Phospholipase A2 from krait Bungarus fasciatus venom induces human cancer cell death in vitro

Thien V Tran; Andrei E Siniavin; Anh N Hoang; My T T Le; Chuong D Pham; Trung V Phung; Khoa C Nguyen; Rustam H Ziganshin; Victor I Tsetlin; Ching-Feng Weng; Yuri N Utkin

doi:10.7717/peerj.8055

Phospholipase A₂ from krait Bungarus fasciatus venom induces human cancer cell death in vitro

PeerJ. 2019 Dec 3:7:e8055. doi: 10.7717/peerj.8055. eCollection 2019.

Authors

Thien V Tran^{1

2}, Andrei E Siniavin³, Anh N Hoang^{2

4}, My T T Le⁵, Chuong D Pham⁵, Trung V Phung⁶, Khoa C Nguyen^{2

4}, Rustam H Ziganshin⁷, Victor I Tsetlin⁸, Ching-Feng Weng⁹, Yuri N Utkin³

Affiliations

¹ Tra Vinh University, Tra Vinh City, Vietnam.
² Graduate University of Science and Technology VAST, Hanoi, Vietnam.
³ Laboratory of Molecular Toxinology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Moscow, Russian Federation.
⁴ Institute of Applied Materials Science VAST, Ho Chi Minh City, Vietnam.
⁵ Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
⁶ Center for Research and Technology Transfer VAST, Ho Chi Minh City, Vietnam.
⁷ Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Moscow, Russian Federation.
⁸ Department of Molecular Neuroimmune Signalling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Moscow, Russian Federation.
⁹ Department of Life Science and Institute of Biotechnology, National Dong Hwa University, Shoufeng, Hualien, Taiwan.

Abstract

Background: Snake venoms are the complex mixtures of different compounds manifesting a wide array of biological activities. The venoms of kraits (genus Bungarus, family Elapidae) induce mainly neurological symptoms; however, these venoms show a cytotoxicity against cancer cells as well. This study was conducted to identify in Bungarus fasciatus venom an active compound(s) exerting cytotoxic effects toward MCF7 human breast cancer cells and A549 human lung cancer cells.

Methods: The crude venom of B. fasciatus was separated by gel-filtration on Superdex HR 75 column and reversed phase HPLC on C18 column. The fractions obtained were screened for cytotoxic effect against MCF7, A549, and HK2 cell lines using colorimetric assay with the tetrazolium dye MTT- 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. The primary structure of active protein was established by ultra high resolution LC-MS/MS. The molecular mechanism of the isolated protein action on MCF7 cells was elucidated by flow cytometry.

Results: MTT cell viability assays of cancer cells incubated with fractions isolated from B. fasciatus venom revealed a protein with molecular mass of about 13 kDa possessing significant cytotoxicity. This protein manifested the dose and time dependent cytotoxicity for MCF7 and A549 cell lines while showed no toxic effect on human normal kidney HK2 cells. In MCF7, flow cytometry analysis revealed a decrease in the proportion of Ki-67 positive cells. As Ki-67 protein is a cellular marker for proliferation, its decline indicates the reduction in the proliferation of MCF7 cells treated with the protein. Flow cytometry analysis of MCF7 cells stained with propidium iodide and Annexin V conjugated with allophycocyanin showed that a probable mechanism of cell death is apoptosis. Mass spectrometric studies showed that the cytotoxic protein was phospholipase A₂. The amino acid sequence of this enzyme earlier was deduced from cloned cDNA, and in this work it was isolated from the venom as a protein for the first time. It is also the first krait phospholipase A₂ manifesting the cytotoxicity for cancer cells.

Keywords: Breast cancer; Cytotoxicity; Human cancer cells; Krait; Lung cancer; Mass spectrometry; Phospholipase A2; Venom.

Grants and funding

The work was supported by the Vietnam Academy of Science and Technology (research project QTRU01.03/18-19) and Russian Foundation for Basic Research (Project No: 18-54-54006). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.