Search

Nuclease from tomato (TBN1) was produced by in planta biotechnology purified and tested for its anticarcinogenic properties. The nuclease was cytostatic after its intratumoral administration to nude mice bearing human melanoma or prostate carcinoma or after tumor targeting by TBN1 administration intravenously as conjugate with polyethylene glycol (PEG). Inhibitory effects of TBN1 on tumor growth were comparable to effects of bovine seminal RNase (BS-RNase), but the inhibition was reached at about ten times lower protein concentration. Simultaneously, TBN1 exhibited a lower degree of embryotoxicity compared to BS-RNAse and other nucleases. TBN1 showed significant stability in vivo, because it was readily detected after its administration intratumorally or intravenously by the fluorescence methods. Intravenous administration of TBN1-PEG caused significant inhibition of tumor proliferation without obvious degenerative changes, while direct administration of TBN1 into melanoma tumors led to rapid tumor tissue degeneration. The fact can be essential for the mode of TBN1 biological action that mature nuclease is a small (36 kDa) thermostable glycoprotein that has ability to destroy human 28S, 18S, 7S and 5.8S RNA, circular RNAs, double-stranded RNA in vitro and shows DNase and 3'nucleotidase activities.

The antitumor effect of black pine (Pinus nigra) pollen nuclease (PN) tested in vitro was negligible in comparison with bovine seminal ribonuclease (BS-RNase). However, in the experiments in vivo a significant decrease of the human melanoma tumor size was observed in the mice treated with this nuclease and also with the animal RNases and DNase I. In nude mice injected intratumoraly with PN (10 microg/dose) the tumor size decreased from 100% in the control mice to 46% in treated mice whereas in counterparts treated with BS-RNase and DNase I the tumor growth was reduced a little more, however after ten times higher doses (100 and 80 microg per dose). Certain aspermatogenic and embryotoxic activity as an expression of side effects of PN and comparative enzymes also appeared, but it was lower compared to the effect of bovine seminal ribonuclease. Immunogenicity of PN was significantly weaker in comparison with BS-RNase. The antibodies against black pine nuclease produced in the injected mice did not inactivate the biological effects of this plant nuclease in vivo. In conclusion PN nuclease proved in vivo higher antitumor activity against human melanoma tumors growing in athymic mice in comparison with animal bovine seminal ribonuclease and DNase I.