Gene profiling of primary cultures from human prostate tumors

The histopathological and molecular heterogeneity of prostate cancer and the limited availability of human tumor tissue make unraveling the mechanisms of prostate carcinogenesis a challenging task. Our goal was to develop an ex vivo model that could be reliably utilized to define a prognostic signature based on gene expression profiling of cell cultures that maintained the tumor phenotype. To this end, we derived epithelial cultures from tissue explanted from 59 patients undergoing radical prostatectomy or cistoprostatectomy because of Prostate Benign Hyperplasia/Prostate Cancer or Bladder Carcinoma. Patient selection criteria were absence of hormonal neo-adjuvant treatment before surgery and diagnosis of clinically localized disease. Using this unique experimental material we analyzed expression of 22.500 transcripts on the Affymetrix Human U133A Gene Chips platform. Cultures from normal/hyperplastic tissues with a prevalent luminal phenotype, and from normal prostate epithelial tissue with basal phenotype (PrEC) served as controls. We have established a large number of prostate primary cultures highly enriched in the secretory phenotype. From them we derived an epithelial-restricted transcriptional signature that: 1) differentiated normal from tumor cells; and 2) clearly separated cancer derived lines into two distinct groups which correlated with indolent and aggressive clinical behavior of the disease. Our findings provide:1) a method to expand human primary prostate carcinoma cells with a luminal phenotype; 2) a powerful experimental model to study primary prostate cancer biology; and 3) a novel means to characterize these tumors from a molecular genetic standpoint for prognostic and/or predictive purposes. Keywords: prostate cancer; gene profile; primary cultures; prognosis; molecular pathology. Gene expression profiling: normal versus PCa-derived cells. RNA was isolated from 22 tumor cultures and hybridized to U133A Affymetrix GeneChips arrays. Since cultures representing matched case controls could not be generated from normal prostate tissue adjacent or controlateral to the lesion, cultures derived from normal/hyperplastic tissues (N1, C10, C17, C16sx) with a prevalent luminal phenotype, and from normal prostate epithelial cells with the basal phenotype (PrEC) were used as controls.This analysis was performed using 30 samples (22 cancer-derived cultures, 4 from normal/hyperplastic tissues, 3 different batches of commercial PREC and 1 LNCAP).