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Sensitive immunoassay of tissue cell proteins procured by laser capture microdissection
N L Simone1, A T Remaley, L Charboneau
1Laboratory of Pathology, National Cancer Institute, and the Clinical Pathology Department, Clinical Center, National Institutes of Health, Bethesda, Maryland, USA.
The American Journal of Pathology
|February 10, 2000
Summary
Laser capture microdissection (LCM) combined with chemiluminescent immunoassays allows precise quantification of prostate-specific antigen (PSA) molecules per cell in human prostate tissue. This method reveals significant variations in PSA levels across normal, pre-cancerous, and cancerous cells.
Area of Science:
- Proteomics
- Molecular Biology
- Biochemistry
Background:
- Quantitative proteomics is crucial for understanding cellular function and disease mechanisms.
- Analyzing specific cell populations within heterogeneous tissues presents significant challenges.
- Laser capture microdissection (LCM) offers a method for isolating pure cell populations from tissue sections.
Purpose of the Study:
- To develop and validate a method for quantifying prostate-specific antigen (PSA) molecules per cell using LCM and chemiluminescent immunoassays.
- To assess the applicability of this technique for analyzing protein expression in pure cell populations from human prostate tissue.
- To compare quantitative immunoassay results with immunohistochemical staining for PSA.
Main Methods:
- Human prostate tissue sections were microdissected using LCM to isolate specific cell types.
- Solubilized macromolecules from captured cells were assayed using a sensitive sandwich chemiluminescent immunoassay.
- A standard curve with known PSA concentrations was used for assay calibration.
- Immunohistochemical staining for PSA was performed on adjacent tissue sections for comparison.
Main Results:
- The LCM-coupled immunoassay demonstrated high sensitivity, precision (within-run SD ≤10%), and linearity.
- Quantification revealed a wide range of PSA molecules per cell (2 x 10^4 to 6.3 x 10^6) in normal, PIN, and invasive carcinoma tissues.
- Quantitative immunoassay results correlated well with qualitative immunohistochemical staining intensity, confirming tissue heterogeneity for PSA expression.
Conclusions:
- Coupling LCM with sensitive quantitative chemiluminescent immunoassays is a robust method for determining protein levels in pure cell populations.
- This technique provides valuable insights into protein heterogeneity within complex tissues like the prostate.
- The method is adaptable for quantifying both secreted and membrane-bound proteins, with broad applications in proteomics research.