Keratin profiling in the developing human prostate. A different approach to understanding epithelial lineage.

BACKGROUND Keratin profiling studies in the developing human prostate have characterized cells thought to be stem cells and so-called intermediate cells. In a series of human prostates of various gestational ages, we extended on these studies using a comprehensive panel of keratin antibodies. MATERIALS AND METHODS Autoptic tissue from 19 fetal prostates, gestational ages between 16 and 40 weeks, were immunostained with a panel of keratin antibodies: these recognize the luminal type keratins 7, 8, 18, 19, 20 and the basal/squamous type keratins 5, 6, 13, 14, 17. RESULTS Keratin8 and vimentin were important constituents of the cytoskeleton of budding tips in early gestational age fetuses. Very early in gestation, additional expression of keratins 5 and 13 was noted and, with time, increasing expression of keratins 7, 18 and 19, and also incidentally keratins 14 and 17. With differentiation into basal cell and luminal cell compartments and the formation of prostate acini, the keratin complement of basal and luminal cells became more pronounced, but only partial compartmentalization of keratin expression occurred. CONCLUSION We suggest that prostate stem cells may contain only keratin8 and not 5 or 14. The acquisition of other keratins could be indicative of the function the cells will eventually acquire.