New colorimetric cytotoxicity assay for anticancer-drug screening

Area of Science:

• Biochemistry
• Cell Biology
• Drug Discovery

Background:

• Accurate measurement of cellular protein is crucial for assessing cell viability and drug efficacy.
• Existing protein assays can be time-consuming, expensive, or lack sensitivity for high-throughput screening.

Purpose of the Study:

• To develop and validate a rapid, sensitive, and inexpensive method for quantifying cellular protein content.
• To establish an assay suitable for both standard laboratory use and large-scale drug screening applications.

Main Methods:

• Utilized sulforhodamine B (SRB) staining of trichloroacetic acid-fixed cells in 96-well microtiter plates.
• Measured protein-bound SRB dye via optical density using a microtiter plate reader.
• Compared SRB assay results with Lowry and Bradford protein assays and fluorescence-based methods.

Main Results:

• The SRB assay demonstrated linearity with cell number and protein content across a wide density range.
• Achieved a signal-to-noise ratio of approximately 1.5 with as few as 1,000 cells per well.
• SRB assay sensitivity was superior to Lowry, Bradford, and 20 other visible dyes, and comparable to fluorescence assays.

Conclusions:

• The SRB assay is a robust, cost-effective, and sensitive method for measuring cellular protein.
• Its suitability for high-volume, automated screening makes it valuable for drug discovery and cytotoxicity assessment.
• The assay provides a stable, visible endpoint and can be used for clonogenicity and single-cell analysis.