The needle in the haystack: application of breast fine-needle aspirate samples to quantitative protein microarray...

Area of Science:

• Oncology
• Proteomics
• Molecular Diagnostics

Background:

• Clinical need for economical, minimally invasive tumor molecular profiling using limited cells.
• Reverse-phase protein microarray (RPPM) technology successfully applied to various cancers from frozen specimens.

Purpose of the Study:

• Investigate RPPM for analyzing archival cytology smears and frozen fine-needle aspiration (FNA) samples.
• Assess RPPM's utility in breast cancer patient samples during neoadjuvant therapy.

Main Methods:

• RPPM analysis of 63 breast FNA samples from 21 patients undergoing neoadjuvant capecitabine and docetaxel therapy.
• Validation using MCF7 breast adenocarcinoma cell line for sensitivity and linearity assessments.

Main Results:

• RPPM demonstrated femtomolar sensitivity and coefficient of variance <13.5% for dilute samples.
• Assay linearity confirmed from 1.0 microg/microL to 7.8 ng/microL for total protein and EGFR.

Conclusions:

• RPPM technology can quantify low-abundance, phosphorylated, and non-phosphorylated proteins from FNA specimens (few thousand cells).
• Monitoring in vivo cell-signaling proteins before and after treatment aids individualized therapy design.
• Mapping protein pathways facilitates rational drug target development.