title: Increase of Bax/ Bcl-XL ratio and arrest of cell cycle by luteolin in immortalized human hepatoma cell line.
abstract: Luteolin is a common constituent of many kinds of fruits and vegetables. It possesses the anti-neoplastic activities against several human cancers, but its activity against hepatocellular carcinoma (HCC) is seldom mentioned. To evaluate the activity against HCC and to provide information about the mechanism, we tested luteolin against five human hepatoma cell lines, namely HepG2, SK-Hep-1, PLC/PRF/5, Hep3B, and HA22T/VGH, with XTT assay and flow cytometry. The results showed that luteolin inhibited PLC/PRF/5, Hep3B and HA22T/VGH at a concentration of 1 microg/ml, but it needed 5 microg/ml to inhibit HepG2 and 10 microg/ml for SK-Hep1 (P <0.05). The inhibitive concentrations of 50% (IC50) of luteolin were between 7.29 microg/ml and 32.59 microg/ml, which were comparable with those of 5-FU (15.35 microg/ml to 32.84 microg/ml). The least effective cell line as affected by luteolin (SK-Hep1) was the most effective one when treating with 5-FU. The least effective cell line as affected by 5-FU (HA22T/VGH) was effectively affected by luteolin. It seemed that luteolin had some complementary activity to 5-FU against these HCC cell lines. The luteolin-treated PLC/PRF/5 cells exhibited typical changes of apoptosis with a characteristic DNA laddering pattern on gel electrophoresis. Luteolin also activated casepase-3, increased Bax protein with a concomitant decrease in Bcl-XL level. Increase in Bax/ Bcl-XL ratio and activation of caspase-3 supported the apoptotic finding on gel electrophoresis. Luteolin also induced cell cycle arrest at G0/G1 phase. We suggested that luteolin might exhibit anti-HCC activity as efficient as 5-FU by the mechanism of not only cell cycle arrest but also apoptosis.
authors.affiliation: Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, No. 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan.
authors.forename: Jungsan
authors.initials: J
authors.lastname: Chang
authors.forename: Yaling
authors.initials: Y
authors.lastname: Hsu
authors.forename: Polin
authors.initials: P
authors.lastname: Kuo
authors.forename: Yuchun
authors.initials: Y
authors.lastname: Kuo
authors.forename: Lienchai
authors.initials: L
authors.lastname: Chiang
authors.forename: Chunching
authors.initials: C
authors.lastname: Lin
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D016193:G1 Phase / Q000187:drug effects; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology; D047311:Luteolin / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis*; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
chemical_list: D000970:Antineoplastic Agents; C494826:BAX protein, human; C494811:BCL2L1 protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D047311:Luteolin