CONFOCAL LASER-SCANNING MICROSCOPY OF ONCOGENE LOCALIZATION IN RAINBOW-TROUT CELL-LINES DERIVED FROM NORMAL AND TUMOR-TISSUE

We examined the localization and expression of the nuclear oncoprotein c-myc and the cytoplasmic membrane-associated oncoprotein c-ras in ra inbow trout cell lines derived from both normal and tumor tissue in or der to question whether c-myc and ras oncoprotein immunostaining was i ncreased in cells derived from tumors compared to cells derived from n ormal tissue. Cell lines examined were derived from normal rainbow tro ut gonadal cells (RTG-2), a rainbow trout hepatoma (RTH-149), and a ra inbow trout mesothelioma (RTM). Protein products of c-ras and c-myc we re visualized in these 3 cell lines by employing fluorescein-labeled a nti-mouse pan-ras and c-myc antibodies. The RTG-2 cells were used in t his study as normal, control cells, and they exhibited little pan-ras and c-myc staining. The RTH-149 cell line (a tumorigenic cell line) ex hibited positive pan-ras staining in regions of the membrane and cell cytoplasm. Localization of c-myc staining to perinuclear regions was p unctate in RTH-149 cells. RTM cells (also a tumorigenic cell line) dis played a ms staining localization similar to the pattern seen in RTH-1 49 cells. RTM cells exhibit a diffuse perinuclear staining and, thus, display a more ubiquitous localization of c-myc than RTH-149 cells. No rthern blot analysis indicated that c-myc expression was highest in RT M cells, whereas RTG-2 cells and RTH-149 cells expressed similar lower levels of c-myc expression. We were unable to detect significant ms e xpression in any of the cell lines by Northern blot analysis. in summa ry, the cell line derived from normal tissue, the RTG-2 cells, display ed little ras and c-myc immunostaining, whereas the cell lines derived from tumorigenic tissue, RTH and RTM cells, displayed increased immun ostaining for c-myc and ras proteins.