Enhanced expression of vimentin in motile prostate cell lines and in poorly differentiated and metastatic prostate carcinoma

BACKGROUND. The metastatic potential of a series of prostate cell lines was analysed by measuring motility and invasiveness, and further correlated to the expression of epithelial differentiation markers. METHODS. Invasion and motility were measured using in vitro assays. Immunohistochemistry of cell lines and tissues was used to identify expression of cytokeratins 8 and 1, 5, 10, 14, vimentin, prostate specific antigen, prostate specific membrane antigen, androgen receptor, desmoglein, E-cadherin, beta1 integrin, CD44, hmet, vinculin and actin. RESULTS. Expression of vimentin was the only marker to correlate with motility, no markers correlated to invasion. Lower vimentin expression was observed in cells with low motility (PNT2-C2) and high expression in cells with high motility (P4E6, PNT1a, PC-3). Vimentin expression was not detected in well differentiated tumours, moderately differentiated tumors contained vimentin positive cells (1/9 bone scan negative, 2/5 bone scan positive), but the majority of poorly differentiated cancers (4/11 bone scan negative, 9/14 bone scan positive) and bone metastases (7/8) had high vimentin expression in tumor cells. CONCLUSIONS. Motile prostate cancer cell lines express vimentin. In tissue sections, the presence of vimentin positive tumour cells correlated positively to poorly differentiated cancers and the presence of bone metastases.