Exploiting yoeB‐yefM toxin‐antitoxin system of Streptococcus pneumoniae on the selective killing of miR‐21 overexpressing breast cancer cell line (MCF‐7)

Abstract

Toxin-antitoxin (TA) systems are two-component genetic modules widespread in bacterial and archaeal genomes, in which the toxin module is rendered inactive under resting conditions by its antitoxin counterpart. Under stress conditions, however, the antitoxin is degraded, freeing the toxin to exert its lethal effects.Although not evolved to function in eukaryotes, some studies have established the lethal activity of these bacterial toxins by inducing apoptosis in mammalian cells, an effect that can be neutralized by its cognate antitoxin. Inspired by the way the toxin can become active in eukaryotes cells, we produced an engrained yoeB-yefM TA system to selectively kill human breast cancer cells expressing a high level of miR-21. Accordingly, we generated an engineered yefM antitoxin gene with eight miR-21 target sites placed in its 3′untranslated region. The resulting TA system acts autonomously in human cells, distinguishing those that overexpress miR-21, killed by YoeB, from those that do not, remaining protected by YefM. Thus, we indicated that microRNA-control of the antitoxin protein of bacterial TA systems constitutes a novel strategy to enhance the selective killing of human cancer cells by the toxin module. The present study provides significant insights for developing novel anticancer strategies avoiding off-target effects, a challenge that has been pursued by many investigators over the years. K E Y W O R D Sbreast cancer, cancer cell killing, miR-21, toxin-antitoxin system, YefM, YoeB

Interference Reduction Biosensing Strategy for Highly Sensitive microRNA Detection

“…Application of NEM-IR-RCA in Real Sample Analysis. It was reported that miRNA-21 is overexpressed in many cancer cells including human breast adenocarcinoma (MCF-7) cells and adenocarcinoma cervical cancer (HeLa) cells, 73,74 while its expression status is normal in human hepatic (LO2) cells. 75 In order to investigate the capability of the NEM-IR-RCA method for complex cell samples, miRNA-21 detection was performed in MCF-7, HeLa, and LO2 cell extracts.…”

Functional and Structural Diversity of Bacterial Contact-Dependent Growth Inhibition Effectors

“…When the toxin and immunity genes are transcribed, the oncomiRNA binds the complementary sequence and initiates degradation of the immunity mRNA. Thus, in cancer cells, transcription of the immunity gene is silenced while toxin transcription continues, leading to toxin-induced cell death ( Turnbull et al, 2019 ; Houri et al, 2020 ).…”

“…Anti-cancer applications to date involve the design of TA pairs where the antitoxin is specifically degraded in cancer cells freeing the toxin to eradicate cancer cells ( Preston et al, 2016 ; Turnbull et al, 2019 ; Houri et al, 2020 ). For example, in human papilloma virus (HR-HPV) induced cervical cancer cells, oncoprotein E6 binds and induces the polyubiquitination of specific target proteins, resulting in target protein degradation.…”

“…Another approach takes advantage of microRNA-driven oncogenic stress, where miRNA (noncoding RNA) base pairs with complementary target sites (miRts) to inhibit translation or induce degradation of target mRNAs. Here, a cancer cell specific miRt is encoded downstream of the antitoxin gene, resulting in cancer cell specific silencing of the antitoxin resulting in toxin activation ( Figure 5D ) ( Turnbull et al, 2019 ; Houri et al, 2020 ). This strategy has been utilized by two different TA pairs along with two different miRNA/miRt sequences indicating that this approach could be applied to target specific cancer cells utilizing a variety of different TA systems.…”

Applications of phage-derived RNA-based technologies in synthetic biology

“…The MazF-MazE TA system was demonstrated to selectively eradicate cancer cells by an innovative cassette for controllable toxin expression [ 185 ]. Different RNA-targeted TA systems for the selective killing of cancer cells continue to be developed and optimized using rationally designed programmed synthetic genetic devices [ 186 , 187 ]. TA systems for selective cancer cell removal show great promise, but the interaction among functional TA modules, cancer cells and normal cells should be better evaluated.…”