The potential use of laser capture microdissection to selectively obtain distinct populations of cells for proteomic analysis - Preliminary findings

Proteomics-based studies offer a powerful complementary approach to DNA/RNA -based investigations and are now being applied to investigate aspects of m any diseases including cancer. However, the heterogeneous nature of tissue samples often makes interpretation difficult. We have undertaken a study in to the potential use of a novel laser capture microdissection (LCM) system to isolate cells of interest for subsequent proteomic analysis. Retrieval o f selected cells is achieved by activation of a transfer film placed in con tact with a tissue section, by a laser beam (30 or 60 mu m diameter) which is focused on a selected area of tissue using an inverted microscope. The p recise area of film targeted by the laser bonds to the tissue beneath it an d these cells are then lifted free of surrounding tissue. Although the tech nique has been shown to be readily compatible with subsequent analysis of n ucleic acids, little information is yet available regarding the application of protein-based analyses to the captured tissue. We report here prelimina ry data regarding the potential use of the LCM system in combination with t wo-dimensional electrophoresis to examine protein profiles of selected tiss ue areas. Electrophoretic profiles of proteins from normal and malignant re nal tissue samples showed little change following LCM, nine selected protei ns showed identical mass spectrometric sequencing profiles, and two selecte d proteins retained antigenicity. Dissection of epithelial tissue from a sa mple of normal human cervix resulted in enrichment of some proteins compare d with analysis of the whole tissue. LCM will be a valuable adjunct to prot eomic studies although further detailed validation is necessary.