Melanoma inhibitor of apoptosis protein is expressed differentially in melanoma and melanocytic naevus, but similarly in primary and metastatic melanomas

Abstract

Background: Malignant melanoma is highly resistant to current treatments. The inhibitor of apoptosis protein (IAP) family member, melanoma IAP (ML-IAP), is overexpressed in some melanoma cell lines, rendering them resistant to apoptotic signals. Targeting ML-IAP is a promising approach to treating melanoma. However, the status of ML-IAP expression in human melanoma tissues and the difference in expression between melanoma and melanocytic naevus are not known.

Aims: To investigate these issues.

Methods: ML-IAP expression in 48 archived patient samples (34 melanomas and 14 dermal naevi) was assessed by immunohistochemistry and by in situ hybridisation and reverse transcription polymerase chain reaction (RT-PCR) assays developed for the study.

Results: Expression of ML-IAP was detected in 47.6–70.6% (10 of 21 to 24 of 34) of the melanomas, varying with detection methods. The expression rate in melanoma was much higher than that in melanocytic naevus (10.0–21.4%; one of 10 to three of 14). No significant difference was seen between primary and secondary melanomas. ML-IAP expression rates assessed by the three methods were in agreement.

Conclusions: The ML-IAP expression rate in archived melanoma tissues is around 50–70%, with no difference between primary and secondary melanomas. A small number of dermal naevi (~ 20%) also expressed ML-IAP.