Pierre Rudolph

Culprit and victim - DNA topoisomerase II

The phylogenetic antiquity of DNA topoisomerases indicates their vital function. Structure and maintenance of genomic DNA depend on the activity of these enzymes, and without them DNA replication and cell division are impossible. Topoisomerase II alpha has therefore become the main target of many antitumour therapy regimens, even though the exact mechanism of cell killing remains elusive. The success of this approach is limited by the development of spontaneous resistance, and drug-induced DNA damage can increase malignancy. Nevertheless, the combined use of topoisomerase-inhibiting drugs with different mechanisms of action promises to improve particular treatment designs. The degree of topoisomerase II expression in tumours may predict the clinical course and responsiveness to therapy.

Immunophenotype, proliferation, DNA ploidy, and biological behavior of gastrointestinal stromal tumors: a multivariate clinicopathologic study.

To determine the prognostic impact of clinical, immunohistochemical, and biological parameters, we examined 52 gastrointestinal stromal tumors (GIST) by conventional light microscopy and immunohistochemistry. DNA ploidy was analyzed by image cytometry on cytospin preparation. The proliferative activity was determined by mitosis counting and assessment of Ki-67 reactivity by means of monoclonal antibody Ki-S5. A histopathologic grade was assigned to each tumor according to the French Federation of Cancer Centers (FNCLCC) grading system. Next to vimentin, CD34 was the most prevalent antigen, followed by markers of neural and muscular differentiation. Many tumors exhibited a mixed phenotype. Twenty-one tumors were diploid, eight hypodiploid, and 23 aneuploid. In univariate analysis, tumor grade, Ki-S5 labeling index, mitotic count, atypical mitoses, cellularity, and sex were predictive of both mortality and metastasis risk. DNA ploidy only correlated with overall survival, whereas the tumor location affected the occurrence of metastases. Multivariate analysis selected Ki-S5 scores (P < .0001) and atypical mitoses (P=.012) as independent prognosticators for overall survival, and tumor grade (P=.0036) and size (P=.0055) as predictors of metastatic spread. We conclude that GIST are primitive mesenchymal tumors capable of divergent differentiation, which does not influence their prognosis. The latter appears to be best predicted by histopathologic grading and the Ki-67 labeling index.

Correlation between p53, c-erbB-2, and topoisomerase II alpha expression, DNA ploidy, hormonal receptor status and proliferation in 356 node-negative breast carcinomas: prognostic implications

Various new prognostic indicators have been identified for mammary carcinomas, but the issue of their significance remains unsettled. The prognostic impact of p53, c‐erbB‐2, and topoisomerase IIα expression was investigated in relation to standard prognostic factors for carcinomas of the breast and to the tumour cell growth fraction. Paraffin‐embedded specimens of 356 node‐negative infiltrating ductal carcinomas were stained immunohistochemically using a polyclonal antiserum to c‐erb B‐2, and the monoclonal antibodies DO‐1 (p53), Ki‐S4 (topoisomerase IIα), and Ki‐S5 (Ki‐67). The patients were followed for a median duration of 99 months. Both p53 and c‐erb B‐2 were significantly associated with high tumour grade, large tumour size, DNA aneuploidy, lack of steroid hormone receptors, young age, and increased topoisomerase IIα and Ki‐67 expression levels. The correlation of p53 and c‐erb B‐2 was not significant. Topoisomerase IIα and Ki‐67 scores closely paralleled each other, indicating that both reflect the proliferative activity of tumour cells. A univariate analysis of overall (OS), specific (SS), and disease‐free survival (DFS) revealed all the above‐mentioned parameters to be statistically significant except patient age, which was relevant only to overall survival. Multivariate analysis with inclusion of all covariates selected tumour size and proliferation (topoisomerase IIα and Ki‐67) indices as independent predictors of survival in all three models. No additional information was gained by p53 or c‐erb B‐2. It is concluded that the proliferative activity, as assessed by topoisomerase IIα or Ki‐67 immunostaining, is the most useful indicator of breast cancer prognosis, except for tumour size. Copyright

Decline in the expression of the serine proteinase inhibitor maspin is associated with tumour progression in ductal carcinomas of the breast

Maspin is an inhibitor of serine proteinases with tumour suppressor activity. Its expression appears to be reduced in advanced stages of breast cancer. A large series of archival breast tissue specimens has been examined, including normal glands (n=7), fibrocystic change (n=22), ductal carcinoma in situ (DCIS, n=12), infiltrating carcinomas (n=128) and their lymph node metastases (n=65), using a specific monoclonal antibody. Myoepithelium invariably showed strong maspin expression. In epithelial cells, the strongest expression was found in normal breast and fibrocystic change. A significant stepwise decrease in maspin expression (p<0.0001) occurred in the sequence DCIS – invasive cancer – lymph node metastasis. However, a subset of infiltrating carcinomas showed strong maspin expression, significantly associated with a lower rate of lymph node metastasis at the time of diagnosis (p<0.01). This was independent of tumour size and grade. The in vivo observations presented here are in keeping with data obtained in prior in vitro experiments. Maspin emerges as an indicator of tumour progression and metastatic potential, and might be exploited to predict breast cancer prognosis. According to in vitro data, its tumour suppressor activity is likely to involve both the modulation of cell motility/invasiveness and the inhibition of angiogenesis. Copyright

Expression of cyclins E, A, and B, and prognosis in lymph node-negative breast cancer.

Unexpected outcomes in breast cancer demand a refinement of prognostic criteria. This study therefore investigated the prognostic relevance of cyclin expression in a cohort of 332 T1–T2 N0 infiltrating ductal carcinomas with long‐term follow‐up (median 99 months). By univariate analysis, tumour size, histopathological grade, hormone receptor content, cyclin E, cyclin B, and the Ki‐S5 (Ki‐67) index significantly predicted disease‐specific and metastasis‐free survival. Cyclin A did not achieve statistical significance. In a multivariate analysis, both cyclin E [relative risk (RR) 2.01, p = 0.021] and cyclin B (RR 1.85, p = 0.033) were selected as independent prognosticators of metastasis‐free survival when the Ki‐67 index was omitted, but only cyclin E expression was associated with disease‐specific survival (RR 2.56, p = 0.006). When Ki‐67 was included as a covariate, cyclin E lost its significance with respect to disease‐specific survival but remained significant for metastasis‐free survival. In an analogous analysis including Ki‐67, the number of concurrently overexpressed cyclins did not attain statistical significance regarding disease‐specific survival but was selected as the leading predictor of metastatic disease. It is concluded that combined overexpression of cyclins may imply genetic instability enhancing metastatic potential, but that survival ultimately depends on the proliferative activity of tumour cells. Copyright

DNA topoisomerase IIα expression and the response to primary chemotherapy in breast cancer

The α isoform of Topoisomerase IIα (Topo IIα) is a proliferation marker as well as a target for several chemotherapeutic agents such as anthracyclines. In vitro studies have demonstrated the relationship between the Topo IIα expression level and chemosensitivity of target cancer cells. To verify this effect in vivo, we selected 125 patients presenting with T2>3 cm and T3 N0–1 M0 breast tumours who were treated by six cycles of primary chemotherapy, including epirubicin before any surgery. Therapy response was assessed by clinical and X-ray mammogram measurements of tumour shrinkage. The pretherapeutic core biopsies were immunostained with a monoclonal antibody (Ki-S7) against Topo IIα. Ki-S7 positivity ranged from 0 to 50% (median, 15%). A high percentage of Ki-S7-positive cells (>15%) was associated with tumour regression under chemotherapy (OR=2.88, CI: 1.3–6.4, P=0.004). Ki-S7 further emerged as an independent predictor of tumour regression (OR=3.34, CI: 1.41–7.93, P=0.006), together with tumour size of less than 40 mm (OR=3.82, CI: 1.58–9.25, P=0.002) and negative oestrogen receptor (ER) status (OR=3.35, CI: 1.43–7.86, P=0.005), in a multivariate analysis including tumour size, SBR grade, ER and PR status, Ki-67, p53 and Her-2/neu. Our clinical results confirm in vitro data on the relationship between Topo IIα expression and tumour chemosensitivity and thus may have important practical implications.

Differential prognostic impact of the cyclins E and B in premenopausal and postmenopausal women with lymph node-negative breast cancer

Searching for new prognostic factors, we investigated the influence of cyclin expression on breast cancer prognosis. A total of 273 archival tumor specimens from patients with pT1/pT2 N0 breast cancers treated by surgery and local irradiation were immunostained for cyclins E, A and B. Outcome was evaluated as metastasis‐free (MFS) and disease‐specific survival (DSS) over a median observation period of 99 months. In postmenopausal women, DSS was significantly predicted by cyclin E, and in premenopausal patients by cyclin B. No statistical significance was found for cyclin A. When the prognostic impact of cyclins was compared to that of standard prognostic indicators in a multivariate analysis, both cyclin E and cyclin B were selected as independent predictors of survival in postmenopausal and premenopausal patients, respectively. After inclusion of Ki‐67 in the model, cyclin E lost its significance, whereas cyclin B remained the only independent prognostic factor with a hazard ratio of 4.5 (p = 0.026) for tumor‐related death. Assessment of cyclin expression may, therefore, refine current prognostic models if considered in relation to menopausal status. The prognostic relevance of cyclins is likely attributable to an influence on proliferation, cell survival and genetic instability. Awareness of the molecular mechanisms leading to deregulated cyclin expression may guide decisions for risk‐adapted therapy regimens.

Telomerase Activity in Melanocytic Lesions : A Potential Marker of Tumor Biology

Telomerase activation, being a cardinal requirement for immortalization, is a crucial step in the development of malignancy. With a view toward diagnostic and biological aspects in melanocytic neoplasia, we investigated the relative levels of telomerase activity in 72 nevi and 16 malignant melanomas by means of a modified telomeric repeat amplification protocol (TRAP) assay, including an internal amplification standard. We further compared telomerase activity with the expression of two different proliferation-specific proteins, Ki-67 and repp86, a protein expressed exclusively in the cell cycle phases S, G2, and M. Telomerase activity was associated with the overall growth fraction (Ki-67) but showed a closer correlation with the expression of repp86. Both telomerase activity and proliferation indices discriminated clearly between malignant melanomas and nevi, but not between common and dysplastic nevi. Nonetheless, a portion of nevi exhibited markedly elevated telomerase activity levels without proportionally increased proliferation. This was independent of discernible morphological changes. Clinicopathological correlations showed an association between high telomerase activity and early metastatic spread in melanomas, linking telomerase to tumor biology. Our results provide arguments in favor of an occasional progression from nevi to melanomas and imply that proliferation measurements in combination with telomerase assays may help to elicit early malignant transformation that is undetectable by conventional morphology.

Prognostic significance of Ki‐67 and topoisomerase IIα expression in infiltrating ductal carcinoma of the breast

To evaluate the prognostic relevance of Ki‐67 and topoisomerase IIα expression in relation to tumor stage, grade, and hormone receptor content, 942 ductal infiltrating carcinomas of the breast were examined by means of the monoclonal antibodies Ki‐S11 (Ki‐67) and Ki‐S4 (topoisomerase IIα). pS2, c‐erbB2, and p53 were additionally considered as prognostic variables. The median follow‐up time was 149 months. Eight‐hundred‐and‐sixty‐three tumors reacted with Ki‐S11 and Ki‐S the labeling indices of the two antigens were closely associated (r=0.93). Both correlated positively with the tumor size, c‐erbB2, and p53 expression, and negatively with patient age, hormone receptor content, and pS2 immunostaining. In the univariate analysis, Ki‐S11 and Ki‐S4 scores, nodal status, tumor size, tumor grade, and progesterone receptor content strongly predicted both overall and metastasis‐free survival (p <0.00001). Estrogen receptor status, p53, and c‐erbB2 were of minor significance. Concerning overall survival, multivariate Cox regression analysis selected a Ki‐S4 score >25% (p < 0.00001) next to the nodal status, and before tumor size, progesterone receptor content, and patient age. Independent predictors of the occurrence of distant metastases were nodal status, Ki‐S4, tumor size, grade 1, and progesterone receptor negativity, in that order. The Ki‐S11 score was of independent prognostic significance only if examined as a continuous variable. We conclude that topoisomerase IIα expression as assessed by monoclonal antibody Ki‐S4 may add valuable information to current prognostic models for breast cancer. Its predictive value appears to be essentially related to the proliferative activity of tumor cells.

Proliferation marker Ki-S5 as a diagnostic tool in melanocytic lesions

BACKGROUND A discrimination between benign and malignant melanocytic lesions is not always possible by conventional histology. OBJECTIVE Our purpose was to determine the proliferative activity in various types of melanocytic neoplasms and to appraise its value as a diagnostic adjunct. METHODS The growth fraction was assessed immunohistochemically in 398 melanocytic lesions by means of the monoclonal antibody Ki-S5 directed to the Ki-67 antigen. In this way, a cut-off level was defined and applied to 112 lesions of equivocal histology. The revised diagnoses were correlated to the clinical courses. RESULTS Common nevi, Spitz nevi, and melanomas exhibited significantly different proliferation indices and distinctive distribution patterns of cycling cells. In agreement, malignancy diagnosed on the basis of a growth fraction greater than 5% was confirmed by disease progression in 68% of our cases with uncertain diagnosis. CONCLUSION Determination of the proliferative activity in melanocytic lesions may usefully complement conventional histology to improve diagnostic accuracy.