2--4--dihydroxy-6--methoxy-3--5--dimethylchalcone and Carcinoma--Hepatocellular

2',4'-Dihydroxy-6'-methoxy-3',5'-dimethylchalcone (DMC) is a major active constituent of the buds of Cleistocalyx operculatus (Roxb.) Merr. et Perry (Myrtaceae), a main ingredient of herbal tea in tropical zones. DMC has been reported to significantly reverse drug resistance in BEL-7402/5-FU cells. Glutathione (GSH) and glutathione S-transferase (GST) play important roles in an efflux system that protects the cells from anticancer drugs. In this study, DMC remarkably decreased the intracellular GSH content and GST activity. Furthermore, DMC suppressed the expression of factor erythroid 2-related factor 2 (Nrf2), prevented Nrf2 nuclear translocation, and inhibited the binding of Nrf2 to the antioxidant response element (ARE). The glutamate-cysteine ligase catalytic subunit (GCLC) and glutamate-cysteine ligase modifier subunit (GCLM) were down-regulated by inhibiting Nrf2 with DMC treatment. These results suggested that DMC reduced drug efflux to reverse drug resistance by suppressing the Nrf2/ARE signaling pathway in human hepatocellular carcinoma BEL-7402/5-FU cells.

Topics: Animals; Antineoplastic Agents; Carcinoma, Hepatocellular; Cell Line, Tumor; Chalcones; Drug Resistance, Neoplasm; Glutathione; Humans; Liver Neoplasms; NF-E2-Related Factor 2

To study the in-vitro inducing apoptosis mechanism of human hepatoma SMMC-7721 cells by 2',4'-di- hydroxy-6'-methoxy-3',5'-dimethylchalcone (DMC), a chalcone compound from Cleistocalyx operculatus.. Quantitative DNA fragmentation assay was carried out to detect the effect of DMC of different concentrations on SMMC-7721 cells, according to the method of Sellins and Cohen with some modifications. Telomerase activities of the cells were determined by PCR-ELISA methods. The expression quantity of c-myc and hTERT mRNA were determined by semi-quantitative RT-PCR The effect of DMC on expression levels of cmyc and hTERT protein were measured by western blot.. The percentage of DNA fragmentation increased with notable concen- tration dependence, after treatment with DMC for 48 h. Compared with that of control group, the telomerase activity of the cells de- creased by (66.2 ± 2.1)% after 48 h treatment with 20 μmol x L(-1) DMC, the mRNA expression of c-myc and hTERT decreased by (67.3 ± 2.1)% and (64.4 ± 2.3)%, respectively, and the protein expression of c-myc and hTERT decreased by (69.6 ± 1.9)% and (71.3 ± 2.4)%, respectively.. DMC can induce SMMC-7721 cell apoptosis and the apoptosis mechanism may be related to the decreased mRNA and protein expression of c-myc and hTERT.

Topics: Antineoplastic Agents; Apoptosis; Carcinoma, Hepatocellular; Cell Line, Tumor; Chalcones; DNA Fragmentation; Dose-Response Relationship, Drug; Humans; Liver Neoplasms; Proto-Oncogene Proteins c-myc; RNA, Messenger; Syzygium; Telomerase

Multi drug resistance (MDR) is a major obstacle in the chemotherapeutic treatment of many human cancers. 2',4'-Dihydroxy-6'-methoxy-3',5'-dimethylchalcone (DMC), a chalcone, isolated from the buds of Cleistocalyx operculatus, has been shown to have antitumor effects on human carcinoma SMMC-7721 cells in vitro and in vivo. In this paper, we studied the reversal effect and the mechanism of DMC on human hepatocellular carcinoma drug-resistant cells BEL-7402/5-FU in vitro. Administration of DMC reversed the multi-drug resistance of human hepatocellular carcinoma BEL-7402/5-FU cells significantly. DMC enhanced the sensitivity of BEL-7402/5-FU cells to 5-fluorouracil (5-FU) and doxorubicin (DOX). Staining with Hoechst 33258 and flow cytometric analysis showed that DMC has apoptosis-inducing effect on BEL-7402/5-FU cells. It could also increase the concentration of 5-FU in the resistant multi-drug-resistant cells. We also observed that over-expression of the multi-drug resistance-associated protein (MRP1) and of the glutathione S-transferase π (GST-π) contributed to MDR in BEL-7402/5-FU cells. The mRNA expressions of MRP1 and GST-π and the protein expression of MRP1 were decreased by DMC. These data demonstrated that DMC could effectively reverse MDR in BEL-7402/5-FU cells.

Topics: Antimetabolites, Antineoplastic; Carcinoma, Hepatocellular; Cell Line, Tumor; Chalcones; Chromatography, High Pressure Liquid; Drug Evaluation, Preclinical; Drug Resistance, Neoplasm; Flow Cytometry; Fluorouracil; Gene Expression Regulation, Neoplastic; Humans; Liver Neoplasms