Abstract
Structural glycoproteins and cytoskeletal proteins play a major role in the regulation of cellular organization and function. Changes in the structure and function of these proteins are involved in the cascade of events which lead to neoplastic transformation. We evaluated RNA levels, protein localization, and organization of selected proteins in an in vitro model system of respiratory carcinogenesis to examine alterations in cell architecture. Localization of fibronectin (Fn), thrombospondin (Tsp), and F-actin was examined in (1) primary rat tracheal epithelial (RTE) cells; (2) spontaneously immortalized nonneoplastic cells (SPOC-1); and (3) neoplastic cells (EGV5T) derived from tumors arising following transplantation of an N -methyl- N′-nitro- N-nitrosoguanidine-transformed RTE cell line into nude mice. Proteins were stained with fluorescein-labeled antibodies or phalloidin compound and analysis was performed with a confocal laser scanning microscope. Primary RTE cells display organized F-actin stress fibers, perinuclear Fn and Tsp, and pericellular Fn in fibrillar arrays. In larger colonies, Tsp occurs between cells and occasionally in fibrillar arrays. SPOC-1 cells, unlike primary RTE cells and neoplastic EGV5T cells, seldom form junctions and exhibit few cell surface extensions. F-actin stress fibers are reduced in these immortalized cells. F-actin in SPOC-1 cells occurs in the perinuclear region, scattered diffusely throughout the cell and in punctate adhesions. Fn and Tsp are localized to the perinuclear region with Fn staining more intensely. EGV5T neoplastic cells also display a dramatic loss of stress fibers and F-actin is concentrated mainly near the cell periphery. Perinuclear staining of Fn and Tsp occurs in some cells within the colony. Levels of Tsp RNA and Fn RNA and protein are significantly reduced in both cell lines compared to primary RTE cells. We conclude that structural protein disruptions are early events in the transformation of these respiratory epithelial cells.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.