Differential Prognostic Relevance of Promoter DNA Methylation of CDO1 and HOPX in Primary Breast Cancer

BACKGROUND/AIM: We previously identified that promoter DNA methylation of cysteine dioxygenase type 1 (CDO1) and homeobox only protein homeobox (HOPX) were both cancer specific, and have a clinical potential as prognostic biomarkers in breast cancer (BC). The present study compared the differential prognostic relevance of methylation status of the CDO1 and HOPX genes in BC. MATERIALS AND METHODS: Methylation levels (TaqMethVs) were quantified in 7 BC cell lines and 133 BC patients by TaqMan methylation-specific PCR and functional traits were explored for CDO1. RESULTS: TaqMethVs were associated between CDO1 and HOPX (r2=0.072, p=0.002). Multivariate Cox proportional hazards model could identify CDO1 hypermethylation as well as Ki-67 as independent prognostic factors related to disease-specific survival (p=0.016, p<0.001). Overexpression of CDO1 decreased the anchorage-independent growth capacity in BC cell lines. CONCLUSION: CDO1 is a definite tumor suppressor gene, while its prognostic relevance was more than expected in the context of its functional relevance.