Expression of topoisomerase IIIalpha in normal and neoplastic tissues determined by immunohistochemistry using a novel monoclonal antibody

Significance of topoisomerase IIIβ expression in breast ductal carcinomas: strong associations with disease-specific survival and metastasis

Topoisomerases are ubiquitous nuclear enzymes that regulate DNA structure in eukaryotic cells. The role of topoisomerase IIIβ, the newest member of the topoisomerase family, in the clinical outcome of breast cancer is still poorly understood. This study aims to investigate the immunoexpression of topoisomerase IIIβ in breast cancer and its relationships with clinicopathologic features and immunohistochemical markers of prognostic significance in breast pathology. Using tissue microarrays containing 171 cases of primary invasive breast cancer, we analyzed the immunoexpression of topoisomerase IIIβ, estrogen receptor, progesterone receptor, HER-2, BRCA-1, p53, and Ki67. Immunostaining for topoisomerase IIIβ was found in 33.9% of breast carcinomas, and immunopositivity was correlated with distant metastasis (P = .036) and death (P = .006). Decreased expression of topoisomerase IIIβ correlated with low expression of Ki67 (P < .001) and negativity for HER-2 (P < .001), BRCA-1 (P = .001), and p53 (P < .001). In the multivariate analysis, topoisomerase IIIβ expression was a significant predictor of survival (hazard ratio, 3.006 [95% confidence interval, 1.582-5.715]; P = .001). In conclusion, topoisomerase IIIβ expression can be a useful marker in assessing the prognosis of patients with breast cancer and is an independent predictor of survival.

Topoisomerase II alpha and II beta expression in childhood acute lymphoblastic leukaemia: relation to prognostic factors and clinical outcome

BACKGROUND/AIMS

Many regimens used in the treatment of childhood acute lymphoblastic leukaemia (ALL) include Daunorubicin or Etoposide, which act as topoisomerase poisons. It has been suggested that there may be a relation between topoisomerase expression and response to topoisomerase poisons, based mainly on results from in vitro studies. Therefore, the aim of this study was to investigate this relation in a clinical setting and determine whether topoisomerase II alpha and II beta might be of predictive value in ALL.

METHODS

Cellular expression of topoisomerases II alpha and II beta was assessed in 177 cases of ALL by immunohistochemistry using monoclonal antibodies to the two enzymes. The percentages of cell nuclei showing positive staining for topoisomerase II alpha and II beta expression were assessed.

RESULTS

Taking the series as a whole, a clear separation of survival curves was seen with the established prognostic markers white blood cell (WBC) count, CD10 status, and sex. However, topoisomerase II alpha and II beta expression showed no relation to survival. No association was found between the topoisomerases and the prognostic markers CD10 and WBC count; however, topoisomerase II alpha expression was found to be related to sex, with expression being lower in girls (p = 0.002).

CONCLUSIONS

These results suggest that the response to topoisomerase poisons cannot be predicted by the assessment of topoisomerase II alpha and II beta expression as defined by immunohistochemistry.