title: Loss of glutathione S-transferase (GST) mu phenotype in colorectal adenocarcinomas from patients with a GSTM1 positive genotype.
abstract: Glutathione S-transferase (GST) mu phenotype was assessed in colon tissue from patients with ulcerative colitis and colorectal neoplasms that were positive for GSTM1 genotype. GST mu protein (enzyme linked immunosorbent assay) was absent in 2/9 unaffected colon tissue (22.3%), 4/13 tissues with chronic ulcerative colitis (CUC) (30.7%), 4/11 adenomas (36.4%) and 7/14 adenocarcinomas (50.0%; P<or=0.05). GST-3H-trans-stilbene oxide activity was detected in all tissues except 1/13 (7.6%) CUC tissues and 7/14 (50.0%, P<or=0.05) colorectal adenocarcinomas. Immunoreactive GST mu was observed in colonic epithelial cells but not in adjacent neoplastic cells by immunohistochemistry. Two-dimensional electrophoresis revealed several mu class isoforms in cytosol from unaffected colon that were absent in matched tumor cytosol. These results indicate that GSTM1 genotype may not necessarily reflect GST mu phenotype in colorectal tumors.
authors.affiliation: Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada, N1G 2W1.
authors.forename: Heather J
authors.initials: HJ
authors.lastname: Barker
authors.forename: Lesley C
authors.initials: LC
authors.lastname: Alpert
authors.forename: Carolyn C
authors.initials: CC
authors.lastname: Compton
authors.forename: Ann
authors.initials: A
authors.lastname: Maslen
authors.forename: Gordon M
authors.initials: GM
authors.lastname: Kirby
mesh_terms: D000230:Adenocarcinoma / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D000236:Adenoma / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D014408:Biomarkers, Tumor; D015153:Blotting, Western; D003093:Colitis, Ulcerative / Q000201:enzymology / Q000235:genetics; D015179:Colorectal Neoplasms / Q000201:enzymology* / Q000235:genetics; D004247:DNA / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D015180:Electrophoresis, Gel, Two-Dimensional; D004797:Enzyme-Linked Immunosorbent Assay; D005838:Genotype; D005982:Glutathione Transferase / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D010641:Phenotype; D016133:Polymerase Chain Reaction
chemical_list: D014408:Biomarkers, Tumor; D004247:DNA; D017931:DNA Primers; D005982:Glutathione Transferase