Laser-capture microdissection impairs activity-based protein profiles for serine hydrolase in human lung...

Laser-capture microdissection (LCM) enables the selection of a specific and pure cell population from a heterogenous tissue such as tumors. Activity-based protein profiling/profile (ABPP) is a chemical technology using enzyme-specific active site-directed probes to read out the functional state of many enzymes directly in any proteome. The aim of this work was to assess the compatibility of LCM with downstream ABPP for serine hydrolase (SH) in human lung adenocarcinoma. Fresh frozen lung adenocarcinoma tissue was stained with hematoxylin, toluidine blue, or methyl green (MG). Proteome from stained tissue was labeled further with SH-directed probes, and ABPPs were determined on a one-dimensional gel-based approach. This allowed us to assess the impact of staining procedures on their ABPPs. The effect of the LCM process on ABPPs was assessed furthermore using MG-stained lung adenocarcinoma tissue. The staining procedures led to strong changes in ABPPs. However, MG staining seemed the most compatible with downstream ABPP. MG-stained, laser-captured, microdissected tissue showed additional change in profiles as a result of the denaturing property of extraction buffer but not to the microdissection process itself. LCM staining procedures but not microdissection per se interfered with downstream ABPP and led to a strong change in ABPPs of SHs in human lung adenocarcinoma.