Cytotoxicity of RNase Sa to the acute myeloid leukemia Kasumi-1 cells depends on the net charge
Vladimir A. Mitkevich1, Ksenia M. Burnysheva1, Olga N. Ilinskaya1,2, C. Nick Pace3,4 and Alexander A. Makarov1
1 Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
2 Department of Microbiology, Kazan Federal (Volga-Region) University, Kazan, Russia
3 Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
4 Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, Texas A&M University, College Station, Texas, USA
Correspondence:
Alexander A. Makarov, email:
Keywords: RNase; cytotoxicity; net charge; cationization; N-terminus; apoptosis
Received: October 24, 2014 Accepted: Novemeber 10, 2014 Published: November 10, 2014
Abstract
The majority of known cytotoxic RNases are basic proteins which destroy intracellular RNA. Cationization of RNases is considered to be an effective strategy for strengthening their antitumor properties. We constructed a set of RNase Sa variants consisting of charge reversal mutants, charge neutralization mutants, and variants with positively charged cluster at the N-terminus. All constructs retain a high level of catalytic activity and differ in net charge. Using acute myeloid leukemia cells Kasumi-1 we have shown that (i) cytotoxicity of RNase Sa mutants is linearly enhanced by cationization, (ii) the ability of cytotoxic mutants to induce cell death is caused by induction of apoptosis and (iii) localization of positive charge on N-terminus does not contribute to RNase Sa cytotoxicity. Capacity to induce apoptosis in malignant cells and the absence of necrotic effects make the RNase Sa mutants with high positive charge a suitable anti-cancer agent.
