The antiproliferative and antitumor effect of leaf
ribonuclease was tested in vitro on the human ML-2 tumor cell line and in vivo on athymic nude mice bearing human
melanoma tumors. The antiproliferative activity of this plant
ribonuclease in vitro studies was negligible. In the experiments in vivo a significant decrease of the
tumor size, however was observed. From nucleases the
mung bean nuclease (PhA) was studied first from nucleases. The antitumor effect of this
enzyme on ML2 human tumor cell line was almost non-effective. However, significant antitumor activity was detected on human
melanoma tumors in vivo. The antitumor effect of black pine pollen nuclease (PN) tested in vitro was also negligible. On the other side, in the experiments in vivo a significant decrease of the human
melanoma tumor size was observed too. Recombinant plant nucleases of tomato (TBN1) and hop (HBN1) (submitted to patenting under no. PV 2008-384;Z7585) were isolated to homogeneity and examined for their antitumor effects and cytotoxicity. Although antiproliferative effects of both recombinant nucleases were not significant on the ML-2 cell culture in vitro, the nucleases were strongly
cytostatic in vivo after their administration intravenously as stabilized conjugates with
polyethylene glycol (PEG). Recombinant both nucleases were as effective against human
melanoma tumors as previously studied pine pollen (PN) and mung bean nucleases and their effects were reached at about ten times lower concentrations compared to the use of bovine seminal
RNase (
BS-RNase).