Cell Culture Model of Stepwise Prostate Carcinogenesis

The novel cell culture model started with primary immortalized prostate epithelial cells (EP156T) (Kogan et al., 2006) of known passage number from our collaborator in Israel, Professor Varda Rotter. EP156T cells passed through epithelial to mesenchymal transition (EMT) during continuous cultivation for several months at saturation density (Ke et al., 2008) (see figure). In subsequent cultivation experiments for several weeks at full confluence, multiple foci were formed in EPT1 cell monolayers (see figure). In contrast, no foci were formed in control EP156T cell monolayers. EPT2 cells were cloned from foci of EPT1 cells by selection of colonies that grew anchorage independently in soft agar. Ability to grow in soft agar is considered a hallmark of malignantly transformed cells.

Our new cell culture model of prostate carcinogenesis is presently characterized using

- microarray gene expression analysis
- microarray microRNA analysis
- microarray ChIP-chip analysis
- numerous phenotypic assays

in order to further explore regulatory patterns involved in EMT, early prostate carcinogenesis and full malignant transformation.

A high priority goal using the cell culture model is to establish conditions that reverse EMT and critical gene expression modules involved in malignant transformation. Different approaches are taken to understand the molecular mechanisms including retroviral vector-mediated overexpression and knockdown of protein- and microRNA-coding genes.

The malignantly transformed EPT2 cells are presently used for the establishment of new animal models in collaboration with Emmet McCormack, Frits Thorsen and Jim Lorens in Bergen.