Background beta -catenin plays a crucial role in the function of cell adhes
ion molecules and also participates in growth regulatory signalling pathway
s that may be involved in malignant transformation.
Objectives To examine beta -catenin expression in lesions of melanocytic or
igin for associations with clinicopathological markers of disease progressi
on and for its significance as a predictor of disease recurrence and progno
sis.
Methods beta -catenin expression was examined by immunoperoxidase staining
in 50 melanocytic naevi and 91 primary and 50 metastatic melanomas,
Results beta -catenin was expressed in 96% of melanocytic naevi, in 94% and
65%, respectively, of radial and vertical growth phase primary melanomas,
and in 38% of metastatic melanomas. Benign and malignant melanocytic lesion
s had distinct patterns of beta -catenin localization. Most lesions express
ing beta -catenin exhibited cytoplasmic staining: however. over 40% of beni
gn lesions also displayed nuclear staining, which was present only in 10% o
f primary and 15% of metastatic melanomas. Absent or weak expression of bet
a -catenin in primary melanomas was associated with several markers of dise
ase progression, including tumour thickness and presence of lymph node meta
stases. A similar but not statistically significant trend was observed for
the association of beta -catenin expression with disease recurrence and pro
gnosis.
Conclusions These results suggest that loss or downregulation of beta -cate
nin expression in melanoma cells plays a significant role in progression of
the disease.