A QC-guided Framework for Performance Assessment in Plate-Based RNAi Screening with Fluorescence and Metabolic Readouts

RNA interference (RNAi) screening is widely used for systematic gene perturbation, but reproducible readouts depend on careful assay design and consistent performance. Here, we describe a plate-based small interfering RNA (siRNA) screening workflow that combines repeated green fluorescent protein (GFP) fluorescence measurements (0-72 h) with an orthogonal endpoint XTT metabolic readout performed in the same wells. Using a medium-scale siRNA library and technical replicate plates, we establish a quality control (QC)-guided framework for evaluating assay performance, providing a robust basis for downstream gene-level hit identification. Complementary metrics, including coefficient of variation (CV), strictly standardized mean difference (SSMD), and Spearman rank correlation, were used to assess variability, control separation, and replicate concordance across plates and time points. These analyses revealed improved assay performance at later time points, with increased control separation and reproducibility, supporting the selection of 72 h as the most robust endpoint for downstream comparisons in the present screening workflow. Together, the workflow and QC framework provide a transferable strategy for qualifying plate-based RNAi screening experiments, enabling reliable downstream hit selection and follow-up studies.