1. ¹Department of Surgery, Division of Urology, Division of Hematology, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
2. ²Department of Urology, Qilu Hospital, Shandoing University, Jinan, 250012, PR China
3. ³Department of Oncology-Pathology, Division of Hematology, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
4. ⁴Aging and Health Center, Nursing School, Shandong University, Jinan, 250012, PR China
5. ⁵Institute of Urology, Shandong University, Jinan, 250012, PR China
6. ⁶Department of Medicine, Division of Hematology, Karolinska University Hospital, SE-171 76 Stockholm, Sweden

Correspondence: Dr D Xu, Haematology Laboratory, Center for Molecular Medicine (CMM), L8:03, Karolinska University Hospital, SE-171 76 Stockholm, Sweden. E-mail: Dawei.Xu@cmm.ki.se; X Fang, Institute of Urology, Shandong University, Jinan, 250033, PR China. E-mail: xiaoleifang@sdu.edu.cn

⁷These authors contributed equally to this work.

Received 15 June 2005; Revised 3 April 2006; Accepted 5 April 2006; Published online 2 May 2006.

Abstract

Nucleostemin (NS), a p53-binding protein, has been shown essential for stem and cancer cell proliferation and implicated in oncogenesis. To explore potential contributions of NS to the development of clear cell renal cell carcinomas (ccRCCs), we determined NS expression in ccRCC cell lines, and in paired normal and malignant renal tissues from 31 patients with ccRCC. Nucleostemin mRNA and/or protein expression was observed in all four cell lines and 27 of 31 (87%) tumour specimens. Surprisingly, 16 of 31 (52%) adjacent normal renal samples also expressed NS mRNA and its levels in four of them were comparable with those in paired tumour tissues. Three of the patients had detectable NS mRNA in their normal renal tissues whereas lacked its expression in the matched tumours. Compared to the oncogene c-MYC expression in these same samples, NS expression showed a much less specificity for ccRCC. We further demonstrated that NS mRNA expression was closely associated with cellular proliferation in normal fibroblasts or T lymphocytes and renal cell carcinoma cell lines. Collectively, NS expression widely occurs in normal and malignant renal tissues, and is likely a proliferation marker rather than a unique regulator of cell proliferation and survival in stem and cancer cells.