title: Label-free detection of telomerase activity using guanine electrochemical oxidation signal.
abstract: Telomerase is an important biomarker for cancer cells and its activation in 85% of all cancer types confers a clinical diagnostic value. A label-free electrochemical assay based on guanine oxidation signal to measure telomerase activity is described. This developed technology combined with a disposable sensor, carbon graphite electrode (CGE), and differential pulse voltammetry (DPV) was performed by using PCR amplicons with/without telomeric repeats as the guanine oxidation signal observed at +1.0 V measured after the immobilization of PCR products. Guanine oxidation signal was chosen as a measure of telomerase activity because a substantial increase in the number of guanines was introduced by the action of telomerase which adds hexameric repeats (TTAGGG)n that contain 50% guanine. The developed assay was shown to specifically measure telomerase activity from cell extracts, and elongation rates increased linearly in a concentration dependent manner. Telomerase activity could be detected in cell extracts containing as low as 100 ng/microL of protein. All of the electrochemical measurements were also confirmed with the conventional TRAP-silver staining assay. Rapidity, simplicity, and the label-free nature of the developed assay make it suitable for practical use in quantitative determination of telomerase activity from clinical samples for diagnosis of cancer.
authors.affiliation: Department of Biological Sciences, Middle East Technical University, 06531 Ankara, Turkey.
authors.forename: Ugur
authors.initials: U
authors.lastname: Eskiocak
authors.forename: Dilsat
authors.initials: D
authors.lastname: Ozkan-Ariksoysal
authors.forename: Mehmet
authors.initials: M
authors.lastname: Ozsoz
authors.forename: Huseyin Avni
authors.initials: HA
authors.lastname: Oktem
mesh_terms: D004563:Electrochemistry; D006147:Guanine / Q000737:chemistry* / Q000378:metabolism*; D010084:Oxidation-Reduction; D019098:Telomerase / Q000032:analysis* / Q000378:metabolism*
chemical_list: D006147:Guanine; D019098:Telomerase