Changes in topoisomerase I (topo I) levels and localization were examined during the course of granulocytic maturation in vitro and in vivo. Western blotting revealed that granulocytic maturation in DMSO-treated HL-60 human leukemia cells was accompanied by a 5-fold decrease in topo I polypeptide content. Consistent with this result, 3- to 5-fold higher concentrations of the topo I poison campt...

INTRODUCTION There is an ongoing search for markers of pituitary tumor proliferation and progression that could facilitate further treatment and patient monitoring. OBJECTIVES We studied topoisomerase IIα (topo IIα) expression in different types of pituitary adenomas to evaluate its prognostic value. PATIENTS AND METHODS In a retrospective study of 60 patients (mean age, 46.7 ±17.6 y) who u...

In Alternative Lengthening of Telomeres (ALT) cell lines, specific nuclear bodies called APBs (ALT-associated PML bodies) concentrate telomeric DNA, shelterin components and recombination factors associated with telomere recombination. Topoisomerase IIIalpha (Topo III) is an essential telomeric-associated factor in ALT cells. We show here that the binding of Topo III to telomeric G-overhang is ...

Physiological cell conditions, such as glucose deprivation and hypoxia, play a role in developing drug resistance in solid tumors. These tumor-specific conditions cause decreased expression of DNA topoisomerase IIalpha (topo IIalpha), rendering cells resistant to topo II-targeted drugs, such as etoposide and doxorubicin. We show here that inhibition of proteasome attenuated drug resistance by i...

Metnase is a human SET and transposase domain protein that methylates histone H3 and promotes DNA double-strand break repair. We now show that Metnase physically interacts and co-localizes with Topoisomerase IIalpha (Topo IIalpha), the key chromosome decatenating enzyme. Metnase promotes progression through decatenation and increases resistance to the Topo IIalpha inhibitors ICRF-193 and VP-16....

Nicotinic acid (also known as pyridine-3-carboxylic acid) is widely used in food, pharmaceutical and biochemical industries. The extraction of nicotinic acid by tri-noctylphosphine oxide (TOPO) with kerosene (diluent) is studied. The equilibrium experiments are carried out to investigate the effects of diluent, extractant (TOPO) composition and initial acid concentration on extraction efficienc...

The anticancer agent saintopin induces DNA cleavage mediated by both topoisomerase (topo) I and topo II in vitro through stabilization of the reversible enzyme-DNA cleavable complex. We established saintopinresistant cell lines (KB/STP-1 and KB/STP-2) from human epidermoid cancer KB cells by stepwise exposure to increasing doses of the drug. KB/STP-1 and KB/STP-2 cells showed 12and 44-fold incr...

DNA topoisomerase I (topo I) has been identified as a principal target of a plant alkaloid camptothecin (CPT) and its derivative (CPT-11). The latter compound is expected to be a clinically useful antitumor agent. Three human tumor cell lines resistant to CPT (A549/CPT, HT-29/CPT, St-4/CPT) were isolated in vitro, and a murine tumor cell line resistant to CPT-11 (P388/CPT) was isolated in vivo ...

7-ethyl-10-[4-(1-piperidyl)-1-piperidyl] carbonyloxy-camptothecin, a topoisomerase I (topo I) inhibitor, is one of the most active agent against lung cancer, and its radiosensitizing effect has been reported recently. We evaluated a combination in vitro effect of irradiation and 7-ethyl-10-hydroxy-CPT (SN-38), an active metabolite of 7-ethyl-10-[4- (1-piperidyl)-1-piperidyl] carbonyloxy-camptot...

DNA topoisomerase I (topo I) has been identified as a principal target of a plant alkaloid camptothecin (CPT) and its derivative (CPT-11). The latter compound is expected to be a clinically useful antitumor agent. Three human tumor cell lines resistant to CPT (A549/CPT, HT-29/CPT, St-4/CPT) were isolated in vitro, and a murine tumor cell line resistant to CPT-11 (P388/CPT) was isolated in vivo ...