title: Mechanisms involved in development of resistance to adenovirus-mediated proapoptotic gene therapy in DLD1 human colon cancer cell line.
abstract: To evaluate resistance that develops in cancer cells during treatment with adenoviral vectors expressing proapoptotic genes, we repeatedly treated the human colon cancer cell line DLD1 with adenoviral vectors expressing the human Bax gene and the human tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) gene. DLD1 cells resistant to the Bax- or TRAIL-expressing adenoviral vectors were then selected and designated as DLD1/Bax-R or DLD1/TRAIL-R cells, respectively. Further study showed that resistance in DLD1/Bax-R cells was caused by resistance to adenoviral infection, which can be overcome by dose escalation of the adenoviral vectors. However, resistance in DLD1/TRAIL-R cells was caused by resistance to the TRAIL gene. Therefore, different mechanisms are involved in the development of resistance during adenovirus-mediated proapoptotic gene therapy. A survey of molecules involved in TRAIL- or Bax-mediated apoptotic pathways showed no significant change in expression of death receptors, death decoy receptors; FLIP; Bcl-2; Bcl-xS; Bax; Bak; XIAP or caspase-2, -7, -8, or -9 in either DLD1/Bax-R or DLD1/TRAIL-R cells. Bcl-xL expression detected in both mRNA and protein level assays was three times higher in DLD1/TRAIL-R cells than in parental or DLD1/Bax-R cells. However, transfection of DLD1 cells with the Bcl-xL gene showed that overexpression of Bcl-xL is not sufficient for the resistance. Moreover, DLD1/Bax-R cells were sensitive to adenoviral vectors that expressed the TRAIL gene, but resistant to adenoviral vectors that expressed the Bak gene. In contrast, DLD1/TRAIL-R cells were sensitive to adenoviral vectors that expressed either Bax or Bak gene. Thus, alternative application of adenoviral vectors that expressed proapoptotic genes in different pathways or different cell killing models may delay or prevent development of resistance in adenovirus-mediated proapoptotic gene therapy.
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.forename: J
authors.initials: J
authors.lastname: Gu
authors.forename: T
authors.initials: T
authors.lastname: Lin
authors.forename: X
authors.initials: X
authors.lastname: Huang
authors.forename: J A
authors.initials: JA
authors.lastname: Roth
authors.forename: B
authors.initials: B
authors.lastname: Fang
mesh_terms: D000256:Adenoviridae / Q000235:genetics* / Q000276:immunology; D017209:Apoptosis / Q000235:genetics; D051017:Apoptosis Regulatory Proteins; D002460:Cell Line; D003110:Colonic Neoplasms / Q000276:immunology / Q000628:therapy*; D015870:Gene Expression; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000008:administration & dosage* / Q000276:immunology; D006801:Humans; D007113:Immunity, Innate / Q000235:genetics; D008562:Membrane Glycoproteins / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D019253:Proto-Oncogene Proteins c-bcl-2; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053221:TNF-Related Apoptosis-Inducing Ligand; D014162:Transfection / Q000379:methods; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein
chemical_list: D051017:Apoptosis Regulatory Proteins; C494772:BAK1 protein, human; C494826:BAX protein, human; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein