TY - JOUR
T1 - Topoisomerase II α Status in Renal Medullary Carcinoma
T2 - Immuno-Expression and Gene Copy Alterations of a Potential Target of Therapy
AU - Albadine, Roula
AU - Wang, Wenle
AU - Brownlee, Noel A.
AU - Toubaji, Antoun
AU - Billis, Athanase
AU - Argani, Perdram
AU - Epstein, Jonathan I.
AU - Garvin, A. Julian
AU - Cousi, Rima
AU - Schaeffer, Edward M.
AU - Pavlovich, Christian
AU - Netto, George J.
N1 - Funding Information:
Supported by the Patrick C. Walsh Foundation Award.
PY - 2009/8
Y1 - 2009/8
N2 - Purpose: Renal medullary carcinoma is an aggressive renal neoplasm without currently available effective therapy to our knowledge. Topoisomerase II α is a gyrase involved in cell proliferation, and DNA maintenance and repair. Topoisomerase II α is a target of inhibiting agents such as anthracyclines. Triggered by a recent response to topoisomerase II α inhibitors in a patient with renal medullary carcinoma, we evaluated topoisomerase II α expression in relation to the proliferation index and topoisomerase II α gene copy number status in a larger series of patients with renal medullary carcinoma. Materials and Methods: Archival tissues from 14 renal medullary carcinomas were retrieved from our 3 institutions. Immunohistochemistry was performed using monoclonal antibodies for topoisomerase II α and Ki67. The percent of cells with positive nuclear staining was assessed in the highest area of expression for each marker. A previously suggested greater than 5% cutoff was used for topoisomerase II α over expression. The topoisomerase II α gene copy number was evaluated using fluorescence in situ hybridization. Locus specific topoisomerase II α gene and chromosome 17 centromere probes were used. The total number of topoisomerase II α and chromosome 17 centromere signals was counted in 150 cells per tumor and a topoisomerase II α-to-chromosome 17 centromere signal ratio was calculated in each tumor. A topoisomerase II α-to-chromosome 17 centromere ratio of 2.0 or greater and less than 0.8 was used as a cutoff for amplification and deletion, respectively. The percent of tumor cells with polysomic, eusomic or monosomic chromosome 17 status was also determined. Results: On immuno-expression analysis topoisomerase II α immunohistochemistry was technically inconclusive in 1 renal medullary carcinoma. Topoisomerase II α was over expressed in 11 of 13 renal medullary carcinomas (85%) (median 50%, range 1% to 80%). As expected, a high Ki67 proliferation index was noted in 13 of 14 tumors (median 87.5%, range 2% to 100%). Ki67 expression was greater than topoisomerase II α expression in all 13 informative tumors. A strong, statistically significant correlation was found for topoisomerase II α and Ki67 expression (pairwise CC 0.9, p = 0.0000). Topoisomerase II α over expression was associated with shorter survival (p = 0.000). On fluorescence in situ hybridization no topoisomerase II α amplification was detected in any of the 14 renal medullary carcinomas, including the 11 with topoisomerase II α over expression. Topoisomerase II α gene deletions were noted in 4 tumors. Two of 4 deletions were associated with chromosome 17 monosomy and 2 were in eusomic chromosome 17 tumors. Conclusions: Topoisomerase II α is over expressed in 85% of renal medullary carcinomas, potentially supporting the use of topoisomerase II α inhibitor agents to treat this aggressive renal tumor. Our findings suggest that topoisomerase II α over expression in our renal medullary carcinoma cohort was not due to gene amplification, but rather to transcriptional or post-transcriptional modifications. The significance of the incidentally found topoisomerase II α deletions in 28% of renal medullary carcinomas requires further evaluation.
AB - Purpose: Renal medullary carcinoma is an aggressive renal neoplasm without currently available effective therapy to our knowledge. Topoisomerase II α is a gyrase involved in cell proliferation, and DNA maintenance and repair. Topoisomerase II α is a target of inhibiting agents such as anthracyclines. Triggered by a recent response to topoisomerase II α inhibitors in a patient with renal medullary carcinoma, we evaluated topoisomerase II α expression in relation to the proliferation index and topoisomerase II α gene copy number status in a larger series of patients with renal medullary carcinoma. Materials and Methods: Archival tissues from 14 renal medullary carcinomas were retrieved from our 3 institutions. Immunohistochemistry was performed using monoclonal antibodies for topoisomerase II α and Ki67. The percent of cells with positive nuclear staining was assessed in the highest area of expression for each marker. A previously suggested greater than 5% cutoff was used for topoisomerase II α over expression. The topoisomerase II α gene copy number was evaluated using fluorescence in situ hybridization. Locus specific topoisomerase II α gene and chromosome 17 centromere probes were used. The total number of topoisomerase II α and chromosome 17 centromere signals was counted in 150 cells per tumor and a topoisomerase II α-to-chromosome 17 centromere signal ratio was calculated in each tumor. A topoisomerase II α-to-chromosome 17 centromere ratio of 2.0 or greater and less than 0.8 was used as a cutoff for amplification and deletion, respectively. The percent of tumor cells with polysomic, eusomic or monosomic chromosome 17 status was also determined. Results: On immuno-expression analysis topoisomerase II α immunohistochemistry was technically inconclusive in 1 renal medullary carcinoma. Topoisomerase II α was over expressed in 11 of 13 renal medullary carcinomas (85%) (median 50%, range 1% to 80%). As expected, a high Ki67 proliferation index was noted in 13 of 14 tumors (median 87.5%, range 2% to 100%). Ki67 expression was greater than topoisomerase II α expression in all 13 informative tumors. A strong, statistically significant correlation was found for topoisomerase II α and Ki67 expression (pairwise CC 0.9, p = 0.0000). Topoisomerase II α over expression was associated with shorter survival (p = 0.000). On fluorescence in situ hybridization no topoisomerase II α amplification was detected in any of the 14 renal medullary carcinomas, including the 11 with topoisomerase II α over expression. Topoisomerase II α gene deletions were noted in 4 tumors. Two of 4 deletions were associated with chromosome 17 monosomy and 2 were in eusomic chromosome 17 tumors. Conclusions: Topoisomerase II α is over expressed in 85% of renal medullary carcinomas, potentially supporting the use of topoisomerase II α inhibitor agents to treat this aggressive renal tumor. Our findings suggest that topoisomerase II α over expression in our renal medullary carcinoma cohort was not due to gene amplification, but rather to transcriptional or post-transcriptional modifications. The significance of the incidentally found topoisomerase II α deletions in 28% of renal medullary carcinomas requires further evaluation.
KW - DNA topoisomerase II alpha
KW - carcinoma
KW - gene deletion
KW - kidney
KW - kidney medulla
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U2 - 10.1016/j.juro.2009.03.078
DO - 10.1016/j.juro.2009.03.078
M3 - Article
C2 - 19539329
AN - SCOPUS:67649819325
SN - 0022-5347
VL - 182
SP - 735
EP - 740
JO - Journal of Urology
JF - Journal of Urology
IS - 2
ER -