Expression of the forkhead transcription factor FOXP1 is associated with tumor grade and Ki67 expression in clear cell renal cell carcinoma
M. I Toma1, T. Weber2, M. Meinhardt1, S. Zastrow2, M-O Grimm2, S.Füssel2, B.l Wiedemann3, M. P. Wirth2, G. B. Baretton1
1 Institute of Pathology, Technical University of Dresden
2 Department of Urology, Technical University of Dresden
3 Institute of Medical Informatics and Biometry, Technical University of Dresden
Aims: The aim of this study was to prove the expression of FOXP1 in clear cell renal cell carcinoma and to correlate the FOXP1 expression with clinical and pathological features.
Methods: 129 cases of clear cell renal cell carcinomas treated by radical nephrectomy between 1993 and 2000 with known follow-up were included in the study. Tissue microarrays from malignant and corresponding non malignant formalin fixed, paraffin-embedded archive material were constructed. Immunohistochemical FOXP1 expression was assessed semiquantitatively and correlated with disease specific-, overall -, and recurrence free survival and Ki67 expression.
Results: Disease specific survival of the patients with clear cell renal cell carcinomas correlated with tumor grading (p<0.05). Cases with lymph node metastasis showed a significant shorter overall and disease specific survival than cases without lymph node metastasis (p<0.05). Short recurrence free survival correlated with increasing tumor stage and grade and with lymph node metastasis (p<0.05). Tumor tissues showed loss of FOXP1 expression or low FOXP1 expression in 69 cases (53.4%). Expression of FOXP1 correlated negatively with tumor grading (p=0.02), but not with tumor stage or lymph node metastasis. Significant positive correlation was shown for Ki67 expression and tumor grade, stage and lymph node metastasis (p<0.05). The overall survival as well as disease specific survival correlated with Ki67 status (p<0.05). The Spearman-Rho correlation showed that FOXP1 expression negatively correlates with Ki67 expression in clear cell renal cell carcinomas (p=0.036).
Conclusions: Survival of patients with clear cell renal cell carcinomas is influenced by tumor grade and lymph node metastasis, as well as by tumor proliferation. FOXP1 transcription factor seems to play an important role in loss of differentiation of clear cell renal cell carcinomas and its expression correlates with proliferation of the tumor cells.