EXPRESSION OF E-CADHERIN, ALPHA-CATENIN AND BETA-CATENIN IN NORMAL OVARIAN SURFACE EPITHELIUM AND EPITHELIAL OVARIAN CANCERS

Aims: To study the expression of the epithelial adhesion molecule E-ca dherin and its associated proteins alpha and beta catenin in paraffin sections of normal ovaries, benign cystadenomas and ovarian carcinomas , and in immortalized normal ovarian surface epithelial cells and ovar ian carcinoma cells in culture, Methods and results: Immunocytochemist ry was used to to study expression of the proteins in paraffin section s and western blotting was used to determine levels of expression of t he proteins in cell extracts, E-cadherin expression was found to be ab sent in ovarian surface epithelial cells in culture and infrequently e xpressed in normal ovarian surface epithelial cells in vivo, although apical punctate staining was occasionally seen, Seven of nine benign c ystadenomas and 29/34 epithelial ovarian carcinomas showed some expres sion of E-cadherin, but expression was absent in poorly differentiated tumours, Expression of alpha and beta catenin was consistently detect ed on the lateral membranes of normal ovarian epithelium and benign cy stadenomas, alpha and beta catenin expression was lost in 18% and 21% of ovarian carcinomas, respectively; other ovarian carcinomas expresse d these proteins at a reduced level, A small number of these tumours s howed a diffuse cytoplasmic rather than membranous staining, Reduced s taining for alpha and beta catenin appeared to correlate with a more s pindly, less adhesive morphology and increased invasive potential in m atrigel. Conclusions: The results suggest that E-cadherin expression i s generally induced in well differentiated ovarian cancers, In contras t, alpha and beta catenins are consistently expressed in the normal ov arian surface epitheium and benign tumours, but are sometimes reduced or absent in ovarian carcinomas, It is likely that the catenins associ ate with membrane proteins other than E-cadherin in ovarian epithelium , and they may possibly function as tumour suppressors in this epithel ium.