Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:5.99.1.2 (topoisomerase)
 9,166 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To investigate the effect of ultraviolet (UV) irradiation on the expression of cell cycle-associated proteins, melanocytic nevi from healthy volunteers were partially covered, irradiated with a defined UV dose, and excised 1 week thereafter. The irradiated and the protected parts were examined separately by conventional microscopy and immunohistochemistry using the antibodies Ki-S11 (Ki-67), Ki-S7 (topoisomerase IIalpha), PC10 (proliferating cell nuclear antigen [PCNA]), DO-7 (p53), 6B6 (p21WAF1/Cip1), and the melanocytic marker HMB-45. DNA nick-end labeling was used as a marker of apoptosis. Irradiation resulted in morphological changes and increased HMB-45 reactivity. Proliferation, as assessed by Ki-67 and topoisomerase IIalpha expression, was also clearly enhanced in the UV-exposed areas. This was confirmed by the appearance of occasional mitotic figures. PCNA expression levels markedly exceeded those of the proliferation markers and did not correlate with the latter in most cases. p21 immunolabeling indices were also consistently augmented after UV exposure; hence it is likely that growth-inhibitory mechanisms partly compensate for the proliferative impulse, and the disproportional rise in PCNA expression probably reflects DNA repair activity. Enhanced p53 immunostaining in four cases suggests that the induction of p21 after irradiation may be p53 mediated, whereas no concomitant apoptotic events were observed. We conclude that UV light can stimulate the proliferative activity of melanocytes in melanocytic nevi, but that simultaneously cell cycle inhibitors are activated to permit DNA repair.
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PMID:Enhanced expression of Ki-67, topoisomerase IIalpha, PCNA, p53 and p21WAF1/Cip1 reflecting proliferation and repair activity in UV-irradiated melanocytic nevi. 986 36

To evaluate the prognostic relevance of Ki-67 and topoisomerase IIalpha 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 IIalpha). 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-S4; 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 IIalpha 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.
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PMID:Prognostic significance of Ki-67 and topoisomerase IIalpha expression in infiltrating ductal carcinoma of the breast. A multivariate analysis of 863 cases. 1047 80