Raloxifene, a mixed estrogen agonist/antagonist, induces apoptosis through cleavage of BAD in TSU-PR1 human cancer cells.
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.
Kim
Heung Tae
HT
Laboratory of Cell Regulation and Carcinogenesis, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA.
Kim
Byung Chul
BC
Kim
Isaac Yi
IY
Mamura
Mizuko
M
Seong
Do Hwan
DH
Jang
Ja-June
JJ
Kim
Seong-Jin
SJ
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
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