Pathological Metabolism of Methionine in Malignant Cells Is a Potential Target for the Antitumor Therapy

This review presents the characteristics of the cellular metabolism of methionine, as well as known data on the mechanisms of the development of methionine dependence in malignant cells. The possibilities of using a non-methionine diet for the control of the tumor growth in patients with various forms of cancer are considered. The newest information about methionine-γ-lyase, an enzyme providing elimination of methionine from plasma, is grouped and summarised. Its role as a potential antitumor enzyme is disclosed. Data on methionine-γ-lyase producers, activity of this enzyme, obtained from various sources, and information on tumor models and cell cultures, showing methionine dependence are summarised

Ribonucleases with Antiproliferative Properties: Molecular Biological and Biochemical Characteristics

The article dwells on ribonucleases (RNAses) whose cytotoxic activity depends on the enzymatic activity, i.e. the ability to catalyze the cleavage of phosphodiester bonds of RNA. It presents both well-known information and our own data on RNAses of different origins with antitumor properties; it investigates the relation between the mechanism of cytotoxicity and biochemical and molecular biological characteristics. The analysis of published data demonstrates that all above characteristics contribute to the antiproliferative activity of RNAses. The major challenge for this group of enzymes is the achieving of selective bioavailability. This problem can be solved by creating conjugates as in case with ranpirnase and barnase. Based on their major pharmacological properties, active antitumor RNAses have great perspectives for treatment of not only oncohematological, but also solid malignancies