“Selective cell death mediated by small conditional RNAs” is not selective

Abstract

Small conditional RNAs were used to kill cells selectively in a prior report. The method utilized the cellular innate immune response to dsRNA, causing PKR activation and cell death. We designed small conditional RNAs specific to a highly restricted transcript, that of the mesothelin gene expressed in various cancer lines and specific to a tpc/hpr fusion transcript expressed in a published "control" line. Hairpins of small conditional RNAs were functionally active in cell-free conditions. Hairpins were transfected into 6 types of cells. We observed non-specific killing of cells after transfection of the hairpins targeting the reported fusion transcript or of the mesothelin transcript. Thus when attempting to use this system for a special purpose, to target cancer mutations, the results were not satisfactory. Specifically when repeating the work described in the publication, we could not replicate the results using the methods described. Recently the publication was retracted but without comment on the validity of the reported method. Here we provide scientific basis to consider the method impaired or invalid.

RNA Oncological Therapeutics: Intracellular Hairpin RNA Assembly Enables MicroRNA-Triggered Anticancer Functionality

“…Extending the incubation time from 24 to 48 h resulted in higher cytotoxicity and selectivity, likely due to more advanced polymerization of oHP­(7) (Figure S9). Patel and Kern reported that RNA-HCR triggered by mutated mRNA as a cancer marker mediates cell death with no selectivity, probably because of nonspecific polymerization . Our results suggest that miRNA is a promising cancer biomarker to achieve selective cytotoxicity by RNA-HCR compared with mutated mRNA.…”

“…Patel and Kern reported that RNA-HCR triggered by mutated mRNA as a cancer marker mediates cell death with no selectivity, probably because of nonspecific polymerization. 29 Our results suggest that miRNA is a promising cancer biomarker to achieve selective cytotoxicity by RNA-HCR compared with mutated mRNA.…”