Beta-catenin signaling in prostate cancer: an early perspective.

Further understanding of the molecular mechanisms responsible for prostate cancer (CaP) development and progression is paramount for overcoming the current diagnostic and therapeutic hurdles presented by this urologic disease. The beta-catenin nuclear signaling molecule has been widely implicated as an oncogene in human cancer, including CaP. Pooling together knowledge gathered on the contributions of beta-catenin and other factors to human neoplasia may assist in the development of better strategies for management and treatment of prostate tumors of all stages (early, advanced/androgen-dependent, advanced/androgen-independent). Although there is considerable lack of comprehension regarding the function of beta-catenin transcriptional activity in prostate tumors in vivo, recent evidence indicates the probability that beta-catenin contributes to multiple signaling pathways for which a causative role in CaP is already known. In this review, we will approach such pathway interactions, perhaps the most notable being androgen receptor (AR) signaling, in order to highlight those avenues through which beta-catenin may exert its cancer-related function. To the same end, we will draw attention to normal beta-catenin signaling in the prostate; however, as only very limited knowledge exists on this topic, much of the discussion will be correlative. Our final topic will concentrate on how, given realistic scenarios of androgen stimulation or absence in both normal and neoplastic prostate cells, nuclear beta-catenin may ultimately potentiate wnt cell-cell signaling and AR activities. Heightening our comprehension of beta-catenin signaling mechanisms and its phenotypic consequences in CaP - and in normal prostate - may contribute to that body of knowledge which will eventually prove useful for devising more effective therapies.

Detection and analysis of beta-catenin mutations in prostate cancer.

BACKGROUND: E-cadherin and alpha-catenin are components of adherens junctions which mediate calcium-dependent, cell-cell adhesion in a homotypic manner. Both these molecules have been defined as useful tumor markers as their altered expression correlates with increased tumor aggressiveness and dedifferentiation. More recently, alterations of a third component of adherens junctions, beta-catenin, have been observed to play a role in several human cancers. Dysregulation of beta-catenin, either by direct mutation or by defects in interacting pathways/regulators, can result in its cytoplasmic accumulation and nuclear translocation. In the nucleus, beta-catenin forms a transcriptional complex capable of upregulating target genes, many of which encode proliferative factors. Given its oncogenic activity and connection to human cancer, we examined the beta-catenin gene and its expression in prostate cancer. METHODS: By single-stranded conformational polymorphism (SSCP) and DNA sequencing analyses, we screened exon 3 of beta-catenin from a panel of 81 primary tumors obtained at radical prostatectomy, 22 lymph node metastases from untreated patients, and a unique set of 61 metastatic tissues from 19 patients who died of hormone-refractory disease. RESULTS: We found putative activating mutations (missense and deletion) at a rate of 5% (7/138). One patient had the same 72 base pair deletion in each of nine separate metastases examined, indicating that this change was associated with a clonal population of metastatic cells. CONCLUSIONS: Immunohistological staining of mutation-positive tumors demonstrated beta-catenin accumulation and nuclear localization in a heterogeneous fashion. Consistent with this in vivo finding, our in vitro analyses demonstrate that certain mutations can result in increased beta-catenin nuclear activity in prostate cancer cell lines. These data implicate the beta-catenin signaling pathway in the development of a subset of prostate cancers.