title: Adenoviral-mediated retinoblastoma 94 produces rapid telomere erosion, chromosomal crisis, and caspase-dependent apoptosis in bladder cancer and immortalized human urothelial cells but not in normal urothelial cells.
abstract: Retinoblastoma (RB)94, which lacks the NH(2)-terminal 112 amino acid residues of the full-length RB protein (RB110), is a more potent tumor and growth suppressor than RB110. In this study, Ad-RB94, but not Ad-RB110, produced marked growth inhibition, cytotoxicity, caspase-dependent apoptosis, and G(2)-M block in the human RB-negative, telomerase-positive bladder cancer cell line UM-UC14. This effect was completely inhibited by pretreatment with caspase inhibitors (P < 0.0001). Similar results were seen in RB-positive and other RB-negative bladder cancer cell lines. Ad-RB94 produced rapid telomere length shortening and loss of telomere signal, which was associated with polyploidy and chromosomal aberrations (P < 0.001). Ad-RB94, however, showed no cytotoxicity to telomerase-negative human normal urothelium cells but was highly cytotoxic to telomerase-positive human E6 and E7 immortalized urothelial cells (P < 0.0001). In addition, telomerase-negative cells, which maintain their telomere length through an alternative lengthening of telomeres DNA recombination pathway, showed no cytotoxicity to RB94. These results suggest that the induction of rapid telomere erosion and chromosomal crisis by RB94 in telomerase-positive cancer and in telomerase-expressing immortalized human cells is a major factor in its selective and potent tumor suppression and cytotoxic activity. The lack of cytotoxicity to normal cells should also provide a high therapeutic index when used in gene therapy protocols for the treatment of bladder and other cancers.
authors.affiliation: Department of Genitourinary Medical Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: Xinqiao
authors.initials: X
authors.lastname: Zhang
authors.forename: Asha S
authors.initials: AS
authors.lastname: Multani
authors.forename: Jain-Hua
authors.initials: JH
authors.lastname: Zhou
authors.forename: Jerry W
authors.initials: JW
authors.lastname: Shay
authors.forename: David
authors.initials: D
authors.lastname: McConkey
authors.forename: Li
authors.initials: L
authors.lastname: Dong
authors.forename: Chang-Soo
authors.initials: CS
authors.lastname: Kim
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Rosser
authors.forename: Sen
authors.initials: S
authors.lastname: Pathak
authors.forename: William F
authors.initials: WF
authors.lastname: Benedict
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D017209:Apoptosis / Q000502:physiology*; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002869:Chromosome Aberrations; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D010446:Peptide Fragments / Q000235:genetics / Q000502:physiology*; D016160:Retinoblastoma Protein / Q000235:genetics / Q000502:physiology*; D016615:Telomere / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000235:genetics* / Q000473:pathology / Q000628:therapy*; D019459:Urothelium / Q000166:cytology
chemical_list: D061945:Caspase Inhibitors; D010446:Peptide Fragments; D016160:Retinoblastoma Protein; D020169:Caspases