title: Raloxifene, a mixed estrogen agonist/antagonist, induces apoptosis through cleavage of BAD in TSU-PR1 human cancer cells.
abstract: Selective estrogen receptor modulator is a proven agent for chemoprevention and chemotherapy of cancer. Raloxifene, a mixed estrogen agonist/antagonist, was developed to prevent osteoporosis and potentially reduce the risk of breast cancer. In this study, we examined the effect of raloxifene on the TSU-PR1 cell line. This cell line was originally reported to be a prostate cancer cell line, but recently it has been shown to be a human bladder transitional cell carcinoma cell line. The TSU-PR1 cell line contains high levels of estrogen receptor beta. Following treatment with raloxifene, evidence of apoptosis, including change in nuclear morphology, DNA fragmentation, and cytochrome c release, was observed in a dose-dependent manner in the TSU-PR1 cells (10(-9) to 10(-6) m range). We observed no detectable change in the steady-state levels of Bax, Bcl-2, and Bcl-X(L) following raloxifene treatment. However, raloxifene induced caspase-dependent cleavage of BAD to generate a 15-kDa truncated protein. Overexpression of a double mutant BAD resistant to caspase 3 cleavage blocked raloxifene-induced apoptosis. These results demonstrate that raloxifene induces apoptosis through the cleavage of BAD in TSU-PR1 cells. This molecular mechanism of apoptosis suggests that raloxifene may be a therapeutic agent for human bladder cancer.
authors.affiliation: Laboratory of Cell Regulation and Carcinogenesis, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Heung Tae
authors.initials: HT
authors.lastname: Kim
authors.forename: Byung Chul
authors.initials: BC
authors.lastname: Kim
authors.forename: Isaac Yi
authors.initials: IY
authors.lastname: Kim
authors.forename: Mizuko
authors.initials: M
authors.lastname: Mamura
authors.forename: Do Hwan
authors.initials: DH
authors.lastname: Seong
authors.forename: Ja-June
authors.initials: JJ
authors.lastname: Jang
authors.forename: Seong-Jin
authors.initials: SJ
authors.lastname: Kim
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D002352:Carrier Proteins / Q000378:metabolism*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002455:Cell Division; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000473:pathology; D003513:Cycloheximide / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism; D053938:DNA Fragmentation; D004305:Dose-Response Relationship, Drug; D020847:Estrogen Receptor Modulators / Q000494:pharmacology*; D006801:Humans; D020287:In Situ Nick-End Labeling; D008564:Membrane Potentials; D008928:Mitochondria / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D020849:Raloxifene Hydrochloride / Q000494:pharmacology*; D012190:Retroviridae / Q000378:metabolism; D013997:Time Factors; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000378:metabolism* / Q000473:pathology; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D000970:Antineoplastic Agents; C494819:BAD protein, human; C494811:BCL2L1 protein, human; D002352:Carrier Proteins; D003574:Cytochrome c Group; D020847:Estrogen Receptor Modulators; D011500:Protein Synthesis Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D020849:Raloxifene Hydrochloride; D003513:Cycloheximide; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases