title: The combination of 5-fluorouracil plus p53 pathway restoration is associated with depletion of p53-deficient or mutant p53-expressing putative colon cancer stem cells.
abstract: The cancer stem cell hypothesis suggests that rare populations of tumor-initiating cells may be resistant to therapy, lead to tumor relapse and contribute to poor prognosis for cancer patients. We previously demonstrated the feasibility of p53 pathway restoration in p53-deficient tumor cell populations using small molecules including ellipticine or its derivatives. We now establish a single cell p53-regulated green fluorescent protein (EGFP)-reporter system in human DLD1 colon tumor cells expressing mutant p53 protein. We use these p53-EGFP reporter DLD1 cells to investigate the status of p53 transcriptional activity in putative colon cancer stem cell populations following exposure to p53 pathway-restoring drugs and/or classical chemotherapy. We demonstrate induction of p53-specific EGFP reporter fluorescence following overexpression of p53 family member p73 by an Adenovirus vector. We further show that p53-reporter activity is induced in DLD1 putative cancer stem cell side-populations analyzed by their Hoechst dye efflux properties following treatment with the p53 pathway restoring drug ellipticine. Combination of ellipticine with the cytotoxic agent 5-fluorouracil resulted in increased cytotoxicity as compared to either agent alone and this was associated with depletion of putative cancer stem cell populations as compared with 5-FU alone treatment. Our results support the feasibility of therapeutic targeting of mutant p53 in putative cancer stem cells as well as the potential to enhance cytotoxic chemotherapy.
authors.affiliation: Laboratory of Molecular Oncology and Cell Cycle Regulation, Departments of Medicine (Hematology/Oncology), Genetics and Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
authors.forename: Catherine
authors.initials: C
authors.lastname: Huang
authors.forename: Xiang M
authors.initials: XM
authors.lastname: Zhang
authors.forename: Raluca T
authors.initials: RT
authors.lastname: Tavaluc
authors.forename: Lori S
authors.initials: LS
authors.lastname: Hart
authors.forename: David T
authors.initials: DT
authors.lastname: Dicker
authors.forename: Wenge
authors.initials: W
authors.lastname: Wang
authors.forename: Wafik S
authors.initials: WS
authors.lastname: El-Deiry
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000473:pathology*; D004268:DNA-Binding Proteins / Q000502:physiology; D004357:Drug Synergism; D004611:Ellipticines / Q000008:administration & dosage / Q000494:pharmacology*; D005472:Fluorouracil / Q000008:administration & dosage / Q000494:pharmacology*; D017930:Genes, Reporter; D005813:Genes, Synthetic; D016158:Genes, p53; D005822:Genetic Vectors / Q000494:pharmacology; D006801:Humans; D009154:Mutation; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000378:metabolism; D009687:Nuclear Proteins / Q000502:physiology; D011743:Pyrimidines / Q000494:pharmacology; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000096:biosynthesis / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000502:physiology; D000072160:Tumor Protein p73; D016159:Tumor Suppressor Protein p53 / Q000172:deficiency / Q000502:physiology; D025521:Tumor Suppressor Proteins / Q000502:physiology
chemical_list: D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; D004611:Ellipticines; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011743:Pyrimidines; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D011993:Recombinant Fusion Proteins; C000606460:TP73 protein, human; D000072160:Tumor Protein p73; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C034192:ellipticine; C402665:CP 31398; D005472:Fluorouracil