Description
Whole genome microarrays were probed with total mRNA from PTD-DRBD GAPDH siRNA treated H1299 cells at 12 h and 24 h. Using a 1.6x fold increase/decrease filter of cellular mRNAs, we detected a dramatic reduction in the target GAPDH mRNA along with a limited number of both up and down regulated genes. The up regulated genes were reduced in numbers and to nearly background 1.6x levels at 24 h, while the down regulated genes increased slightly in numbers and maintained a similar magnitude at 24 h. In contrast, lipofection treated cells showed both a dramatic increase in both the total number of genes altered and the magnitude of the increase. In addition, the numbers of genes affected increased between 12 h and 24 h, suggesting that lipofection of siRNAs into cells results in a substantial alteration to the transcriptome and may thereby confound interpretation of experimental outcomes. Moreover, the GAPDH specific knockdown was significantly smaller than PTD-DRBD mediated knockdown.