marrow cells. BALB/c mice were administered fumagillin by gastric probe in doses of 5, 10 and 20 mg/kg b.w. Water-sugary syrup was the negative and cyclophosphamide (15 mg/kg b.w.) the positive control. Significantly increased frequencies (p<0.01 or p<0.001) of numerical chromosomal aberrations (aneuploidies and poliploidies) was observed both in the medium (10 mg/kg b.w.) and the highest (20 mg/kg b.w.) dose of fumagillin. Structural chromosomal aberrations (gaps, breaks and insertions) were noticeably more frequent in comparison to negative control only in the highest experimental dose of dycikloheksilamine. These results clearly showed that fumagillin in concetrations 10 and 20 mg/kg b.w. had a genotoxic potential in vivo.