Efficiency of treatment with galactoside-specific lectin from mistletoe against rat glioma

The cytotoxic activity of the galactoside-specific lectin from mistletoe (mistletoe lectin-1, ML-1) towards the anaplastic glioma cell line (F98) was investigated in vitro (three dimensional spheroid model) and in vivo (Fischer 344 rats). Both model systems demonstrated the dose dependent cytotoxicity of ML-1. F98 glioma cell spheroid growth was significantly inhibited after incubation with defined ML-1 concentrations of 10 and 100 ng/mL. To investigate the in vivo efficacy Fischer 344 rats were intracerebrally implanted with F98 glioma cells and assigned to local and systemic ML-1 treatment, respectively. Histological and immunohistochemical evaluations proved a reduction of tumor volume for both treatment modalities, most pronounced and statistically significant after systemic (immunomodulating) administration of the optimal ML-1 dosage (1 ng/kg BW, subcutaneously) and after low dose (10 ng ML-1 per application (10 microL) local treatment. High dose ML-1 administration (10 ng/kg BW; systemically; 100 ng/application, locally) was less effective than low (optimal) dose treatment and apparently the systemic/immunomodulating approach gained greater benefit for glioma bearing rats.