ABSTRACT
BACKGROUND: Cell-free serum DNA levels are increased in patients with cancer, and at least partially, these DNA fragments are derived from cancer cells. A few reports indicated that methylated serum DNA in patients with bladder cancer (BCA) is a useful non-invasive biomarker. The purpose of this prospective multicenter study was to validate earlier studies. MATERIALS AND METHODS: In total, 227 consecutive participants (non-muscle invasive BCA, n=75; muscle-invasive BCA, n=20; transurethral bladder resection (TURB) without BCA, n=48; benign disease, n=31; healthy individuals, n=53), were recruited for this study. Cell-free serum DNA was isolated and digested with methylation-sensitive restriction-enzymes (Bsh1236I, HpaII and HinP1I) to quantify the amount of methylated (TIMP3, APC, RARB, TIG1, GSTP1, p14, p16, PTGS2 and RASSF1A) DNA fragments. RESULTS: The amount of methylated DNA was usually small (<10%), and the methylation frequencies varied for different genes (e.g. frequent: TIMP3; moderate: APC, RARB, TIG1; infrequent: p16, PTGS2, p14, RASSF1A, GSTP1). Methylation levels at each gene site and the number of methylated genes were increased in BCA compared to healthy individuals, but were similar in BCA and patients with non-malignant disease. The number of methylated genes allowed for discrimination (62% sensitivity, 89% specificity) of BCA patients from healthy individuals. DNA hypermethylation was not correlated with advanced stage or grade in patients with BCA. CONCLUSION: The detection of hypermethylated DNA in serum allows for discrimination of patients with BCA and healthy individuals, but there is no difference between patients with BCA and those with non-malignant disease, thereby limiting its value as a non-invasive biomarker.
Subject(s)
DNA Methylation , DNA/blood , Urinary Bladder Neoplasms/genetics , Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Prospective Studies , Urinary Bladder Neoplasms/blood , Urinary Bladder Neoplasms/pathologyABSTRACT
BACKGROUND/AIM: Cell-free DNA may serve as a biomarker for patients with cancer; we designed our study to determine its potential in patients with bladder cancer (BCA). MATERIALS AND METHODS: Short ß-actin (ACTB)-106 and large ACTB-384 fragments were quantified using real time PCR (RT-PCR); the ratio of ACTB-384/ACTB-106 was defined as DNA integrity. We analyzed the serum from 95 patients with and from 132 without BCA. RESULTS: Patients with BCA had increased ACTB-106 levels and lower DNA integrity compared to patients without cancer. However, patients undergoing transurethral bladder resection (TURB) with histological exclusion of BCA had a similar ACTB-106 level and DNA integrity, as patients with BCA. Cell-free DNA was not correlated with smoker status, pT stage, grade or lymph node metastasis, or DNA integrity. There was a weak inverse correlation of age with DNA integrity in patients with BCA. CONCLUSION: Analysis of serum cell-free DNA levels and fragmentation patterns are of limited value regarding the identification of patients with BCA.
