Loss of normal
beta-catenin expression and the
beta-catenin gene mutations have been shown to contribute to the malignant character of various
cancers. Using PCR-single-strand conformation polymorphism and
DNA direct sequencing, we examined the presence of genetic alterations within the third exon of
beta-catenin, which are frequently observed in other
tumors, in transitional cell
cancer (TCC) and
renal cell cancer (RCC) cell lines, and in
tumor specimens. The degrees of expression and intracellular distribution of
beta-catenin were detected by immunohistochemical staining in 77 primary and 12 metastatic RCCs and in 81 primary TCCs. Western blot analysis was also applied to confirm the degree of
beta-catenin expression in the cell lines and some
tumor samples. We failed to reveal any genetic alterations, at least in the third exon of the
beta-catenin gene, in RCC and TCC. Reduced membranous immunoreactivity of
beta-catenin was observed in portions of RCC (15.5%) and TCC (24.7%) and was correlated with advanced stages and nodal involvement in RCC and with advanced stages and multiple
tumors in TCC. Within the power limitations of this small study,
beta-catenin abnormal expression was not correlated with recurrence or survival in either RCC or TCC. Interstitial deletions and mutations in the third exon of
beta-catenin do not play a significant role in RCC or TCC
tumorigenesis. Down-regulation of normal
beta-catenin expression might contribute to the malignant character of RCC and TCC and result in
tumor progression. However, this event is not an independent prognostic factor for recurrence or
tumor specific survival.