• Cancer
• Virus
• Histopathology

Human endogenous retrovirus group 3 member 1 (ERV3-1) has been implicated in the pathogenesis of several human diseases, including tumours. The gene expression profiles of ERV3-1 could provide us with important insights into the pathogenic relationship between ERV3-1 and cancer. Several studies have explored the mRNA expression profiles of ERV3-1 in normal and cancer tissues.1–6 Although the importance of ERV3-1 has been demonstrated in human tissues and cancers, few studies have investigated the expression pattern of ERV3-1 protein in human tissues and tumours. Here, we analysed the expression pattern of ERV3-1 viral envelope (env) protein in adult human organs and in tumours using a tissue microarray. We also compared the expression of ERV3-1 between normal and tumour tissues to study the relationship between ERV3-1 and tumour formation.

Tissue microarray slides were purchased from SuperBioChips (SuperBioChips Laboratories, Seoul, Korea). Around 60 patients’ normal or tumour surgical specimens were put on individual tissue microarray slides. The normal tissue and tumours were obtained from patient surgical specimens and no clinical information except for the age and gender of each patient was available for the obtained tissues.

For immunohistochemical analysis, tissue microarray slides were immunostained with rabbit polyclonal antibody to ERV3-1 (1:500 dilution; ab116723, Abcam, Cambridge, Massachusetts, USA) and stained using the Dako EnVision System (DAKO, Carpinteria, California, USA). Background staining was measured by the immunostaining of all slides without primary antibody or rabbit immunoglobulin G (IgG), and also confirmed antibody specificity by western blot analysis (figure 1). For protein expression assessment, staining intensity was scored as negative (−), weak (+), moderate (++), and strong (+++). The focal intensity of …