Testosterone regulates cell proliferation in aggressive fibromatosis (desmoid tumour)

BACKGROUND: Aggressive fibromatosis (desmoid tumour) is a locally invasive tumour caused by mutations resulting in β-catenin protein stabilisation. Apc1638N mice are predisposed to developing aggressive fibromatosis tumours, and male mice develop greater numbers of tumours than female mice, suggesting a role for androgens in this tumour type. METHODS: Human aggressive fibromatosis tumours were examined for the expression of the androgen receptor, and primary human tumour cell cultures were treated with testosterone. Orchidectomised Apc1638N mice were investigated for the development of tumours, and were treated with testosterone to study the effect of tumour formation and the level of β-catenin. RESULTS: Androgen receptors are universally expressed in human aggressive fibromatosis tumours. Testosterone increased the proliferation rate and β-catenin protein level in a dose-dependent manner in human aggressive fibromatosis tumours. Orchiectomy reduced the number and size of tumours that formed in male Apc1638N mice to a similar level as observed in female mice. Testosterone treatment increased the number of tumours that formed in orchidectomised male mice, and resulted in a marked increase in β-catenin protein levels. CONCLUSION: Testosterone regulates β-catenin protein level and proliferation rate in this mesenchymal tumour. This work identifies the therapeutic use of testosterone blockade in aggressive fibromatosis as an area for further investigation.