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Query: UMLS:C0001511 (Adhesion)
 5,955 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adhesion to the extracellular matrix is required for the expression and activation of the cyclin-cyclin-dependent kinase (CDK) complexes, and for G1 phase progression of non-transformed cells. However, in non-adherent cells no molecular mechanism has yet been proposed for the cell adhesion-dependent up-regulation of the p27 cyclin-dependent kinase inhibitor (CKI), and the associated inhibition of cyclin E-CDK2. We now show that in epithelial cells the expression of c-Myc is tightly regulated by cell-substrate adhesion. When deprived of adhesion, two independently derived mammary epithelial cell lines, 184A1N4 and MCF-10A, rapidly decrease their level of c-Myc mRNA and protein. This decrease in levels of c-Myc correlates with G1 phase arrest, as indicated by hypophosphorylation of pRb and inhibition of the activity of the cyclin E-CDK2 complex. In 184A1N4 cells, cell-substrate adhesion is required for the suppression of p27, and induction of cyclin E, E2F-1, but not cyclins D1 and D3. Enforced expression of c-Myc in non-adherent 184A1N4 and MCF-10A cells reverses the adhesion-dependent inhibition of cell cycle progression. Restoration of c-Myc in non-adherent cells induces the expression of E2F-1, and hyperphosphorylation of pRb in response to EGF treatment. In addition, expression of c-Myc results in the anchorage-independent activation of the CDK2 complex, the associated upregulation of cyclin E, and the destabilization and degradation of p27 by the ubiquitin-proteasome pathway. Our study thus suggests that c-Myc is the link between cell adhesion and the regulation of p27 and cyclin E-CDK2. Furthermore, we describe a role for c-Myc in adhesion-mediated regulation of E2F-1.
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PMID:Adhesion-regulated G1 cell cycle arrest in epithelial cells requires the downregulation of c-Myc. 1149 51

E-cadherin, an intercellular adhesion molecule, is important in cell growth and differentiation. Adhesion between cells is thought to decrease as cancers develop and disseminate. Knowledge of the effect of cell adhesion on proliferation and chemosensitivity may help individualize cancer treatment. Lovo and MCF-7 cells, which express E-cadherin, and PC-3 cells, which do not, were used in this study. Proliferation and chemosensitivity were measured in two-dimensional (2-D) culture and three-dimensional (3-D) culture. Protein and mRNA expression of E-cadherin, catenin, and cyclin-dependent kinase inhibitors were determined. Growth of Lovo and MCF-7 but not PC-3 cells was markedly suppressed in 3-D relative to 2-D. MCF-7 cells express high levels for E-cadherin, catenin, and p27 in 3-D, but catenin and p27 expression was decreased by exposure to anti-E-cadherin neutralizing antibody. Chemosensitivity of PC-3 was similar in 2-D and 3-D, but chemosensitivity of Lovo and MCF-7 was less in 3-D than 2-D. Moreover, the presence of anti-E-cadherin antibody increased chemosensitivity of MCF-7 in 3-D. E-cadherin affected the regulation of cell proliferation and differentiation, and decreased chemosensitivity. Chemosensitivity of cancer is affected by the state of cell adhesion and expression of intercellular adhesion molecules. Consideration of intercellular adherence characteristics in different chemosensitivity tests is likely to improve their reliability.
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PMID:E-cadherin-dependent intercellular adhesion enhances chemoresistance. 1453 95