pregna-4-17-diene-3-16-dione and Leukemia--Myeloid

Multidrug resistance (MDR) has been a major problem in cancer chemotherapy. The development of P-glycoprotein inhibitors could be effective to reverse multidrug resistance. The aim of this study was to observe the effects of guggulsterone, the active component of gugulipid, on multidrug resistance in doxorubicin-resistant K562 cells (K562/DOX) and the parental K562 cells. Its cytotoxicity and reversal effects on multidrug resistance were assessed by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. Apoptosis percentage of cells was obtained from Annexin V/fluorescein isothiocyanate (FITC) and propridium iodide (PI) double staining. The effects of guggulsterone on P-glycoprotein activity were evaluated by measuring rhodamine 123 (Rh123)-associated mean fluorescence intensity and P-glycoprotein expression on the basis of the flow cytometric technology, respectively. The results showed that guggulsterone up to 100 microM had little cytotoxicity against K562/DOX cells. When combined with doxorubicin, it significantly promoted the sensitivity of K562/DOX cells toward doxorubicin through increasing intracellular accumulation of doxorubicin in a dose-dependent manner. Further study demonstrated that the inhibitory effect of guggulsterone on P-glycoprotein activity was the major cause of increased stagnation of doxorubicin inside K562/DOX cells, indicating that guggulsterone may effectively reverse multidrug resistance in K562/DOX cells via inhibiting expression and drug-transport function of P-glycoprotein.

Topics: Antibiotics, Antineoplastic; Apoptosis; ATP Binding Cassette Transporter, Subfamily B; Calcium Channel Blockers; Cell Line, Tumor; Cell Survival; Doxorubicin; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Flow Cytometry; Fluorescent Dyes; Humans; K562 Cells; Leukemia, Myeloid; Pregnenediones; Rhodamine 123; Verapamil

In this study, the antileukemic effects of three isomeric pregnadienedione steroids [i.e., cis-guggulsterone, trans-guggulsterone, and 16-dehydroprogesterone] were investigated in HL60 and U937 cells as well as in primary leukemic blasts in culture. Our results show that all three compounds inhibited the proliferation of HL60 and U937 cells, with IC50s ranging from 3.6 to 10.9 micromol/L after treatment for 6 days. These growth inhibitory effects correlated with externalization of phosphatidylserine and loss of mitochondrial membrane potential, suggesting that these isomeric steroids induce apoptosis in leukemia cells. z-VAD-fmk prevented phosphatidylserine externalization but not mitochondrial membrane potential loss, indicating that mitochondrial dysfunction occurred in the absence of caspase activation. Interestingly, although all three compounds increased the generation of reactive oxygen species and decreased phosphorylation of extracellular signal-regulated kinase, only cis-guggulsterone induced a rapid depletion of reduced glutathione levels and oxidation of the mitochondrial phospholipid cardiolipin. 16-Dehydroprogesterone and trans-guggulsterone induced differentiation of HL60 and NB4 cells as evidenced by increased surface expression of CD11b and/or CD14, and all three steroids rapidly induced mitochondrial dysfunction and phosphatidylserine externalization of CD34-positive blasts from primary leukemic samples. This study is the first to show that guggulsterones and 16-dehydroprogesterone exert antileukemic effects via the induction of apoptosis and differentiation and, more importantly, identifies the pregnadienedione structure as a potential chemotherapeutic scaffold.

Topics: Acute Disease; Antineoplastic Agents; Apoptosis; Blotting, Western; Cardiolipins; Cell Differentiation; Extracellular Signal-Regulated MAP Kinases; Flow Cytometry; Glutathione; Heme Oxygenase (Decyclizing); HL-60 Cells; Humans; Isomerism; Leukemia, Myeloid; Phosphorylation; Pregnadienes; Pregnenediones; Progesterone; Reactive Oxygen Species; U937 Cells