Enhanced Missing Proteins Detection in NCI60 Cell Lines Using an Integrative Search Engine Approach

Area of Science:

• Proteomics
• Human Proteome Project (HPP)
• Mass Spectrometry

Background:

• The Human Proteome Project (HPP) aims to map the entire human proteome.
• Significant efforts focus on identifying 'missing proteins' lacking mass spectrometry evidence.
• Shotgun proteomics data analysis is crucial for validating protein existence.

Purpose of the Study:

• To identify missing proteins within the NCI60 cell line proteome.
• To leverage complementary search engine results for increased proteome coverage.
• To suggest strategies for further validation of identified missing proteins.

Main Methods:

• Utilized proteomic experiments from NCI60 cell lines.
• Applied an integrative approach using Comet, Mascot, OMSSA, and X!Tandem search engines.
• Combined proteomic data with gene expression levels from NCI60 and CCLE projects.

Main Results:

• Identified five missing proteins compliant with C-HPP guidelines, requiring further validation.
• Detected 165 missing proteins with single unique peptides, functionally linked to cellular pathways.
• Proposed alternative validation strategies by integrating gene expression and proteomic data.

Conclusions:

• The integrative analysis of NCI60 proteomic data successfully identified several missing proteins.
• Functional analysis supports the biological relevance of proteins detected with limited evidence.
• Combined gene expression and proteomic data offer a pathway for future missing protein validation.