title: Roscovitine sensitizes breast cancer cells to TRAIL-induced apoptosis through a pleiotropic mechanism.
abstract: The tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL/APO2L) is a member of the TNF gene superfamily that induces apoptosis upon engagement of cognate death receptors. While TRAIL is relatively non-toxic to normal cells, it selectively induces apoptosis in many transformed cells. Nevertheless, breast tumor cells are particularly resistant to the effects of TRAIL. Here we report that, in combination with the cyclin-dependent kinase inhibitor roscovitine, exposure to TRAIL induced marked apoptosis in the majority of TRAIL-resistant breast cancer cell lines examined. Roscovitine facilitated TRAIL death-inducing signaling complex formation and the activation of caspase-8. The cFLIP(L) and cFLIP(S) FLICE-inhibitory proteins were significantly down-regulated following exposure to roscovitine and, indeed, the knockdown of cFLIP isoforms by siRNA sensitized breast tumor cells to TRAIL-induced apoptosis. In addition, we demonstrate that roscovitine strongly suppressed Mcl-1 expression and up-regulated E2F1 protein levels in breast tumor cells. Significantly, the silencing of Mcl-1 by siRNA sensitized breast tumor cells to TRAIL-induced apoptosis. Furthermore, the knockdown of E2F1 protein by siRNA reduced the sensitizing effect of roscovitine in TRAIL-induced apoptosis. In summary, our results reveal a pleitropic mechanism for the pro-apoptotic influence of roscovitine, highlighting its potential as an antitumor agent in breast cancer in combination with TRAIL.
authors.affiliation: Centro Andaluz de Biología Molecular y Medicina Regenerativa, Consejo Superior de Investigaciones Cientificas (CSIC), Avda Américo Vespucio s/n, 41092 Sevilla, Spain.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Ortiz-Ferrón
authors.forename: Rosario
authors.initials: R
authors.lastname: Yerbes
authors.forename: Adriana
authors.initials: A
authors.lastname: Eramo
authors.forename: Ana I
authors.initials: AI
authors.lastname: López-Pérez
authors.forename: Ruggero
authors.initials: R
authors.lastname: De Maria
authors.forename: Abelardo
authors.initials: A
authors.lastname: López-Rivas
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000235:genetics / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D053418:Death Domain Receptor Signaling Adaptor Proteins / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D050687:E2F1 Transcription Factor / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D053200:Fas-Associated Death Domain Protein / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics; D011687:Purines / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism; D000077546:Roscovitine; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D053418:Death Domain Receptor Signaling Adaptor Proteins; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D053200:Fas-Associated Death Domain Protein; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D020033:Protein Isoforms; D019253:Proto-Oncogene Proteins c-bcl-2; D011687:Purines; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D053221:TNF-Related Apoptosis-Inducing Ligand; D000077546:Roscovitine; D020169:Caspases