An activating beta1 integrin mutation increases the conversion of benign to malignant skin tumors.

Abstract

Identifying the physiologic relevance of cancer-associated genetic polymorphisms is a major challenge. Several changes in the coding sequence of beta integrin subunits have now been described in human tumors. One of these, T188Ibeta1, was identified as a heterozygous mutation in a poorly differentiated squamous cell carcinoma (SCC) and shown to activate extracellular matrix adhesion and inhibit keratinocyte differentiation in vitro. To study its contribution to tumor development, we overexpressed the mutant or wild-type (WT) human beta1 subunit in the basal layer of mouse epidermis using the keratin 14 promoter. The transgenic integrins were expressed at the cell surface and were functional, with the T188Ibeta1 subunit promoting cell spreading to a greater extent than WTbeta1. Epidermal proliferation and differentiation were unaffected and no expansion of the stem cell compartment was detected. During chemical carcinogenesis, both transgenes increased papilloma formation, but only the T188Ibeta1 transgene stimulated the conversion of papillomas to SCCs. Papillomas bearing the mutation showed increased Erk activity and reduced differentiation. SCCs expressing T188Ibeta1 were less well-differentiated than those expressing WTbeta1. These observations establish that the expression of a genetic variant in the I-like domain of beta1 integrins does not affect normal epidermal homeostasis, but increases tumor susceptibility and influences tumor type.

• Authors: Manuela Ferreira, Hironobu Fujiwara, Kazumasa Morita, Fiona M Watt
• Journal: Cancer research (Cancer Res) Vol. 69 Issue 4 Pg. 1334-42 (Feb 15 2009) ISSN: 1538-7445 [Electronic] United States
• PMID: 19190332 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Integrin beta1

Topics

• Animals
• Carcinoma, Squamous Cell (genetics, pathology)
• Cell Adhesion
• Cell Differentiation
• Cell Division
• Female
• Flow Cytometry
• Genetic Carrier Screening
• Humans
• In Situ Hybridization
• Integrin beta1 (genetics)
• Keratinocytes (cytology, physiology)
• Mice
• Mice, Transgenic
• Mutation
• Polymerase Chain Reaction
• Polymorphism, Genetic
• Skin (cytology)
• Skin Neoplasms (genetics, pathology)