1. ¹Department of Cytopathology, University of Göttingen, Göttingen, Germany
2. ²Department of General Surgery, University of Göttingen, Göttingen, Germany
3. ³Division of Molecular Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
4. ⁴Department of Pathology, Reinhard Nieter Hospital, Wilhelmshaven, Teaching Hospital of the University of Göttingen, Göttingen, Germany

Correspondence: PD Dr M Korabiowska, MD, PhD, Department of Cytopathology, University of Göttingen, Robert Koch Str. 40, 37075 Göttingen, Germany. E-mail: UBRINCK@AOL.COM

Received 19 March 2004; Revised 1 June 2004; Accepted 1 June 2004; Published online 16 July 2004.

Abstract

Adenomatous polyposis coli gene (APC) defects have been demonstrated for the first time in familial adenomatous polyposis. Recent reports indicate that the APC gene is an intermediary between cell adhesion molecules and the cytoskeleton and that it may function as a gatekeeper of colonic epithelial proliferation. The objective of this study was to analyse APC's presence in lentigos, primary melanomas and melanoma metastases. By immunohistochemistry, APC was demonstrated in all lentigos, in 75 out of 88 primary melanomas and in 16 out of 28 melanoma lymphatic metastases. The percentage of immunolabelled tumour cells (APC index) in lentigos ranged between 5 and 69%, in primary melanomas between 0 and 98% and in melanoma metastases between 0 and 52%. Statistically significant differences between lentigos and primary melanomas and between lentigos and metastases in APC expression were found. In a multivariate analysis, APC showed an independent prognostic impact. Analysis of microsatellite instability in the APC locus was performed on 29 melanomas. Microsatellite instability was found in 5/29 melanomas and loss of heterozygosity in 1/29 melanomas. Promoter methylation of APC was found in 6/10 APC-negative primary melanomas and in 9/10 APC-negative melanoma lymphatic metastases investigated. We conclude about important role of APC alterations for melanoma progression.