title: Increased sensitivity of glioma cells to 5-fluorocytosine following photo-chemical internalization enhanced nonviral transfection of the cytosine deaminase suicide gene.
abstract: Despite advances in surgery, chemotherapy and radiotherapy, the outcomes of patients with GBM have not significantly improved. Tumor recurrence in the resection margins occurs in more than 80% of cases indicating aggressive treatment modalities, such as gene therapy are warranted. We have examined photochemical internalization (PCI) as a method for the non-viral transfection of the cytosine deaminase (CD) suicide gene into glioma cells. The CD gene encodes an enzyme that can convert the nontoxic antifungal agent, 5-fluorocytosine, into the chemotherapeutic drug, 5-fluorouracil. Multicell tumor spheroids derived from established rat and human glioma cell lines were used as in vitro tumor models. Plasmids containing either the CD gene alone or together with the uracil phosphoribosyl transferase (UPRT) gene combined with the gene carrier protamine sulfate were employed in all experiments.PCI was performed with the photosensitizer AlPcS2a and 670 nm laser irradiance. Protamine sulfate/CD DNA polyplexes proved nontoxic but inefficient transfection agents due to endosomal entrapment. In contrast, PCI mediated CD gene transfection resulted in a significant inhibition of spheroid growth in the presence of, but not in the absence of, 5-FC. Repetitive PCI induced transfection was more efficient at low CD plasmid concentration than single treatment. The results clearly indicate that AlPcS2a-mediated PCI can be used to enhance transfection of a tumor suicide gene such as CD, in malignant glioma cells and cells transfected with both the CD and UPRT genes had a pronounced bystander effect.
authors.affiliation: Beckman Laser Institute and Medical Clinic, University of California Irvine, 1002 Health Sciences Rd, Irvine, CA, 92617, USA, frederick.wang.ix@gmail.com.
authors.forename: Frederick
authors.initials: F
authors.lastname: Wang
authors.forename: Genesis
authors.initials: G
authors.lastname: Zamora
authors.forename: Chung-Ho
authors.initials: CH
authors.lastname: Sun
authors.forename: Anthony
authors.initials: A
authors.lastname: Trinidad
authors.forename: Changho
authors.initials: C
authors.lastname: Chun
authors.forename: Young Jik
authors.initials: YJ
authors.lastname: Kwon
authors.forename: Kristian
authors.initials: K
authors.lastname: Berg
authors.forename: Steen J
authors.initials: SJ
authors.lastname: Madsen
authors.forename: Henry
authors.initials: H
authors.lastname: Hirschberg
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor / Q000187:drug effects; D043525:Cytosine Deaminase / Q000235:genetics* / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005437:Flucytosine / Q000494:pharmacology*; D005910:Glioma / Q000473:pathology; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D009942:Organometallic Compounds / Q000494:pharmacology; D010430:Pentosyltransferases / Q000235:genetics / Q000378:metabolism; D055668:Photochemical Processes / Q000187:drug effects; D017319:Photosensitizing Agents / Q000494:pharmacology; D014162:Transfection
chemical_list: D000935:Antifungal Agents; D007211:Indoles; D009942:Organometallic Compounds; D017319:Photosensitizing Agents; C064331:aluminum phthalocyanine disulfonate; D005437:Flucytosine; D010430:Pentosyltransferases; C023269:uracil phosphoribosyltransferase; D043525:Cytosine Deaminase