Open Access Research article

5-allyl-7-gen-difluoromethoxychrysin enhances TRAIL-induced apoptosis in human lung carcinoma A549 cells

Zhao-Hui Xie12, Mei-Fang Quan2, Fei Liu2, Jian-Guo Cao2 and Jian-Song Zhang2*

Author Affiliations

1 Changsha Health Vocational College, Changsha 410010, Hunan Province, China

2 Medical College, Hunan Normal University, Changsha 410013, Hunan Province, China

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BMC Cancer 2011, 11:322  doi:10.1186/1471-2407-11-322

Published: 29 July 2011

Abstract

Background

5-allyl-7-gen-difluoromethoxychrysin (AFMC) is a novel synthetic analogue of chrysin that has been reported to inhibit proliferation in various cancer cell lines. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising anti-cancer agent.

Methods

The cytotoxicity of A549 and WI-38 cells were determined using colorimetry. Apoptosis was detected by flow cytometry (FCM) after propidium iodide (PI) fluorescence staining and agarose gel electrophoresis. Caspase activities were evaluated using enzyme-linked immunosorbent assay (ELISA).The expressions of DR4 and DR5 were analyzed using FCM and western blot.

Results

Subtoxic concentrations of AFMC sensitize human non-small cell lung cancer (NSCLC) A549 cells to TRAIL-mediated apoptosis. Combined treatment of A549 cells with AFMC and TRAIL significantly activated caspase-3, -8 and -9. The caspase-3 inhibitor zDEVD-fmk and the caspase-8 inhibitor zIETD-fmk blocked the apoptosis of A549 cells induced by co-treatment with AFMC and TRAIL. In addition, we found that treatment of A549 cells with AFMC significantly induced the expression of death receptor 5 (DR5). AFMC-mediated sensitization of A549 cells to TRAIL was efficiently reduced by administration of a blocking antibody or small interfering RNAs against DR5. AFMC also caused increase of the Sub-G1 cells by TRAIL treatment and increased the expression levels of DR5 in other NSCLC H460 and H157 cell lines. In contrast, AFMC-mediated induction of DR5 expression was not observed in human embryo lung WI-38 cells, and AFMC did not sensitize WI-38 cells to TRAIL-induced apoptosis.

Conclusions

AFMC synergistically enhances TRAIL-mediated apoptosis in NSCLC cells through up-regulating DR5 expression.

Keywords:
Lung cancer; chrysin; 5-allyl-7-gen-difluoromethoxychrysin; TRAIL; apoptosis; therapeutic action