This study addresses the immunohistochemical expression of the
E-cadherin and
catenin families and mutations of the
beta-catenin gene detected by PCR-SSCP in
synovial sarcoma. Immunohistochemical analysis was performed for 72 cases, with follow-up data available on 62. The prognostic value of the expression of these
proteins was evaluated. Reduced immunoreactivity for
E-cadherin and
alpha-catenin was significantly correlated with a poor survival rate (p=0.0040 and 0.0053, respectively). According to multivariate analysis, low AJC stage (stages I and II: p<0.0001), the preservation of
alpha-catenin expression (p=0.0001), and a low necrotic rate (<50%: p=0.0139) were independent favourable prognostic factors. Widespread aberrant staining of
beta-catenin protein within cytoplasm and/or nuclei was observed in 28 cases (38.9%) and was significantly correlated with poor survival (p=0.0122). In addition, there was a trend towards a correlation between widespread aberrant staining of
beta-catenin and the MIB-1 labelling index (p=0.0535). Mutational analysis of exon 3 of the
beta-catenin gene was performed for 49 cases.
Nucleotide sequencing analysis revealed that four (8.2%) contained point mutations (three in
codon 32, GAC to TAC; one in
codon 37, TCT to TTT). Survival data were available for three out of four cases with
beta-catenin mutations; two of these patients died within 1 year (died of disease at 6 and 11 months, respectively). These results suggest that
E-cadherin and
alpha-catenin undertake important roles as
intercellular adhesion molecules; their preserved expression is associated with a better overall survival rate in
synovial sarcoma and may have prognostic value. Abnormal levels of
beta-catenin, with or without mutation, could contribute to the development and progression of
synovial sarcoma, through increasing the proliferative activity of the tumour cells.