Identification of metastasis-associated genes in prostate cancer by genetic profiling of human prostate cancer cell lines.

OBJECTIVES: Prostate cancer (PCa) is a heterogeneous tumour entity with known interindividual differences in biological behaviour regarding tumour aggressiveness and metastatic potentiaL To date, the prediction of the metastatic status of patients with PCa has not been possible. To identify the molecular causes behind these differences, the gene expression profiles of two cell lines (LNCaP and LNCaP C4-2) with different metastatic potentials were examined using DNA microarray technology. MATERIALS AND METHODS: LNCaP and LNCaP C4-2 cells were cultured under standard conditions. RNA was isolated using Trizol extraction. After processing the total RNA according to the manufacturer's instructions, we performed Affymetrix GeneChip analysis with HG-U133A chips. Data analysis was performed using NetAffx, dChip, GenMAPP and OMIM software. RESULTS: After statistical evaluation of the raw data, we obtained a set of 158 differently expressed probe sets in the LNCaP and LNCaP C4-2 cells. The search for genes associated with proliferation, cell metabolism, growth factors, metastatic potential and tumour progression in this list revealed a number of 42 differently expressed probe sets. The comparison of this list of probe sets with the literature resulted in a list of 14 differently expressed genes which could well contribute to the metastatic potential and progression of PCa. Of these 14 genes only 6 (Cip1, IGF-1, NK4, CXCL 12, ILGF2R, RHOE) have already been associated with PCa, whereas the other 8 genes (FSTL-1, SOCS-2, Midkine, Thrombospondin 1, Secretory leukocyte protease inhibitor, Desmoglein 2, MLT 1, PTPRF) had not been previously related to PCa. CONCLUSION: DNA microarray technology offers the possibility of screening a large number of genes with regard to alterations in the expression level or mutations. In this study, we identified 14 genes that are most probably associated with the higher metastatic potential of LNCaP C4-2 cells as compared to LNCaP cells. Eight of these 14 genes are potential new molecular markers for assessing the metastatic potential of PCa, or may serve as therapeutical targets.