EXPRESSION OF CYTOKERATIN-19 AS A MARKER OF NEOPLASTIC PROGRESSION OFHUMAN PROSTATE EPITHELIAL-CELLS

BACKGROUND. Our earlier studies demonstrated neoplastic transformation of SV40-immortalized neonatal human prostate epithelial cells (267B1) by fractionated doses of ionizing radiation or by introduction of v-k i-ras oncogene. X-ray-treated 267B1 cells represent three different st ages of neoplastic progression: nontumorigenic F3-SAC cells that acqui red morphological changes and anchorage independence when treated with 2 x 2 Gy of X-rays; malignantly transformed 267B1-XR and 267B1-SXR ce lls that received 2-Gy doses to a total of 30 Gy. We also reported alt erations in cell size, morphology, actin stress fibers, and levels of actin-binding proteins in these transformed human prostate cells. METH ODS. We analyzed intermediate filament-nuclear matrix (IF-NM) protein expression in the various 267B1 cells as a consequence of neoplastic p rogression by two-dimensional gel electrophoresis and immunofluorescen ce. RESULTS. Our present study revealed that the 267B1 cells experienc ed progressive changes in their intermediate filament protein composit ion during the process of neoplastic conversion, achieved either by X- rays or by ras-oncogene. In particular, we observed a stepwise downreg ulation of cytokeratin-19 in these in vitro transformed 267B1 cells. C ONCLUSIONS. Our data suggest that loss of expression of cytokeratin-19 accompanied the morphological alterations associated with in vitro ne oplastic transformation of SV40-immortalized prostate epithelial cells . (C) 1998 Wiley-Liss, Inc.