Bothrops moojeni L-amino acid oxidase induces apoptosis and epigenetic modulation on Bcr-Abl+ cells

 

Sandra Mara Burin1, Maira da Costa Cacemiro1, Juçara Gastaldi Cominal1, Rone Aparecido De Grandis1, Ana Rita Thomazela Machado1, Flavia Sacilotto Donaires2, Adelia Cristina Oliveira Cintra1, Luciana Ambrosio1, Lusânia Maria Greggi Antunes1, Suely Vilela Sampaio1, Fabíola Attié de Castro1

 

1 Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences, University of São Paulo (USP), Ribeirão Preto, SP, Brazil.

2 Department of Internal Medicine, Ribeirão Preto Medical School, University of São Paulo (USP), Ribeirão Preto, SP, Brazil.

 

Abstract

Background: Resistance to apoptosis in chronic myeloid leukemia (CML) is associated with constitutive tyrosine kinase activity of the Bcr-Abl oncoprotein. The deregulated expression of apoptosis-related genes and alteration in epigenetic machinery may also contribute to apoptosis resistance in CML. Tyrosine kinase inhibitors target the BcrAbl oncoprotein and are used in CML treatment. The resistance of CML patients to tyrosine kinase inhibitors has guided the search for new compounds that may induce apoptosis in Bcr-Abl+ leukemic cells and improve the disease treatment.

 

Methods: In the present study, we investigated whether the L-amino acid oxidase isolated from Bothrops moojeni snake venom (BmooLAAO-I) (i) was cytotoxic to BcrAbl+ cell lines (HL-60.Bcr-Abl, K562-S, and K562-R), HL-60 (acute promyelocytic leukemia) cells, the non-tumor cell line HEK-293, and peripheral blood mononuclear cells (PBMC); and (ii) affected epigenetic mechanisms, including DNA methylation and microRNAs expression in vitro.

 

Results: BmooLAAO-I induced ROS production, apoptosis, and differential DNA methylation pattern of regulatory apoptosis genes. The toxin upregulated expression of the pro-apoptotic genes BID and FADD and downregulated DFFA expression in leukemic cell lines, as well as increased miR-16 expression – whose major predicted target is the anti-apoptotic gene BCL2 – in Bcr-Abl+ cells.

 

Conclusion: BmooLAAO-I exerts selective antitumor action mediated by H2 O2 release and induces apoptosis, and alterations in epigenetic mechanisms. These results support future investigations on the effect of BmooLAAO-I on in vivo models to determine its potential in CML therapy.

 

Keywords: Apoptosis MicroRNA Chronic myeloid leukemia Snake toxins BmooLAAO-I Bothrops moojeni

 

Correspondence: castrofa@fcfrp.usp.br

 

Received: 14 August 2020; Accepted: 24 November 2020; Published online: 14 December 2020.