Cytomatrix reorganization in dimethyl sulfoxide‐induced “Qi” substate murine hepatic tumor cells

Abstract

Cultured murine hepatic tumor (HT) cells respond to the polar solvent dimethylsulfoxide (DMSO) with specific alterations in morphology, proliferative kinetics, and biochemical properties. These include entrance into a quiescent "Qi" substate (characterized by accumulation of cells in G1 phase and lowered cellular RNA content), enhanced production of liver-specific proteins, and decreased expression of growth traits characteristic of the transformed phenotype. Entrance of HT cells into Qi was associated with increased monolayer compaction and a shift from an elaborate surface fibronectin (FN) network to a sparse and restricted distribution of FN fibers. This marked decrease in the extent and complexity of the cellular FN network, as a consequence of DMSO exposure, was reflected in a 90% decline in the amount of FN secreted into the culture medium. These data complement previous studies indicating that the accumulation and composition of liver cell matrix substances reflect altered patterns of hepatocyte-specific gene expression. In the HT cell system, DMSO appears to act in a bifunctional manner, increasing the production of certain tissue-specific proteins (e.g., albumin and alpha-fetoprotein) while decreasing the secretion and deposition of other cellular components (FN). DMSO may directly regulate expression of these proteins in HT cells or alter the pattern of cellular response to specific autocrine growth factors.

Cytoarchitecture of kirsten sarcoma virus‐transformed rat kidney fibroblasts: Butyrate‐induced reorganization within the actin microfilament network

“…ments and may actually promote MF bundle formation (Singer and Paradiso, 1981). Adhesion site proteins, which likely contribute significantly to the determination of cell shape, attachment, and locomotion (Geiger et al, 1984;Mangeat and Burridge, 1984), have been examined in several cell types (e.g., Mangeat and Burridge, 1984;Ryan and Higgins, 1988a) including NRK and its retrovirally transformed derivatives (Stickel and Wang, 1987). Changes in the protein composition of cellular substratum contact sites do, in fact, accompany transformation of NRK cells with KiMSV (Ryan and Higgins, 1988b); whether such alterations contribute to anomalies within the MF system of KiMSV-infected cells remains to be determined.…”

p52 induction by cytochalasin D in rat kidney fibroblasts: Homologies between p52 and plasminogen activator inhibitor type‐1

“…Immunoprecipitation (IP) protocols varied depending as to whether immune complexes were collected with formalin-fixed Staphylococcus aureus cells (Immuno-Precipitin; BRL, Gaithersburg, MD) or with Protein A-Sepharose beads (Sigma Chem., Co.) and the method of final product analysis (l-D or 2-D gel electrophoresis; proteolytic fragmentation). Preimmune rabbit serum (NRS), PBS, and a n unrelated antibody (rabbit anti-fibronectin; Ryan and Higgins, 1988b) were substituted for the primary anti-p52 or anti-PAI-1 sera in control IP assays. In l-D electrophoretic analyses of IP products, labeling medium containing 35Smethionine-labeled SP was diluted in a n equal volume of 2 x I P buffer (1 x I P buffer = 10 mM Tris-HC1, pH 7.5,0.5% [vivl Triton X-100, 0.1% lw/vl SDS, 0.5% [w/vl deoxycholate).…”