169O - Identification of endoglin (CD105) as an epigenetically regulated candidate tumour suppressor gene in lung cancer

Date 29 September 2012
Event ESMO Congress 2012
Session Biomarkers in lung cancer
Topics Lung and other Thoracic Tumours
Translational Research
Presenter Karen O'Leary
Authors K. O'Leary1, A. Shia1, V. Haley1, F. Cavicchioli1, A. Comino2, P. Vanella3, M. Wischnewsky4, T. Crook5, C. Lo Nigro3, P. Schmid6
  • 1Oncology, Brighton and Sussex Medical School, BN1 9RY - Brighton/UK
  • 2Pathology, S. Croce General Hospital, Cuneo/IT
  • 3Oncology, S. Croce General Hospital, Cuneo/IT
  • 4Escience Lab, University of Bremen, Bremen/DE
  • 5Dundee Cancer Centre, University of Dundee, Dundee/UK
  • 6Medical Oncology, Brighton and Sussex Medical School, BN1 9RY - Brighton/UK

Abstract

Background

The transforming growth factor-beta (TGF-�) pathway is implicated in proliferation, migration, invasion, and metastasis of various cancers. Endoglin, a TGF-� accessory receptor which modulates TGF-� signalling, was identified in a genome-wide methylation screen for candidate tumour suppressors as a novel gene subject to transcriptional silencing in lung cancer. The aim of this project was to investigate whether epigenetic mechanisms play a role in loss of Endoglin expression in lung cancer and secondly, whether this has an impact on clinical outcome.

Methods

Genome-wide methylation analysis was performed using methylation microarrays (Human 450K Methylation BeadChip) and demethylation assays with 5-aza-2-deoxycytidine treatment coupled with mRNA array (Illumina HumanHT12 v4 Expression BeadChip Kit) in lung cancer cell lines. Methylation was validated in a panel of 21 lung cancer cell lines (16 NSCLC, 6 SCLC), a series of 134 surgically resected, stage I or II non-small cell lung cancers and 19 non-malignant lung tissue samples using pyrosequencing and methylation-specific PCR (MSP). To assess the functional consequences of Endoglin methylation in cell lines, expression was silenced by transfection with Endoglin-specific siRNA.

Results

Methylation-dependent transcriptional silencing of Endoglin is a frequent event in lung cancer. Pyrosequencing and MSP analyses demonstrated dense methylation in the CpG island located in the 5' regulatory sequences of the gene in 20/22 lung cancer cell lines. Methylation of Endoglin correlated with absent or down-regulated mRNA and protein expression which could be reactivated by demethylation treatment. Using pyrosequencing, methylation was detected in 54.5% of lung cancer tissues. There was a strong trend for reduced survival in patients with Endoglin methylation (HR 1.44, 95%CI 0.74-2.79). Conclusion: Our data show that Endoglin is a common target of epigenetic silencing in lung cancer and that the resulting loss of expression may be associated with shorter survival. Work is ongoing to elucidate the mechanistic basis for this and to expand our cohort of patients to explore the value of Endoglin as a potential biomarker in lung cancer.

Disclosure

All authors have declared no conflicts of interest.