Expression of HSP 90, PTEN and Bcl-2 in conjunctival melanoma

Abstract

Background: In conjunctival melanoma, little is known about the tumour biology and protein-expression patterns. In this study, the authors analysed the expression of the antiapoptotic oncoprotein B cell leukaemia/lymphoma-2 protein (Bcl-2), the tumour-suppressor phosphatase and tensin homologue deleted on chromosome ten (PTEN), and the heat-shock-protein HSP-90 in conjunctival melanoma (CoM) and conjunctival nevi (CoN) by immunohistochemistry (IHC).

Material and methods: IHC was performed on 70 samples of CoM and 12 samples of CoN. Expression patterns between the diagnosis groups were compared. A receiver operating characteristic analysis was performed to determine the diagnostic value of the antigens.

Results: HSP-90 (p<0.0001) and PTEN (p=0.001) showed the potential to differentiate between CoM and CoN. Bcl-2 expression was higher in CoM than in CoN (p=0.04). The loss of nuclear PTEN expression was more pronounced in the malignant melanomas than in CoN (p=0.02). Tumours located at unfavourable sites (fornix, palpebral conjunctiva, caruncle) that had developed recurrences expressed almost twice as much HSP-90 than recurrence-free tumours.

Conclusions: Conjunctival melanocytes differentially express Bcl-2, HSP-90 and PTEN, depending on their entity. HSP-90- and PTEN expression may add relevant information for the differentiation between conjunctival melanoma and nevi.