title: Apigenin, chrysin, and luteolin selectively inhibit chymotrypsin-like and trypsin-like proteasome catalytic activities in tumor cells.
abstract: The ubiquitin-proteasome pathway has an important role in regulating apoptosis and the cell cycle. The function of proteasomes is mediated by three main catalytic activities: (1) chymotrypsin-like (CT-L), (2) trypsin-like (T-L), and (3) peptidylglutamyl peptide hydrolyzing (PGPH). Recently, proteasome inhibitors have been revealed to have an antitumor effect, and have been used to treat cancers such as multiple myeloma. Previous studies have reported that some flavonoids can inhibit proteasome activity in tumor cells. To further investigate the proteasome-inhibitory mechanism of flavonoids, we examined the effects of the plant flavonoids apigenin, chrysin, and luteolin on the three individual catalytic activities in various cancer cell lines. Using fluorogenic substrates specific for proteasome catalytic subunits, we demonstrated the subunit specificity of each flavonoid. Addition of apigenin, chrysin and luteolin inhibited CT-L and T-L catalytic activities in a dose-dependent manner, whereas their effect on PGPH catalytic activity was weak. Our study suggested that these flavonoids have a specific role in inhibition of CT-L and T-L proteasome catalytic activities.
authors: Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan. yixinwu@hama-med.ac.jp
authors: Yi-Xin
authors: YX
authors: Wu
authors: Xin
authors: X
authors: Fang
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology* / Q000627:therapeutic use; D047310:Apigenin / Q000494:pharmacology / Q000627:therapeutic use; D045744:Cell Line, Tumor; D002918:Chymotrypsin / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005419:Flavonoids / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D006868:Hydrolysis; D047311:Luteolin / Q000494:pharmacology / Q000627:therapeutic use; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology* / Q000627:therapeutic use; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D014357:Trypsin / Q000378:metabolism*; D025801:Ubiquitin
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D005419:Flavonoids; D010455:Peptides; D010936:Plant Extracts; D025801:Ubiquitin; C043561:chrysin; D047310:Apigenin; D002918:Chymotrypsin; D014357:Trypsin; D046988:Proteasome Endopeptidase Complex; D047311:Luteolin