title: BMI-1 expression is inversely correlated with the grading of renal clear cell carcinoma.
abstract: BMI-1 regulates cell proliferation and differentiation, is involved in stem cell maintenance and can act as an oncogene. We investigated BMI-1 expression in healthy normal kidney and in 77 renal tumours by immunohistochemistry, and correlated it with tumour differentiation. BMI-1 could regularly be demonstrated in distal tubules and in Bowman's capsule, whereas it was mostly lacking in proximal tubules, indicating that it may rather be a differentiation marker of different renal cell populations than a stem cell marker. In contrast to previous studies demonstrating a correlation between BMI-1 expression and malignancy, we showed that its expression was inversely correlated with the differentiation grade of clear cell carcinoma. Furthermore, despite their different biologies, BMI-1 was strongly expressed in both papillary carcinomas and oncocytomas. Thus, in renal clear cell carcinomas BMI-1 is rather a differentiation marker lost in carcinomas with high malignancy than an oncogene involved in tumour progression.
authors.affiliation: Institute of Clinical Pathology, Medical University of Vienna, Währinger Gürtel 18-20, 1097 Vienna, Austria.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Kozakowski
authors.forename: Afschin
authors.initials: A
authors.lastname: Soleiman
authors.forename: Johannes
authors.initials: J
authors.lastname: Pammer
mesh_terms: D018249:Adenoma, Oxyphilic / Q000378:metabolism / Q000473:pathology; D015153:Blotting, Western; D002292:Carcinoma, Renal Cell / Q000378:metabolism* / Q000473:pathology*; D045744:Cell Line, Tumor; D018450:Disease Progression; D006801:Humans; D007150:Immunohistochemistry; D007668:Kidney / Q000378:metabolism / Q000473:pathology; D007680:Kidney Neoplasms / Q000378:metabolism* / Q000473:pathology*; D014411:Neoplastic Stem Cells / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D063150:Polycomb Repressive Complex 1; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism*; D018709:Statistics, Nonparametric
chemical_list: C069077:BMI1 protein, human; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D063150:Polycomb Repressive Complex 1