title: Role of Bcl-xL/Beclin-1 in synergistic apoptotic effects of secretory TRAIL-armed adenovirus in combination with mitomycin C and hyperthermia on colon cancer cells.
abstract: In this study, we attempted to develop a multimodality approach using chemotherapeutic agent mitomycin C, biologic agent tumor necrosis factor-related apoptosis-inducing ligand (TRAIL/Apo-2L), and mild hyperthermia to treat colon cancer. For this study, human colon cancer LS174T, LS180, HCT116 and CX-1 cells were infected with secretory TRAIL-armed adenovirus (Ad.TRAIL) and treated with chemotherapeutic agent mitomycin C and hyperthermia. The combinatorial treatment caused a synergistic induction of apoptosis which was mediated through an increase in caspase activation. The combinational treatment promoted the JNK-Bcl-xL-Bak pathway which transmitted the synergistic effect through the mitochondria-dependent apoptotic pathway. JNK signaling led to Bcl-xL phosphorylation at serine 62, dissociation of Bak from Bcl-xL, oligomerization of Bak, alteration of mitochondrial membrane potential, and subsequent cytochrome c release. Overexpression of dominant-negative mutant of Bcl-xL (S62A), but not dominant-positive mutant of Bcl-xL (S62D), suppressed the synergistic death effect. Interestingly, Beclin-1 was dissociated from Bcl-xL and overexpression of dominant-negative mutant of Bcl-xL (S62A), but not dominant-positive mutant of Bcl-xL (S62D), suppressed dissociation of Beclin-1 from Bcl-xL. A combinatorial treatment of mitomycin C, Ad.TRAIL and hyperthermia induced Beclin-1 cleavage, but the Beclin-1 cleavage was abolished in Beclin-1 double mutant (D133A/D146A) knock-in HCT116 cells, suppressing the apoptosis induced by the combination therapy. We believe that this study supports the application of the multimodality approach to colon cancer therapy.
authors.affiliation: Department of Surgery, School of Medicine, University of Pittsburgh, Hillman Cancer Center, 5117 Centre Ave. Room 1.46C, Pittsburgh, PA, 15213, USA.
authors.forename: Seog-Young
authors.initials: SY
authors.lastname: Kim
authors.forename: Dae-Hee
authors.initials: DH
authors.lastname: Lee
authors.forename: Xinxin
authors.initials: X
authors.lastname: Song
authors.forename: David L
authors.initials: DL
authors.lastname: Bartlett
authors.forename: Yong Tae
authors.initials: YT
authors.lastname: Kwon
authors.forename: Yong J
authors.initials: YJ
authors.lastname: Lee
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D000071186:Beclin-1; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology*; D045304:Cytochromes c / Q000378:metabolism; D005822:Genetic Vectors; D006801:Humans; D006979:Hyperthermia, Induced; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D016685:Mitomycin / Q000494:pharmacology*; D055503:Protein Multimerization; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000235:genetics / Q000378:metabolism*; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000378:metabolism; D051020:bcl-X Protein / Q000378:metabolism*
chemical_list: D000903:Antibiotics, Antineoplastic; D051017:Apoptosis Regulatory Proteins; C494811:BCL2L1 protein, human; C491997:BECN1 protein, human; D000071186:Beclin-1; D008565:Membrane Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051020:bcl-X Protein; D016685:Mitomycin; D045304:Cytochromes c; D048670:MAP Kinase Kinase 4