The oncogene Wnt7b is implicated in the development of superficial bladder tumours
O'Brien T., Bui T., Crew J., Cranston D., Harris A.
Introduction: The Wut genes are a family of eight genes which are involved in cell adhesion and embryonic tissue pattern formation. Some of the family are transforming genes, e.g. Wnt7b, whilst others are not, e.g. Wnt5a. Both Wnt5a and Wnt7b have recently been implicated in breast oncogenesis. Materials and methods: The expression of Wnt 5a and 7b mRNA was determined by ribonuclease protection analysis in eight normal bladder samples and 48 tumours (nine pTa, 22 pT1 and 17 pT2-4). Results: Wnt7b expression was highest in superficial tumours (the median expression was fivefold higher than normal bladder: P < 0.002. Maun-Whitney). There was no difference in median Wnt7b expression between normal tissue and invasive tumours (P < 0.3). Wnt7b expression was most markedly and consistently elevated in pTa tumours (the median pTa expression was sevenfold higher than normal; P < 0.008). Eight of nine pTa tumours expressed levels above the highest normal sample, whereas only one of 17 invasive tumours did so. Expression was more variable in pT1 tumours, perhaps in keeping with their more unpredictable biological potential. The median Wnt5a expression was similar in normal tissue and in the tumours of different stages, although occasional over-expression was seen in individual tumours. Conclusion: This study implicates Wnt7b in the development of superficial bladder tumours, and lends support to the idea of separate genetic pathways in the evolution of bladder cancers. © 1997 British Journal of Urology.