1. ¹Department of Clinical Biochemistry and Molecular Biology, Medical Centre for Postgraduate Education, Marymoncka 99/103, 01-813 Warsaw, Poland
2. ²Department of Gastroenterology and Hepatology, Medical Centre for Postgraduate Education and Maria Skodowska-Curie Memorial Cancer Centre and Institute of Oncology, Roentgena 5, 02-781 Warsaw, Poland
3. ³Department of Pathology, Medical Centre for Postgraduate Education, Ceglowska 80, 01-809 Warsaw, Poland
4. ⁴Department of Nuclear Medicine and Endocrine Oncology, Maria Skodowska-Curie Memorial Cancer Centre and Institute of Oncology, Wybrzeze Armii Krajowej 15, 44-101 Gliwice, Poland

Correspondence: Dr B Czarnocka, E-mail: barbarac@cmkp.edu.pl

Received 5 February 2007; Revised 5 July 2007; Accepted 5 July 2007; Published online 31 July 2007.

Abstract

NrCAM (neuron-glia-related cell-adhesion molecule) is primarily, although not solely, expressed in the nervous system. In the present study, NrCAM expression was analysed in a series (46) of papillary thyroid carcinomas (PTCs) and paired normal tissues (NT). Quantitative reverse transcriptase (QRT)-PCR revealed that NrCAM expression was upregulated in all PTCs compared to normal thyroid, whatever the stage or size of the primary tumour. NrCAM transcript levels were 1.3- to 30.7-fold higher in PTCs than in NT. Immunohistochemistry (IHC) confirmed that the expression of NrCAM was considerably higher in tumours (score 2+/3+) than in adjacent normal paratumoural thyroid tissue. The NrCAM protein was detected in all but three (93.3%) PTC samples, and it was mainly cytoplasmic; in some cases there was additional membranous localisation – basolateral and partly apical. In the normal thyroid and tissues surrounding tumours, focal NrCAM immunolabelling was seen only in follicles containing tall cells, where staining was restricted to the apical pole of thyrocytes. Western blot analysis corroborated the QRT–PCR and IHC results, showing higher NrCAM protein levels in PTCs than in paired NT. The level of overexpression of the NrCAM mRNA in tumourous tissue appeared to be independent of the primary tumour stage (pT) or the size of the PTC. These data provide the first evidence that NrCAM is overexpressed in human PTCs at the mRNA and protein levels, whatever the tumour stage. Thus, the induction and upregulation of NrCAM expression could be implicated in the pathogenesis and behaviour of papillary thyroid cancers.