DISSECTION OF TUMOR AND HOST-CELLS FROM TARGET ORGANS OF METASTASIS FOR TESTING GENE-EXPRESSION DIRECTLY EX-VIVO

We report on a new methodology which allows the direct analysis ex viv o of tumour cells and host cells (lymphocytes, macrophages, endothelia l cells) from a metastasised organ (liver or spleen) at any time point during the metastatic process and without any further in vitro cultur e. First, we used a tumour cell line transduced with the bacterial gen e lacZ, which permits the detection of the procaryotic enzyme beta-gal actosidase in eukaryotic cells at the single cell level thus allowing Bow adhesion cell sorting (FACS) analysis of tumour cells from metasta sised target organs. Second, we established a method for the separatio n and enrichment of tumour and host cells from target organs of metast asis with a high viability and reproducibility. As exemplified with th e murine lymphoma ESb, this new methodology permits the study of molec ules of importance for metastasis or anti-rumour immunity (adhesion, c ostimulatory and cytotoxic molecules, cytokines, etc.) at the RNA or p rotein level in tumour and host cells during the whole process of meta stasis. This novel approach may open new possibilities of developing s trategies for intervention in tumour progression, since it allows the determination of the optimal window in time for successful treatments. The possibility of direct analysis of tumour and host cell properties also provides a new method for the evaluation of the effects of immun isation with tumour vaccines or of gene therapy.