title: In vitro induction of PDT resistance in HT29, HT1376 and SK-N-MC cells by various photosensitizers.
abstract: Our approach to examine the mechanism(s) of action for photodynamic therapy (PDT) has been via the generation of PDT-resistant cell lines. In this study we used three human cell lines, namely, human colon adenocarcinoma (HT29), human bladder carcinoma and human neuroblastoma. The three photosensitizers used were Photofrin, Nile Blue A and aluminum phthalocyanine tetrasulfonate. The protocol for inducing resistance consisted of repeated in vitro photodynamic treatments with a photosensitizer to the 1-10%-survival level followed by regrowth of single surviving colonies. Varying degrees of resistance were observed. The three induced variants of the HT29 cell line were the most extensively studied. Their ratios of increased survival at the LD90 level range between 1.5- and 2.62-fold more resistant.
authors: Hamilton Regional Cancer Center, 699 Concession Street, Hamilton, Ontario, Canada L8V 5C2. gurmit.singh@hrcc.on.ca
authors: G
authors: G
authors: Singh
authors: M
authors: M
authors: Espiritu
authors: X Y
authors: XY
authors: Shen
authors: J G
authors: JG
authors: Hanlon
authors: A J
authors: AJ
authors: Rainbow
mesh_terms: D002470:Cell Survival / Q000187:drug effects; D004351:Drug Resistance; D019073:HT29 Cells; D006801:Humans; D018462:Photobiology; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D014410:Tumor Stem Cell Assay
chemical_list: D017319:Photosensitizing Agents