In vitro development and validation of a non-invasive 13C-stable isotope assay for ornithine decarboxylase

Simone Jaenisch, Michelle Squire, Ross Butler, Roger Yazbeck

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    2 Citations (Scopus)


    Oesophageal cancer is a significant cause of cancer related mortality, with increasing incidence worldwide. Ornithine decarboxylase (ODC) is an enzyme involved in polyamine synthesis and cellular proliferation, and ODC expression and activity has been implicated as a prognostic marker of oesophageal cancer. This study aimed to develop and optimise an in vitro 13C-stable isotope assay for ODC activity as a non-invasive marker of oesophageal cancer. Experiments were performed in triplicate (n = 3/group/cell line) using Caco2, HeLa, Flo-1, OE33, TE7 and OE21 cell lines (colorectal, cervical, oesophageal adenocarcinoma and oesophageal squamous carcinoma respectively). Following addition of 2mM 13C-ornithine to cells, 10 ml gas samples were collected from the headspace every 20 min for a total of five hours. Gas samples were analysed using isotope ratio mass spectrometry to quantify 13CO2. Assay specificity was determined using the selective ODC inhibitor, N-(4′-Pyridoxil)-Ornithine(BOC)-OMe (POB). All data is expressed as δ 13CO2 from baseline. High ODC activity was detected by 13C-ornithine assay in Caco2 (32.00 ±< 1.12 δ 13CO2) in contrast to HeLa cells (5.44 ± 0.14 δ 13CO2) cells. POB inhibited activity in Caco2 cells to 12.87 ± 1.10 δ 13CO2. Differential ODC activity was detected in all oesophageal cancer cells, and 53 h incubation of cell lines with POB reduced activity by 72%, 56%, 64% and 69% in the Flo-1, OE33, OE21 and TE7 cell lines respectively. We have shown that ODC activity can be selectively detected by a non-invasive, stable-isotope 13C-ornithine assay. ODC activity was detected in all oesophageal cancer cell lines in vitro. Further studies are indicated to quantify ODC activity in oesophageal cancer patients.

    Original languageEnglish
    Article number026009
    Number of pages9
    JournalJournal of Breath Research
    Issue number2
    Publication statusPublished - 3 May 2016


    • breath test
    • cancer
    • headspace
    • oesophageal cancer
    • ornithine decarboxylase
    • stable isotope


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