Quantitative and qualitative analysis of integrin subtype expression in melanocytes and melanoma cells

Abstract

Objectives: Changes in the integrin expression pattern have been associated with the malignant transformation of melanocytes suggesting that integrins may be potential biomarkers as well as molecular targets for individualized therapy. Since there is a lack of comprehensive qualitative and quantitative expression data, we characterized the integrin expression profile in normal and malignant human cells of the melanocytic lineage.

Methods: Seven melanoma cell lines as well as normal human melanocytes were investigated in western blots including recombinant integrin subunits for quantification.

Results: Expression patterns were heterogeneous. In melanoma, overexpression of α4, α6, αL, β5, and β6 was found. Integrins α7, α9, and β4 were overexpressed in a subset of the melanoma cell lines. Overexpression was defined as a lack of expression in melanocytes but expression in more than half (4) of the melanoma lines. 1.9 to 6.7 × 10⁶ integrin molecules (about 0.3% of total cellular protein) were estimated to be expressed per cell. Expression of integrin αE at the protein level was found in melanoma and melanocytes, to the best of our knowledge, for the first time. Integrins αM and β2 were not detected.

Conclusion: Integrins α4, α6, αL, β5, and β6 appear to be overexpressed in melanoma cells. These subunits may serve as biomarkers and/or therapeutic targets.

Keywords:

• Integrin
• quantification
• melanoma
• melanocytes
• in vitro

Acknowledgments

The authors thank W. Berger for providing melanoma cell lines and R. Hoffmann for technical assistance. Images were taken in cooperation with the Core Facility Imaging of the Medical University of Vienna, which is hereby gratefully acknowledged.

Disclosure statement

This research did not receive any specific grant from funding agencies in the public, commercial, or nonprofit sectors. The authors have no conflicts of interest to declare.