Integration of Chromogenic RNAscope In Situ Hybridization for Target Validation in Drug Discovery

Area of Science:

• Biopathology
• Molecular Pathology
• Genomics

Background:

• Target validation requires characterizing novel targets in normal and diseased tissues.
• Traditional methods like RNA sequencing lack spatial expression data.
• Immunohistochemistry (IHC) is common but requires specific antibodies.

Purpose of the Study:

• To present a Chromogenic RNAscope in situ hybridization (CISH) workflow for spatial gene expression analysis.
• To demonstrate CISH as a valuable tool for target validation and spatial characterization.
• To highlight CISH as a complement or alternative to IHC.

Main Methods:

• RNAscope ISH workflow on frozen or FFPE tissues.
• Initial RNA quality assessment using housekeeping genes.
• CISH for target mRNA detection.
• Quantification of CISH signals using VisioPharm software (color deconvolution, size gating, dot density thresholding).

Main Results:

• The CISH workflow successfully detects and quantifies mRNA expression spatially within tissues.
• RNA qualification ensures reliable assay performance.
• Quantification methods allow for objective assessment of target expression.

Conclusions:

• CISH is an effective method for spatial characterization of novel targets.
• This workflow can support IHC assay development or serve as a surrogate for single-cell IHC.
• The presented RNA workflow is valuable for target validation in pathology.