title: Optimization of photodynamic therapy response by survivin gene knockdown in human metastatic breast cancer T47D cells.
abstract: Photodynamic therapy (PDT) leads to the generation of cytotoxic oxygen species that appears to stimulate several different signaling pathways, some of which lead to cell death, whereas others mediate cell survival. In this context, we observed that PDT mediated by methyl-5-aminolevulinic acid as the photosensitizer resulted in over-expression of survivin, a member of the inhibitor of apoptosis (IAP) family that correlates inversely with patient prognosis. The role of survivin in resistance to anti-cancer therapies has become an area of intensive investigation. In this study, we demonstrate a specific role for survivin in modulating PDT-mediated apoptotic response. In our experimental system, we use a DNA vector-based siRNA, which targets exon-1 of the human survivin mRNA (pSil_1) to silence survivin expression. Metastatic T47D cells treated with both pSil_1 and PDT exhibited increased apoptotic indexes and cytotoxicity when compared to single-agent treated cells. The treatment resulted in increased PARP and caspase-3 cleavage, a decrease in the Bcl-2/Bak ratio and no participation of heat shock proteins. In contrast, the overexpression of survivin by a survivin-expressed vector increased cell viability and reduced cell death in breast cancer cells treated with PDT. Therefore, our data suggest that combining PDT with a survivin inhibitor may attribute to a more favorable clinical outcome than the use of single-modality PDT.
authors.affiliation: Departamento Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de Río Cuarto, Ruta 8 Km 601, Río Cuarto, Argentina. sol_cogno@yahoo.com.ar
authors.forename: Ingrid S
authors.initials: IS
authors.lastname: Cogno
authors.forename: Natalia B Rumie
authors.initials: NB
authors.lastname: Vittar
authors.forename: Maria Julia
authors.initials: MJ
authors.lastname: Lamberti
authors.forename: Viviana A
authors.initials: VA
authors.lastname: Rivarola
mesh_terms: D000622:Aminolevulinic Acid / Q000031:analogs & derivatives / Q000627:therapeutic use / Q000633:toxicity; D017209:Apoptosis; D001943:Breast Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000628:therapy*; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D009362:Neoplasm Metastasis; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use / Q000633:toxicity; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D000077022:Survivin; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000378:metabolism
chemical_list: C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D017319:Photosensitizing Agents; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D000077022:Survivin; D050998:bcl-2 Homologous Antagonist-Killer Protein; C114767:delta-aminolevulinic acid methyl ester; D000622:Aminolevulinic Acid; D011065:Poly(ADP-ribose) Polymerases; D053148:Caspase 3