Norcantharidin-induced apoptosis in oral cancer cells is associated with an increase of proapoptotic to antiapoptotic protein ratio.
Norcantharidin (NCTD), the demethylated analogue of cantharidin, has been used to treat human cancers in China since 1984. It was recently found to be capable of inducing apoptosis in human colon carcinoma, hepatoma and glioblastoma cells by way of an elusive mechanism. In this study, we demonstrated that NCTD also induces apoptosis in human oral cancer cell lines SAS (p53 wild-type phenotype) and Ca9-22 (p53 mutant) as evidenced by nuclear condensation, TUNEL labeling, DNA fragmentation and cleavage of PARP. Apoptosis induced by NCTD was both dose- and time-dependent. We found NCTD did not induce Fas and FasL, implying that it activated other apoptosis pathways. Our data showed that NCTD caused accumulation of cytosolic cytochrome c and activation of caspase-9, suggesting that apoptosis occurred via the mitochondria mediated pathway. NCTD enhanced the expression of Bax in SAS cells consistent with their p53 status. Moreover, we showed that NCTD downregulated the expression of Bcl-2 in Ca9-22 and Bcl-XL in SAS. Our results suggest that NCTD-induced apoptosis in oral cancer cells may be mediated by an increase in the ratios of proapoptotic to antiapoptotic proteins. Since oral cancer cells with mutant p53 or elevated Bcl-XL levels showed resistance to multiple chemotherapeutic agents, NCTD may overcome the chemoresistance of these cells and provide potential new avenues for treatment.
Kok
Sang-Heng
SH
School of Dentistry, College of Medicine, National Taiwan University, 1 Chang-Te Street, Taipei 10016, Taiwan, ROC.
Cheng
Shih-Jung
SJ
Hong
Chi-Yuan
CY
Lee
Jang-Jaer
JJ
Lin
Sze-Kwan
SK
Kuo
Ying-Shiung
YS
Chiang
Chun-Pin
CP
Kuo
Mark Yen-Ping
MY
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D015153:Blotting, Western; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology*; D020169:Caspases / Q000187:drug effects / Q000378:metabolism; D045744:Cell Line, Tumor; D045304:Cytochromes c / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D005434:Flow Cytometry; D006801:Humans; D020287:In Situ Nick-End Labeling; D009062:Mouth Neoplasms / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000187:drug effects / Q000378:metabolism; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
C494826:BAX protein, human; C494811:BCL2L1 protein, human; D019086:Bridged Bicyclo Compounds, Heterocyclic; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; C069741:norcantharidin; D045304:Cytochromes c; D020169:Caspases