Epidermal Growth Factor Is Increased in Conjunctival Malignant Melanoma

Abstract

Background/aim: Conjunctival malignant melanoma (CMM) is a rare, but very aggressive tumor with a high metastasis rate. Not much is known about the CMM metastasis mechanisms. So far, epidermal growth factor (EGF) and its receptor (EGF-R) as well as macrophages and matrix metalloproteinase 9 (MMP-9) have been reported to lead to metastasis by epithelial-mesenchymal-transition and tumor migration in different solid tumors. Therefore, we evaluated whether EGF and EGF-R, CD68 and MMP-9 are altered in CMM samples in comparison to conjunctival nevi and healthy conjunctiva.

Patients and methods: EGF, EGF-R, the macrophage marker CD68 and MMP-9 expression were analyzed in human conjunctival melanoma (CMM, n=16), human conjunctival nevi (n=13) and disease-free human conjunctiva (controls, n=14) by immunohistology. Staining of each sample was evaluated using a standardized score ranging from negative (0) to triple positive (3). The groups were then compared by ANOVA, followed by Tukey's post-hoc test.

Results: A statistically significant increase of EGF was seen in CMM samples in comparison to conjunctival nevi (p=0.03). In contrast, no statistically significant differences in EGF-R expression were noted between the three groups. A statistically significant increase of CD68 was only seen in conjunctival nevi compared to controls (p=0.04). MMP-9 expression was similar in all groups.

Conclusion: In CMM, the study data demonstrated an up-regulation of EGF in comparison to conjunctival nevi. Hence, EGF might promote proliferation of CMM cells and induce the epithelial-mesenchymal transition. Therefore, our data suggest that an interplay between EGF and CMM might have a critical role in the developing CMM tumors and metastasis.

Keywords: EGF; EGF-receptor; MMP-9; conjunctival malignant melanoma; macrophage.