ABSTRACT
PURPOSE: Identification of serum biomarkers enabling earlier diagnosis of pancreatic ductal adenocarcinoma (PDAC) could improve outcome. Serum protein profiles in patients with preclinical disease and at diagnosis were investigated. EXPERIMENTAL DESIGN: Serum from cases up to 4 years prior to PDAC diagnosis and controls (UKCTOCS,n= 174) were studied, alongside samples from patients diagnosed with PDAC, chronic pancreatitis, benign biliary disease, type 2 diabetes mellitus, and healthy subjects (n= 298). Isobaric tags for relative and absolute quantification (iTRAQ) enabled comparisons of pooled serum from a test set (n= 150). Validation was undertaken using multiple reaction monitoring (MRM) and/or Western blotting in all 472 human samples and samples from a KPC mouse model. RESULTS: iTRAQ identified thrombospondin-1 (TSP-1) as reduced preclinically and in diagnosed samples. MRM confirmed significant reduction in levels of TSP-1 up to 24 months prior to diagnosis. A combination of TSP-1 and CA19-9 gave an AUC of 0.86, significantly outperforming both markers alone (0.69 and 0.77, respectively;P< 0.01). TSP-1 was also decreased in PDAC patients compared with healthy controls (P< 0.05) and patients with benign biliary obstruction (P< 0.01). Low levels of TSP-1 correlated with poorer survival, preclinically (P< 0.05) and at clinical diagnosis (P< 0.02). In PDAC patients, reduced TSP-1 levels were more frequently observed in those with confirmed diabetes mellitus (P< 0.01). Significantly lower levels were also observed in PDAC patients with diabetes compared with individuals with type 2 diabetes mellitus (P= 0.01). CONCLUSIONS: Circulating TSP-1 levels decrease up to 24 months prior to diagnosis of PDAC and significantly enhance the diagnostic performance of CA19-9. The influence of diabetes mellitus on biomarker behavior should be considered in future studies.
Subject(s)
Biomarkers, Tumor , Pancreatic Neoplasms/blood , Pancreatic Neoplasms/diagnosis , Thrombospondin 1/blood , Aged , Animals , Carcinoma, Pancreatic Ductal/blood , Carcinoma, Pancreatic Ductal/complications , Carcinoma, Pancreatic Ductal/diagnosis , Case-Control Studies , Diabetes Mellitus, Type 2/complications , Disease Models, Animal , Early Detection of Cancer , Female , Humans , Male , Mice , Middle Aged , Neoplasm Staging , Pancreatic Neoplasms/complications , Pancreatic Neoplasms/mortality , Patient Outcome Assessment , Platelet Count , Proteomics/methods , Reproducibility of Results , Time FactorsABSTRACT
DNA methylation of polycomb group target (PCGT) genes is an early step in carcinogenesis and could potentially be assayed to determine cancer risk prediction. To assess whether methylation changes in PCGT genes in normal tissue is able to predict the presence of cancer, we studied HOXA gene methylation in normal endometrium from premenopausal ovarian cancer patients and age-matched healthy controls without ovarian cancer. DNA methylation of HOXA9 and HOXA11 genes in normal endometrium was associated with ovarian cancer in an initial test set and this was subsequently confirmed in independent validation sample sets. The overall risk of ovarian cancer was increased 12.3-fold by high HOXA9 methylation for all stages, and 14.8-fold for early stage ovarian cancers, independent of age, phase of the menstrual cycle and histology of the cancer. The results of this proof of principle study demonstrate the potential to detect ovarian cancer via analysis of normal endometrial cells and provide insight into the possible contribution of this novel approach in ovarian cancer risk prediction and prevention.
