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Accurate quantitative analysis of cellular proteins using a computerised scanning-aided dot blot technique
A M Nouri1, S J Compton, R T Oliver
1Department of Medical Oncology, Royal London Hospital, England, UK.
Insights
This study introduces a computer-assisted dot blot technique to measure cellular protein expression in tumor cells. The method accurately detects changes in major histocompatibility complex (MHC) Class I and ICAM-1 proteins after interferon stimulation.
Area of Science:
- Molecular Biology
- Immunology
- Biotechnology
Background:
- Cellular protein expression is crucial for understanding tumor behavior and response to therapy.
- Accurate quantification of proteins like MHC Class I and ICAM-1 is vital in cancer research.
Purpose of the Study:
- To develop and validate a computer-assisted dot blot technique (CSDBT) for assessing cellular protein expression.
- To investigate the expression of MHC Class I and ICAM-1 in tumor cell lines.
- To evaluate the impact of interferons (IFN) and drug treatments on these proteins.
Main Methods:
- Utilized a dot blot technique combined with a computerised scanning program (CSDBT).
- Assessed constitutive and induced expression of MHC Class I and ICAM-1 in various tumor cell lines.
- Analyzed protein expression changes following stimulation with IFN-alpha, IFN-gamma, and drug combinations (cycloheximide, indomethacin).
Main Results:
- CSDBT successfully quantified MHC Class I and ICAM-1 expression, showing variations across tumor lines.
- IFN-gamma significantly upregulated MHC Class I and ICAM-1, while IFN-alpha primarily upregulated MHC Class I.
- Drug treatments, particularly cycloheximide, demonstrated significant inhibition of protein expression, with P values < 0.05.
Conclusions:
- The CSDBT is a novel, sensitive, and accurate method for quantifying cellular proteins, including MHC Class I and ICAM-1.
- This technique can detect minor protein expression changes under various conditions.
- Results were consistent with established methods like radiobinding and immunocytochemistry, highlighting CSDBT's potential in cancer research.
Abstract:
The aim of this study was to use a dot blot technique (DB) aided by a computerised scanning programme (CSDBT) to assess expression of cellular proteins in various tumour cell lines. Two groups of proteins, i.e. major histocompatibility complex (MHC) Class I and cell adhesion molecules (e.g. ICAM-1) were investigated. The constitutive expression of Class I antigens was measured and found to vary for different tumour lines. Exposure of SKV14 (SV40 transformed epithelial cells) and 5637 lines (bladder) to interferons (IFN) alpha or gamma resulted in upregulation of Class I antigens. IFN gamma, but not IFN alpha, induced ICAM-1 on all the lines studied. Thus, the stimulatory indices (SI) for Class I antigens in the case of SKV14, J82 (bladder) and 5637 lines after IFN gamma and IFN alpha stimulation were 2.02, 1.77, 4.68 and 1.65, 1.36, 2.08 respectively. The corresponding values for ICAM-1 were 1.65, 1.87, 3.43 and 1.75, 1.0, 0.96. In all the cases, the P values (using a paired t-test), except ICAM-1 for IFN alpha-stimulated J82 cells, were below 0.05. Following exposure of cells to combinations of drugs and IFN alpha, the percentage inhibition for Class I and ICAM-1 in the case of SKV14 and 5367 lines in the presence of cycloheximide (10 micrograms/mL) were 82%, 85% and 57%, 45% respectively. The corresponding values for indomethacin (10 micrograms/mL) were -23%, -52% and -20%, -24%. In all cases, the P values (using a paired t-test) were below 0.05. To our knowledge this is the first report describing a computerised scanning programme for assessing the presence of cellular proteins. The results were consistent with those obtained by radiobinding and immunocytochemistry. This simple and sensitive approach highlighted two important issues: (a) that it can be used to detect minor changes, under various conditions, of cellular proteins whether cytoplasmic or otherwise; and (b) that the accuracy of the measurements was enhanced by the use of computer scanning.
