Cytotoxic and apoptosis-inducing effects of wildtype and mutated Hydra actinoporin-like toxin 1 (HALT-1) on various cancer cell lines

Teng Jia Ng; Michelle Yee Mun Teo; Dek Shen Liew; Paul Etim Effiong; Jung Shan Hwang; Crystale Siew Ying Lim; Lionel L A In

doi:10.7717/peerj.6639

Cytotoxic and apoptosis-inducing effects of wildtype and mutated Hydra actinoporin-like toxin 1 (HALT-1) on various cancer cell lines

PeerJ. 2019 May 2:7:e6639. doi: 10.7717/peerj.6639. eCollection 2019.

Authors

Teng Jia Ng¹, Michelle Yee Mun Teo¹, Dek Shen Liew¹, Paul Etim Effiong¹, Jung Shan Hwang², Crystale Siew Ying Lim¹, Lionel L A In¹

Affiliations

¹ Department of Biotechnology, Faculty of Applied Sciences, UCSI university, Cheras, Wilayah Persekutuan Kuala Lumpur, Malaysia.
² Department of Medical Sciences, School of Healthcare and Medical Sciences, Sunway University, Subang Jaya, Selangor, Malaysia.

Abstract

Background: Hydra actinoporin like toxin -1 (HALT-1), is a small 18.5 kDa pore forming toxin derived from Hydra magnipapillata which has been shown to elicit strong haemolytic and cytolytic activity when in contact with cell membranes. Due to its cytotoxic potency, HALT-1 was further investigated for its potential as a toxin moiety candidate in immunotoxin developmental efforts, ideally as a form of targeted therapy against cancer.

Methods: In this study, wtHALT-1 (wild type) and its Y110A mutated binding domain counterpart (mHALT-1) were produced and evaluated for their cytotoxic and apoptotic effects on various cancer cell lines. A total of seven different tumour and non-tumour cell lines including HeLa, HepG2, SW-620, MCF-7, CCD841CoN, NHDF and HCT116 were used. Immunofluorescence assays were used to observe membrane binding and localization changes between both HALT-1 recombinant proteins based on 6xHis-tag detection.

Result: Based on MTT data, mHALT-1 demonstrated a significant reduction of 82% ± 12.21% in cytotoxic activity across all cell lines after the membrane recognition domain had been mutated in comparison to the wtHALT-1. Annexin V FITC/PI assay data also indicated that HeLa, HepG2 and MCF-7 demonstrated an apoptosis-mediated cell death after being treated with wtHALT-1. Additionally, a notable difference between wtHALT-1 and mHALT-1 binding affinity was clearly observed where emission of green fluorescence along the cell membrane was observed only in wtHALT-1 treated cells.

Discussion: These results suggest that mHALT-1 (Y110A) can be potentially developed as a toxin-moiety candidate for the development of future immunotoxins against various human cell-based diseases.

Keywords: Apoptosis; Cancer; Cytotoxicity; Hydra actinoporin; Immunotoxin; Pore-forming toxins.

Grants and funding

This work was financially supported by UCSI University CERVIE Conference Funding (CONF-NATN-FAS-126), UCSI University Postgraduate Student Conferences Funding (CONF-NAT-FAS-10), The Ministry of Higher Education Malaysia (MOHE) through the Fundamental Research Grant Scheme (FRGS/1/2017/STG05/UCSI/03/2) and UCSI University PSIF Grants (Proj-In-FAS-041 & Proj-In-FAS-061). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.