Annexin II mRNA coding for a calcium binding protein was found to be absent
in prostate cancer by subtractive hybridization and Northern analysis. In
contrast to high expression in normal and benign hyperplastic glandular and
basal epithelium, Annexin II heavy (p36) and light (p11) chains in 31/31 p
rostate cancer specimens were lost immunohistochemically. In glands involve
d by prostate intraepithelial neoplasia, 65% lost both chains in glandular
epithelial cells, whereas basal cells were all positively stained. Southern
analysis of cancer DNA showed no noticeable deletion in p36 gene. LNCaP ce
lls treated with 5-azacytidine re-expressed p36, suggesting methylation cou
ld be responsible for the silencing.