Oxidative stress increases frameshift mutations in human colorectal cancer cells

• Published in: Cancer research (Chicago, Ill.) Vol. 61; no. 20; pp. 7444 - 7448
• Main Authors: GASCHE, Christoph, CHANG, Christina L, RHEES, Jennifer, GOEL, Ajay, BOLAND, C. Richard
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 15.10.2001
• Subjects: Base Pair Mismatch; Biological and medical sciences; Cell metabolism, cell oxidation; Cell physiology; Cell Survival - physiology; Colorectal Neoplasms - genetics; Colorectal Neoplasms - metabolism; DNA Repair; Dose-Response Relationship, Drug; Flow Cytometry; Frameshift Mutation; Fundamental and applied biological sciences. Psychology; Humans; Hydrogen Peroxide - pharmacology; Microsatellite Repeats - drug effects; Microsatellite Repeats - genetics; Molecular and cellular biology; Oxidative Stress - genetics; Tumor Cells, Cultured; Human; Oxidative stress; Rectal disease; Toxicity; Frameshift mutation; Malignant tumor; Mutagen; In vitro; Free radical; Colonic disease; Carcinogen; Base mismatching; Microsatellite DNA; Established cell line; Rectum; Digestive diseases; Intestinal disease; Instability; Colon; Lesion; Mechanism of action; Repair; Tumor cell
• ISSN: 0008-5472; 1538-7445

Chronic inflammation in the gastrointestinal tract increases the risk for development of cancer by an incompletely understood pathway, which may involve microsatellite instability (MSI). Low frequency of MSI referred to as "MSI-L" occurs frequently in chronically inflamed nonneoplastic tissue. In this work, we have tested the hypothesis that oxidative stress may induce the accumulation of frameshift mutations in human microsatellite DNA. Mismatch repair (MMR)-proficient HCT116+chr3 and MMR-deficient HCT116 cells were transfected with pCMV-(CA)13-EGFP, a plasmid that contains a (CA)13 dinucleotide repeat, which disrupts the reading frame of the downstream enhanced green fluorescent protein gene. A dose-dependent increase in frameshift mutations restoring the enhanced green fluorescent protein reading frame was detected in HCT116 by flow cytometry. At 1 mM H2O2, the mutant fraction was 9-fold higher than that in mock-treated control cells. Although demonstrating stability at lower H2O2 concentrations, MMR-proficient HCT116+chr3 cells accumulated mutations at the 1 mM H2O2 level (4.1-fold above mock-treated control). No significant mutations were detected when HCT116 cells were transfected with the pCMV-(N)26-EGFP construct that contains 26 nucleotides in a random sequence. These data indicate that oxidative stress is a potential mutagen leading to accumulation of frameshift mutations and may contribute to MSI in the setting of chronic inflammation.