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

Abstract

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). 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. 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. 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.