The Drug Targets siRNA library consists of high-confidence gene targets based on publications that characterize potential druggable targets and was assembled with use of innovative bioinfomatics tools to analyze genetic and ontological information from multiple databases. This siRNA collection excludes gene targets available in other siRNA libraries: kinases, g-protein coupled receptors, proteases, phosphatases, ion channels, and genes involved with ubiquitin conjugation.
The effect of silencing ARPC1B on cell migration was studied in a breast cancer cell line. A monolayer of cells was uniformly scraped and the rate of cell migration to close the scrape (wound healing) was evaluated. Both unmodified and ON-TARGETplus siRNA reagents induced potent target knockdown. Inconsistent phenotypes due to off-target effects (red outline), were observed for cells transfected with unmodified individual siRNAs. The unmodified SMARTpool improved the false phenotype considerably, while the ON-TARGETplus SMARTpool significantly reduced off-target effects to produce a consistent phenotype. In collaboration with Kaylene Simpson, Laura Selfors and Joan Brugge, Harvard Medical School.
(A) and (B) are representative examples of off-target signatures with and without application of ON-TARGETplus modifications to (A) a single siRNA and (B) a SMARTpool reagent. Green bars indicate genes with 2-fold or more reduction of expression when treated with the indicated siRNA reagent. The ON-TARGETplus modifications reduced the off-targets when compared to unmodified siRNA. Pooling of siRNA and the ON-TARGETplus modification pattern independently, and in combination, provide significant reduction in off-target gene silencing. Panel (C) represents quantitation of off-targets (down-regulated by 2-fold or more) induced by the indicated siRNA reagents targeting 10 different genes (4 siRNAs per gene or a single SMARTpool reagent). Off-targets were quantified using microarray analysis (Agilent) then compiled. Each shaded box represents the middle 50% of the data set. Horizontal line in box: Median value of the data set. Vertical bars: minimum and maximum data values.