phenanthrenes and Leukemia--Erythroblastic--Acute

The discovery of oncogene addiction in myeloproliferative disorders (MPDs) driven by the gain-of-function mutant Jak2V617F has attracted intense interest in targeted therapy for MPDs. In this report, we demonstrate that triptolide potently downregulated the transcription of Jak2 by inhibiting the activity of RNA polymerase. Triptolide inhibited the in vitro and in vivo growth of tumor cells harboring Jak2V617F. Triptolide induced abundant apoptosis with a prominent decline of Bcl-2, Bcl-X(L), survivin and Mcl-1. As well, triptolide induced caspase-3-dependent Mcl-1 cleavage, which may potentiate apoptosis. These findings suggest that triptolide is a promising agent to kill Jak2V617F-harboring cells.

Topics: Amino Acid Substitution; Anti-Inflammatory Agents, Non-Steroidal; Apoptosis; Caspase 3; Caspase Inhibitors; Cell Cycle; Cell Line, Tumor; Cycloheximide; Diterpenes; DNA Primers; Epoxy Compounds; Flow Cytometry; Humans; Janus Kinase 2; Leukemia, Erythroblastic, Acute; Myeloid Cell Leukemia Sequence 1 Protein; Myeloproliferative Disorders; Phenanthrenes; Proto-Oncogene Proteins c-bcl-2; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Signal Transduction; Transcription, Genetic

Tanshinone II-A is a derivative of phenanthrene-quinone isolated from Salvia miltiorrhiza BUNGE, a traditional herbal medicine that is known to induce antiinflammatory, anti-oxidative and cytotoxic activity. We have examined cellular effects of Tanshione II-A on HL60 human promyelocytic leukemic cells and K562 human erythroleukemic cells. Tanshione II-A induced a dose- and time-dependent DNA fragmentation into the multiples of 180 bp and specific proteolytic cleavage of poly(ADP-ribose) polymerase in both cell lines. PI-staining and flow cytometry analysis of K562 cells following Tanshione II-A treatment showed an increase of the cells possessing hypodiploid DNA indicative of apoptotic state of cells. Caspase-3 activity was significantly increased during Tanshinone II-A treatment of both HL60 and K562 cells, whereas caspase-1 activity was not changed. These results suggest that Tanshione II-A induced HL60 and K562 cellular apoptosis that may be associated with the selective members of caspase family.

Topics: Abietanes; Antineoplastic Agents, Phytogenic; Apoptosis; Caspase 3; Caspases; Cell Cycle; DNA Fragmentation; Dose-Response Relationship, Drug; Drugs, Chinese Herbal; Enzyme Activation; HL-60 Cells; Humans; Lamiaceae; Leukemia; Leukemia, Erythroblastic, Acute; Phenanthrenes; Tumor Cells, Cultured

Carbonyl reductase (CBR) catalyzes the reduction of daunorubicin (DN) to its corresponding alcohol, daunorubicinol (DNOL), and changes the pharmacological properties of this cancer chemotherapeutic drug. The DN reductase associated with CBR reduces the C13 methyl ketone group and does not metabolize the quinone ring of DN. Reports comparing DN and DNOL toxicity have resulted in various conclusions depending on the cells tested. Differences in toxicity could be due to variations in several enzymes involved in DN metabolism. In this report, the effects of CBR expression on DN metabolism and cell toxicity were determined by cloning and expressing a human CBR cDNA in DN reductase-deficient myeloid erythroleukemia K562 cells. CBR activity increased 83-fold in the K562-transfected cells and was associated with a 2-3-fold reduction in DN toxicity. Maximum protection occurred at 30 nM DN where 94% of the intracellular DN was converted to DNOL within 2 h. The reduced toxicity was specific for DN. Other CBR substrates such as menadione, phenanthrenequinone, and doxorubicin were equally toxic to both the CBR expresser cells and the control cells under the conditions tested. Our results suggest that high levels of CBR in tumor cells could contribute to drug resistance. The results also suggest that reduction of DN to DNOL protects against DN toxicity by altering interaction of the drug at one or more of the many target sites.

Topics: Alcohol Oxidoreductases; Aldehyde Reductase; Aldo-Keto Reductases; Antibiotics, Antineoplastic; Base Sequence; Cells, Cultured; Cloning, Molecular; Daunorubicin; DNA Primers; Doxorubicin; Drug Resistance, Neoplasm; Gene Expression; Humans; In Vitro Techniques; Leukemia, Erythroblastic, Acute; Mitomycin; Molecular Sequence Data; Oxidation-Reduction; Phenanthrenes; Recombinant Proteins; RNA, Messenger; RNA, Neoplasm; Vitamin K