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Overexpression of epidermal growth factor receptor restricted to macrophages in uveal melanoma
A G Scholes1, S Hagan, P Hiscott
1Unit of Ophthalmology, Department of Medicine, Duncan Building, University of Liverpool, Liverpool L69 3GA, England.
Objective:
To determine whether expression of the epidermal growth factor receptor (EGFR) is of prognostic value in uveal melanoma.
Methods:
Thirty consecutive patients treated for primary posterior uveal melanoma by enucleation or local resection were studied. Tumors were examined for EGFR and CD68 expression by immunohistochemistry on formalin-fixed, paraffin-embedded sections. Extracted DNA from paired frozen tumor and blood samples was examined for loss of heterozygosity on chromosome 3 using polymerase chain reaction-based microsatellite analysis. Immunoreactivity for EGFR was correlated with clinicopathological, chromosome 3, and follow-up data.
Results:
Immunoreactivity for EGFR was observed in 7 (23%) of 30 uveal melanomas, but was restricted to solitary or small groups of cells with macrophage-like morphology. Immunoreactive cells were confirmed as macrophages using an antibody to the macrophage marker CD68. Chromosome 3 loss, epithelioid cells, and microvascular loops were detected in 17 (57%), 22 (73%) and 19 (63%) of the 30 tumors, respectively. Metastatic disease was detected in 5 patients (17%). No correlation was found between any of these variables and EGFR positivity.
Conclusions:
The absence of EGFR immunoreactivity in tumor cells does not support the use of EGFR expression as a prognostic indicator in patients with uveal melanoma. Future EGFR studies in uveal melanoma should be interpreted with caution in view of our findings that tumor-associated macrophages can express this receptor.
Insights
Epidermal growth factor receptor (EGFR) expression is not a prognostic indicator in uveal melanoma. Tumor-associated macrophages, not tumor cells, expressed EGFR, warranting caution in future studies.
Area of Science:
- Ophthalmology
- Oncology
- Immunohistochemistry
Background:
- Uveal melanoma is the most common primary intraocular malignancy.
- Prognostic markers are crucial for guiding treatment and predicting outcomes in uveal melanoma.
- Epidermal growth factor receptor (EGFR) has been investigated as a potential therapeutic target and prognostic factor in various cancers.
Purpose of the Study:
- To investigate the prognostic value of epidermal growth factor receptor (EGFR) expression in uveal melanoma.
- To determine if EGFR expression in tumor cells correlates with clinicopathological features and patient outcomes.
Main Methods:
- Immunohistochemistry was used to detect EGFR and CD68 expression in 30 uveal melanoma samples.
- Loss of heterozygosity on chromosome 3 was analyzed using microsatellite analysis.
- EGFR immunoreactivity was correlated with tumor characteristics and follow-up data.
Main Results:
- EGFR immunoreactivity was found in 23% of uveal melanomas, exclusively in macrophages (confirmed by CD68 staining).
- No correlation was observed between EGFR positivity and chromosome 3 loss, cell type, microvascular loops, or metastatic disease.
- EGFR expression was absent in uveal melanoma tumor cells.
Conclusions:
- EGFR expression in tumor cells is not a prognostic indicator for uveal melanoma.
- Findings suggest that tumor-associated macrophages express EGFR, which must be considered in future research.
- Caution is advised when interpreting EGFR studies in uveal melanoma due to macrophage expression.