Epithelial and prostatic marker expression in short-term primary cultures of human prostate tissue samples

Despite the high incidence and mortality of prostate cancer (PCa), molecular and genetic events involved in its progression remain poorly understood due to difficulty in establishing premalignant lesions and primary tumors in vitro. The most used cancer cell lines, which have been established primarily from metastatic lesions, do not accurately recapitulate the biological behaviour of primary tumors as compared to primary cultures generated from clinical PCa specimens. However, prostate primary cultures contain a mixture of different cell types which must be characterized completely to obtain reproducible information for studying the biology of single tumors and for evaluating the effectiveness of therapeutical approaches. In this report we show the differential expression of epithelial and prostatic markers in 30 PCa-, 6 high grade prostate intraepithelial neoplasia (PIN)- and 6 BPH-derived primary cell cultures. After organoids attached, outgrowths appeared with cells maintaining close cell-to-cell associations: cell colonies express either cyto-keratin 14 [K14 (20-60%)], or cytokeratin 18 [K18 (10-70%)] with moderately high levels of androgen receptor (AR), prostate-specific antigen (PSA) and kallikrein (hK2). The differences observed for K14 immunostaining was not statistically different between PIN- and BPH-derived cultures, whereas the difference of expression of the same marker resulted highly significant (p<0.001) in the comparison between PIN- and PCa-derived cultures and between BPH- and PCa-derived cultures. In addition, the percentage of positivity for lumenal K18 was statistically lower for BPH cultures respect to the positivity observed for both PIN and PCa-derived cultures (p<0.05 and p<0.001, respectively). A reduced expression of K18+ cells, without modification in K14 expression, was evident in high grade PCa in which we observed also an increment in K5 expression representing an intermediate basal/differentiating epithelial cell marker. The primary cultures derived from prostatic tissues can be an extremely important method to study genetic and molecular changes involved in PCa progression.