Baicalein induces apoptosis in SCC-4 human tongue cancer cells via a Ca2+-dependent mitochondrial pathway.
BACKGROUND
The effects of baicalein on SCC-4 human tongue cancer cells were examined to better understand its effect on apoptosis and associated possible signal pathways in vitro.


METHODS
Apoptosis induction, reactive oxygen species (ROS), cytoplasmic Ca2+, mitochondrial membrane potential (MMP) and caspase-3 activity were analyzed using the flow cytometric assay. Apoptosis-associated proteins, such as p53, BAX, BCL-2, cytochrome c, caspase-3 and -9, EndoG and AIF were determined by Western blotting.


RESULTS
Our results showed that baicalein promoted the levels of p53, BAX, cytochrome c, capase-3 and -9 and reduced the level of BCL-2, which were associated with the induction of apoptotic cell death of SCC-4 cells. A release of cytochrome c from mitochondria into cytosol was demonstrated and an activation of caspase-3, which led to the occurrence of apoptosis in SCC-4 cells treated with baicalein as determined by Western blot. In order to understand the role of Ca2+ in the induction of apoptosis, cells were pre-treated with BAPTA (intracellular calcium chelator) and baicalein. It was shown that the MMP was restored, and the level of cytoplasmic Ca2+ suppressed, the proportion of cells undergoing apoptosis was also markedly diminished. Our data suggest that cellular Ca2+ modulates baicalein-induced cell death via a Ca2+-dependent mitochondrial death pathway in SCC-4 cells.
Lin
Yuh-Tzy
YT
Department of Nursing and Management, Jen-Teh Junior College of Medicine, Taiwan, ROC.
Yang
Jai-Sing
JS
Lin
Hui-Ju
HJ
Tan
Tzu-Wei
TW
Tang
Nou-Ying
NY
Chaing
Jo-Hua
JH
Chang
Yung-Hsien
YH
Lu
Hsu-Feng
HF
Chung
Jing-Gung
JG
D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D044950:Flavanones / Q000494:pharmacology*; D006801:Humans; D020782:Matrix Metalloproteinases / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D014062:Tongue Neoplasms / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*
D044950:Flavanones; D017382:Reactive Oxygen Species; C006680:baicalein; D020782:Matrix Metalloproteinases; D002118:Calcium