Upregulation of the oncogene c-myc in Barrett’s adenocarcinoma: induction of c-myc by acidified bile acid in vitro
- C Tselepis1,
- C D Morris2,
- D Wakelin1,
- R Hardy1,
- I Perry1,
- Q T Luong1,
- E Harper1,
- R Harrison4,
- S E A Attwood3,
- J A Z Jankowski5
- 1Epithelial Laboratory, Division of Medical Sciences, University of Birmingham, UK
- 2Epithelial Laboratory, Division of Medical Sciences, University of Birmingham, UK, and Department of Surgery, Hope Hospital, Manchester, UK
- 3Department of Surgery, Hope Hospital, Manchester, UK
- 4Department of Pathology, University of Birmingham, UK
- 5Digestive Disease Centre, University Department of Medicine and Oncology, Leicester Royal Infirmary, LE1 5WW, UK
- Correspondence to:
Dr C Tselepis, Department of Medicine, University of Birmingham, Vincent Drive, Birmingham B15 2TH, UK;
- Accepted 20 August 2002
Background and aims: C-myc over expression is implicated in malignancy although to date this has not been studied in Barrett’s metaplasia. We sought to determine c-myc expression in the malignant progression of Barrett’s metaplasia and whether it may be induced by bile acids seen in gastro-oesophageal refluxate.
Methods: C-myc protein and mRNA levels were assessed in 20 Barrett’s metaplasia and 20 oesophageal adenocarcinoma samples by western blotting and real time polymerase chain reaction. Levels of c-myc and proliferation were also assessed in cell lines OE21, OE33, SW-480, and TE-7 stimulated with pulses or continuous exposure to the bile acids deoxycholic acid and chenodeoxycholic acid.
Results: C-myc protein was upregulated in 50% of Barrett’s metaplasia and 90% of oesophageal adenocarcinoma samples compared with squamous, gastric, and duodenal controls. C-myc immunolocalisation in Barrett’s metaplasia revealed discrete nuclear localisation, becoming more diffuse with progression from low to high grade dysplasia to adenocarcinoma. Both continual and pulsed bile acid induced c-myc at pH 4, with no effect at pH 7 or with acidified media alone. Pulsed bile acid treatment induced proliferation (p<0.05); in contrast, continuous exposure led to suppression of proliferation (p<0.05).
Conclusions: We have shown upregulation of c-myc with malignant progression of Barrett’s metaplasia and suggest that acidified bile may be a novel agent responsible for induction of this oncogene.
- GORD, gastro-oesophageal reflux disease
- DCA, deoxycholic acid
- CDCA, chenodeoxycholic acid
- PCR, polymerase chain reaction
- Ct, cycle threshold
- ESA, epithelial cell specific antigen