Restricted expression and function of laminin 1-binding integrins in normal and malignant oral mucosal keratinocytes.

Abstract

Squamous cell carcinoma of the oral cavity spreads by initial invasion of the laminin-rich basement membrane. We examined the adhesion and motility of human oral SCC cells and normal mucosal keratinocytes and found that the SCC cells readily attached and migrated on laminin 1 substrates but migrated poorly on collagen type I and fibronectin. The normal keratinocytes, however, adhered poorly to and were non-motile on laminin 1 yet readily and preferentially attached and migrated on fibronectin and collagen type I. Analysis with blocking anti-integrin antibodies showed that the SCC cells used the alpha 6 beta 1 complex to attach and migrate on laminin 1 and that this activity was confined to the E8 long arm fragment of laminin. Affinity chromatography on laminin-Sepharose columns revealed that the SCC cells, but not normal keratinocytes, expressed high levels of the alpha 6 beta 1 laminin 1 receptor. Metabolic pulse-chase analysis indicated that in contrast to the SCC cells, keratinocytes did not have a stable pool of beta 1 subunit precursor. Preferential pairing of alpha 6 with beta 4 and the deficiency in pre-beta 1 levels appear to account for the failure of keratinocytes to form significant alpha 6 beta 1 complex. Additionally, the presence of laminin 1 in co-coating experiments blocked keratinocyte adhesion to other immobilized ligands, such as collagen type I or fibronectin. This anti-adhesive effect seemed to reflect a general paralysis of cell adhesive function, since laminin 1 also diminished the adhesion of keratinocytes to substrates coated with immobilized anti-integrin subunit antibody. The inhibitory activity of laminin 1 resided in the E1' and E8 fragments, and not in the E3, E4 or G domains. Collectively, our results indicate that laminin 1 is a restrictive ligand for normal keratinocytes, apparently because of their failure to assemble and express the alpha 6 beta 1 complex or other functional laminin receptors and their sensitivity to the anti-adhesive activity of laminin itself. The elevated expression of alpha 6 beta 1 following malignant conversion of muscosal keratinocytes promotes their migration on laminin, a process important during invasion and metastasis.

• Authors: K Zhang, J P Kim, D T Woodley, N S Waleh, Y Q Chen, R H Kramer
• Journal: Cell adhesion and communication (Cell Adhes Commun) Vol. 4 Issue 3 Pg. 159-74 (Sep 1996) ISSN: 1061-5385 [Print] Switzerland
• PMID: 8969862 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Cell Adhesion Molecules
• Fibronectins
• Integrins
• Laminin
• Ligands
• RNA, Messenger

Topics

• Binding, Competitive
• Carcinoma, Squamous Cell (pathology)
• Cell Adhesion
• Cell Adhesion Molecules (metabolism)
• Cell Movement
• Cells, Cultured
• Fibronectins (metabolism)
• Gene Expression
• Gingiva (cytology)
• Humans
• Integrins (metabolism)
• Keratinocytes (cytology)
• Laminin (metabolism)
• Ligands
• Mouth Neoplasms (pathology)
• RNA, Messenger (genetics)