Abstract: AIM: To investigate whether capsaicin induces apoptosis in drug-resistant leukemia K562/ADM cells mediated by endoplasmic reticulum stress-related pathway.METHODS: The drug-resistant leukemia K562/ADM cells were used as the target cells. The cell proliferating activity was assessed with MTT colorimetric assay. The apoptosis of K562/ADM cells was identified by double staining of FITC-Annexin V and propidium iodide (PI) and the cellular morphology. The ultrastructure of the cells and endoplasmic reticulum were observed by transmission electron microscopy. The expression of GRP78 gene mRNA and protein were analyzed by real-time reverse transcription-polymerase chain reaction(RT-PCR) and Western blotting, respectively.RESULTS: Capsaicin of different concentrations markedly inhibited the proliferation of K562/ADM cells and also induced the cells to apoptosis. After the treatment with 20 and 50 μmol/L capsaicin for 48 h, K562/ADM cells showed the typical morphological characteristics of apoptosis, and the apoptotic rate of the cells increased to 39.67% and 41.78%, respectively. During the apoptotic process of K562/ADM cells induced with capsaicin, the endoplasmic reticulum exhibited obvious expansion and degranulation. The expression of GRP78 gene mRNA of K562/ADM cells increased and then decreased slightly, the expression of GRP78 protein increased by 1.5 and 2.2 times respectively, and gradually reduced with the inducing time.CONCLUSION: Capsaicin may induce drug-resistant K562/ADM cells to apoptosis via endoplasmic reticulum stress-mediated pathway.

Key words: Capsaicin, K562/ADM cells, Endoplasmic reticulum stress, Apoptosis