Cytotoxic and pro-apoptotic action of MjTX-I, a phospholipase A2 isolated from Bothrops moojeni snake venom, towards leukemic cells

Rogério Bodini Benati,Sandra Mara Burin,Maira da Costa Cacemiro,Suely Vilela Sampaio,Tássia Rafaela Costa,Fabíola Attié de Castro

doi:10.1186/s40409-018-0180-9

Abstract

BackgroundChronic myeloid leukemia (CML) is a BCR-ABL1+ myeloproliferative neoplasm marked by increased myeloproliferation and presence of leukemic cells resistant to apoptosis. The current first-line therapy for CML is administration of the tyrosine kinase inhibitors imatinib mesylate, dasatinib or nilotinib. Although effective to treat CML, some patients have become resistant to this therapy, leading to disease progression and death. Thus, the discovery of new compounds to improve CML therapy is still challenging. Here we addressed whether MjTX-I, a phospholipase A2 isolated from Bothrops moojeni snake venom, affects the viability of imatinib mesylate-resistant Bcr-Abl+ cell lines.MethodsWe examined the cytotoxic and pro-apoptotic effect of MjTX-I in K562-S and K562-R Bcr-Abl+ cells and in the non-tumor HEK-293 cell line and peripheral blood mononuclear cells, using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and the hypotonic fluorescent solution methods, associated with detection of caspases 3, 8, and 9 activation and poly (ADP-ribose) polymerase (PARP) cleavage. We also analyzed the MjTX-I potential to modulate the expression of apoptosis-related genes in K562-S and K562-R cells.ResultsMjTX-I decreased the viability of K562-S and K562-R cells by 60 to 65%, without affecting the viability of the non-tumor cells, i.e. it exerted selective cytotoxicity towards Bcr-Abl+ cell lines. In leukemic cell lines, the toxin induced apoptosis, activated caspases 3, 8, and 9, cleaved PARP, downregulated expression of the anti-apoptotic gene BCL-2, and upregulated expression of the pro-apoptotic gene BAD.ConclusionThe antitumor effect of MjTX-I is associated with its potential to induce apoptosis and cytotoxicity in Bcr-Abl positive cell lines sensitive and resistant to imatinib mesylate, indicating that MjTX-I is a promising candidate drug to upgrade the CML therapy.

Highlights

Chronic myeloid leukemia (CML) is a BCR-ABL1+ myeloproliferative neoplasm marked by increased myeloproliferation and presence of leukemic cells resistant to apoptosis
Considering the need to search for new molecules to treat CML, and the knowledge that Myotoxin phospholipase A2 (PLA2)-Lys49 isolated from Bothrops moojeni (MjTX-I) is cytotoxic, here we examined whether this myotoxin exerts antitumor effect against the Bcr-Abl+ cell lines sensitive (K562-S) or resistant (K562-R) to imatinib mesylate, a drug used as first-line treatment for CML
MjTX-I is cytotoxic towards leukemic cells but not towards non-tumor cells We examined the cytotoxicity of MjTX-I towards the tumor cell lines K562-S and K562-R, and towards the non-tumor cells HEK-293 and peripheral blood mononuclear cells (PBMC), after a 24-h treatment with toxin concentrations ranging from 3.15 to 400 μg/mL

Summary

Introduction

Chronic myeloid leukemia (CML) is a BCR-ABL1+ myeloproliferative neoplasm marked by increased myeloproliferation and presence of leukemic cells resistant to apoptosis. The current first-line therapy for CML is administration of the tyrosine kinase inhibitors imatinib mesylate, dasatinib or nilotinib. We addressed whether MjTX-I, a phospholipase A2 isolated from Bothrops moojeni snake venom, affects the viability of imatinib mesylate-resistant Bcr-Abl+ cell lines. Chronic myeloid leukemia (CML) is a BCR-ABL1+ myeloproliferative neoplasm [1], characterized by increased myeloproliferation rate and presence of apoptosis-resistant leukemic cells [2, 3]. The current CML treatment relies on administration of the tyrosine kinase inhibitors imatinib mesylate (IM), dasatinib or nilotinib as first-line therapy. Studies have reported the cytotoxic and pro-apoptotic effects of a variety of PLA2 isolated from snake venoms in different tumor cell lines such as HL-60 (human promyelocytic leukemia), HepG2 (human hepatoma), PC12 (adrenal phaeochromocytoma), B16F10 (melanoma), Jurkat (acute T cell leukemia), SKBR-3 (human breast cancer), and Ehrlich ascites tumor [17,18,19,20,21,22]

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