A noninvasive cancer detection strategy based on gold nanoparticle surface-enhanced raman spectroscopy of urinary modified nucleosides isolated by affinity chromatography.

The search for tumor biomarkers in the urine for cancer diagnosis is currently a hot topic in clinical oncology, with potential for cancer screening and diagnosis. Modified nucleosides excreted through the urine are considered to be a general tumor marker for various cancer types. Herein, we explore a new method that utilizes surface-enhanced Raman scattering (SERS) spectroscopy to obtain a complete biochemical profile of urinary modified nucleosides. In our method, modified nucleosides are first isolated from urine sample utilizing the excellent separation ability of affinity chromatography; then supplemented with gold (Au) nanoparticles as substrate for SERS spectroscopy analysis. The obtained SERS spectra present rich diagnostic and fingerprinting type signatures of urinary modified nucleosides. The utility of this new method in cancer detection was evaluated by analyzing urine samples from three groups of subjects: nasopharyngeal cancer patients (n=62), esophageal cancer patients (n=55), and healthy volunteers (n=52). Partial least squares and linear discriminant analysis (PLS-DA) were used to analyze and classify the SERS spectra of urinary modified nucleosides from nasopharyngeal cancer, esophageal cancer, and the normal group, achieving diagnostic sensitivities of 95.2%, 90.9% and 98.1% and specificities of 97.2%, 98.2% and 95.7%, respectively. These results demonstrated great potential of this novel method for non-invasive and label-free cancer detection and screening.

Does radiotherapy increase oxidative stress? A study with nasopharyngeal cancer patients revealing anomalies in isoprostanes measurements.

This study aimed to examine if exposure to ionizing radiation during clinical radiotherapy (RT) causes increased oxidative damage. Seven patients with nasopharyngeal cancer (NPC) who underwent RT took part in this controlled-trial study. Blood and urine samples were obtained for F(2)-isoprostanes (F(2)-IsoPs) measurement. Urinary F(2)-IsoPs levels were elevated pre-treatment and remained high (but did not increase) during treatment, but decreased to the normal range after treatment. Plasma F(2)-IsoPs decreased significantly after the start of treatment before rising midway through treatment. Levels decreased significantly to below baseline following treatment. However, the patients were observed to have substantially lower levels of plasma esterified arachidonic acid (AA) residues than controls. The data shows that NPC is associated with elevated F(2)-isoprostanes in urine and in plasma after correction for decreased AA levels. RT did not increase these levels and, indeed, was associated with falls in F(2)-IsoPs. The validity and usefulness of correction of plasma F(2)-IsoPs for lowered AA levels is discussed.

Quantitative analysis of the transrenal excretion of circulating EBV DNA in nasopharyngeal carcinoma patients.

PURPOSE: The existence of transrenal clearance of circulating cell-free DNA is controversial. In this study, we used NPC as a model to investigate if circulating EBV DNA can be excreted into urine and to quantify the contribution of renal excretion to the clearance of plasma EBV DNA. EXPERIMENTAL DESIGN: Quantitative analysis of urine EBV DNA was done for 74 NPC patients using real-time PCR with two different amplicon sizes. The urine concentration of EBV DNA was expressed as copies per millimole of creatinine (copies/mmol Cr) to minimize the effects of interindividual variations in hydration status. RESULTS: EBV DNA was detectable in the urine of 56% NPC patients using a 59-bp real-time PCR assay. The median urine EBV DNA concentrations measured by the 59- and 76-bp assays were 7,040 and 290 copies/mmol Cr, respectively. Patients with detectable urine EBV DNA had significantly higher plasma concentrations, with a positive correlation between the plasma and urine concentrations of EBV DNA. The fraction of plasma EBV DNA excreted into the urine was 0.0026% of that for creatinine. CONCLUSIONS: We have shown that circulating EBV DNA can be excreted transrenally into urine in NPC patient and the fraction of excretion is negatively associated with the size of the DNA molecules. Because there is a positive correlation between plasma and urine EBV DNA concentration, urine EBV DNA analysis may potentially be applicable as an ultra-noninvasive test for the monitoring and prognostication of NPC patients.

Urinary excretion of nitrosamino acids and nitrate by inhabitants of high- and low-risk areas for nasopharyngeal carcinoma in southern China.

The hypothesis that endogenous synthesis of nitrosamines from dietary precursors is a risk factor for nasopharyngeal carcinoma (NPC) in China was tested by applying the nitrosoproline (NPRO) test to subjects living in high- and low-risk districts for NPC in Zangwu county, Guangxi region, in southern China. Samples of 12-h urine were collected from 77 subjects: (a) before any treatment; (b) after ingestion of proline; and (c) after ingestion of proline together with vitamin C. NPRO, other nitrosamino acids, and nitrate were measured as indices of exposure to preformed and endogenously formed nitrosamines or their precursors. The NPRO level after proline intake was significantly increased in subjects from the high-risk area (P = 0.012) and markedly reduced after ingestion of ascorbic acid (P = 0.007), but such an effect was not seen in subjects from the low-risk area. Levels of N-nitrosothiazolidine-4-carboxylic acid and the sum of nitrosamino acids in subjects in the high-risk area were significantly reduced by ascorbic acid (P < 0.01) but were not reduced in subjects from the low-risk area. The urinary nitrate level was about twice as high in subjects from the high-risk area. In subjects from high- and low-risk areas combined, NPRO levels in any of the three dose groups were highly correlated with nitrate levels (P = 0.0001). These results demonstrate a higher potential for endogenous nitrosation in subjects living in the high-risk area of NPC and suggest the occurrence of nitrosation inhibitors in the diet consumed in the low-risk area.(ABSTRACT TRUNCATED AT 250 WORDS)

[Evaluation of urinary polyamines in patients with nasopharyngeal carcinoma].

A new and simple enzymatic assay utilizing an acylpolyamine amidohydrolase and putrescine oxidase was adopted for measuring urinary polyamines (U-Pa). Serum carcinoembryonic antigen (S-CEA) was determined for comparison. The study population consisted of patients with pathologically proven nasopharyngeal carcinoma (NPC) who were referred to Kaohsiung Medical College Hospital. We found that polyamine levels were markedly elevated during radiotherapy but declined when the treatment was completed. Thus mean polyamines and the positive rate of polyamine elevation was higher in patients suffering from an active stage of the disease than in patients whose cancer had stabilized. However, the level of carcinoembryonic antigen was not elevated whilst undergoing radiotherapy. Therefore, routine measurement of polyamine levels may have a clinical utility in monitoring the disease state of the tumor. However, the low sensitivity of U-Pa test (22%) precludes its use as an effective screening method for this condition. Nevertheless, because of its simplicity, convenience and rapidity for monitoring NPC, U-Pa test should be considered a valuable tool in the clinical investigation of NPC patients.