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Protein expression analysis of ALCAM and CEACAM6 in breast cancer metastases reveals significantly increased ALCAM expression in metastases of the skin
  1. Maike Ihnen1,
  2. Ergin Kilic2,
  3. Nadine Köhler1,
  4. Thomas Löning3,
  5. Isabell Witzel1,
  6. Christian Hagel4,
  7. Sylvia Höller2,
  8. Jan F Kersten5,
  9. Volkmar Müller1,
  10. Fritz Jänicke1,
  11. Karin Milde-Langosch1
  1. 1Department of Gynaecology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
  2. 2Institute for Pathology, University Hospital Basel, Basel, Switzerland
  3. 3Albertinen Pathologie Hamburg, Albertinen Hospital, Hamburg, Germany
  4. 4Department of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
  5. 5Department of Medical Biometry and Epidemiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
  1. Correspondence to Dr Maike Ihnen, University of California Los Angeles, David Geffen School of Medicine at UCLA, UCLA Translational Oncology Research Labs, 2825 Santa Monica Blvd, Suite 200, Santa Monica, CA 90404, USA; maihnen{at}gmx.ch

Abstract

Aims For prediction and understanding of underlying mechanisms of organ-specific metastases, various gene and protein expression signatures have been identified in primary breast carcinomas. These expression signatures often include several genes coding for adhesion molecules, such as activated leucocyte cell adhesion molecule (ALCAM/CD166) and carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6), both of which may play an important role in the development of distant metastases because of their adherent properties. Owing to their predominantly membranous localisation, they are also considered to have certain therapeutic potential. Apart from expression data obtained in the primary tumour, data for gene and protein expression patterns in distant breast cancer metastases are rare. Therefore this study focuses on analysing the distribution of ALCAM and CEACAM6 protein expression in breast cancer metastases from different sites.

Methods Immunohistochemical staining for ALCAM and CEACAM6 in 117 breast cancer metastases derived from liver (n=24), lung (n=19), brain (n=21), bone (n=36) and skin (n=17) was performed.

Results Immunoreactive scores (IRS) for ALCAM in all metastases except skin metastases ranged from 2.63 to 5.10 (membranous) and 2.79 to 3.67 (cytoplasmic), showing a positive correlation with each other (r=0.690, p<0.001). In skin metastases, ALCAM expression was significantly stronger (membranous IRS, 8.76; cytoplasmic IRS, 7.12; p<0.001). Mean staining intensity for CEACAM6 was IRS 3.88. No or weak CEACAM6 and ALCAM staining (IRS 0–3) was seen in 53% vs 27% of all metastases.

Conclusions Compared with CEACAM6, ALCAM showed significantly stronger protein expression in breast cancer skin metastases compared with metastases in all other sites.

  • ALCAM
  • CEACAM6
  • breast cancer metastasis
  • adhesion molecule
  • skin metastasis

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Footnotes

  • MI and EK contributed equally.

  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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