Down-regulation of cytokeratin 14 mRNA in polyoma virus middle T-transformed rat liver epithelial cells.
We have recently shown that rat liver nonparenchymal epithelial cells, such as T51B cells, selectively express cytokeratin (CK) 14 as a partner of CK8 in their intermediate filaments, and we proposed CK14 as a unique cell lineage marker of the liver epithelial cell population (R. Blouin, M-J. Blouin, I. Royal, A. Grenier, A. Loranger, D. R. Roop, and N. Marceau, Differentiation, submitted for publication, 1992). In the present study, T51B-261A (spontaneously transformed) and T51B-261B (aflatoxin B1-treated) clones and clones derived from T51B cells transfected with SV40 large T (LT) and polyoma virus middle T (MT) were used to investigate CK gene expression in nontransformed and transformed liver epithelial cells. T51B-261A, T51B-261B, MT-T51B, and LT/MT-T51B clones all grew in calcium-deficient medium and formed colonies in soft agar, whereas LT-T51B clones did not grow at all in either one of these assays. T51B-261A and T51B-261B clones formed small, slow growing tumors when injected into newborn syngenic rats, whereas the MT-T51B and LT/MT-T51B clones produced rapidly forming, large tumors. There was no effect of cell transformation on CK expression, except in the clones expressing MT, where the CK intermediate filaments were completely lost. Analyses of [35S]methionine incorporation into the Triton-resistant cytoskeleton and of total proteins confirmed that CKs were absent. In contrast, vimentin intermediate filaments remained unaffected in all of the clones.(ABSTRACT TRUNCATED AT 250 WORDS)
Royal
I
I
Centre de Recherche en Cancérologie, Université Laval, Hôtel-Dieu de Québec, Canada.
Gourdeau
H
H
Blouin
R
R
Marceau
N
N
D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics*; D002467:Cell Nucleus / Q000502:physiology; D002472:Cell Transformation, Viral; D003593:Cytoplasm / Q000502:physiology; D004847:Epithelial Cells; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D007633:Keratins / Q000235:genetics* / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000502:physiology*; D011120:Polyomavirus / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D014746:Vimentin / Q000378:metabolism
D000952:Antigens, Polyomavirus Transforming; D012333:RNA, Messenger; D014746:Vimentin; D007633:Keratins