miRNA expression profile of pre-transfected HEY cells

MicroRNAs (miRNAs) are short (~22 nucleotides) regulatory RNAs that can modulate gene expression and are aberrantly expressed in many diseases including cancer. We wanted to quantify the levels of endogenous miRNAs in pre-transfected HEY ovarian cancer cells to identify the highly expressed miRNAs. It was previously established that transfection of small RNAs can globally perturb gene expression, and one mechanism responsible for such alterations may involve de-repression of targets of endogenous miRNAs because of the saturation of the RISC complexes by the exogenously administered small RNA (Khan et al., 2009. Nat Biotechnol 27, 549-555). By measuring the levels of miRNAs in the pre-transfected HEY cells, we wanted to determine the miRNAs most highly expressed in HEY cells, and therefore, most likely to experience the effects of such competition. miRNAs were collected from duplicate wells of HEY cells grown in 6-well plates after ~64 hours of seeding (~1.5E5 cells/well). The miRNA expression pattern was determined using an Affymetrix GeneChip miRNA Array.